Tropical Storm Dorian

Hurricane Dorian Track 1100 Hours September 7 2019
Hurricane Dorian Track 1100 Hours September 7 2019

Hurricane Dorian Satellite 0800 Hours September 7 2019NWS National Hurricane Center Miami FL 1100 AM AST Sat Sep 07 2019

Satellite imagery this morning indicates that Dorian (see Saturday video below) is starting extratropical transition, with cold air clouds entraining into the southwestern side of the cyclone and a developing warm front to the north and east. However, the cyclone still has persistent convection just north and northeast of the center, so it remains a hurricane on this advisory. NOAA buoy 44011 reported a minimum pressure of 955.3 mb as the center passed just to the west, so the initial central pressure is lowered to 953 mb. The initial intensity remains 75 kt based partly on recently-received WindSat data showing hurricane-force winds southwest of the center.

Dorian continues to move rapidly northeastward with an initial motion of 040/25 kt. The current motion should bring the center of Dorian over central and eastern Nova Scotia in about 12 h and near or over Prince Edward Island shortly thereafter. Subsequently, Dorian is forecast to move near or through northern Newfoundland and southeastern Labrador before turning east-northeastward over the far north Atlantic. There are no significant changes to the previous forecast, and the new forecast is again close to the various consensus aids.

Dorian is expected to complete extratropical transition during the next 24 h as it merges with a strong mid- to upper-level trough and associated surface frontal zone. The global models agree on a gradual decay of the winds after transition is complete. However, the cyclone will likely still be producing hurricane-force winds as it moves through portions of eastern Canada. The global models also agree that the post-tropical cyclone should become absorbed by another extratropical low in 2-3 days. The NHC intensity forecast again leans towards the GFS and ECMWF models, which typically handle large extratropical lows better that than the intensity models that are made for tropical cyclones.

Key Messages:

  • 1. Regardless of whether it is a hurricane or a post-tropical cyclone, Dorian is expected to have a significant impact in portions of eastern Canada beginning during the next several hours. Dangerous storm surge impacts are likely in portions of the Gulf of St. Lawrence, southwestern Newfoundland and eastern Nova Scotia. Hurricane-force winds are also likely in Nova Scotia, Prince Edward Island and Newfoundland later today and tonight. Refer to information from the Canadian Hurricane Centre for more information on these hazards.
FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 42.0N  66.0W   75 KT  85 MPH - Category 1 (ESE Provincetown, MA)
 12H  08/0000Z 45.1N  63.0W   70 KT  80 MPH - Category 1 (ESE Greenwood, Nova Scotia)
 24H  08/1200Z 48.9N  59.7W   65 KT  75 MPH - Category 1 (WsW Rocky Harbour, Newfoundland)
 36H  09/0000Z 51.7N  54.6W   55 KT  65 MPH - Tropical Storm (ESE Belle Isle, Newfoundland )
 48H  09/1200Z 54.2N  47.8W   45 KT  50 MPH - Tropical Storm (ESE ESE Prins Christianssund, Greenland)
 72H  10/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Fri Sep 06 2019

During the past couple of hours, Dorian’s eye has become no longer apparent in conventional satellite imagery. Microwave data shows an eye-like feature just to the south of the convection, and also indicates that the hurricane is becoming asymmetric. The lack of symmetry is the first indication or hint that Dorian is slowly beginning to acquire some extratropical characteristics. The rain shield is now placed to the northwest of the center, and the wind field is expanding in the southern semicircle. Dvorak numbers are either steady or have decreased slightly, and consequently, the initial intensity is kept at 80 kt in this advisory.

The hurricane is rapidly reaching cooler waters and guidance shows an area of significantly strong shear along the forecast path of Dorian. Given these conditions, the NHC forecast calls for gradual weakening, but Dorian is still expected to make landfall in Nova Scotia with hurricane intensity late Saturday. Dorian is forecast to complete its transition to extratropical once it crosses Nova Scotia.

The hurricane is racing northeastward or 045 degrees at 22 kt. Since Dorian is already embedded within a fast southwesterly flow ahead of a mid-latitude trough, the current northeast heading should continue until dissipation occurs in about 3 days, if not sooner. The track guidance is in remarkably good agreement, and the NHC forecast is in the middle of the guidance envelope, increasing the confidence in the track forecast.

Key Messages:

1. Regardless of whether it is a hurricane or a post-tropical cyclone, Dorian is expected to have a significant impact in portions of eastern Canada. Dangerous storm surge impacts are likely in portions of the Gulf of St. Lawrence, southwestern Newfoundland and eastern Nova Scotia this weekend. Hurricane-force winds are also likely in Nova Scotia, Prince Edward Island and possibly Newfoundland Saturday and Sunday. Refer to information from the Canadian Hurricane Centre for more information on these hazards.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 38.3N  70.2W   80 KT  90 MPH - Category 1 (ESE Ocean City, MD)
 12H  07/1200Z 40.8N  66.9W   75 KT  85 MPH - Category 1 (ESE Nantucket, MA)
 24H  08/0000Z 45.0N  63.0W   70 KT  80 MPH - Category 1 (WSW Caribou Mines, Nova Scotia)
 36H  08/1200Z 49.0N  59.5W   55 KT  65 MPH - Tropical Storm (WSW Corner Brook, Newfoundland)
 48H  09/0000Z 52.0N  55.0W   40 KT  45 MPH - Tropical Storm (ESE Battle Harbour, Labrador)
 72H  10/0000Z 56.0N  41.0W   40 KT  45 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)
 96H  11/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Fri Sep 06 2019

The eye of Dorian made landfall over Cape Hatteras, North Carolina, at about 1235 UTC and then moved quickly northeastward into the Atlantic. A combination of surface observations and Air Force Reserve Hurricane Hunter aircraft data indicate that the maximum winds are near 80 kt and the central pressure is near 957 mb. The hurricane remains well-organized in satellite imagery, with the 30 n mi wide eye surrounded by cold convective banding.

The initial motion is now 045/15. Dorian should accelerate northeastward during the next 24-36 h as a mid- to upper-level trough, currently over the U.S. Great Lakes, approaches the system and accelerates the steering flow. The track guidance remains tightly clustered, and the new track forecast is changed little in either direction or speed from the previous forecast.

The new forecast calls for Dorian to move away from the North Carolina coast today, pass well southeast of southern New England tonight and Saturday, and then move over Nova Scotia Saturday or Saturday night. A continued northeastward motion is then expected to bring the cyclone across Newfoundland into the far north Atlantic. Dorian is expected to slowly weaken due to increased shear and entrainment of drier air during the next 24 h or so. After that time, the hurricane is expected to undergo extratropical transition and become a large and powerful post-tropical low.

It is unclear whether the transition will be complete before Dorian reaches Nova Scotia. However, whether Dorian is a hurricane or a hurricane-force extratropical low, it is expected to bring strong winds, storm surge, and heavy rains to portions of Nova Scotia and Newfoundland. The new NHC intensity forecast is little changed from the previous forecast, and it follows the trend of the intensity guidance.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds will continue along portions of the North Carolina coast, portions of southeast Virginia and the southern Chesapeake Bay for the next several hours.
  • 2. Areas of flash flooding, some of which may be significant and life-threatening, will continue into early afternoon across portions of northeastern North Carolina into far southeast Virginia.
  • 3. Dangerous storm surge impacts are likely in portions of the Gulf of St. Lawrence, southwestern Newfoundland and eastern Nova Scotia this weekend. Hurricane-force winds are also likely in Nova Scotia, Prince Edward Island and possibly Newfoundland Saturday and Sunday. Refer to information from the Canadian Hurricane Centre for more information on these hazards.
FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 35.7N  74.8W   80 KT  90 MPH - Category 1 (ESE Nags Head, NC)
 12H  07/0000Z 37.4N  72.2W   80 KT  90 MPH - Category 1 (ESE Ocean City, MD)
 24H  07/1200Z 40.7N  67.7W   75 KT  85 MPH - Category 1 (WSW Nantucket, MA)
 36H  08/0000Z 44.9N  63.5W   70 KT  80 MPH - Category 1 (WNW Goffs, Nova Scotia,)
 48H  08/1200Z 48.8N  60.0W   60 KT  70 MPH - Tropical Storm (WSW Lourdes, Newfoundland)
 72H  09/1200Z 54.5N  48.0W   45 KT  50 MPH - Tropical Storm (WNW Cartwright, Newfoundland )
 96H  10/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 AM EDT Fri Sep 06 2019

The center of the eye of Hurricane Dorian is located just off the coast of North Carolina not far from Cape Lookout. Based on data from the Air Force Hurricane Hunters and Doppler radar velocities, the initial intensity is set at 80 kt. This estimate is a compromise between the flight-level winds and SFMR values. The minimum pressure remains quite low, 956 mb, based on surface observations and aircraft fixes. There have been several reports in eastern North Carolina of sustained tropical-storm-force winds and hurricane-force gusts, with the strongest winds being reported in the northern eyewall.

Dorian is moving northeastward at 12 kt. A faster northeastward motion is expected during the next few days as a mid- to upper-level trough, currently over the U.S. Great Lakes, approaches the system and accelerates the steering flow. This track forecast takes the hurricane along the coast of North Carolina during the next several hours and near or over Atlantic Canada this weekend. The models are tightly clustered, and the NHC track forecast lies near the middle of the guidance envelope.

The hurricane is expected to gradually weaken during the next couple of days due to an increase in wind shear and drier air. Dorian is expected to cross the north wall of the Gulf Stream current in about 36 hours, and head over much colder waters after that. These atmospheric and oceanic conditions should cause the cyclone to become a powerful hurricane-force extratropical in about 2 days. As the system gains latitude, the tropical-storm-force winds are expected to expand significantly. The NHC intensity forecast is largely an update of the previous one and in line with the various consensus aids.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected to continue along portions of the North Carolina coast, portions of southeast Virginia and the southern Chesapeake Bay. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding is occurring, and will continue to become more widespread across the eastern Carolinas and far southeast Virginia this morning. There is a high risk of flash flooding over these areas, where significant, life-threatening flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  06/0900Z 34.6N  76.2W   80 KT  90 MPH - Category 1 (ENE Cape Lookout, NC)
 12H  06/1800Z 36.0N  74.1W   75 KT  85 MPH - Category 1 (ESE Kill Devil Hills, NC)
 24H  07/0600Z 38.8N  69.9W   75 KT  85 MPH - Category 1 (ESE Atlantic City, NJ)
 36H  07/1800Z 42.5N  65.4W   70 KT  80 MPH - Category 1 (ESE Shelburne, Nova Scotia)
 48H  08/0600Z 46.7N  61.6W   60 KT  70 MPH - Tropical Storm (ESE Pleasant Bay, Nova Scotia)
 72H  09/0600Z 53.0N  52.0W   45 KT  50 MPH - Tropical Storm (ESE Black Tickle, Newfoundland)
 96H  10/0600Z 58.0N  36.0W   40 KT  45 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)
120H  11/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Thu Sep 05 2019

Hurricane Dorian Moves Through Carolinas  – SHELTER IN PLACE! 

Data from NOAA and Air Force Hurricane Hunter planes and surface data nearby Hurricane Dorian indicate that although the central pressure is a little bit lower, and NOAA Doppler weather radar data from Wilmington and Morehead City indicate that winds have decreased as the circulation of the hurricane expands. The initial intensity is now estimated to be 85 kt.

Dorian is moving toward higher shear, and gradual weakening is anticipated. As indicated in the previous forecast, the extratropical transition should begin in about 48 hours and be complete by 72 hours. However, Dorian is forecast to maintain hurricane-force-winds while moving near or over Nova Scotia.

The initial motion is 045 degrees at 11 kt. The hurricane is already embedded in the southwesterly flow ahead of an eastward-moving mid-latitude trough. This flow pattern should steer the hurricane on a northeastward track with increasing forward speed. Track guidance continues to be in remarkably good agreement with this solution, and the NHC forecast remains in the middle of the guidance envelope. The current forecast track is very similar to the previous advisory.

The center of Dorian is expected to move very near or over the coastline of eastern North Carolina and the southern Mid-Atlantic states during the next day or so. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains. It also appears that Dorian will affect portions of eastern Canada with hurricane-force winds.

Key Messages:

  • 1. Regardless of the exact track of Dorian’s core, life-threatening storm surge and dangerous winds are expected along portions of the North Carolina coast, portions of southeast Virginia and the southern Chesapeake Bay. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding is occurring and will continue to become more widespread across the eastern Carolinas and far southeast Virginia overnight. There is a high risk of flash flooding over these areas, where significant, life-threatening flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 33.8N  77.4W   85 KT 100 MPH - Category 2 (ESE Bald Head Island, NC)
 12H  06/1200Z 35.0N  75.8W   80 KT  90 MPH - Category 1 (ESE Hatteras, NC)
 24H  07/0000Z 37.2N  72.2W   80 KT  90 MPH - Category 1 (ENE Virginia Beach, NC)
 36H  07/1200Z 40.2N  67.7W   75 KT  85 MPH - Category 1 (ENE New York City, NY)
 48H  08/0000Z 44.5N  63.0W   70 KT  80 MPH - Category 1 (ESE Little Harbour, Nova Scotia)
 72H  09/0000Z 52.5N  55.0W   45 KT  50 MPH - Tropical Storm (ESE Williams Harbor, Newfoundland and Labrador )
 96H  10/0000Z 57.5N  40.0W   40 KT  45 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)
120H  11/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM EDT Thu Sep 05 2019

Hurricane Dorian Moves Toward Carolinas  – SHELTER IN PLACE! 

During the last 12 h, Dorian appears to have started the expected slow weakening trend. Air Force Reserve Hurricane Hunter data show that the central pressure inside the 35-45 n mi wide eye is slowly rising, and satellite imagery indicates that the eye is becoming less well defined. The current Hurricane Hunter aircraft has reported maximum SFMR surface wind estimates of 88 kt, along with 700 mb flight-level winds of 91 kt. Based on these data, the initial intensity is reduced to 90 kt.

The hurricane is continuing its expected northeastward turn, and the initial motion is now 035/9. The mid-latitude westerlies should steer Dorian generally northeastward at an increasing forward speed, with the eye passing near of over portions of the North Carolina coast during the next 12-24 h. After that, Dorian is forecast to move quickly across the northwest Atlantic and be near or over the Canadian Maritimes/Atlantic provinces by 60 h. As was the case in the previous advisory, the track guidance remains tightly clustered, and the new forecast track is changed little from the previous one. Due to increasing shear, Dorian is forecast to slowly weaken as it moves near and along the South and North Carolina coasts.

The extratropical transition should begin around 36-48 h and be complete by 60 h, although Dorian is forecast to maintain hurricane-force winds through the transition. After transition is complete, the extratropical low should weaken over the far north Atlantic and be absorbed into a larger low-pressure area by 120 h. The center of Dorian is expected to move very near or over the coastline of the Carolinas and the southern Mid-Atlantic states. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains. It also appears that Dorian will affect portion of eastern Canada as a hurricane-force extratropical low.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions the coasts of South Carolina and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding is occurring, and will continue to become more widespread across the eastern Carolinas and far southeast Virginia through tonight. There is a high risk of flash flooding over these areas, where significant, life-threatening, flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 33.1N  78.5W   90 KT 105 MPH - Category 2 (ESE Pawleys Island, SC)
 12H  06/0600Z 34.2N  77.2W   90 KT 105 MPH - Category 2 (ESE Topsail Beach, NC)
 24H  06/1800Z 36.0N  74.4W   85 KT 100 MPH - Category 2 (ESE Topsail Beach, NC)
 36H  07/0600Z 38.5N  70.4W   80 KT  90 MPH - Category 2 (ESE Nags Head, NC)
 48H  07/1800Z 42.0N  65.9W   75 KT  85 MPH - Category 1 (ESE Boston, MA)
 72H  08/1800Z 50.0N  57.5W   65 KT  75 MPH - Category 1 (Parson's Pond, Labrador)
 96H  09/1800Z 56.0N  45.5W   50 KT  60 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)
120H  10/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Thu Sep 05 2019

Hurricane Dorian Moves Toward Carolinas  – SHELTER IN PLACE! 

The latest NOAA Doppler radar data, along with Air Force Reserve and NOAA Hurricane Hunter reports, indicate that Dorian has an well- defined eye with a diameter of about 40 n mi, with the northwestern edge of the eyewall not far from the South Carolina coast. The Hurricane Hunter data indicate that the flight-level and SFMR surface winds have decreased some since 12 h ago, accompanied by a rise in the central pressure. Based on this, the initial intensity is decreased to a possibly generous 95 kt. The central pressure of 958 mb is based partly on data from NOAA buoy 41004, which is currently inside the eye.

Dorian has nudged eastward during the past several hours and the initial motion is now 020/7. The hurricane is now moving into the mid-latitude westerlies, and during the next several hours it is expected to turn northeastward with an increase in forward speed. This should bring the eye near or over the coasts of eastern South Carolina and southeastern North Carolina during the next 12-24 h. After that, Dorian is forecast to move quickly across the northwest Atlantic and be near or over the Canadian Maritimes/Atlantic provinces by 72 h. The track guidance remains tightly clustered, and the new forecast track is changed little from the previous forecast.

Dorian is forecast to slowly weaken as it moves along the South and North Carolina coasts. Extratropical transition should begin around 48 h and be complete by 72 h, although Dorian is forecast to maintain hurricane-force winds through the transition. After 72 h, the extratropical low should weaken over the far north Atlantic.

The center of Dorian is expected to move very near or over the coastline of the Carolinas and the southern Mid-Atlantic states. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions the coasts of South Carolina and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding will become more widespread across the eastern Carolinas and far southeast Virginia today into tonight. There is a high risk of flash flooding over these areas, where significant, life-threatening, flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 32.5N  79.1W   95 KT 110 MPH - Category 2 (ESE Folly Beach, SC)
 12H  06/0000Z 33.5N  78.0W   90 KT 105 MPH - Category 2 (ESE Myrtle Beach, SC)
 24H  06/1200Z 35.1N  75.8W   85 KT 100 MPH - Category 2 (ESE Hatteras, NC)
 36H  07/0000Z 37.2N  72.4W   80 KT  90 MPH - Category 1 (ESE Cape Charles, VA)
 48H  07/1200Z 40.1N  68.0W   80 KT  90 MPH - Category 1 (ESE Nantucket, MA)
 72H  08/1200Z 48.0N  59.5W   65 KT  75 MPH - Category 1 (WNW Codroy, Newfoundland)
 96H  09/1200Z 54.5N  48.5W   50 KT  60 MPH - Tropical Storm (WNW Cartwright, Labrador)
120H  10/1200Z 59.5N  32.0W   40 KT  45 MPH - Tropical Storm (WSW Reykjavik, Iceland)

NWS National Hurricane Center Miami FL 500 AM EDT Thu Sep 05 2019

Hurricane Dorian Moves Toward Carolinas  – SHELTER IN PLACE!

Dorian continues to exhibit a large eye of about 50 n mi in diameter on satellite and radar images. Earlier data from hurricane hunter aircraft indicate little change to the minimum central pressure, and flight-level winds still support an intensity close to 100 kt at this time. Dorian should soon begin to experience increasing southwesterly shear, which should lead to at least slow weakening during the next couple of days. The official forecast maintains the cyclone at hurricane strength through 72 hours, which is in general agreement with the LGEM guidance and on the high side of the guidance suite. By 72 hours, the global models show Dorian becoming embedded within a baroclinic zone, and simulated satellite imagery from the ECMWF model depicts a highly asymmetric cloud pattern. Therefore, the NHC forecast shows the system becoming extratropical by that time.

Dorian’s initial motion is about 010/6 kt. The hurricane is currently moving through a break in the subtropical ridge. Within a day or so, the cyclone should turn northeastward with increasing forward speed in response to a broad mid-tropospheric trough to the north. The official track forecast remains in good agreement with the dynamical model consensus. The forecast track and wind radii now require the issuance of a tropical storm watch for extreme southeastern New England.

The center of Dorian is still expected to move very near or over the coastline of the Carolinas and the southern Mid-Atlantic states. Residents of these areas should already be prepared for damaging winds, life-threatening storm surges, and flooding rains.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions the coasts of South Carolina and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding will become increasingly likely across the eastern Carolinas today. There is a high risk of flash flooding over coastal sections of the Carolinas where life-threatening flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 31.7N  79.5W  100 KT 115 MPH - Category 3 (ESE Tybee Island, GA)
 12H  05/1800Z 32.7N  78.9W   95 KT 110 MPH - Category 2 (ESE Dewees Island, SC)
 24H  06/0600Z 34.2N  77.2W   90 KT 105 MPH - Category 2 (ESE Surf City, NC)
 36H  06/1800Z 36.1N  74.5W   85 KT 100 MPH - Category 2 (ENE Likk Devil Hills, NC)
 48H  07/0600Z 38.3N  70.8W   80 KT  90 MPH - Category 1 (ESE Ocean City, MD)
 72H  08/0600Z 46.0N  61.5W   65 KT  75 MPH - Category 1 (Dunmore, Nova Scotia)
 96H  09/0600Z 53.0N  52.5W   50 KT  60 MPH - Tropical Storm (ESE Cartwright, Labrador)
120H  10/0600Z 58.0N  38.0W   40 KT  45 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)

NWS National Hurricane Center Miami FL 1100 PM EDT Wed Sep 04 2019

Hurricane Dorian Moves Toward Carolinas  – SHELTER IN PLACE!

Satellite imagery indicated that the cloud pattern associated with Dorian was a little better organized with a clear eye surrounded by a ring of very deep convection. This trend was confirmed with data from both NOAA and Air Force reconnaissance planes, which measured a minimum central pressure of 955 mb. SFMR and flight-level winds support an initial intensity of 100 kt. In fact, Dvorak numbers also call for 100 kt.

Dorian could maintain this intensity for about 12 hours or so, but guidance is showing shear increasing, and that should result in gradual weakening. The intensity forecast is basically the same as the previous advisory, keeping Dorian at the border of category 2 or 3 intensity as it moves near the southeast coast of the United States. This forecast is consistent with the intensity models, which unanimously gradually weaken the cyclone. On the other hand, the wind field is expected to gradually expand during the next several days until the cyclone becomes extratropical near Atlantic Canada.

Aircraft fixes yield a northward motion or 010 degrees at 6 kt. Dorian is already recurving as it is becoming steered by the south- southwesterly flow ahead of an eastward-moving mid-level trough. The track guidance is tightly clustered, and the NHC forecast follows very closely the multi-model consensus. No significant change to the previous track forecast was necessary. The forecast motion should bring the core of Dorian near the coast of South Carolina during the next 6 to 12 hours and over the Outer Banks of North Carolina between 24 and 36 hours.

Since the NHC track prediction continues to take Dorian dangerously close to the southeast U.S. coast, all interests from Georgia to the Carolinas should remain vigilant to the possibility of experiencing destructive winds, flooding rains, and life-threatening storm surges from this hurricane.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions the coasts of Georgia, South Carolina, and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. Flash flooding will become increasingly likely across coastal Georgia into the eastern Carolinas overnight. On Thursday, there is a high risk of flash flooding over coastal sections of the Carolinas, where significant, life-threatening, flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 31.3N  79.6W  100 KT 115 MPH - Category 3 (E Sapelo Island, GA)
 12H  05/1200Z 32.2N  79.4W  100 KT 115 MPH - Category 3 (ESE Kiawah, SC)
 24H  06/0000Z 33.6N  78.1W   90 KT 105 MPH - Category 2 (ESE Myrtle Beach, SC)
 36H  06/1200Z 35.2N  75.9W   85 KT 100 MPH - Category 2 (N Ocracoke Island, NC)
 48H  07/0000Z 37.5N  72.2W   80 KT  90 MPH - Category 1 (ESE Ocean City, MD)
 72H  08/0000Z 45.0N  62.8W   65 KT  75 MPH - Category 1 (ENE Mooseland, Nova Scotia)
 96H  09/0000Z 53.5N  52.5W   50 KT  60 MPH - Category 1 (ESE Cartwright, Labrador)
120H  10/0000Z 58.0N  38.5W   40 KT  45 MPH - Category 1 (ESE Prins Christianssund, Greenland)

NWS National Hurricane Center Miami FL 500 PM EDT Wed Sep 04 2019

Hurricane Dorian Moves Toward Carolinas  – SHELTER IN PLACE! 

Hurricane Dorian has become a little better organized during the past several hours, with the eye becoming somewhat more distinct and the cold cloud tops in the eyewall becoming more symmetric. An Air Force Reserve Hurricane Hunter aircraft has twice reported 110-kt flight-level winds in the eastern eyewall, and the central pressure has fallen to 961 mb. Based on these data and that of eyewall dropsondes, the initial intensity is increased to 95 kt. The aircraft data show that hurricane-force winds are 50-60 n mi offshore of northeastern coast of Florida, while surface observations show that tropical-storm conditions are affecting portions of the coasts of Georgia and South Carolina.Hurricane Dorian Tropical Force Wind Arrival Time

The initial motion is now 345/8. Dorian is moving around the western end of the subtropical ridge, and it should recurve northward and northeastward into the mid-latitude westerlies during the next 12-36 h. This motion should bring the center of Dorian near the coast of South Carolina in about 24 h and near or over the coast of North Carolina during the 36-48 h period. After that time, the cyclone is forecast to accelerate northeastward into the Atlantic toward the Canadian Maritimes, with a quick northeastward motion continuing through 120 h. The track guidance remains very tightly clustered, and the new forecast track is little changed from the previous forecast. It should be noted that the track is close to and almost parallel to the coast of the southeastern United State, and any deviation to the left of the track could bring the center onshore anywhere in the Carolinas.

Dorian is expected to remain in an environment of light to moderate vertical wind shear and warm sea surface temperatures during the next 36 h or so. None of the guidance shows significant strengthening during this time, and the official forecast is similar to, but slightly stronger than, the previous forecast. However, based on current trends it is possible that Dorian could briefly regain major hurricane strength during the next 12-24 h. The hurricane is expected to maintain Category 2 intensity as it passes near the southeastern United States coast during the 24-48 h period, followed by a weakening trend due to increasing shear and dry air entrainment. Extratropical transition is now expected to begin between 48-72 h and be complete just after 72 h, with Dorian forecast to become a hurricane-force extratropical low as it moves towards Nova Scotia and Newfoundland.

Since the NHC track prediction continues to take Dorian dangerously close to the southeast U.S. coast, all interests from northeast Florida to the Carolinas should remain vigilant to the possibility of experiencing destructive winds, flooding rains, and life- threatening storm surges from this hurricane.

Key Messages:

1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast, the coasts of Georgia, South Carolina, and North Carolina, and portions of southeast Virginia and the southern Chesapeake Bay, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.

2. Flash flooding will become increasingly likely across coastal Georgia into the eastern Carolinas tonight into Friday. There is a high risk of flash flooding over coastal sections of the Carolinas, where significant, life-threatening, flash flooding is expected.

FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 30.6N  79.8W   95 KT 110 MPH - Category 2 (ESE Fernandina Beach, FL)
 12H  05/0600Z 31.4N  79.8W   95 KT 110 MPH - Category 2 (ESE Sapelo Island, GA)
 24H  05/1800Z 32.7N  79.0W   90 KT 105 MPH - Category 2 (ESE Isle of Palms, SC)
 36H  06/0600Z 34.0N  77.3W   85 KT 100 MPH - Category 2 (ENE Carolins Abeach, NC)
 48H  06/1800Z 35.9N  74.4W   85 KT 100 MPH - Category 2 (ESE Nags Head, NC)
 72H  07/1800Z 42.1N  65.6W   75 KT  85 MPH - Category 1 (ESE Boston, MA)
 96H  08/1800Z 50.5N  56.0W   65 KT  75 MPH - Category 1 (ESE Canada Harbour, Newfoundland )
120H  09/1800Z 56.5N  42.5W   50 KT  60 MPH - Tropical Storm (ESE Prins Christianssund, Greenland)

NWS National Hurricane Center Miami FL 1100 AM EDT Wed Sep 04 2019

Hurricane Dorian  – SHELTER IN PLACE! 

Satellite imagery indicates that the cloud tops in the eyewall of Dorian have cooled significantly during the past few hours, with the eye becoming better defined in NOAA Doppler radar data. However, just-received reports from an Air Force Reserve Hurricane Hunter aircraft show that the hurricane has changed little in intensity, with maximum winds remaining near 90 kt and the central pressure near 964 mb. The aircraft data show that hurricane-force winds are roughly 50 n mi offshore of the northeastern Florida peninsula, while surface observations show that tropical-storm conditions are affecting portions of the coast of northeastern Florida.Earliest Arrival Times

The initial motion is now 335/8. Dorian is moving around the western end of the subtropical ridge, and it should recurve northward and northeastward into the mid-latitude westerlies during the next 24-48 h. This motion should bring the center of Dorian near or over the coast of North Carolina during the 36-48 h period. After that time, the cyclone is forecast to accelerate northeastward into the Atlantic toward the Canadian Maritimes, with a quick northeastward motion continuing for the remainder of the cyclone’s life. The track guidance is very tightly clustered, and the new forecast track, which has only minor changes from the previous forecast, lies in the center of the guidance envelope near the consensus models. It should be noted that the track is close to and almost parallel to the coast of the southeastern United State, and any deviation to the left of the track could bring the center onshore anywhere in the Carolinas.

Dorian is expected to remain in an environment of light to moderate vertical wind shear and warm sea surface temperatures during the next 48 h. As a result, the hurricane is expected to maintain Category 2 intensity as it passes near the southeastern United States coast. After 48 h, increasing shear and dry air entrainment should cause a weakening trend. Extratropical transition should begin near the 72 h time, and the cyclone is forecast to become a hurricane-force extratropical low by 96 h near or over Nova Scotia and Newfoundland.

Since the NHC track prediction continues to take Dorian dangerously close to the southeast U.S. coast, all interests from northeast Florida to the Carolinas should remain vigilant to the possibility of experiencing destructive winds, flooding rains, and life- threatening storm surges from this hurricane.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia, South Carolina, North Carolina, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. The risk of dangerous storm surge, wind, and rain impacts along portions of the Virginia coast and the southern Chesapeake Bay continues to increase. Residents in these areas should continue to monitor the progress of Dorian.
  • 3. Flash flooding will become increasingly likely across coastal Georgia into the eastern Carolinas tonight into Friday. There is a high risk of flash flooding over coastal sections of the Carolinas, where significant, life-threatening, flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 29.8N  79.7W   90 KT 105 MPH - Category 2 (ENE Palm Coast, FL)
 12H  05/0000Z 30.8N  80.0W   90 KT 105 MPH - Category 2 (ESE Cumberland Island, FL)
 24H  05/1200Z 31.9N  79.8W   85 KT 100 MPH - Category 2 (ESE Hilton Head Island, SC)
 36H  06/0000Z 33.1N  78.6W   85 KT 100 MPH - Category 2 (ESE Georgetown, SC)
 48H  06/1200Z 34.8N  76.4W   85 KT 100 MPH - Category 2 (ESE New York City, NY)
 72H  07/1200Z 39.9N  68.2W   75 KT  85 MPH - Category 1 (ESE Tom's River, NJ)
 96H  08/1200Z 47.5N  59.0W   70 KT  80 MPH - Category 1 (ESE Cartwright, Labrador)
120H  09/1200Z 55.0N  46.0W   60 KT  70 MPH - Category 1 ()

NWS National Hurricane Center Miami FL 500 AM EDT Wed Sep 04 2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE!

NOAA Doppler radar data and reports from an Air Force Reserve Unit Hurricane Hunter aircraft indicate that Dorian’s eye has become broad and less well-defined over the past several hours. The hurricane is still producing some healthy bands of deep convection that are causing winds of at least tropical storm force along portions of the northeast coast of Florida. Although the central pressure had been rising, recent observations from the Hurricane Hunters show that it has leveled off near 963 mb. The current intensity is set at 90 kt, which may be generous considering the flight-level wind speeds reported by the aircraft. Dorian will be traversing warm waters for the next couple of days, with some increase in vertical shear after 24 hours. The official intensity forecast maintains the current intensity for a day or so and then shows a very slow weakening thereafter. This is close to the latest statistical-dynamical guidance. The system is expected to maintain close to category 2 strength until it passes near or over the North Carolina Outer Banks.

Dorian is moving slowly north-northwestward to northwestward, or 330/7 kt. There is basically no change to the track forecast reasoning. Over the next day or so, the hurricane is forecast to gradually turn toward the north as it moves through a break in the subtropical ridge. Thereafter, Dorian should accelerate north-northeastward to northeastward on the southern side of a broad mid-latitude trough. The official forecast track remains close to the corrected multi-model consensus.

Since the NHC track prediction continues to take Dorian dangerously close to the southeast U.S. coast, all interests from northeast Florida to the Carolinas should remain vigilant to the possibility of experiencing destructive winds, flooding rains, and life-threatening storm surges from this hurricane.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia, South Carolina, and North Carolina, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. The risk of wind and rain impacts along portions of the Virginia coast and the southern Chesapeake Bay are increasing. Residents in these areas should continue to monitor the progress of Dorian.
  • 3. The flash flood threat will spread up the southeast U.S. coast today and Thursday, then across the coastal Mid-Atlantic region on Friday. There is a high risk of flash flooding on Thursday across coastal sections from northeast South Carolina into southern North Carolina.
  • FORECAST POSITIONS AND MAX WINDS
    
    INIT  04/0900Z 29.2N  79.5W   90 KT 105 MPH - Category 2 (ESE Daytona Beach, FL)
     12H  04/1800Z 30.1N  79.8W   90 KT 105 MPH - Category 2 (ESE Ponte Vedra Beach, FL)
     24H  05/0600Z 31.2N  80.0W   90 KT 105 MPH - Category 2 (ESE Sapelo Island, GA)
     36H  05/1800Z 32.2N  79.4W   85 KT 100 MPH - Category 2 (ESE Charleston, SC)
     48H  06/0600Z 33.7N  77.7W   80 KT  90 MPH - Category 1 (ESE Bald Head Island, NC)
     72H  07/0600Z 38.0N  70.6W   75 KT  85 MPH - Category 1 (ESE Ocean City, MD)
     96H  08/0600Z 45.0N  61.5W   70 KT  80 MPH - Category 1 (ESE Port Bickerton, Nova Scotia)
    120H  09/0600Z 53.5N  50.0W   60 KT  70 MPH - Category 1 (ESE Cartwright, Labrador)

NWS National Hurricane Center Miami FL 500 PM EDT Tue Sep 03 2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE! 

Hurricane Dorian has finally begun a more definitive northwestward motion this afternoon. The satellite presentation of the hurricane is slightly better in one-minute GOES 16 imagery with the large eye becoming a little more apparent. The eye has also become better defined in NWS Doppler radar from Melbourne, Florida. Reconnaissance aircraft data continue to show an expansion of the tropical-storm and 50-kt wind radii, and it is likely that the area of hurricane-force winds will also increase somewhat during the next 24-36 hours. The initial intensity remains 95 kt, and is a blend of the earlier reconnaissance data and the latest satellite estimates.

Dorian will be moving northwestward over untapped waters east of the Florida peninsula, which may lead to some structural re-organization, but little overall change in intensity is expected during the next couple of days. After that time, a gradual decrease in the peak wind speed and an increase in storm size are predicted while the vertical shear increases and the storm moves farther north. An approaching mid-latitude trough and front will begin interacting with the hurricane on Saturday and Dorian is forecast to become a powerful extratropical low by 120 hours. Dorian is now moving northwestward or 325/5 kt. The deep-layer trough along the east coast of the United States is expected to amplify on Wednesday, which should cause Dorian to move at a slightly faster north-northwestward motion tonight and Wednesday. After that time, Dorian should turn northward, and then north-northeastward ahead of a shortwave trough moving into the eastern United States. Once Dorian is offshore of eastern North Carolina, it should accelerate northeastward within the mid-latitude westerlies. The track envelope has edged closer to the coasts of South Carolina and North Carolina and the NHC track has been adjusted in that direction. A track that close to the coast, even if landfall does not occur, is likely to bring dangerous winds, life-threatening storm surge, and flooding rains across the eastern portions of the Carolinas.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia, South Carolina, and North Carolina, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 2. The risk of wind and rain impacts along portions of the Virginia coast and the southern Chesapeake Bay are increasing. Residents in these areas should continue to monitor the progress of Dorian.
  • 3. The flash flood threat will increase tonight along the Florida east coast and then spread up the southeast and mid-Atlantic coast during the middle and latter part of the week.
FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 27.7N  78.7W   95 KT 110 MPH 
- Category 2 (ENE Vero Beach, FL)
 
12H  04/0600Z 28.7N  79.4W   95 KT 110 MPH 
- Category 2 (ESE Edgewater, FL)
 
24H  04/1800Z 30.0N  80.0W   95 KT 110 MPH 
- Category 2 (ESE Jacksonville Beach, FL)
 
36H  05/0600Z 31.4N  80.0W   95 KT 110 MPH 
- Category 2 (ESE Sapelo Island, GA

48H  05/1800Z 32.6N  79.2W   90 KT 105 MPH 
- Category 2 (ESE Charleston, SC)
 
72H  06/1800Z 36.1N  74.0W   80 KT  90 MPH 
- Category 1 (ENE ill Devil Hills, NC)
 
96H  07/1800Z 42.0N  65.0W   75 KT  85 MPH 
- Category 1 (ESE Boston, MA)

120H  08/1800Z 50.0N  55.0W   60 KT  70 MPH
...POST-TROP/EXTRATROP

NWS National Hurricane Center Miami FL 1100 AM EDT Tue Sep 03 2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE! 

Recent radar and aircraft data show that Dorian has finally begun to move northwestward, but dangerous winds and life-threatening storm surge will continue over Grand Bahama Island for much of today. The eye has become cloud filled in infrared and visible satellite imagery. While aircraft and radar data indicate that the eye has increased in size, it is also a bit more ragged. Recent reports from reconnaissance aircraft and data buoys indicate that overall wind field of the hurricane is slowly expanding, while the peak winds have come down a little more. The latest reports from the aircraft support an initial intensity of 95 kt. As Dorian moves near the east coast of Florida during the next day or two, little overall change in intensity is anticipated. After that time, increasing shear should result in a gradual decrease in the peak wind speed while the hurricane gains latitude and grows in size. The official forecast is in good agreement with the intensity consensus models.

The initial motion estimate is 320/2 kt. A shortwave trough moving into the Great Lakes region is forecast by the global models to amplify a deep-layer trough along the east coast of the United States on Wednesday. This should allow Dorian to begin moving slightly faster toward the north-northwest during the next 36 hours, followed by a northward and then northeastward motion near or over the coasts of South and North Carolina. After moving offshore of the Outer Banks, Dorian should get caught in the mid-latitude westerlies and accelerate northeastward. The NHC track is along the western edge of the interpolated track models through 36 hours, closer to what is depicted in the various global fields. After that time, the official forecast is near a blend of the faster GFS and slower ECMWF models.

Although the official forecast does not show Dorian making landfall along the Florida east coast, the increasing size of Dorian’s wind field along with any deviation to the left of the forecast track will bring hurricane-force winds onshore along portions of the Florida east coast. The new forecast has necessitated numerous changes to watches and warnings along the southeastern United States coast.

Key Messages: 1. Dangerous winds and storm surge will continue to affect Grand Bahama Island for several more hours. Everyone there should remain in shelter. 2. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia and South Carolina, regardless of the exact track of Dorian’s center. Water levels could begin to rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials. 3. The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coast of North Carolina. Residents in these areas should follow advice given by local emergency officials. 4. The flash flood threat will increase today and tonight along the Florida peninsula, then spread up the southeast and mid-Atlantic coast during the middle and latter part of the week.

FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 27.1N  78.6W   95 KT 110 MPH - Category 2 (ENE West End, Bahamas)
 12H  04/0000Z 27.9N  79.0W   95 KT 110 MPH - Category 2 (ESE Palm Bay, FL)
 24H  04/1200Z 29.2N  79.4W   95 KT 110 MPH - Category 2 (ESE Daytona Beach, FL)
 36H  05/0000Z 30.7N  79.8W   95 KT 110 MPH - Category 2 (ESE Cumberland Island, GA)
 48H  05/1200Z 32.1N  79.2W   95 KT 110 MPH - Category 2 (ESE Hilton Head, SC)
 72H  06/1200Z 35.3N  75.0W   85 KT 100 MPH - Category 2 (ESE Avon, NC)
 96H  07/1200Z 40.5N  66.5W   75 KT  85 MPH - Category 1 (ESE New York City, NY)
120H  08/1200Z 48.0N  57.5W   65 KT  75 MPH - Category 1 (ESE Burgeo, Newfoundland)

NWS National Hurricane Center Miami FL 1100 PM EDT Mon Sep 02, 2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE! 

Hurricane Dorian continues to pummel Grand Bahama Island this evening. The hurricane still has an impressive presentation in satellite and radar images, however, there have been occasional dry slots observed in the western part of the eyewall. Both the NOAA and Air Force Hurricane Hunters provided excellent data in Dorian this evening, and based primarily on the flight-level wind data from the aircraft, the initial intensity of Dorian is set to 115 kt. The westernmost outer rain bands are reaching the east coast of south Florida and producing gusty winds.

The major hurricane has been stationary much of the day. The reason the cyclone has moved very little is because it is caught in weak steering currents between high-pressure ridges to its east and northwest and a trough to its north. This weak flow should result in a very slow and likely erratic northwest drift through at least early Tuesday. After that time, the models are in general agreement that the ridge to the east and trough to the north will amplify. This change in the steering pattern should cause Dorian to move a little faster to the north on Wednesday and to the northeast on Thursday and Friday. The NHC track forecast remains consistent and continues to show the core of Dorian offshore, but dangerously close to the east coast of the U.S. from Florida to North Carolina during the next 3 days or so. This track forecast is largely an update of the previous one and it is in good agreement with the various consensus models. Users are reminded that the hurricane is not a point, and that life-threatening storm surge and hurricane-force winds extend far from the center. Regardless of the exact forecast track, Dorian is likely to produce strong winds and a life-threatening storm surge along a portion of the U.S. east coast from Florida through the Carolinas.

The intensity models are in agreement that Dorian should slowly lose strength during the next several days due to a gradual increase in wind shear and perhaps drier air. Regardless of the details of the intensity forecast, the bottom line is that Dorian is expected to remain a powerful hurricane as it tracks very near the east coast of the U.S. from Florida to North Carolina during the next few days. The NHC intensity forecast is the same as the previous one and close to the HCCA and IVCN guidance.

Key Messages:

  • 1. Devastating winds and storm surge will continue to affect Grand Bahama Island for several more hours. Everyone there should remain in shelter.
  • 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast and the coasts of Georgia and South Carolina, regardless of the exact track of Dorian’s center. Water levels could begin to rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 3. The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coast of North Carolina. Residents in these areas should follow advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the southeast and lower mid-Atlantic regions of the United States through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 26.9N  78.5W  115 KT 130 MPH 
- Category 4 (WSW Great Sale Cay, Bahamas)
 
12H  03/1200Z 27.1N  78.7W  115 KT 130 MPH 
- Category 4 (Grand Bahama, Bahamas)

24H  04/0000Z 27.9N  79.1W  110 KT 125 MPH 
- Category 3 (ESE Palm Bay, FL)
 
36H  04/1200Z 29.2N  79.7W  110 KT 125 MPH 
- Category 3 (ESE Daytona Beach, FL)
 
48H  05/0000Z 30.6N  79.7W  105 KT 120 MPH 
- Category 3 (ESE Fernandina Beach, FL)
 
72H  06/0000Z 33.7N  77.3W   90 KT 105 MPH 
- Category 2 (ESE Bald Head Islamd, NC)
 
96H  07/0000Z 38.0N  71.0W   80 KT  90 MPH 
- Category 1 (ESE Ocean City, MD)

120H  08/0000Z 45.4N  61.5W   70 KT  80 MPH 
- Category 1 (Guysborough, NS, Canada)

NWS National Hurricane Center Miami FL 500 PM EDT Mon Sep 02,  2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE! 

Hurricane Dorian remains an impressive hurricane in satellite imagery. Recent radar and aircraft observations are again showing signs of a concentric eyewall structure which might be one of the factors that has led to a decrease in the peak winds and a small expansion of the wind field. An Air Force Reserve Hurricane Hunter aircraft reported peak flight-level winds of 129 kt, SFMR winds of 121 kt, and a central pressure that has risen to 940 mb. Based on these observations, the initial wind speed has been set at 125 kt. Some additional decrease in wind speed is likely in the short term due due to a possible eyewall replacement and upwelling of cooler waters caused by the very slow motion of the hurricane. Although some additional slow weakening is forecast while the hurricane moves northward along the southeastern United States coastline due to increasing southwesterly shear,

Dorian is forecast to remain a powerful hurricane during that time. The NHC intensity forecast is a blend of the latest statistical and consensus model guidance. Dorian has become nearly stationary this afternoon with the two most recent aircraft fixes showing essentially no motion. A slow westward to west-northwestward motion should resume overnight and continue into early Tuesday, with the eye and devastating winds only slowly pulling away from Grand Bahama Island. By Tuesday afternoon, Dorian should begin its much anticipated northwestward turn as a weakness becomes more pronounced in the subtropical ridge. Although the center of Dorian is forecast to move near, but parallel to, the Florida east coast, only a small deviation of the track toward the west would bring the core of the hurricane onshore. A broad mid-latitude trough should help turn Dorian northeastward by Wednesday night, and the track models show the center coming precariously close to the southeastern United States coast. The tracks from the 1200 UTC runs of the global models have remained fairly stable, which has resulted in little overall change to the latest NHC track forecast.

Users are reminded that the hurricane is not a point, and that life-threatening storm surge and hurricane-force winds extend far from the center. Regardless of the exact forecast track, strong winds and a life-threatening storm surge are likely along a portion of the U.S east coast from Florida through the Carolinas.

Key Messages:

  • 1. Devastating winds and storm surge will continue to affect Grand Bahama Island through tonight. Everyone, there should remain in shelter and not venture into the eye.
  • 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast and the coasts of Georgia and South Carolina, regardless of the exact track of Dorian’s center. Water levels could begin to rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 3. The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coast North Carolina. Residents in these areas should follow advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the southeast and lower mid-Atlantic regions of the United States through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  02/2100Z 26.8N  78.4W  125 KT 145 MPH - Category 4 (ENE West End, Bahamas)
 12H  03/0600Z 27.0N  78.7W  115 KT 130 MPH - Category 4 (ENE West End, Bahamas)
 24H  03/1800Z 27.6N  79.1W  110 KT 125 MPH - Category 3 (ESE Vero Beach, FL)
 36H  04/0600Z 28.7N  79.7W  110 KT 125 MPH - Category 3 (ESE Allenhurst, FL)
 48H  04/1800Z 30.0N  80.1W  105 KT 120 MPH - Category 3 (ESE Nocatee, FL)
 72H  05/1800Z 32.8N  78.6W   95 KT 110 MPH - Category 2 (ESE McClellanville, SC)
 96H  06/1800Z 36.6N  73.1W   80 KT  90 MPH - Category 1 (ESE Virginia Beach, VA)
120H  07/1800Z 43.5N  64.0W   75 KT  85 MPH - Category 1 (ESE Liverpool, Nova Scotia)

NWS National Hurricane Center Miami FL 1100 AM EDT Mon Sep 02 2019

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE! 

Corrected missing word in last sentence Satellite and radar imagery show that Dorian is moving very slowly over Grand Bahama Island this morning.

Hurricane Dorian remains quite symmetric and still exhibits a very well-defined eye, but there is somewhat less evidence of concentric eyewalls in Bahamas radar imagery. Satellite intensity estimates from UW/CIMSS, SAB, and TAFB are slightly lower this morning, and the initial intensity has been reduced to 135 kt.

As Dorian moves very slowly during the next 24 hours, some upwelling in the deeper waters around the Bahamas could cause some gradual weakening. After that time, the hurricane is expected to experience a gradual increase in southwesterly shear, which should lead to a slow decrease in wind speed. However, Dorian is forecast to remain a very powerful hurricane while it moves near the southeastern United States coast. The NHC intensity forecast is close to the statistical guidance during the first day or so, then near the HFIP corrected consensus model later in the period.Hurricane Dorian Arrival Times

As anticipated, the ridge to the north of the storm has weakened and the eye of Dorian has only been inching westward this morning. The hurricane is expected to drift westward or west-northwestward over the next 24 hours, which will cause a prolonged period of devastating winds and storm surge over Grand Bahama Island.

By late Tuesday, the weakness in the ridge becomes more pronounced and Dorian should turn northwestward near the east coast of the Florida. By day 3, the hurricane is expected to make a northeastward turn ahead of a broad mid-latitude trough. The overall track envelope has not changed much, and little adjustment to the previous NHC forecast was required.

It cannot be stressed enough that only a small deviation to the left of the NHC forecast could bring the core of the extremely dangerous hurricane onshore of the Florida east coast within the hurricane warning area. In addition, Dorian’s wind field is predicted to expand, which would bring hurricane-force winds closer to the east coast of Florida even if the track does not change.

Key Messages:

  • 1. A prolonged period of catastrophic winds and storm surge will continue to affect Grand Bahama Island through today and tonight. Everyone there should remain in shelter and not venture into the eye.
  • 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast and Georgia coast, regardless of the exact track of Dorian’s center. Water levels could begin to rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
  • 3. The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coasts of South Carolina and North Carolina. Residents in these areas should follow advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the Southeast and lower Mid-Atlantic regions of the United States into Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 26.8N  78.3W  135 KT 155 MPH - Category 4 (WNW West End, Bahamas)
 12H  03/0000Z 26.9N  78.7W  130 KT 150 MPH - Category 4 (WNW West End, Bahamas)
 24H  03/1200Z 27.2N  79.1W  125 KT 145 MPH - Category 4 (WNW Grand Bahama, Bahamas)
 36H  04/0000Z 28.1N  79.6W  115 KT 130 MPH - Category 4 (ESE Cocoa Beach, FL)
 48H  04/1200Z 29.3N  80.2W  110 KT 125 MPH - Category 3 (ESE Flagler Beach, FL)
 72H  05/1200Z 32.0N  79.4W   95 KT 110 MPH - Category 2 (ESE ilton Head Island, SC)
 96H  06/1200Z 35.4N  75.1W   85 KT 100 MPH - Category 2 (ESE Nags Head, NC)

NWS National Hurricane Center Miami FL 500 AM EDT Mon Sep 02 2019 

Hurricane Dorian Becomes Category 5 Storm  – SHELTER IN PLACE!

Hurricane Dorian– Satellite imagery continues to show that Dorian has an extremely well-defined eye embedded within very cold cloud tops. The diameter of the eye appears to have expanded to near 20 n mi, and radar data, especially from the Bahamas Department of Meteorology radar, show that there are concentric eyewalls. The hurricane also continues to exhibit strong upper-tropospheric outflow.

The initial intensity estimate has been reduced to 145 kt, which lies between earlier Hurricane Hunter estimates and satellite intensity estimates from TAFB and SAB. This lowering of intensity is consistent with the development of a concentric eyewall. During the next few days, Dorian should be encountering some increase in shear, which will likely result in weakening. However it is anticipated that the system will remain a dangerous major hurricane for the next several days. The official intensity forecast lies between the statistical-dynamical guidance and the corrected multi-model consensus.

Steering currents have weakened, and Dorian has almost come to a standstill over eastern Grand Bahama Island, with an initial motion of 270/1 kt. The mid-tropospheric high to the north of the hurricane that had been steering Dorian westward has collapsed. Global models indicate that, in a couple of days, a weakness in the ridge will develop along 75W-80W. This would likely cause Dorian to move northwestward to northward toward and through this weakness. Later in the forecast period, the system is expected to accelerate northeastward on the southern side of a broad mid-tropospheric trough. The official track forecast is very close to the previous one and to the corrected dynamical model consensus, HCCA. Although the official forecast does not show Dorian making landfall along the Florida east coast, it is still possible for the hurricane to deviate from this forecast, and move very near or over the coast. Users are reminded not to focus on the exact forecast track.

Key Messages:

  • 1. A prolonged period of catastrophic winds and storm surge will continue to affect Grand Bahama Island through today and tonight. Everyone there should remain in shelter and not venture into the eye.
  • 2. Life-threatening storm surges and dangerous hurricane-force winds are expected along portions of the Florida east coast through mid-week, and storm surge and hurricane warnings are in effect. Only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the Florida east coast. Residents should listen to advice given by local emergency officials.
  • 3. There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian and listen to advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the Southeast and lower Mid-Atlantic regions of the United States into Friday.
INIT  02/0900Z 26.6N  78.2W  145 KT 165 MPH 
- Category 5 (WSW Grand Bahama, Bahamas)
 
12H  02/1800Z 26.7N  78.7W  140 KT 160 MPH 
- Category 5 (Grand Bahama, Bahamas)
 
24H  03/0600Z 26.9N  79.0W  130 KT 150 MPH 
- Category 4 (ESE Jupiter, FL)
 
36H  03/1800Z 27.6N  79.5W  120 KT 140 MPH 
- Category 4 (ESE Vero Beach, FL)
 
48H  04/0600Z 28.7N  80.0W  110 KT 125 MPH 
- Category 3 (ESE Sapelo Island, GA)
 
72H  05/0600Z 31.3N  79.8W  100 KT 115 MPH 
- Category 3 (ESE Sapelo Island, GA)
 
96H  06/0600Z 34.5N  76.5W   85 KT 100 MPH 
- Category 2 (ESE Moorehead City, NC)

120H  07/0600Z 38.5N  70.0W   75 KT  85 MPH 
- Category 1 (ESE Atlantic City, NJ)

NWS National Hurricane Center Miami FL 1100 PM EDT Sun Sep 01 2019

Hurricane Dorian Becomes Category 5 Storm 

Hurricane Dorian remains an incredibly powerful hurricane and it is currently making landfall on the eastern end of Grand Bahama Island. Satellite images show an symmetrical cyclone with a circular 10 n mi diameter eye and intense eyewall convection with lots of lightning being detected. Doppler radar data from Miami and the Bahamas show that Dorian has developed concentric eyewalls, and this feature is also noted by a double wind maximum that is evident in data from the Air Force Hurricane Hunters. The initial intensity of Dorian is set at 155 kt based mostly on the SFMR winds from the aircraft. The aircraft data also indicated that the radii of tropical-storm-force winds are a little larger than they were earlier today.

Dorian is still moving slowly westward at about 5 kt. The ridge to the north of Dorian is gradually weakening and shifting eastward in response to a mid- to the upper-level trough that is moving across the eastern U.S. This change in the steering pattern should cause Dorian to slow down even more and perhaps stall before it turns to the northwest late Monday or early Tuesday. This expected slow motion will likely be devastating to the Great Abaco and Grand Bahama Islands since it would prolong the catastrophic winds, storm surge, and rainfall over those areas. The timing of the northwest or north turn is very critical in determining how close Dorian will get to the Florida peninsula on Tuesday and Wednesday. In general, the track models have changed little from the previous cycle, and the NHC forecast continues to show the core of Dorian very near, but offshore, of the Florida peninsula on Tuesday and Wednesday. The hurricane is then expected to track near the Georgia and Carolina coasts late this week. This forecast is in best agreement with the various consensus models, which typically have the lowest errors. It is once again emphasized that although the official track forecast does not show landfall, users should not focus on the exact track. A small deviation to the left of the track could bring the intense core of the hurricane and its dangerous winds closer to or onto the Florida coast.

Category 5 hurricanes like Dorian usually don’t hold that intensity for very long, and it is expected that Dorian will weaken slowly during the next few days. However, the observed eyewall replacement cycle will likely cause fluctuations in strength, both up and down, while the system is near Florida. The models show an increase in shear when Dorian tracks near Georgia and the Carolinas, which should cause more notable weakening. This forecast is near the high end of the latest model guidance.

Based on this forecast, the hurricane watch has been extended northward to the Florida-Georgia line.

Key Messages:

  • 1. A prolonged period of catastrophic winds and storm surge will affect the Abaco Islands and Grand Bahama Island for several more hours. Everyone there should take immediate shelter and not venture into the eye.
  • 2. Life-threatening storm surges and dangerous hurricane-force winds are expected along portions of the Florida east coast through mid-week, and storm surge and hurricane warnings are in effect. Only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the Florida east coast. Residents should listen to advice given by local emergency officials.
  • 3. There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian and listen to advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the southeast and lower mid-Atlantic regions of the United States through late this week.
FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 26.6N  77.9W  155 KT 180 MPH 
- Category 5 (Sweetings Cay, Bahamas)
 
12H  02/1200Z 26.8N  78.5W  145 KT 165 MPH 
- Category 5 (Grand Bahama, Bahamas)
 
24H  03/0000Z 26.9N  79.0W  135 KT 155 MPH 
- Category 4 (ENE West End, Bahamas)
 
36H  03/1200Z 27.3N  79.3W  125 KT 145 MPH 
- Category 4 (ESE Hutchinson Island, FL)
 
48H  04/0000Z 28.2N  79.8W  120 KT 140 MPH 
- Category 4 (ESE Cocoa Beach, FL)
 
72H  05/0000Z 30.6N  80.2W  105 KT 120 MPH 
- Category 3 (ESE Amelia Island, FL)
 
96H  06/0000Z 33.5N  77.7W   85 KT 100 MPH 
-Category 2 (ESE Myrtle Beach< SC)

120H  07/0000Z 37.5N  71.8W   75 KT  85 MPH 
- Category 1 (ESE Ocean City, MD)

NWS National Hurricane Center Miami FL 500 PM EDT Sun Sep 01 2019

Hurricane Dorian Becomes Category 5 Storm 

The distinct eye of powerful Hurricane Dorian is moving over Great Abaco. The latest wind and pressure data from an Air Force reconnaissance plane just before the eye hit the island indicated that the winds reached 160 kt, which is the initial intensity for this advisory. It is not very often that we measure such strong winds. The minimum pressure measured by the plane was 910 mb.

The eye has been shrinking, and an eyewall replacement cycle is possibly occurring. The effect of the island terrain and the eyewall replacement cycle should result in some slight fluctuations in intensity during the next 24 to 36 hours, but the hurricane will continue to be extremely dangerous one during that time. After 3 days, a more definite weakening trend should begin as the hurricane encounters stronger shear. Dorian however, it is forecast to remain a hurricane for the next 5 days.

Dorian has slowed down even more and is now moving toward the west or 270 degrees at 4 kt. The steering currents are collapsing and Dorian is expected to slow down a little more, prolonging its catastrophic effects in the northwestern Bahamas. The NHC forecast calls for a slow west to west-northwest motion during the next 48 hours. A turn to the north and northeast with a gradual increase in forward speed is expected thereafter, as the mid-level trough over the eastern United States deepens. The current forecast is not very different from the previous one, and it is very close to the multi-model consensus TVCA. Both the deterministic and consensus tracks have shown the usual variability to the right or to the left from run to run, but the overall trend is for the hurricane to turn northward offshore but dangerously close to the Florida peninsula.

Given the uncertainty in the track forecast and the anticipated increase in size of the hurricane, a Hurricane Warning and Storm Surge Warning have been issued for a portion of the Florida east coast. It is once again emphasized that although the official track forecast does not show landfall, users should not focus on the exact track. A small deviation to the left of the track could bring the intense core of the hurricane its dangerous winds closer to or onto the Florida coast.

Key Messages:

  • 1. A prolonged period of catastrophic winds and storm surge will affect the Abaco Islands and Grand Bahama Island tonight. Everyone there should take immediate shelter and not venture into the eye.
  • 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast through mid-week, and storm surge and hurricane warnings are in effect. Only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the Florida east coast. Residents should listen to advice given by local emergency officials.
  • 3. There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian and listen to advice given by local emergency officials.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the southeast and lower mid-Atlantic regions of the United States through late this week.
  • FORECAST POSITIONS AND MAX WINDS
    
    INIT  01/2100Z 26.6N  77.3W  160 KT 185 MPH 
    - Category 5 (Great Abaco Islamd, Bahamas)
     
    12H  02/0600Z 26.7N  78.1W  155 KT 180 MPH 
    - Category 5 (Grand Bahama, Bahamas)
     
    24H  02/1800Z 26.8N  78.7W  145 KT 165 MPH 
    - Category 5 (ENE West End, Bahamas)
     
    36H  03/0600Z 27.0N  79.0W  135 KT 155 MPH 
    - Category 4 (ENE West End, Bahamas)
     
    48H  03/1800Z 27.7N  79.5W  125 KT 145 MPH 
    - Category 4 (ESE Sebastian, FL)
     
    72H  04/1800Z 30.0N  80.3W  105 KT 120 MPH 
    - Category 3 (ESE Jacksonville Beach, FL)
     
    96H  05/1800Z 33.0N  78.5W   90 KT 105 MPH 
    - Category 2 (ESE Pawleys Island, SC)
    
    120H  06/1800Z 36.5N  73.5W   80 KT  90 MPH 
    - Category 1 (ESE Virginia Beach, VA)

NWS National Hurricane Center Miami FL 1100 AM EDT Sun Sep 01, 2019

Hurricane Dorian Becomes Category 5 Storm 

Air Force and NOAA reconnaissance planes penetrated the distinct eye of Dorian, and found that the hurricane has become extremely intense with a stadium effect in the eye. The NOAA plane reported a peak flight-level wind of 159 kt, while the SFMR from both planes have measured winds between 155 and 170 kt. A dropsonde from the NOAA plane measured a wind gust of 176 kt at the surface. A blend of these measurements yield to an initial intensity of 155 kt, making Dorian the strongest hurricane on record in the northwestern Bahamas.

For the next few days, Dorian should experience some fluctuations in intensity, and in addition to eyewall replacement cyclone, the interaction with the northwestern Bahamas should weaken the hurricane slightly. After 3 days, as Dorian moves northward along or offshore of southeast United States coast, the shear is forecast to increase, resulting in a more distinct gradual weakening.

Reconnaissance plane and satellite fixes indicate that Dorian, as anticipated, has slowed down and is moving toward the west or 270 degrees at 6 kt. The steering currents are collapsing and Dorian is expected to slow down even more, prolonging its catastrophic effects in the northwestern Bahamas. The NHC forecast calls for a slow west to west-northwest motion during the next 48 hours, with a turn to the north and an increase in forward speed as the mid-level trough along the eastern United States deepens and becomes the dominant steering feature. The current forecast is only a few miles west of the previous one and is basically on top of the multi-model consensus. Both the deterministic and consensus tracks have shown the usual variability to the right or to the left from run to run, but the overall trend is for the hurricane to turn northward offshore but very close to the Florida peninsula.

Given the uncertainty in the track forecast and the anticipated increase in size of the hurricane, a Hurricane Watch and Storm Surge Watch have been issued for a portion of the east Florida coast. It is emphasized that although the official track forecast does not show landfall, users should not focus on the exact track. A small deviation to the left of the track could bring the intense core of the hurricane its dangerous winds closer to or onto the coast.

Key Messages:

  • 1. A prolonged period of catastrophic winds and storm surge will affect the Abaco Islands today. Everyone there should take immediate shelter and not venture into the eye. These catastrophic conditions are likely on Grand Bahama Island later today or tonight, and efforts to protect life and property there should be rushed to completion.
  • 2. Storm surge and hurricane watches and tropical storm warnings are in effect for portions of the Florida east coast. Life-threatening storm surge and dangerous hurricane-force winds are possible along portions of the Florida east coast through mid-week, as only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the coast. Residents should listen to advice given by local emergency officials.
  • 3. There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are possible over northern portions of the Bahamas and coastal sections of the southeast and lower mid-Atlantic regions of the United States through late this week.
FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 26.5N  76.8W  155 KT 180 MPH 
- Category 5 (ESE ESE Elbow Cay, Bahamas)
 
12H  02/0000Z 26.6N  77.7W  150 KT 175 MPH 
- Category 5 (ESE Great Guaya cay, Bahamas)
 
24H  02/1200Z 26.8N  78.5W  145 KT 165 MPH 
- Category 5 (East Grand Bahama, Bahamas)
 
36H  03/0000Z 27.0N  79.0W  135 KT 155 MPH 
- Category 4 (ENE West End, bahamas)
 
48H  03/1200Z 27.4N  79.4W  120 KT 140 MPH 
- Category 4 (ENE West End, bahamas)
 
72H  04/1200Z 29.7N  80.2W  100 KT 115 MPH 
- Category 3 (ESE New Smyrna Beach, FL)
 
96H  05/1200Z 32.5N  79.0W   85 KT 100 MPH 
- Category 2 (ESE Folly Beach, SC)

120H  06/1200Z 35.5N  74.5W   80 KT  90 MPH 
- Category 1 (ESE Nags Head, NC)

NWS National Hurricane Center Miami FL 500 AM EDT Sun Sep 01 2019

Hurricane Dorian Becomes Category 5 Storm – 

Hurricane Dorian – Dorian continues to exhibit a well-defined eye surrounded by very cold cloud tops on satellite images. Observations from an Air Force Hurricane Hunter aircraft from several hours ago indicated that the intensity was still near 130 kt, and since the cloud pattern remains very impressive, it is assumed that Dorian has at least maintained that strength through the present time. The hurricane will remain in a fairly low-shear environment for the next few days, however since it is forecast to move quite slowly over the shallow waters of the northwesternn most Bahamas through Monday, this would likely result in less available oceanic heat content. Therefore, a very slow weakening is anticipated to commence after 12 hours or so. The official intensity forecast is near the high end of the numerical guidance suite.

The hurricane continues moving westward, or about 280/7 kt. A high-pressure ridge to the north of Dorian should maintain this westward movement through today. By tonight, the global models show the ridge weakening, and this evolution should result in a slowing of the forward speed, with the hurricane becoming nearly stationary around 48 hours. In comparison to its earlier runs, the new ECMWF track forecast takes the system farther to the west during the next couple of days, and is the southwesternmost model through 48 hours. As a result, the official track forecast has been shifted a little west during that time frame. In 2 to 4 days, Dorian should turn northward in response to a trough over the eastern United States. By the end of the period, the flow on the south side of the trough should cause the cyclone to move northeastward near the Carolinas.

The westward shift of the NHC track within the first 48 hours necessitates the change from a Tropical Storm Watch to a Tropical Storm Warning for a portion of the Florida east coast. Although the official track forecast does not show landfall, users should not focus on the exact track since a Florida landfall is still a distinct possibility.

Key Messages:

  • 1. A prolonged period of life-threatening storm surge, devastating hurricane-force winds, and heavy rains capable of producing life-threatening flash floods are expected on the Abaco Islands and Grand Bahama through Monday, and a hurricane warning is in effect for these areas.
  • 2. A tropical storm warning is now in effect for a portion of the Florida east coast. Since Dorian is forecast to slow down and turn northward as it approaches the coast, life-threatening storm surge and dangerous hurricane-force winds are still possible along portions of the Florida east coast by the middle part of this week. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. There is an increasing risk of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian.
  • 4. Heavy rains, capable of producing life-threatening flash floods, are possible over coastal sections of the southeast and lower mid-Atlantic regions of the United States through late this week.
FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 26.4N  76.0W  130 KT 150 MPH - Category 5 (ESE ESE Elbow Cay, Bahamas)
 12H  01/1800Z 26.6N  77.1W  135 KT 155 MPH - Category 5 (ESE Great Guaya cay, Bahamas)
 24H  02/0600Z 26.7N  78.1W  125 KT 145 MPH - Category 5 (East Grand Bahama, Bahamas)
 36H  02/1800Z 26.9N  78.7W  120 KT 140 MPH - Category 5 (ENE West End, bahamas)
 48H  03/0600Z 27.0N  79.0W  120 KT 140 MPH - Category 5 (ENE West End, bahamas)
 72H  04/0600Z 28.9N  79.8W  100 KT 115 MPH - Category 3 (ESE New Smyrna Beach, FL)
 96H  05/0600Z 31.8N  79.6W   85 KT 100 MPH - Category 2 (RSR Tybee Island, GA)
120H  06/0600Z 34.5N  76.0W   80 KT  90 MPH - Category 1 (ESE Cape Lookout, NC)

NWS National Hurricane Center Miami FL 1100 PM EDT Sat Aug 31, 2019

Hurricane Dorian Projected Florida Landfall Category 4

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD – CHECK BACK OFTEN

Data from both Air Force and NOAA Hurricane Hunter aircraft indicate that Dorian remains a very powerful hurricane, and the satellite presentation is still quite impressive with a very stable, well-defined eye. There has been no evidence of concentric eyewalls in aircraft or microwave data, which is somewhat surprising given that the intensity has been at category 4 strength for 24 hours. Both aircraft measured peak flight-level winds that support an initial intensity of 130 kt. There have been some higher surface wind estimates from the SFMR, but these data are questionable based on our experience of very high SFMR-measured wind speeds in recent strong hurricanes that didn’t match standard flight-level wind reductions.

Dorian is forecast to continue moving over very warm waters and into a low-shear environment during the next 12-24 hours, so some additional strengthening is possible. Difficult-to-predict eyewall cycles, however, are likely to begin at some point within the next day or so and could cause fluctuations in intensity. After 72 hours, increasing southerly shear is likely to produce gradual weakening, but Dorian is forecast to remain a dangerous hurricane through the forecast period.

The hurricane is moving westward or 280/7 kt. A high-pressure ridge to the north of Dorian is predicted to remain intact into early Sunday and the hurricane should continue westward. By late Sunday, the dynamical models erode the western portion of the ridge, which should cause the hurricane to slow down and become nearly stationary over the northwestern Bahamas in 36 to 48 hours. After that time, the weakness in the ridge becomes more pronounced, and Dorian is expected to turn northwestward, and eventually northeastward near the southeastern United States coast. Although there is general agreement on this overall scenario, there is still considerable spread on how close the storm will track to the east coast of Florida and the southeastern coast of the United States. The latest HWRF run has shifted westward and takes Dorian across the coast of central Florida. The 18Z GFS also shifted a little left closer to the Florida coast. The latest multi-model consensus aids shifted west closer to the previous NHC track, so very little change to that forecast was made. Although the exact NHC track forecast lies east of the Florida peninsula, a track closer to the coast or even a landfall remain a possibility. Since the updated track was slightly slower than the previous advisory, no additional watches are needed for Florida at this time.

Key Messages:

  • 1. A prolonged period of life-threatening storm surge, devastating hurricane-force winds, and heavy rains capable of life-threatening flash floods are expected on the Abaco Islands and Grand Bahama Sunday through Monday and a hurricane warning is in effect for these areas.
  • 2. A tropical storm watch is in effect for a portion of Florida east coast. Since Dorian is forecast to slow down and turn northward as it approaches the coast, life-threatening storm surge and dangerous hurricane-force winds are still possible along portions of the Florida east coast by the early to middle part of next week. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. There is an increasing risk of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina during the middle of next week. Residents in these areas should continue to monitor the progress of Dorian.
  • 4. Heavy rains, capable of life-threatening flash floods, are possible over coastal sections of the southeastern United States from Monday through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  01/0300Z 26.3N  75.1W  130 KT 150 MPH 
- Category 4 (ESE ESE Elbow Cay, Bahamas)
 
12H  01/1200Z 26.4N  76.3W  135 KT 155 MPH 
- Category 4 (ESE ESE Elbow Cay, Bahamas)
 
24H  02/0000Z 26.6N  77.4W  130 KT 150 MPH 
- Category 4 (SE Big Joe Downer Cay, Bahamas)
 
36H  02/1200Z 26.8N  78.1W  125 KT 145 MPH 
- Category 4 (W Big Cross Cay, Bahamas)
 
48H  03/0000Z 27.0N  78.5W  120 KT 140 MPH 
- Category 4 (N Grand Bahama, Bahamas)
 
72H  04/0000Z 28.5N  79.3W  110 KT 125 MPH 
- Category 4 (ENE Port Canaveral, FL)
 
96H  05/0000Z 31.1N  80.0W   95 KT 110 MPH 
- Category 2 (ESE Jekyll Island, GA)

120H  06/0000Z 34.0N  77.0W   85 KT 100 MPH 
- Category 2 (ESE Carolina Beach, NC)

NWS National Hurricane Center Miami FL 500 PM EDT Sat Aug 31, 2019

Hurricane Dorian Projected Florida Landfall Category 4

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD

Dorian’s satellite presentation continues to be outstanding. The eye has remained very distinct and is surrounded by a ring of very deep convection. The latest information from the Air Force plane before it departed Dorian supports keeping an initial intensity of 130 kt. Dorian is forecast to move over a deep layer of very warm waters, and with the prevailing low shear along the hurricane’s path, some additional strengthening is possible during the next day or so. Most likely, however, the hurricane will experience some fluctuations in intensity due to eyewall replacement cycles that are difficult to predict. Beyond 3 days, as the hurricane begins to gain latitude and encounters increasing shear, gradual weakening is anticipated, but Dorian will remain a dangerous hurricane through 5 days.

The best estimate of the initial motion is toward the west or 280 degrees at 8 kt. The hurricane is being steered by the weak flow to the south of the ridge of high pressure over the western Atlantic. In about a day or two, most of the global models shift the high eastward and deepen a trough over the eastern United States. Consequently, the steering currents should collapse and Dorian is anticipated to drift toward the northwest and north-northwest while is moving over the northwestern Bahamas and near the east coast of Florida. After that time, the hurricane should begin to move a little faster northward as the trough over the eastern U.S deepens and should then steer the hurricane toward the northeast by the end of the forecast period.

The guidance has not changed significantly since the earlier run, so it has not been necessary to adjust the NHC forecast in this advisory. The uncertainty in the track is high while the hurricane is moving slowly across the northwestern Bahamas and near the east coast of Florida. Any deviation of Dorian’s core to the left would result in an increase in the winds along the east coast of Florida. Given that the area of tropical-storm-force winds could expand, and taking into account the uncertainty in the track forecast, a tropical storm watch was issued for the east of Florida from Deerfield Beach to Sebastian Inlet.

Key Messages:

  • 1. A prolonged period of life-threatening storm surge, devastating hurricane-force winds, and heavy rains capable of life-threatening flash floods are expected on the Abaco Islands and Grand Bahama Sunday through Monday, and a hurricane warning is in effect for these areas.
  • 2. A tropical storm watch is in effect for a portion of the Florida east coast. Since Dorian is forecast to slow down and turn northward as it approaches the coast, life-threatening storm surge and dangerous hurricane-force winds are still possible along portions of the Florida east coast by the early to middle part of next week. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. There is an increasing risk of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina during the middle of next week. Residents in these areas should continue to monitor the progress of Dorian.
  • 4. Heavy rains, capable of life-threatening flash floods, are possible over coastal sections of the southeastern United States from Sunday through much of next week.
  • FORECAST POSITIONS AND MAX WINDS
    
    INIT  31/2100Z 26.2N  74.4W  130 KT 150 MPH 
    - Category 4 (ESE ESE Elbow Cay, Bahamas)
     
    12H  01/0600Z 26.4N  75.7W  135 KT 155 MPH 
    - Category 4 (ESE ESE Elbow Cay, Bahamas)
     
    24H  01/1800Z 26.6N  77.0W  130 KT 150 MPH 
    - Category 4 (E Man-O-War Cay, Bahamas)
     
    36H  02/0600Z 26.8N  78.0W  125 KT 145 MPH 
    - Category 4 (WSW Cross Cays, Bahamas)
     
    48H  02/1800Z 27.2N  78.5W  120 KT 140 MPH 
    - Category 4 (N Grand Bahama Island, Bahamas)
     
    72H  03/1800Z 28.3N  79.1W  110 KT 125 MPH 
    - Category 4 (ESE Cocoa Beach,  FL)
     
    96H  04/1800Z 31.0N  80.0W   95 KT 110 MPH 
    - Category 2 (ESE Jekyll Island, GA)
    
    120H  05/1800Z 34.0N  77.0W   85 KT 100 MPH 
    - Category 2 (ESE Carolina Beach, NC)

Hurricane Dorian Projected Florida Landfall Category 4 

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD – CHECK BACK OFTEN

Hurricane Dorian’s satellite presentation is outstanding with a distinct eye of about 15 n mi in diameter. Both NOAA and Air Force Hurricane Hunter planes have been penetrating the eye this morning and based on a blend of the flight-level and SFMR winds, the initial intensity has been adjusted upward to 130 kt in this advisory. Dorian is forecast to move over a deep layer of very warm waters, which is like high octane-fuel for hurricanes. The combination of the warm ocean and the prevailing low shear along Dorian’s path should favor some additional strengthening, but most likely the hurricane will experience some fluctuations in intensity due to eyewall replacement cycles that are difficult to predict. Beyond 3 days, as the hurricane begins to gain in latitude a gradual weakening is anticipated.

Plane fixes indicate that Dorian is moving toward the west or 280 degrees at 7 kt, steered by weak flow to the south of the ridge of high pressure over the western Atlantic. Most of the global models shift the high eastward and deepens a trough over the eastern United States beyond 2 days. This steering flow would typically favor a gradual turn of the hurricane to the northwest and north, however, there is large uncertainty in the exact location and timing of this northward turn. Although the latest guidance has shifted a little bit eastward again this morning, there are still ECMWF and GFS ensemble members that do not forecast the northward turn so soon. On this basis, NHC prefers to shift the track forecast just a little bit to the right of the previous one, and the new official forecast lies along the western edge of the guidance envelope. This will allow for further adjustments in the track during future forecast cycles.

Key Messages:

  • 1. A prolonged period of life-threatening storm surge and devastating hurricane-force winds are expected in portions of the northwestern Bahamas, particularly on the Abaco Islands and Grand Bahama Island. A hurricane warning is in effect for these areas, and residents should listen to advice given by local emergency officials and have their hurricane preparations completed today.
  • 2. Life-threatening storm surge and dangerous hurricane-force winds are still possible along portions of the Florida east coast by the early to middle part of next week, but since Dorian is forecast to slow down and turn northward near or just offshore of the coast, it is too soon to determine when or where the highest surge and winds could occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. The risk of strong winds and dangerous storm surge is increasing along the coasts of Georgia, South Carolina, and North Carolina during the middle of next week. Residents in these areas should continue to monitor the progress of Dorian.
  • 4. Heavy rains, capable of life-threatening flash floods, are expected over portions of the Bahamas and coastal sections of the southeastern United States this weekend through much of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  31/1500Z 26.0N  73.4W  130 KT 150 MPH 
- Category 4 (ENE Crossing Rocks, Bahamas)
 
12H  01/0000Z 26.2N  74.7W  135 KT 155 MPH 
- Category 4 (ENE Crossing Rocks, Bahamas)
 
24H  01/1200Z 26.6N  76.2W  130 KT 150 MPH 
- Category 4 (ESE ESE Elbow Cay, Bahamas)
 
36H  02/0000Z 26.8N  77.4W  125 KT 145 MPH 
- Category 4 (ESE Coopers Town, Bahamas)
 
48H  02/1200Z 27.0N  78.0W  120 KT 140 MPH 
- Category 4 (E Great Sale Cay, Bahamas)
 
72H  03/1200Z 28.0N  79.0W  115 KT 130 MPH 
- Category 4 (ESE Palm Bay, FL)
 
96H  04/1200Z 30.5N  80.0W  100 KT 115 MPH 
- Category 4 (ESE Fernandina Beach, FL)

120H  05/1200Z 33.5N  78.0W   95 KT 110 MPH 
- Category 2 (ESE Myrtle Beach)

NWS National Hurricane Center Miami FL 500 AM EDT Sat Aug 31, 2019

Hurricane Dorian Projected Florida Landfall Category 4 – 

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD – CHECK BACK OFTEN

Hurricane Dorian continues to look impressive in satellite imagery this morning, with a fairly symmetric area of cold cloud tops surrounding a 10-15 n mi wide eye. There have been no new aircraft data from the storm since the last advisory. However, the satellite appearance has changed little since the aircraft were last in the storm, and the various subjective and objective satellite intensity estimates have changed little over the past several hours. Based on this, the initial intensity remains 120 kt.

The initial motion is now 290/10. A low- to the mid-level subtropical ridge to the north of the hurricane should steer it west- northwestward to westward for the next 48 h or so, with the forward speed becoming very slow as the center passes near or over the Abacos and Grand Bahama. The track guidance for this part of the track is tightly clustered, and the new forecast track is near the ECMWF, UKMET, and HCCA corrected consensus models. The track forecast becomes much more problematic after 48 h. The global models the NHC normally uses, along with the regional HWRF and HMON models, have made another shift to the east to the point where none of them forecast Dorian to make landfall in Florida. However, the UKMET ensemble mean still brings the hurricane over the Florida peninsula, as do several GFS and ECMWF ensemble members. The new track forecast for 72-120 h will be moved eastward to stay east of the coast of Florida, and it lies between the old forecast and the various consensus models. Additional adjustments to the forecast track may be necessary later today if current model trends continue. It should be noted that the new forecast track does not preclude Dorian making landfall on the Florida coast, as large portions of the coast remain in the track cone of uncertainty. Also, significant impacts could occur even if the center stays offshore.

Dorian should remain in a generally favorable environment for the next 3-4 days, and the intensity guidance indicates it will remain a powerful hurricane during this time. The new intensity forecast calls for a little more strengthening today, then it shows a slow weakening that follows the trend of the intensity guidance. During this time, the biggest intensity changes may come from hard-to- forecast eyewall replacement cycles. Late in the forecast period, increased vertical shear and proximity to land is expected to cause some weakening.

Key Messages:

  1. 1. A prolonged period of life-threatening storm surge and devastating hurricane-force winds are likely in portions of the northwestern Bahamas, particularly on the Abaco Islands and Grand Bahama Island. A hurricane warning is in effect for these areas, and residents should listen to advice given by local emergency officials and have their hurricane preparations completed today.
  2. 2. Life-threatening storm surge and devastating hurricane-force winds are still possible along portions of the Florida east coast by the early to middle part of next week, but since Dorian is forecast to slow down and turn northward near the coast, it is too soon to determine when or where the highest surge and winds will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  3. 3. The risk of strong winds and life-threatening storm surge is increasing along the coasts of Georgia and South Carolina during the middle of next week. Residents in those areas should continue to monitor the progress of Dorian.
  4. 4. Heavy rains, capable of life-threatening flash floods, are expected over portions of the Bahamas and coastal sections of the southeastern United States this weekend through much of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  31/0900Z 25.8N  72.6W  120 KT 140 MPH 
- Category 4 (ESE Crossing Rocks, Bahamas)
 
12H  31/1800Z 26.1N  74.0W  125 KT 145 MPH 
- Category 4 (ESE Little Harbor,  Bahamas)
 
24H  01/0600Z 26.5N  75.8W  125 KT 145 MPH 
- Category 4 (ESE ESE Elbow Cay, Bahamas)
 
36H  01/1800Z 26.7N  77.2W  125 KT 145 MPH 
- Category 4 (ESE Whale Cay, Bahamas)
 
48H  02/0600Z 26.9N  78.1W  120 KT 140 MPH 
- Category 4 (E Little Abaco Island, Bahamas)
 
72H  03/0600Z 27.5N  79.4W  115 KT 130 MPH 
- Category 4 (ESE Vero Beach, Fl)
 
96H  04/0600Z 29.5N  80.5W  110 KT 125 MPH 
- Category 4 (ESE Flagler Beach, FL)

120H  05/0600Z 32.0N  80.5W   95 KT 110 MPH 
- Category 2 (Hilton Head Island, SC)

NWS National Hurricane Center Miami FL 1100 PM EDT Fri Aug 30,  2019

Hurricane Dorian Projected Florida Landfall Category 4 – (see Friday 11:00 pm video)

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD – CHECK BACK OFTEN

The cloud pattern of Dorian has become quite impressive in infrared satellite imagery this evening. The eye has become very distinct and is surrounded by a very symmetric ring of deep convection. The upper-level outflow has also improved. A NOAA Hurricane Hunter aircraft this evening has measured peak SFMR winds of 119 kt, and a dropsonde dropped in the northeastern eyewall had mean winds in the lowest 150 m that also supported winds of 118 kt, so the initial wind speed has been raised to 120 kt. The latest center drop indicates a minimum pressure of around 948 mb, down 22 mb since this afternoon. Since Dorian will be traversing SSTs of around 29C and remain in a low shear environment, the current intensification phase may not be over. The NHC forecast is above the guidance and calls for some additional strengthening in the short-term. After that, fluctuations in intensity are likely due to eyewall replacement cycles that are difficult to predict. Although some decrease in wind speed could occur when Dorian slows down and causes some upwelling, all indications are that Dorian will remain an extremely powerful hurricane for the next several days.

The hurricane is moving west-northwestward or 300 degrees at 9 kt. The ridge to the north of Dorian is expected to build during the next 24 hours, and this should cause Dorian’s heading to bend westward toward the northwestern Bahamas. After 48 hours, the global models show an erosion of the western portion of the ridge, which is expected to cause the steering currents to collapse and the hurricane to slow down considerably by day 3. Later in the period, the models have again trended to a more significant weakness in the ridge which allows Dorian to turn northwestward, then northward near the east coast of Florida. Although the deterministic versions of the global models have trended northeastward again, the GFS and UKMET ensemble means are farther to the left. The updated NHC track forecast has been nudged northeastward and lies between the multi-model consensus aids and the aforementioned ensemble means. Although the official forecast track has been nudged northeastward to near the east coast of Florida the risk of significant impacts over much of the Florida peninsula remains high.

Key Messages:

  • 1. A prolonged period of life-threatening storm surge and devastating hurricane-force winds are likely in portions of the northwestern Bahamas, where a hurricane warning is in effect. Residents should execute their hurricane plan and listen to advice given by local emergency officials.
  • 2. Life-threatening storm surge and devastating hurricane-force winds are possible along portions of the Florida east coast by early next week, but since Dorian is forecast to slow down and turn northward near the coast, it is too soon to determine when or where the highest surge and winds will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. A prolonged period of storm surge, high winds, and rainfall is possible in portions of Florida into next week, including the possibility of hurricane-force winds over inland portions of the Florida peninsula.
  • 4. Heavy rains, capable of life-threatening flash floods, are expected over portions of the Bahamas and coastal sections of the southeastern United States this weekend through much of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 25.5N  71.4W  120 KT 140 MPH 
- Category 4 (Spanish Wells, Bahamas)

 12H  31/1200Z 25.9N  72.8W  130 KT 150 MPH 
- Category 4 (ESE Elbow Cay, Bahamas)

 24H  01/0000Z 26.3N  74.5W  130 KT 150 MPH 
- Category 4 (ENE Elbow Cay, Bahamas)

 36H  01/1200Z 26.6N  76.0W  125 KT 145 MPH 
- Category 4 (ENE Elbow Cay, Bahamas)

 48H  02/0000Z 26.8N  77.3W  125 KT 145 MPH 
- Category 4 (ESE Crab Cay, Bahamas)

 72H  03/0000Z 27.0N  78.6W  115 KT 130 MPH 
- Category 4 (W Great Sale Cay, Bahamas)

 96H  04/0000Z 28.3N  80.5W  110 KT 125 MPH 
- Category 3 (ESE Cocoa Beach, Fl)

120H  05/0000Z 30.8N  81.2W   90 KT 105 MPH 
- Category 2 (ESE Cumberland Island, Georgia)

NWS National Hurricane Center Miami FL 500 PM EDT Fri Aug 30, 2019

Hurricane Dorian Projected Florida Landfall Category 4 – 

NOTE: VIDEOS WILL BE UPDATED THROUGHOUT THE STORM AS NEW VIDEOS UPLOAD – CHECK BACK OFTEN

High-resolution satellite images show that Dorian’s cloud pattern has become much better organized, with a distinct eye surrounded by a ring of very deep convection and fair upper-level outflow. Satellite intensity estimates, both objectivs from CIMMS and subjective from TAFB and SAB, are in good agreement with the 100-kt winds recently measured by a reconnaissance aircraft. This is the intensity assigned to Dorian in this advisory.

Since the upper-level environment is already becoming more favorable for intensification and Dorian will be over high sea surface temperatures, the NHC forecast calls for additional intensification. Dorian is expected to be an extremely dangerous major hurricane as it moves through the northwestern Bahamas and near the east coast of the Florida peninsula in about 2 to 4 days.

The ridge over the western Atlantic appears to be already building to the north of Dorian and is beginning to force the hurricane on a more west-northwest track or 300 degrees at 9 kt. The ridge is forecast to build even more and steer Dorian on a westward track for the next 3 to 4 days. However, the steering currents will then weaken, and this should result in a decrease in the hurricane’s forward speed. Given the collapse of the steering currents, the track forecast by the end of the forecast period is highly uncertain, and any small deviation in the track could bring the core of the powerful hurricane well inland over Florida, keep it near the coast, or offshore. The models have not been very consistent from run to run in terms of the timing of the northward turn, but there are more models now indicating that the turn could occur near the east coast of Florida instead of well inland. Given this latest change, the NHC forecast has been shifted just a little to the right at this time, but users should be prepared for additional adjustments to the left or right depending on future model trends. Based on the new forecast, a hurricane warning has been issued for portions of the northwest Bahamas. However, given the slower forecast speed of Dorian, it is too soon to issue and watches for the Florida coast at this time.

Key Messages:

  • 1. Life-threatening storm surge and devastating hurricane-force winds are likely in portions of the northwestern Bahamas, where a hurricane warning is in effect. Residents should execute their hurricane plan and listen to the advice given by local emergency officials.
  • 2. Life-threatening storm surge and devastating hurricane-force winds are likely along portions of the Florida east coast by early next week, but since Dorian is forecast to slow down and turn northward near the coast, it is too soon to determine when or where the highest surge and winds will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to the advice given by local emergency officials.
  • 3. A prolonged period of storm surge, high winds and rainfall is possible in portions of Florida into next week, including the possibility of hurricane-force winds over inland portions of the Florida peninsula.
  • 4. Heavy rains, capable of life-threatening flash floods, are expected over portions of the Bahamas and coastal sections of the southeastern United States this weekend through much of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 25.0N  70.7W  100 KT 115 MPH 
- Category 3 (ENE Authur's Town, Bahamas)
 
12H  31/0600Z 25.6N  72.0W  105 KT 120 MPH 
- Category 3 (ENE North Palmetto Point, Bahamas)
 
24H  31/1800Z 26.2N  73.8W  110 KT 125 MPH 
- Category 3 (ESE Elbow Cay, Bahamas)
 
36H  01/0600Z 26.5N  75.4W  115 KT 130 MPH 
- Category 4 (ENE Elbow Cay, Bahamas)
 
48H  01/1800Z 26.8N  76.9W  120 KT 140 MPH 
- Category 4 (WNE Cooper's Town. Bahamas)
 
72H  02/1800Z 27.0N  78.8W  120 KT 140 MPH 
- Category 4 (ENE West End, Bahamas)
 
96H  03/1800Z 27.5N  80.4W  120 KT 140 MPH 
- Category 4 (WNW St. Lucie, Fl)

120H  04/1800Z 30.0N  81.5W   85 KT 100 MPH 
- Category 2 (ESE St. Johns, FL)

NWS National Hurricane Center Miami FL 1100 AM AST Fri Aug 30, 2019

Hurricane Dorian Projected Florida Landfall Category 4 – 

Both Air Force and NOAA aircraft have been sending data from Dorian this morning. The flight-level winds from both planes have peaks at 100 kt and the SFMR measured 94 kt. The minimum central pressure has been oscillating between 972 and 976 mb. On this basis, the initial intensity has been set to 95 kt. The upper-low currently over Cuba which has been inducing some shear over Dorian is moving away from the hurricane, and the upper-level flow pattern is evolving toward a more favorable environment. In fact, the eye is becoming apparent on visible images as we speak and in radar data from the NOAA P3 aircraft. Consequently, the NHC forecast calls for additional intensification, and Dorian is expected to become an extremely dangerous major hurricane soon with additional strengthening likely as it heads for the northwestern Bahamas and the Florida peninsula.

Fixes from both reconnaissance planes indicate that Dorian is moving toward the northwest of 310 degrees at 9 kt. As the upper-low over Cuba moves westward and a strong subtropical ridge builds over the western Atlantic as indicated by global models, the hurricane should be forced to turn west-northwestward and westward on a track toward the northwestern Bahamas and the Florida peninsula. By the end of the forecast period, the ridge is forecast to erode and the steering currents will weaken, resulting in Dorian slowing down considerably near and over the Florida peninsula. This increases the uncertainty in the track forecast during the 4- to -5 day period, and also will lead to a prolonged duration of wind, storm surge, and rainfall. The official forecast has been very consistent so far, and this one is very similar to the previous NHC forecast. It follows the multi-model and corrected consensus, and is in the middle of the guidance envelope.

Key Messages:

  • 1. Life-threatening storm surge and devastating hurricane-force winds are likely in portions of the northwestern Bahamas, where a hurricane watch is in effect. Residents should execute their hurricane plan and listen to advice given by local emergency officials.
  • 2. Life-threatening storm surge and devastating hurricane-force winds are likely along portions of the Florida east coast by early next week, but it is too soon to determine where the highest storm surge and winds will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. A prolonged period of storm surge, high winds and rainfall is likely in portions of Florida into next week, including the possibility of hurricane-force winds over inland portions of the Florida peninsula.
  • 4. Heavy rains are expected over portions of the Bahamas, Florida, and elsewhere in the southeastern United States this weekend into the middle of next week.\
FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 24.5N  69.8W   95 KT 110 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands)
 
2H  31/0000Z 25.3N  71.0W  105 KT 120 MPH 
- Category 3 (ENE North Palmetto Point, Bahamas)
 
24H  31/1200Z 25.9N  72.7W  110 KT 125 MPH 
- Category 3 (ENE North Palmetto Point, Bahamas)
 
36H  01/0000Z 26.3N  74.5W  115 KT 130 MPH 
- Category 4 (ESE Elbow Cay, Bahamas)
 
48H  01/1200Z 26.6N  76.1W  115 KT 130 MPH 
- Category 4 (ENE Elbow Cay, Bahamas)
 
72H  02/1200Z 26.8N  78.6W  120 KT 140 MPH 
- Category 4 (ENE West End, Bahamas)
 
96H  03/1200Z 27.0N  80.4W  110 KT 125 MPH 
- Category 3 (WSW Indiantown, FL)

120H  04/1200Z 29.0N  81.5W   65 KT  75 MPH 
- Categoey 1 (WNW Paisley, FL)

NWS National Hurricane Center Miami FL 500 AM AST Fri Aug 30, 2019

Hurricane Dorian Projected Florida Landfall Category 4 

There hasn’t been a lot of new data since the Hurricane Hunter planes departed Dorian several hours ago. The convective pattern on infrared satellite imagery has been nearly steady state, although the latest Dvorak estimates from TAFB and SAB rose to T5.0/90 kt. These estimates, combined with the earlier aircraft data, support maintaining an initial intensity of 90 kt.

Dorian’s heading is very gradually turning toward the left, with the latest estimate northwestward, or 320 degrees at 10 kt. Dorian is now being steered between a mid-tropospheric high centered near Bermuda and a mid-/upper-level low located over the Bahamas. The high is expected to expand westward, with a blocking ridge becoming established over the western Atlantic during the next several days. With the exception of COAMPS-TC and HMON, the other reliable models are in excellent agreement through day 3, with Dorian turning westward south of the ridge and moving near or over the northernmost islands in the Bahamas Sunday and Monday. After day 3, steering currents collapse as a break develops in the ridge, and Dorian will likely slow down considerably as it approaches the Florida peninsula. There is more spread among the deterministic models and their ensemble members during that time, with disagreement on exactly when and where Dorian will turn northwestward and northward on days 4 and 5. That being said, the tracks of the simple and corrected consensus models on this cycle did not warrant much change to the official NHC forecast, with perhaps just a slight southward adjustment on days 3 and 4. The biggest concern will be Dorian’s slow motion when it is near Florida, placing some areas of the state at an increasing risk of a prolonged, drawn-out event of strong winds, dangerous storm surge, and heavy rainfall.

The upper-level low to the west of Dorian continues to impart some southwesterly shear over the hurricane, which has prevented it from strengthening rapidly. However, Dorian is expected to enter a more favorable upper-level environment during the next 24 hours, which should allow its structure to become more well developed. Although overall the environment ahead of the storm appears conducive for strengthening, some models (in particular the ECMWF) suggest that some northerly shear could come into play while Dorian moves through the northwestern Bahamas, and for that reason the NHC official intensity forecast is not quite as bullish as the HCCA, Florida State Superensemble, and HWRF models. Still, Dorian is forecast to become a dangerous major hurricane later and maintain that status as it heads for the northwestern Bahamas and the Florida peninsula.

Key Messages:

  • 1. A Hurricane Watch is now in effect for the northwestern Bahamas, where the risk of life-threatening storm surge and hurricane-force winds this weekend has continued to increase. Residents should begin to execute their hurricane plans and listen to advice given by local emergency officials.
  • 2. There is an increasing likelihood of a prolonged period of hazardous weather conditions that could last for a couple of days in parts of Florida early next week.
  • 3. The risk of life-threatening storm surge along portions of the Florida east coast has increased, although it is too soon to determine where the highest storm surge will occur. The risk of devastating hurricane-force winds along the Florida east coast and peninsula early next week has also increased, although it is too soon to determine where the strongest winds will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 4. Regardless of the exact track of Dorian, heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States this weekend and into the middle of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 23.8N  69.1W   90 KT 105 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands)
 
12H  30/1800Z 24.8N  70.3W  100 KT 115 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands)
 
24H  31/0600Z 25.6N  72.0W  105 KT 120 MPH 
- Category 3 (ESE Dunmore Town, Bahamas)
 
36H  31/1800Z 26.1N  73.8W  110 KT 125 MPH 
- Category 3 (ESE Elbow Cay, Bahamas)
 
48H  01/0600Z 26.4N  75.5W  115 KT 130 MPH 
- Category 4 (ESE Elbow Cay, Bahamas)
 
72H  02/0600Z 26.7N  78.3W  120 KT 140 MPH 
- Category 4 (E High Rock, Bahamas)
 
96H  03/0600Z 26.9N  80.1W  115 KT 130 MPH 
- Category 4 (E Valencia, Florida)

120H  04/0600Z 28.1N  81.4W   65 KT  75 MP 
- Category 1 (ESE Poinciana, FL)

NWS National Hurricane Center Miami FL 1100 PM AST Thu Aug 29, 2019 – Hurricane Dorian

Hurricane Dorian Projected Florida Landfall Category 4

The NOAA and Air Force Reserve Hurricane Hunter aircraft have been tag-teaming the reconaissance of Dorian tonight, providing useful information about what has changed during the past several hours. They found the pressure has dropped to about 977 mb, with recent SFMR data of about 90 kt (also supported by flight-level winds). These data are also consistent with satellite imagery that show Dorian with a larger, deeper central dense overcast than this afternoon. Thus the wind speed is raised to 90 kt on this advisory.

The initial motion is about the same as before, 325/10 kt. Dorian is expected to gradually turn to the west-northwest on Saturday, and westward on Sunday due to a building ridge over the southwestern Atlantic. While the model guidance generally shows this scenario in a broad sense, there are substantial timing differences among the guidance. The source of the uncertainty can be attributed to challenges in forecasting the strength and orientation of the mid-level ridge over the southeastern United States in a few days, along with exactly where and how large Dorian is by then. As you can imagine, with so many complex variables in play, it is no wonder the models have been having a difficult time nailing down the path of the hurricane. There’s been a notable trend on this model cycle toward a slower, more westward track beyond 36 hours, which can be seen most strongly in the GFS-based guidance. The track forecast is shifted southward beyond 36 hours, and is about 30 n mi south of the previous one at 96 h. We will see if this southward trend in the models continues after the dropsonde data collected by the G-IV gets incorporated into the 00Z models. Users are reminded to not focus on the exact forecast track, as typical forecast errors at days 4 and 5 are around 155 and 205 miles, respectively.

There is still substantial middle- and upper-level dry air on the south side of the hurricane, as shown by tonight’s G-IV mission, which has been allowing only slow strengthening during the day. As Dorian turns west-northwestward, however, shear should drop somewhat due to it moving on the northeast side of an upper-level low near the Florida Straits, and the winds aloft will no longer be pointed toward the core, which will help decrease dry air entrainment. All these changes should promote intensification while Dorian moves over the 29C waters east of Florida, so the intensity forecast is raised from the previous one, consistent with the corrected-consensus guidance. Unfortunately, I don’t see any large-scale factors that would prevent Dorian from becoming an extremely dangerous category 4 hurricane during the next few days.

Key Messages:

  • 1. The risk of life-threatening storm surge and hurricane-force winds this weekend continues to increase in the northwestern Bahamas, and hurricane watches could be issued on Friday. Residents should have their hurricane plan in place and listen to advice given by local emergency officials.
  • 2. There is an increasing likelihood of life-threatening storm surge along portions of the Florida east coast late this weekend or early next week, although it is too soon to determine where the highest storm surge will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. The risk of devastating hurricane-force winds along the Florida east coast and peninsula late this weekend and early next week continues to increase, although it is too soon to determine where the strongest winds will occur.
  • 4. Regardless of the exact track of Dorian, heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States this weekend and into the middle of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z 23.3N  68.4W   90 KT 105 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands)
 
12H  30/1200Z 24.3N  69.4W  100 KT 115 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands)
 
24H  31/0000Z 25.4N  71.1W  105 KT 120 MPH 
- Category 3 (ESE Dunmore Town, Bahamas)
 
36H  31/1200Z 26.0N  73.0W  110 KT 125 MPH 
- Category 3 (ESE Crossing Rocks, Bahamas)
 
48H  01/0000Z 26.3N  74.7W  115 KT 130 MPH 
- Category 4 (ESE Elbow Cay, Bahamas)
 
72H  02/0000Z 26.8N  77.9W  120 KT 140 MPH 
- Category 4 (E Big Jerry Cay, Bahamas)
 
96H  03/0000Z 27.0N  79.8W  120 KT 140 MPH 
- Category 4 (ESE Jupiter Island, FL)

120H  04/0000Z 27.5N  81.0W   65 KT  75 MPH 
- Category 1 (ENE YeeHaw Junction)

NWS National Hurricane Center Miami FL 500 PM AST Thu Aug 29, 2019

Hurricane Dorian Projected Florida Landfall Category 4  – There has been little overall change in the structure of Dorian today. The hurricane has several well-defined bands of convection wrapping into the center and a small central dense overcast. The small eye has not been as apparent in geostationary satellite imagery this afternoon, but the NOAA Hurricane Hunter aircraft reported concentric eyewall diameters of 4 and 22 n mi several hours ago. The latest satellite intensity estimates still support an initial intensity of 75 kt, which is also in line with the earlier SFMR data from the aircraft. The next reconnaissance aircraft is scheduled to investigate the hurricane this evening.

Dorian is moving northwestward or 325 at 11 kt. The hurricane should continue moving northwestward tonight between an upper-level low just to the west of Dorian and a mid-level ridge near Bermuda. On Friday, the ridge is forecast to begin building westward to the north of the cyclone, and this pattern is expected to cause the hurricane to turn west-northwestward. A west-northwestward to westward motion should then continue into the weekend with Dorian moving near or over the northwestern Bahamas and toward the Florida peninsula. The guidance envelope has nudged southward this cycle, with the ECMWF and HMON along the southern side, and the GFS bracketing the northern side. There has also been an increase in along-track spread or speed differences with day 5 positions among the dynamical models ranging from near the northwestern Bahamas to the northeastern Gulf of Mexico. This appears to be the result of differences in the models’ depiction of the strength or lack thereof of the western portion of the ridge by day 5. The new NHC track forecast is essentially unchanged through the first 2 to 3 days, but has been adjusted southward and somewhat slower than the previous advisory at 96 and 120 hours. Users are reminded to not focus on the exact forecast track, as typical forecast errors at days 4 and 5 are around 155 and 205 miles, respectively.

The new intensity forecast is unchanged from the previous one. Dorian will be moving through a favorable environment of low vertical wind shear and warm sea surface temperatures. This should allow for at least steady intensification, and Dorian is forecast to become major hurricane on Friday. Dorian is predicted to remain a dangerous hurricane throughout the remainder of the forecast period. The NHC intensity forecast is again near the upper end of the guidance in best agreement with the HWRF and FSSE models. The National Weather Service has begun 6-hourly upper-air soundings across portions of the mid-Atlantic and southeastern United States. Six-hourly balloons are also being launched in Bermuda and Nassau in the Bahamas. A NOAA G-IV synoptic surveillance mission is ongoing, and the data from this flight will be assimilated into the 0000 UTC model cycle.

Key Messages:

  • 1. The risk of life-threatening storm surge and hurricane-force winds this weekend continues to increase in the northwestern Bahamas, and hurricane watches could be issued there tonight or Friday. Residents should have their hurricane plan in place and listen to advice given by local emergency officials.
  • 2. There is an increasing likelihood of life-threatening storm surge along portions of the Florida east coast late this weekend or early next week, although it is too soon to determine where the highest storm surge will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. The risk of devastating hurricane-force winds along the Florida east coast and peninsula late this weekend and early next week continues to increase, although it is too soon to determine where the strongest winds will occur.
  1. 4. Regardless of the exact track of Dorian, heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States this weekend and into the middle of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 22.5N  67.7W   75 KT  85 MPH 
- Category 1 (ENE Cockburn Town, Turks and Caicos Islands)
 
12H  30/0600Z 23.8N  68.7W   90 KT 105 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
24H  30/1800Z 25.2N  70.4W  100 KT 115 MPH 
- Category 3 (E North Palmetto Point, Bahamas)
 
36H  31/0600Z 26.0N  72.3W  105 KT 120 MPH 
- Category 3 (ESE Elbow Cay, Bahamas)
 
48H  31/1800Z 26.5N  74.2W  110 KT 125 MPH 
- Category 3 (Guineamans Cay, Bahamas) 
 
72H  01/1800Z 27.0N  77.7W  115 KT 130 MPH 
- Category 4 (WNE Pensacola Island, Bahamas)
 
96H  02/1800Z 27.5N  80.0W  115 KT 130 MPH 
- Category 4 (ESE St. Lucie, FL)

120H  03/1800Z 28.1N  81.4W   65 KT  75 MPH 
- Category 1 (WSW Poinciana, Fl)

NWS National Hurricane Center Miami FL 1100 AM AST Thu Aug 29, 2019

Hurricane Dorian Projected Florida Landfall Category 4 – The small eye of Dorian has appeared intermittently in infrared satellite imagery this morning. Recent reports from a NOAA P-3 aircraft indicate that there is now a double eyewall structure, with a small inner eye only 5 n mi in diameter and a larger 25-n mi diameter outer eyewall. The minimum pressure has fallen to around 986 mb. The concentric eyewall structure is likely why the aircraft has not found any stronger winds yet in the storm, despite the decrease in central pressure. The initial intensity remains 75 kt for this advisory.

Aircraft and satellite fixes show that Dorian is moving northwestward, or 325 degrees at 11 kt. Dorian is forecast to continue moving northwestward during the next 24-36 hours between an upper-level low that will be dropping southwestward across the Florida Straits and a mid-level ridge to the northeast of the hurricane. After that time, a ridge is forecast to build to the north of Dorian, which should cause the track to bend back toward the west-northwest. The track guidance becomes more divergent beyond 72 hours, primarily due to model differences in the strength of the ridge and whether a weakness develops in the ridge late in the period. The new NHC track forecast is virtually unchanged from the previous advisory, and lies very close to the multi-model consensus. It should be noted that the ECMWF, UKMET, and HFIP corrected consensus models remain south of the official forecast. The spread of the deterministic models and the various ensemble guidance is still considerable at days 4 and 5, and it is too soon to specify where along the Florida east coast the greatest impacts could occur.

Environmental conditions consisting of warm waters and low vertical wind shear along the path of the hurricane should allow for at least steady intensification during the next 2 to 3 days. With the small inner core and favorable conditions, rapid strengthening also remains a possibility, although not likely in the very short term given the concentric eyewall structure. The updated NHC intensity forecast calls for Dorian to become a major hurricane on Friday, and shows a slightly higher peak intensity than the previous forecast. The official forecast is at the upper end of the guidance, in best agreement with the HCCA and HWRF models.

Key Messages:

  • 1. The risk of life-threatening storm surge and hurricane-force winds this weekend continues to increase in the northwestern Bahamas, and hurricane watches could be issued there tonight or Friday. Residents should have their hurricane plan in place and listen to advice given by local emergency officials.
  • 2. There is an increasing likelihood of life-threatening storm surge along portions of the Florida east coast late this weekend or early next week, although it is too soon to determine where the highest storm surge will occur. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials.
  • 3. The risk of devastating hurricane-force winds along the Florida east coast and peninsula late this weekend and early next week continues to increase, although it is too soon to determine where the strongest winds will occur.
  • 4. Regardless of the exact track of Dorian, heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States this weekend and into the middle of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  29/1500Z 21.4N  67.2W   75 KT  85 MPH 
- Category 1 (WNW San Juan, Puerto Rico)
 
12H  30/0000Z 22.9N  68.1W   85 KT 100 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
24H  30/1200Z 24.5N  69.6W  100 KT 115 MPH 
- Category 3 (ENE Cockburn Town, Turks and Caicos Islands) 
 
36H  31/0000Z 25.6N  71.4W  105 KT 120 MPH 
- Category 3 (ENE Arthur's Town, Bahamas) 
 
48H  31/1200Z 26.3N  73.4W  110 KT 125 MPH 
- Category 3 (ESE Elbow Cay, Bahamas) 
 
72H  01/1200Z 27.0N  76.9W  115 KT 130 MPH 
- Category 4 (ESE Coopers Town, Bahamas) 
 
96H  02/1200Z 27.5N  79.8W  115 KT 130 MPH 
- Category 4 (ESE St. Lucie, FL)

120H  03/1200Z 28.1N  81.5W   65 KT  75 MPH 
- Category 1 (WSW Poinciana, Fl)

NWS National Hurricane Center Miami FL 500 AM AST Thu Aug 29 2019

Hurricane Dorian  – Soon after the previous advisory was issued, Dorian appeared to have a bit of a hiccup in its structure. A dry slot was noted penetrating into the southeastern portion of the circulation, with the eye becoming cloud- and rain-filled. In fact, dropsonde data from the Air Force Reserve mission indicated that the central pressure had come back up a bit to around 991 mb. That being said, the plane still measured maximum SFMR winds between 70-75 kt, so the initial intensity is being held steady at 75 kt for this advisory.

Dorian continues northwestward, or 325 degrees at 11 kt. Confidence in the track forecast is fairly high for the first 48 hours, with Dorian expected to continue moving northwestward and then begin to turn west-northwestward between mid-level ridging to the north and a mid- to upper-level low retrograding westward across the Straits of Florida. The models, and their ensembles, continue to diverge after 48 hours and have not really budged from their respective solutions compared to yesterday. The GFS is a northern outlier from the rest of the guidance, showing a weaker ridge and bringing Dorian close to the Florida/Georgia border, while the UKMET and ECMWF models show stronger ridges and remain the southernmost solutions near South Florida. Given the spread in the guidance, the new NHC forecast blends the previous forecast with the simple multi-model consensus aids and the HCCA and Florida State Superensemble aids, and it actually ends up in a position very close to the tightly clustered global model ensemble means. The most notable change in the new forecast is that it’s a little bit slower than the previous one as Dorian approaches Florida.

Various shear analyses are indicating 10-15 kt of southwesterly shear over Dorian at the moment, but the global models show this shear diminishing within 12-24 hours. With lower shear and very warm waters, all of the intensity models forecast Dorian to begin strengthening again soon, and rapid intensification could occur. The updated NHC intensity forecast has been increased from the previous one and most closely follows the HCCA and Florida State Superensemble aids during the first day or two. After 48 hours, the official forecast is near or just above the intensity consensus, but it’s still lower than the solutions shown by the HCCA, Florida State Superensemble, and the HWRF.

Dorian is likely to reach major hurricane strength in the next day or two and is forecast to maintain that status until it reaches land. A Hurricane hunter aircrafts is currently investigating this storm system.

Key Messages:

  • 1. The risk of dangerous storm surge and hurricane-force winds later this week and this weekend continues to increase in the central and northwestern Bahamas and along the Florida east coast, although it is too soon to determine where these hazards will occur. Residents in these areas should ensure they have their hurricane plan in place and not focus on the exact forecast track of Dorian’s center.
  • 2. Heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States later this week and into early next week.
FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 20.5N  66.6W   75 KT  85 MPH 
- Category 1 (ENE Arecibo, Purto Rico)
 
12H  29/1800Z 21.9N  67.6W   85 KT 100 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
24H  30/0600Z 23.7N  69.0W   95 KT 110 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
36H  30/1800Z 25.1N  70.6W  100 KT 115 MPH 
- Category 3 (ESE Arthur's Town, Bahamas)
 
48H  31/0600Z 26.0N  72.5W  105 KT 120 MPH 
- Category 3 (ESE Elbow Cay, Bahamas)
 
72H  01/0600Z 27.0N  76.4W  110 KT 125 MPH 
- Category 3 (ESE Coopers Town, Bahamas)
 
96H  02/0600Z 27.5N  79.5W  110 KT 125 MPH 
- Category 3 (ESE Vero Beach, FL)

120H  03/0600Z 28.0N  81.5W   75 KT  85 MPH 
- Category 1 (WSW Poinciana, FL)

NWS National Hurricane Center Miami FL 1100 PM AST Wed Aug 28, 2019

Hurricane Dorian Data from an Air Force Reserve Unit Hurricane Hunter aircraft indicate that Dorian has intensified, and San Juan radar data show that the eye is becoming better defined. Based on SFMR-observed surface wind observations from the aircraft, the intensity is increased to 75 kt. Dorian should remain in an environment of low shear, within a moistening mid-level air mass, and over SSTs near 29 deg C for the next several days. This should allow for Dorian to intensify into a major hurricane. The official intensity forecast is similar to the previous one, and close to the latest DSHIPS model output. The initial motion estimate remains northwestward, or 320/11 kt. Dorian should continue to move northwestward toward a weakness in the subtropical ridge over the next couple of days. Later in the forecast period, a ridge builds over the western Atlantic. This evolution of the steering pattern should cause Dorian to turn west-northwestward and head for the Florida peninsula. The actual track of the hurricane in 3 to 5 days will depend on how much the western Atlantic ridge builds during that time frame. This is, of course, subject to uncertainty. The official track forecast is very similar to the previous one, and close to the latest simple and corrected dynamical model consensus.

Key Messages:

  • 1. The risk of dangerous storm surge and hurricane-force winds later this week and this weekend continues to increase in the central and northwestern Bahamas and along the Florida east coast, although it is too soon to determine where these hazards will occur. Residents in these areas should ensure they have their hurricane plan in place and not focus on the exact forecast track of Dorian’s center.
  • 2. Heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States later this week and into early next week.
FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 19.7N  66.0W   75 KT  85 MPH 
- Category 1 (ENE San Juan, Puerto Rico)
 
12H  29/1200Z 21.0N  67.0W   80 KT  90 MPH 
- Category 1 (ENE Isabela, Puerto Rico)
 
24H  30/0000Z 22.9N  68.3W   85 KT 100 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
36H  30/1200Z 24.5N  69.9W   90 KT 105 MPH 
- Category 2 (ESE Arthur's Town, Bahamas)
 
48H  31/0000Z 25.7N  71.7W   95 KT 110 MPH 
- Category 2 (ENE North Palmetto Point, Bahamas)
 
72H  01/0000Z 27.0N  75.8W  100 KT 115 MPH 
- Category 3 (ESE Coopers Town, Bahamas)
 
96H  02/0000Z 27.8N  79.4W  100 KT 115 MPH 
- Category 3 (ENE Sebastian)

120H  03/0000Z 28.4N  81.8W   80 KT  90 MPH 
- Category 1 (WSW Kissimmee, FL)

NWS National Hurricane Center Miami FL 500 PM AST Wed Aug 28, 2019

Tropical Storm Dorian – The cloud pattern has become better organized with a hint of an eye on high-resolution satellite imagery and plenty of convective bands. In addition, earlier data from a reconnaissance plane and surface observations from St. Thomas as Dorian moved by yield an initial intensity of 70 kt. Now that the hurricane has developed an inner core with a 15 to 20 n mi eye, strengthening is more likely. Given the favorable environment of warm waters and low shear prevailing in the western Atlantic, the NHC forecast calls for a marked intensification and brings Dorian to category 3 intensity in 72 hours, and keeps it at that intensity until landfall. This forecast is very close to the intensity consensus, the HCCA model, and the SHIPS guidance.

Satellite and earlier reconnaissance plane fixes indicate that Dorian has been moving toward the northwest or 320 degrees at 12 kt. The cyclone is heading toward a weakness in the Atlantic subtropical ridge, and this northwest motion should continue for the next 24 to 48 hours. However, after that time, all the global models continue to build a strong ridge over the western Atlantic, and this flow pattern should force Dorian to turn more to the west-northwest toward Florida. All indications are that by this Labor Day weekend, a powerful hurricane will be near or over the Florida peninsula. The new NHC track forecast is a little bit to the south of the previous one, given that global models have a stronger ridge to the north and the track models show more of a westward motion. Users are reminded not to focus on the exact forecast track, as the average 5-day track error is around 200 miles.

Key Messages:

  • 1. Dangerous winds will continue in the Virgin Islands, Culebra, Vieques, and portions of Puerto Rico during the next few hours. Heavy rainfall over portions of Puerto Rico and the Virgin Islands could produce flash flooding through Thursday morning.
  • 2. The risk of dangerous storm surge and hurricane-force winds later this week and this weekend continues to increase in the central and northwestern Bahamas and along the Florida east coast, although it is too soon to determine where these hazards will occur. Residents in these areas should ensure they have their hurricane plan in place and not focus on the exact forecast track of Dorian’s center.
  • 3. Heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern United States later this week and into early next week.
FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 18.8N  65.5W   70 KT  80 MPH 
- Category 1 (ENE Luquillo, Puerto Rico)
 
12H  29/0600Z 20.1N  66.6W   75 KT  85 MPH 
- Category 1 (ENE Arecibo, Puerto Rico)
 
24H  29/1800Z 22.0N  68.0W   80 KT  90 MPH 
- Category 1 (ENE Cockburn Town, Turks and Caicos Islands)
 
36H  30/0600Z 23.8N  69.3W   85 KT 100 MPH 
- Category 2 (ENE Cockburn Town, Turks and Caicos Islands)
 
48H  30/1800Z 25.2N  71.1W   90 KT 105 MPH 
- Category 2 (ENE North Palmetto Point, Bahamas)
 
72H  31/1800Z 26.8N  75.0W  100 KT 115 MPH 
- Category 3 (ENE Copper's Town, Bahamas)
 
96H  01/1800Z 27.7N  79.0W  100 KT 115 MPH 
- Category 3 (ENE Vero Beach, FL)

120H  02/1800Z 28.2N  81.5W   85 KT 100 MPH 
- Category 1 (WSW Kissimmee, FL)

NWS National Hurricane Center Miami FL 1100 AM AST Wed Aug 28,  2019

Tropical Storm Dorian Satellite and radar images indicate that the cloud pattern has become better organized during the past several hours. This was confirmed by data from an Air Force reconnaissance plane currently investigating Dorian, which reported a flight-level wind of 72 kt and a peak SFMR value of 60 kt. The estimated central pressure was 999 mb in the last fix. On this basis the initial intensity has been adjusted upward to 60 kt. Only a slow strengthening is anticipated today while Dorian is moving through the U.S. and British Virgin Islands.

However, once the cyclone reaches the western Atlantic well east of the Bahamas, it will encounter a favorable environment of low shear and warm waters, resulting in a more marked intensification. The NHC foreast is more aggressive than the previous one, and brings Dorian to category 3 intensity by the end of the period. This forecast very closely follows the intensity consensus, the HCCA model, and the SHIPS guidance.Tropical Storm Dorian Wind Speed Projections

Fixes from the reconnaissance plane indicate that Dorian has been moving toward the northwest or 315 degrees at 11 kt. The cyclone is heading toward a weakness in the Atlantic subtropical ridge, and this motion should continue for the next 2 to 3 days. However, after that time, all global models build a robust ridge over the western Atlantic, and this flow pattern should force Dorian to turn more to the west-northwest toward Florida and the southeast coast of the United States. All indications are that by this Labor Day weekend, a powerful hurricane will be near the Florida or southeastern coast of the United States. The new NHC track forecast is not significantly different from the previous one, and it very closely follows the multi-model consensus TVCA and the HCCA. Users are reminded not to focus on the exact forecast track, as the average 5-day track error is around 200 miles.

Key Messages:

1. Hurricane conditions are expected in the U.S. and British Virgin Islands, Culebra, and Vieques today. Tropical storm conditions are expected in Puerto Rico today with hurricane conditions possible.

2. Heavy rainfall over portions of Puerto Rico and the U.S. and British Virgin Islands could produce flash flooding during the next couple of days. Heavy rains are expected to occur over portions of the Bahamas, Florida, and elsewhere in the southeastern Untied States later this week and into early next week.

3. The risk of dangerous storm surge and hurricane-force winds is increasing in the central and northwestern Bahamas and along the Florida east coast, although it is too soon to determine where these hazards will occur. Residents in these areas should ensure that they have their hurricane plan in place and not focus on the exact forecast track of Dorian’s center.

FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 17.5N  64.5W   60 KT  70 MPH - Tropical Storm (ESE USVI)
 12H  29/0000Z 18.7N  65.7W   65 KT  75 MPH - Category 1 (ENE Luquillo, Puerto Rico)
 24H  29/1200Z 20.5N  67.0W   65 KT  75 MPH - Category 1 (ENE Arecibo, Puerto Rico)
 36H  30/0000Z 22.4N  68.4W   70 KT  80 MPH - Category 1 (ENE Cockburn Town, Turks and Caicos Islands)
 48H  30/1200Z 24.2N  69.9W   75 KT  85 MPH - Category 1 (ENE Cockburn Town, Turks and Caicos Islands)
 72H  31/1200Z 26.5N  74.0W   90 KT 105 MPH - Category 2 (E Elbow Cay, Bahamas)
 96H  01/1200Z 27.7N  77.7W  100 KT 115 MPH - Category 3 (ENE Copper's Town, Bahamas)
120H  02/1200Z 28.6N  80.3W  100 KT 115 MPH - Category 3 (ENE Cape Canaveral Air Force Station, FL)

NWS National Hurricane Center Miami FL 500 AM AST Wed Aug 28, 2019

Tropical Storm Dorian  Satellite images and Doppler radar data from Puerto Rico indicate that Dorian is becoming better organized with banding features now more established on the north side of the circulation. The flight-level and SFMR winds from the Air Force Hurricane Hunters were a little higher in the most recent passes through the storm, and a blend of that data supports an initial intensity of about 50 kt. The Hurricane Hunters also reported that Dorian has developed a partial eyewall and that the minimum pressure has dropped to 1003 mb. A combination of the reconnaissance data and recent ASCAT passes were used to modify the initial wind radii, and it confirms that Dorian remains a compact and asymmetric tropical storm.

Dorian is moving northwestward at 11 kt toward a weakness in the ridge caused by a cut off mid- to upper-level low to the north of Hispaniola. This motion should continue for the next few days, taking Dorian across the Virgin Islands or the eastern portion of Puerto Rico later today and to the east of the Bahamas on Thursday and Friday. By late in the week, the steering pattern is expected to change as the models show a ridge building over the western Atlantic. The flow between the ridge and the aforementioned mid- to upper-level low should cause Dorian to turn west-northwestward and approach the southeast U.S. coast this weekend. The new NHC track forecast is adjusted a little to the right at most forecast times trending toward the latest consensus aids. However, there has been considerable run-to-run variability among the models so confidence in the long term track remains low. In addition, users are reminded not to focus on the exact forecast points as the average 5-day track error is around 200 miles.

Some additional slow strengthening seems likely today before Dorian reaches Puerto Rico and the Virgin Islands. The land interaction could end the strengthening trend or even cause some temporary weakening, however, environmental conditions favor intensification after the storm pulls northward into the southwestern Atlantic. Nearly all of the intensity models show Dorian becoming a hurricane in about 2 days, with additional strengthening beyond that time. The NHC intensity forecast is increased from the previous one, especially at the longer forecast times, to be in better agreement with the latest models. This forecast, however, is still on the lower end of the guidance envelope, so additional upward adjustments could be needed if the guidance trends persists. It is also worth noting that the global models show Dorian increasing in size by the time it nears the southeast U.S.

Key Messages:

  • 1. Tropical storm conditions are expected in the U.S. and British Virgin Islands and Puerto Rico today, and are possible in portions of the Dominican Republic tonight and Thursday. Hurricane conditions are possible in Puerto Rico and the U.S. Virgin Islands today.
  • 2. Heavy rainfall over portions of Puerto Rico and the U.S. and British Virgin Islands could produce flash flooding during the next couple of days. Heavy rains are expected to occur over portions of the Bahamas and Florida later this week and into early next week.
  • 3. The threat of tropical storm or hurricane conditions, along with storm surge, in the northwestern Bahamas and along portions of the Florida east coast have increased. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
  • 4. Uncertainty in the intensity forecast late this week remains higher than usual due to a large spread in the model guidance.
  • FORECAST POSITIONS AND MAX WINDS
    
    INIT  28/0900Z 16.8N  63.9W   50 KT  60 MPH - Tropical Storm (ESE Vieques, Puerto Rico)
     12H  28/1800Z 17.9N  65.3W   60 KT  70 MPH - Tropical Storm (ESE Vieques, Puerto Rico)
     24H  29/0600Z 19.5N  66.8W   60 KT  70 MPH - Tropical Storm (ENE Isabela, Puerto Rico)
     36H  29/1800Z 21.4N  68.2W   60 KT  70 MPH - Tropical Storm (ENE Cockburn Town, Turks and Caicos Islands)
     48H  30/0600Z 23.3N  69.6W   65 KT  75 MPH - Category 1 (ENE Cockburn Town, Turks and Caicos Islands)
     72H  31/0600Z 26.1N  73.0W   80 KT  90 MPH - Category 1 (ESE Abaco Islands, Bahaamas)
     96H  01/0600Z 27.7N  77.1W   85 KT 100 MPH - Category 2 (ESE Vero Beach, FL)
    120H  02/0600Z 29.0N  80.0W   85 KT 100 MPH - Category 2 (ESE New Smyrna Beach, Fl)

NWS National Hurricane Center Miami FL 1100 PM AST Tue Aug 27, 2019

Reports from an Air Force Hurricane Hunter aircraft indicate that Dorian is yet to strengthen, and the initial intensity remains near 45 kt. The storm’s cloud pattern remains rather ragged-looking with no clear convective banding features. Since the storm has strong upper-level outflow over the western semicircle of the circulation and vertical shear should remain low for the next day or two, strengthening is still forecast before Dorian reaches Puerto Rico on Wednesday. Some weakening is likely by 24 hours due to the interaction of the circulation with Puerto Rico. The intensity forecast in 3-5 days remains problematic because of a significant spread in the model guidance and some run-to-run inconsistencies. The official intensity forecast has been increased in comparison to the previous ones. However, it is now near the low end of the numerical guidance suite.

Dorian has turned toward the northwest, and the initial motion estimate is 310/11 kt. Over the next couple of days, the cyclone will be headed toward a weakness in the subtropical ridge. In 3-4 days, the global models show the ridge rebuilding somewhat over the western Atlantic. This scenario should cause Dorian to turn toward the left later in the forecast period. The official forecast has been shifted to the north of the previous one. This is in close agreement with the ECMWF model track, but south and southwest of the latest simple and corrected consensus predictions.

Key Messages:

  • 1. Tropical storm conditions are expected in the U.S. and British Virgin Islands and Puerto Rico on Wednesday, and are possible in portions of the Dominican Republic Wednesday night and Thursday. Hurricane conditions are possible in Puerto Rico on Wednesday.
  • 2. Heavy rainfall over portions of Puerto Rico and the Dominican Republic could produce flash flooding during the next few days. Heavy rains are expected to occur over portions of the Bahamas and Florida later this week and into early next week.
  • 3. The threat of tropical storm or hurricane conditions, along with storm surge, in the Bahamas and along portions of the Florida east coast have increased. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
  • 4. Uncertainty in the intensity forecast later this week remains higher than usual due a large spread in model guidance. storm.
FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 16.0N  63.0W   45 KT  50 MPH - Tropical Storm (ENE Basse-Terre, Guadeloupe)
 12H  28/1200Z 17.0N  64.5W   55 KT  65 MPH - Tropical Storm (ESE USVI)
 24H  29/0000Z 18.5N  66.5W   45 KT  50 MPH - Tropical Storm (ENE Mar Chiquita Beach, Puerto Rico) 
 36H  29/1200Z 20.3N  68.1W   50 KT  60 MPH - Tropical Storm (ENE Punta Cana, Dominican Republic) 
 48H  30/0000Z 22.1N  69.6W   55 KT  65 MPH - Tropical Storm (ENE Cockburn Town, Turks and Caicos Islands) 
 72H  31/0000Z 25.3N  72.7W   65 KT  75 MPH - Category 1 (E North Palmetto Point, Bahamas)
 96H  01/0000Z 27.4N  76.8W   70 KT  80 MPH - Category 1 (E Cooper's Town, Bahamas)
120H  02/0000Z 28.8N  81.0W   65 KT  75 MPH - Category 1 (W Maytown, FL)

NWS National Hurricane Center Miami FL 500 PM AST Tue Aug 27, 2019

Dorian’s convective pattern has continued to fluctuate this afternoon due to some interaction with the Windward and Leeward Islands, but mainly due to intrusions of very dry mid-level air. A 10-mile wide eye feature developed in Martinique and Guadeloupe radar data between 1500-1600 UTC and again between 1700-1800 UTC. But this feature had been short-lived due to erosion of the inner-core convection caused by dry air entrainment, although a recent burst of deep convection has developed near and over the low-level center. Dorian’s upper-level outflow has continued to expand and is very symmetrical. The initial intensity has been maintained at 45 kt based on earlier aircraft flight-level and SFMR surface wind data.

Despite the center redeveloping farther north, radar and recon fixes indicate that the motion remains west-northwestward or 300/11 kt. Due to the more northward initial position, the new forecast track was shifted 30-60 n mi northeast of the previous one track through 96 hours. The global models are in good agreement on Dorian moving west-northwestward tonight and then turning northwestward on Wednesday, bringing the cyclone’s center near or over the central or western portions of Puerto Rico. After clearing the island by early Thursday, Dorian is forecast to move cyclonically around the eastern portion of a southwestward-moving mid/upper-level low on days 3-5. The evolution of the upper-low and how strong the mid-level ridge to the north builds in behind the low and across the southeastern U.S. will determine when and how sharp Dorian’s turn back the west-northwest will occur. The new NHC track is close to a blend consensus models TVCN, HCCA, and FSSE, and brings Dorian near the east-central Florida coast in 120 hours. Users are reminded not to focus on the details of the extended track forecast as the average 5-day track error is around 200 miles.

Dry air should continue to plague Dorian for the next 24 hours or so, resulting in only slow strengthening. Land interaction with Puerto Rico should significantly weaken the small cyclone, thus the intensities were lowered at 36 and 48 hours. On days 3-5, the models continue to indicate that the upper-level flow pattern and shear conditions should favor strengthening, especially since Dorian will be moving over SSTs greater than 29 deg C and into a moist mid-level environment. The dynamical models such as the GFS, UKMET, and ECMWF are now showing more strengthening than previous runs but still remain well below the statistical SHIPS and LGEM intensity models, which bring Dorian to category 1 or 2 strength by day 5. The official intensity forecast remains a compromise between these two extremes and is close to the HCCA and FSSE consensus models. Given the large spread in the guidance, there remains lower-than-normal confidence in the intensity forecast, especially on days 4 and 5.

Key Messages:

  • 1. Tropical storm conditions are expected in the U.S. Virgin Islands and Puerto Rico on Wednesday and in portions of the Dominican Republic Wednesday night and Thursday. Hurricane conditions are possible in Puerto Rico and portions of the Dominican Republic.
  • 2. Heavy rainfall over portions of Puerto Rico and the Dominican Republic could produce flash flooding during the next few days. Heavy rains are expected to occur over portions of the Bahamas and Florida later this week and into early next week.
  • 3. The threat of tropical storm or hurricane conditions, along with storm surge, in the Bahamas and along portions of the Florida east coast have increased. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
  • 4. Uncertainty in the intensity forecast later this week remains higher than usual due to the potential for Dorian’s interaction with Puerto Rico and Hispaniola to weaken the storm.
FORECAST POSITIONS AND MAX WINDS

INIT  27/2100Z 15.3N  62.5W   45 KT  50 MPH - Tropical Storm (WSW Roseau, Dominica)
 12H  28/0600Z 16.2N  64.1W   50 KT  60 MPH - Tropical Storm (WSW USVI)
 24H  28/1800Z 17.6N  66.2W   55 KT  65 MPH - Tropical Storm (WSW Cabo Rojo, Puerto Rico)
 36H  29/0600Z 19.1N  67.8W   40 KT  45 MPH - Tropical Storm (ENE Las Galeras, Dominican Republic)
 48H  29/1800Z 20.8N  69.2W   45 KT  50 MPH - Tropical Storm (ESE Cockburn Town, Turks and Caicos Islands)
 72H  30/1800Z 24.2N  72.2W   55 KT  65 MPH - Tropical Storm (ENE Cockburn Town, Turks and Caicos Islands)
 96H  31/1800Z 26.7N  76.1W   60 KT  70 MPH - Tropical Storm (ESE Cooper's Town, Bahamas)
120H  01/1800Z 28.2N  80.6W   60 KT  70 MPH - Tropical Storm (S Patrick Airforce Base, FL)

NWS National Hurricane Center Miami FL 1100 AM AST Tue Aug 27, 2019

Dorian has moved directly across the center of St. Lucia around 1000 UTC, which resulted in a significant disruption of the small inner-core wind field. An Air Force Reserve reconnaissance aircraft had difficulty identifying a clear-cut center and radar data from Martinique indicates that the mid-level circulation has also been disrupted somewhat. Having said that, the overall appearance of the cyclone in both satellite and radar imagery has improved since this time yesterday, although a pronounced dry slot is now evident in the southeastern quadrant of the circulation.

The initial motion remains west-northwestward or 295/11 kt. There is still no significant change to the previous forecast track or reasoning. Although the inner-core wind field and the low-level center have been disrupted, the overall circulation envelope has remained intact and is expected to move west-northwestward to northwestward for the next 36-48 hours toward a break in the subtropical ridge located well north of Dorian. The mid- to upper-level low currently located east of the Bahamas that has weakened the ridge is forecast to gradually weaken while digging southeastward across the central Bahamas and toward central Cuba over the next 3-4 days, resulting in Dorian turning northwestward on day 3 before turning back toward the west-northwest on days 4 and 5. How quickly the west-northwestward turn occurs will depend heavily on the evolution of the upper-low. For now, the previous forecast track remains unchanged other than to push out the track a little northeastward at 48 and 72 hours. The NHC model guidance remains tightly packed and in good agreement on this scenario, and the new forecast track lies very close to an average of the various consensus track models. Users are reminded not to focus on the details of the extended track forecast as the average 5-day track error is around 200 miles.

Dry air continues to plague Dorian, and interaction with the mountainous terrain of St. Lucia will likely hinder significant development in the short term. However, the models continue to indicate that the upper-level flow pattern and shear conditions are expected to remain favorable for strengthening throughout the forecast period, so it is uncertain why the dynamical models are not showing more development and strengthening when compared to the more robust statistical SHIPS intensity models, especially at days 4 and 5 when Dorian will be moving over SSTs greater than 29 deg C and into a fairly moist environment. For now, the official intensity forecast remains basically midway between the stronger SHIPS model and the much weaker global and regional models. Given the large spread in the guidance, there is lower than normal confidence in the intensity forecast, especially on days 4 an 5.

Key Messages:

  • 1. Tropical storm conditions will continue in portions of the Lesser Antilles during the next several hours. Tropical storm conditions are expected and hurricane conditions are possible in Puerto Rico on Wednesday and in portions of the Dominican Republic Wednesday night and Thursday.
  • 2. Heavy rainfall over portions of the Lesser Antilles, Puerto Rico, and the Dominican Republic could produce flash flooding during the next few days.
  • 3. The threat of winds and heavy rains later this week into this weekend in the Turks and Caicos, the Bahamas, and Florida is increasing. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
  • 4. Uncertainty in the intensity forecast later this week remains higher than usual due Dorian’s potential interaction with Hispaniola and Puerto Rico.
FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 14.2N  61.8W   45 KT  50 MPH - Tropical Storm (WSW Les Trois-Îlets, Martinque)
 12H  28/0000Z 15.2N  63.4W   50 KT  60 MPH - Tropical Storm (WSW Roseau, Dominica)
 24H  28/1200Z 16.5N  65.5W   55 KT  65 MPH - Tropical Storm (WSW USVI)
 36H  29/0000Z 17.9N  67.4W   60 KT  70 MPH - Tropical Storm (WSW Cabo Rojo, Puerto Rico)
 48H  29/1200Z 19.5N  69.0W   60 KT  70 MPH - Tropical Storm (ENE Las Galeras, Dominican Republic )
 72H  30/1200Z 22.8N  72.0W   55 KT  65 MPH - Tropical Storm (ENE Pirates Well, bahamas)
 96H  31/1200Z 25.6N  76.0W   60 KT  70 MPH - Tropical Storm (ENE Dunmore Town, Bahamas)
120H  01/1200Z 27.8N  80.4W   60 KT  70 MPH - Tropical Storm (ENE North Beach, FL)

NWS National Hurricane Center Miami FL 500 AM AST Tue Aug 27, 2019

Dorian passed over Barbados a few hours ago and it is now very near the Windward Islands. Data from the Air Force Hurricane Hunters earlier this morning suggest that the storm has held steady in intensity with a blend of the flight-level and SFMR winds supporting a wind speed of 45 kt. The Caribbean composite radar data show that Dorian remains a very compact system and that it still lacks a well-defined inner core.

Dry air in the mid-levels of the atmosphere around Dorian has been causing the storm to remain in a fairly steady state during the past day or so despite relatively low wind shear conditions and warm SSTs. The models show this dry air persisting in the vicinity of the system while it tracks across the Caribbean during the next day or two, so it seems likely that Dorian will continue to only gradually intensify during that time. When Dorian nears Hispaniola in 36 to 48 hours, there will likely be some increase in wind shear and those less favorable winds aloft and the interaction with the landmasses of Puerto Rico and Hispaniola should cause considerable weakening. Once the system moves north of the Greater Antilles, the environmental conditions become more favorable for intensification, and most of the intensity guidance responds by showing an increase in winds. However, there remains considerable uncertainty for this part of the forecast because the future intensity of Dorian will be quite dependent on how much land interaction there is with the mountainous island of Hispaniola. The NHC intensity forecast lies near the upper end of the guidance in the short term, while the system is over the Caribbean Sea, but near the middle of the guidance envelope after that.Tropical Storm Dorian Wind Probabilities

The storm is moving west-northwestward at 11 kt steered by a subtropical ridge to the north. This general motion should continue for another 12 to 24 hours taking Dorian across the eastern Caribbean Sea. After that time, a slight turn to the northwest is likely when the cyclone nears the eastern portion of a cut off mid- to upper-level low and moves toward a weakness in the ridge. This should take Dorian across the Dominican Republic and the Mona Passage and over the Bahamas in the 3 to 4 day time period. A ridge is likely to rebuild to the north of Dorian when it is forecast to be over the Bahamas and that could cause it to turn slightly to the left by the end of the forecast period. The new NHC track forecast is largely unchanged while Dorian is in the Caribbean, but it has been shifted slightly to the north thereafter. Users are reminded not to focus on the details of the extended track forecast as the average 5-day track error is around 200 miles.

Key Messages:

  • 1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles during the next several hours, where tropical storm watches and warnings are in effect. Rainfall of 3 to 6 inches is expected from Martinique to St. Vincent with isolated totals as high as 10 inches possible.
  • 2. Tropical storm conditions are expected and hurricane conditions are possible in Puerto Rico on Wednesday, where a tropical storm warning and hurricane watch have been issued. Rainfall of 2 to 4 inches with maximum totals of 6 inches are possible across Puerto Rico and St. Croix.
  • 3. Hurricane and Tropical Storm Watches have been issued for portions of the Dominican Republic.
  • 4. While uncertainty remains high, wind and rain impacts are possible in the Bahamas and Florida later this week and this weekend. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 13.5N  60.7W   45 KT  50 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 12H  27/1800Z 14.4N  62.3W   50 KT  60 MPH - Tropical Storm (WSW Les Trois-Îlets, Martinique)
 24H  28/0600Z 15.7N  64.5W   55 KT  65 MPH - Tropical Storm (ESE Basse-Terre, Guadeloupe, Dominica)
 36H  28/1800Z 17.0N  66.5W   60 KT  70 MPH - Tropical Storm (S Ponce, Puerto Rico)
 48H  29/0600Z 18.5N  68.2W   60 KT  70 MPH - Tropical Storm (E Punta Cana, Dominican Republic)
 72H  30/0600Z 21.7N  71.4W   50 KT  60 MPH - Tropical Storm (ESE East Caicos,Turks and Caicos)
 96H  31/0600Z 24.7N  75.1W   60 KT  70 MPH - Tropical Storm (ENE Arthur's Town, Bahamas)
120H  01/0600Z 27.1N  79.6W   60 KT  70 MPH - Tropical Storm (ESE Port St. Lucie, FL)

NWS National Hurricane Center Miami FL 1100 PM AST Mon Aug 26, 2019

An Air Force Reserve Unit Hurricane Hunter aircraft has been investigating Dorian this evening. Data from the plane indicate that the storm is not quite as strong as previously estimated, and based on flight-level winds and SFMR-observed surface winds the intensity is set at 45 kt. Fixes from the aircraft show that the center of the cyclone moved just south of the southern coast of Barbados within the last couple of hours, and tropical-storm-force winds were reported over that island. There is fairly well-defined upper-level outflow over the eastern semicircle of the circulation. Although some dry mid-level air is likely to continue to affect Dorian while it moves over the northeastern Caribbean, the dynamical guidance indicates that the shear will not become very strong. Therefore it is still expected that the cyclone will become a hurricane in a couple of days. Some disruption of the system will likely occur when the center moves near eastern Hispaniola. The official intensity forecast is on the high end of the model guidance and is subject to considerable uncertainty, particularly from days 3 to 5.

Dorian continues to move west-northwestward, or 290/11 kt, while being steered by the flow on the south side of the subtropical ridge. In a day or two, the tropical cyclone is expected to turn northwestward due to a weakness in the ridge. The ridge is expected to build somewhat later in the forecast period, which should cause Dorian to turn slightly to the left. The ECMWF model is near the northern side of the guidance suite and the UKMET is near the southern side. The GFS model continues to practically dissipate the system so it was unable to generate a forecast track. The official track forecast was shifted a bit to the north, but lies south of the latest dynamical model consensus. It is advisable that one not focus on small changes in the forecast track due to uncertainties.

Key Messages:

  • 1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles through Tuesday morning, where tropical storm watches and warnings are in effect. Rainfall of 3 to 8 inches is expected from Martinique to St. Vincent, including Barbados, with isolated totals as high as 10 inches possible.
  • 2. Tropical storm conditions are possible in Puerto Rico on Wednesday, where a tropical storm watch has been issued. Rainfall of 2 to 4 inches with maximum totals of 6 inches are possible across Puerto Rico and St. Croix.
  • 3. Watches will likely be issued for portions of Hispaniola early Tuesday, as the threat of wind and rain impacts continues to increase.
  • 4. While uncertainty is high, wind and rain impacts are possible in the Bahamas and Florida later this week and this weekend. Residents in these areas should monitor the progress of Dorian and ensure that they have their hurricane plan in place.
FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 13.2N  59.7W   45 KT  50 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 12H  27/1200Z 14.0N  61.3W   50 KT  60 MPH - Tropical Storm (WSW Vieux Fort, Saint Lucia)
 24H  28/0000Z 15.2N  63.5W   55 KT  65 MPH - Tropical Storm (WSW Roseau, Dominica)
 36H  28/1200Z 16.5N  65.5W   60 KT  70 MPH - Tropical Storm (ESE Guayama, Puerto Rico)
 48H  29/0000Z 17.9N  67.6W   65 KT  75 MPH - Category 1 (Isla de Mona, Puerto Rico)
 72H  30/0000Z 21.0N  71.0W   50 KT  60 MPH - Tropical Storm (ESE Balfour Town,Turks and Caicos)
 96H  31/0000Z 24.0N  74.8W   55 KT  65 MPH - Tropical Storm (W Cockburn Town, Bahamas)
120H  01/0000Z 26.5N  79.0W   60 KT  70 MPH - Tropical Storm (W Bain Town, Bahamas)

NWS National Hurricane Center Miami FL 1100 AM AST Mon Aug 26, 2019

Satellite imagery indicates that Tropical Storm Dorian’s convective and outflow pattern have continued to improve, with a narrow poleward outflow channel now apparent in water vapor images. Passive microwave imagery has shown a persistent low-level eye-like feature along with an intermittent mid-level eyewall forming that quickly erodes due to mid-level dry air entrainment.

The initial motion is now west-northwestward or 285/12 kt. Dorian is expected to continue moving west-northwestward today through Tuesday night as the cyclone moves around the southwestern periphery of a deep-layer subtropical ridge situated to its north. On Wednesday, Dorian is forecast to turn northwestward toward a weakness in the ridge, which could allow the cyclone to pass near or between western Puerto Rico and the eastern Dominican Republic. By late Thursday and Friday, all of the model guidance indicates that the ridge will build back as an upper-level trough/low weakens and lifts out to the north, which should result in Dorian turning back toward the west-northwest in the vicinity of the Bahamas.

The intensity forecast is less straight-forward than the track forecast. Environmental conditions, except for the abundance of dry mid-level air surrounding and occasionally being entrained into Dorian’s inner-core region, would favor at least steady strengthening due to very low vertical wind shear, SSTs of at least 29C, and the small overall circulation and inner-core wind field. The recent development of a poleward outflow channel and possible development of an equatorward channel would also support strengthening. However, until Dorian closes off a solid eyewall, only slow strengthening is likely. Anticipating when an eye will form is challenging, but Dorian could be a hurricane by the time it reaches the Windward Islands. The intensity forecast has been adjusted upward form the previous advisory but is not as high as the statistical-dynamical SHIPS and LGEM intensity models. Interaction with Hispaniola and possibly Puerto Rico should result in some weakening in 72-96 hours, followed by restrengthening on day 5 when Dorian will be moving over the very warm waters in the Bahamas in low shear conditions. Given the unknown degree of interaction with Hispaniola, the intensity forecast at days 4 and 5 is of very low confidence.

Key Messages:

  • 1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles tonight and Tuesday, where tropical storm watches and warnings are in effect. Hurricane conditions are also possible in portions of the Windward Islands, and a hurricane watch has been issued for St. Lucia. Residents in these areas should refer to advice from local government officials and products from their local meteorological service for additional information.
  • 2. Dorian is expected to produce 3 to 8 inches of rainfall from Martinique to St. Vincent, including Barbados, with isolated totals as high as 10 inches in portions of the northern Windward Islands.
  • 3. The risk of direct impacts from wind and rainfall has increased for Puerto Rico and Hispaniola. Interests in those areas should monitor the progress of Dorian and tropical storm or hurricane watches will likely be required later today.
  • 4. Any potential impacts from Dorian in the Bahamas and Florida later this week are highly uncertain, given the potential for the system to interact with the high terrain of Hispaniola.
FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 12.3N  57.7W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 12H  27/0000Z 12.9N  59.4W   55 KT  65 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 24H  27/1200Z 13.9N  61.4W   60 KT  70 MPH - Tropical Storm (WSW Vieux Fort, Saint Lucia)
 36H  28/0000Z 15.1N  63.5W   65 KT  75 MPH - Category 1 (WSW Roseau, Dominica)
 48H  28/1200Z 16.4N  65.6W   70 KT  80 MPH - Category 1 (ESE Guayama, Puerto Rico)
 72H  29/1200Z 19.2N  69.3W   70 KT  80 MPH - Category 1 (Anadel, Dominican Republic)
 96H  30/1200Z 22.0N  72.6W   40 KT  45 MPH - Tropical Storm (WNW Wheeland, Turks and Caicos Islands_
120H  31/1200Z 24.8N  76.5W   45 KT  50 MPH - Tropical Storm (WNW Freetown, Bahamas)

NWS National Hurricane Center Miami FL 500 AM AST Mon Aug 26, 2019

Tropical Storm Dorian  Satellite images indicate that deep convection associated with Tropical Storm Dorian continues to fluctuate curtailing significant strengthening likely due to intrusions of dry air. The overall trend, however, suggests that Dorian is gradually getting better organized with its cloud pattern consisting of a compact central dense overcast and some broken outer bands. The initial intensity is nudged up to 50 kt based on a blend of the satellite intensity estimates. Dorian remains a small storm with its tropical-storm-force winds estimated to extend no more than 40 n mi from the center.

During the next couple of days, as Dorian moves through the Windward Islands and across the eastern Caribbean, slow strengthening seems likely due to low wind shear conditions and high SSTs. However, the surrounding dry air around the cyclone should continue to limit the rate of intensification. When Dorian approaches Hispaniola in about 3 days, the models show an increase in shear and those stronger environmental winds and the potential interaction with the rugged terrain of Hispaniola suggest that significant weakening is likely. The NHC intensity forecast remains between the dynamical models that show little or no strengthening and the statistical DSHP and LGEM that show significant intensification. It should be noted that the GFS and ECMWF have been very consistent in showing Dorian dissipating over the Caribbean Sea. Due to the wide range of the model solutions, the NHC intensity forecast remains of low confidence. It should be noted that compact tropical cyclones like Dorian are often challenging to predict. Dorian is moving westward at 12 kt steered by a subtropical ridge to its north. The storm should turn west-northwestward today and then northwestward on Wednesday when the cyclone gets closer to the eastern end of the mid- to upper-level low. The track models have shifted slightly to the right or north this cycle, and the NHC track forecast has been nudged in that direction.

Key Messages:

  1. 1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles, where tropical storm watches and warnings are in effect. Residents in these areas should refer to advice from local government officials and products from their local meteorological service for additional information.
  2. 2. Dorian is expected to produce 2 to 4 inches of rain in Barbados, the Windward Islands, and Dominica, with isolated amounts as high as 6 inches.
  3. 3. While it is too soon to determine the specific time or magnitude of possible direct impacts in Puerto Rico, the Virgin Islands, or Hispaniola, interests in those areas should monitor the progress of Dorian and watches could be required later today.
FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 11.9N  56.4W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 12H  26/1800Z 12.4N  58.2W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 24H  27/0600Z 13.2N  60.3W   55 KT  65 MPH - Tropical Storm (ESE Bridgetown< Barbados)
 36H  27/1800Z 14.4N  62.4W   55 KT  65 MPH - Tropical Storm (ESE Les Trois-Îlets, Martinque)
 48H  28/0600Z 15.5N  64.5W   60 KT  70 MPH - Tropical Storm (ESE Portsmouth, Dominica)
 72H  29/0600Z 18.0N  68.4W   65 KT  75 MPH - Category 1 (ESE Isla Saona, Dominican Republic)
 96H  30/0600Z 20.8N  71.6W   30 KT  35 MPH - Tropical Depression (S Big Ambergris Cay, Turks and Caicos Islands)
120H  31/0600Z 23.0N  75.0W   30 KT  35 MPH - Tropical Depression (WSW Clarence Town. Bahamas)

NWS National Hurricane Center Miami FL 1100 PM AST Sun Aug 25, 2019

Tropical Storm Dorian’s   cloud pattern hasn’t changed much since this afternoon, with deep convection oscillating up and down. There are few banding features evident, and the upper-level outflow is somewhat restricted over the eastern semicircle of the circulation. The intensity estimate remains at 45 kt and is in agreement with a recent Dvorak estimate from TAFB. The intensity forecast for this storm is a challenge, since the numerical guidance depicts a wide range of possibilities. The GFS and ECMWF global models dissipate Dorian over the Caribbean in about 4 days, probably due to the hostile environment associated with an upper-level low near Hispaniola. Another unfavorable factor could be dry air that is also forecast by the global models over the Caribbean. On the other hand, the statistical/dynamical models DSHIPS and LGEM do not weaken the system until it interacts with the land mass of Hispaniola. The official forecast is close to the intensity model consensus, IVCN, but it should be noted that there is greater than usual uncertainty associated with this forecast.

The motion continues to be slightly north of due west or 280/12. Dorian is moving along the southern side of the subtropical ridge. The track models are in good agreement that the cyclone will gradually turn toward the west-northwest on Monday. A slight weakness in the ridge near 70W longitude in a couple of days should induce a gradual turn to the northwest later in the forecast period. The official track forecast is close to the corrected consensus, HCCA prediction and is also very close to the previous NHC track.

Key Messages:

  • 1. Dorian is expected to bring tropical storm conditions to portions of the Lesser Antilles, where tropical storm watches and warnings are in effect. Residents in these areas should refer to advice from local government officials and products from their local meteorological service for additional information.
  • 2. Dorian is expected to produce 2 to 4 inches of rainfall across portions of the Lesser Antilles, with isolated amounts as high as 6 inches. 3. While it is too soon to determine the specific time or magnitude of possible direct impacts in Puerto Rico, the Virgin Islands, or Hispaniola interests in those areas should monitor the progress of Dorian.
FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 11.7N  55.3W   45 KT  50 MPH - Tropical Storm (ESE St Davids, Grenada)
 12H  26/1200Z 12.1N  57.0W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 24H  27/0000Z 12.8N  59.3W   55 KT  65 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 36H  27/1200Z 13.7N  61.5W   55 KT  65 MPH - Tropical Storm (WSW Vieux Fort, Saint Lucia)
 48H  28/0000Z 14.8N  63.6W   60 KT  70 MPH - Tropical Storm (WSW Roseau, Dominica)
 72H  29/0000Z 17.2N  67.6W   65 KT  75 MPH - Category 1 (WSW Ponce, Puerto Rico)
 96H  30/0000Z 19.5N  71.0W   40 KT  45 MPH...INLAND

NWS National Hurricane Center Miami FL 1100 AM AST Sun Aug 25, 2019

The convective organization of Tropical Storm Dorian has improved a little since the last advisory, as a more persistent area of central convection has formed along with increased, but ragged, outer banding. However, the various satellite intensity estimates remain clustered around 35 kt, and that remains the initial intensity.

A combination of 1-minute GOES-16 visible imagery and microwave satellite data have helped pinpoint the center, and the initial motion is 280/12. The subtropical ridge to the north of the cyclone should steer it generally westward to west-northwestward for the next 3-4 days, with a more northwestward motion possible thereafter as Dorian approaches an upper-level low-pressure area forecast to be over the north-central Caribbean. The model guidance continues the previous trend of being south of and a bit faster than the previous runs, and as a result the new forecast track is again shifted a little to the south. The new forecast lies between the previous forecast and the various consensus models. However, it is south of the forecasts of the HWRF, the UKMET, and the UKMET Ensemble mean. Additional adjustments to the track may be required on the next advisory if the current model trends continue.

While vertical wind shear is decreasing over Dorian, the cyclone still appears to be ingesting dry air based on the ragged convective pattern. Some dry air entrainment is expected to continue for the next few days, and based on this the new intensity forecast again calls for gradual strengthening through 72 h. This part of the intensity forecast is in best agreement with the SHIPS model, and it lies near the upper edge of the intensity guidance. The intensity forecast becomes low confidence after 72 h due to uncertainties in the amount of shear and land that Dorian will encounter. The new forecast calls for some weakening due to shear before Dorian moves over Hispaniola, followed by weakening to a depression due to passage over the island. However, the large range of possibilities includes both Dorian going north of Hispaniola and remaining a hurricane and the small cyclone dissipating completely over Hispaniola.

Key Messages:

  • 1. A Tropical Storm Warning has been issued for Barbados, and a Tropical Storm Watch is in effect for St. Lucia, St. Vincent, and the Grenadines. Additional watches and warnings for other portions of the Lesser Antilles could be required later today.
  • 2. It is too soon to determine the specific timing or magnitude of impacts in Puerto Rico, the Virgin Islands, or Hispaniola, but interests in those areas should monitor the progress of Dorian.
FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 11.2N  52.9W   35 KT  40 MPH - Tropical Storm (ENE Trinidad and Tobago)
 12H  26/0000Z 11.5N  54.6W   40 KT  45 MPH - Tropical Storm (ESE St Davids, Grenada)
 24H  26/1200Z 12.0N  56.9W   45 KT  50 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 36H  27/0000Z 12.7N  59.1W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 48H  27/1200Z 13.5N  61.2W   55 KT  65 MPH - Tropical Storm (WSW Vieux Fort, Saint Lucia)
 72H  28/1200Z 15.6N  65.3W   65 KT  75 MPH - Category 1 (Cité Ozanam Bâtelière,Martinique)
 96H  29/1200Z 17.5N  69.0W   60 KT  70 MPH - Tropical Storm (ESE San Pedro de Macorís, Dominican Republic)
120H  30/1200Z 20.0N  72.0W   25 KT  30 MPH - Tropical Depression (ENE Cap-Haïtien, Dominican Republic)

NWS National Hurricane Center Miami FL 1100 PM AST Sat Aug 24, 2019

Tropical Storm Dorian’s structure hasn’t changed substantially since the last advisory. Although southeasterly shear and surrounding dry air appear to be limiting convection, the most recent available microwave imagery showed that the small cyclone is maintaining well-defined convective banding. The initial intensity is still 35 kt, based primarily on the most recent TAFB Dvorak fix.

Confidence in the intensity forecast is particularly low due to a number of factors. The small size of Dorian could make it susceptible to large short-term swings in intensity (up or down). While SHIPS diagnostics suggest that the wind shear will be below 10 kt for at least the next 72 h, UW-CIMSS shear diagnostics indicate that the current shear is higher, more like 15-20 kt. And the intensity guidance spread is also notably large, further decreasing confidence in the forecast. For now, the NHC intensity forecast has not been significantly changed, and shows Dorian near hurricane strength when it approaches the Lesser Antilles in a few days. This is a little above the intensity consensus and it should be stressed that it is still too soon to pinpoint potential wind impacts across those islands, given the large uncertainty in the forecast.

The official forecast then shows Dorian maintaining hurricane strength across the northeast Caribbean, but it is certainly possible that it could be weaker, especially given the expected surrounding dry environment and a possible increase in wind shear forecast by the GFS and ECMWF models. By the end of the forecast period, the NHC intensity forecast is very close to HCCA and IVCN. An ASCAT-B overpass at 0024 UTC revealed that Dorian is moving slightly faster than previously estimated, now 280/12 kt. Unlike the intensity guidance, the track models are in quite good agreement on the track of Dorian. The tropical storm should continue moving westward to west-northwestward at a similar forward speed, steered primarily by a mid-level ridge stretching across most of the central Atlantic. The NHC forecast is nearly on top of the previous advisory and remains very near the TVCN and HCCA consensus aids.

Key Messages:

  • 1. Dorian is forecast to strengthen and could be near hurricane strength when it approaches the Lesser Antilles on Tuesday.
  • 2. It is too soon to determine the specific timing or magnitude of impacts in the Lesser Antilles, but tropical storm or hurricane watches will likely be needed for a portion of the islands on Sunday.
FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 10.9N  50.4W   35 KT  40 MPH - Tropical Storm (ENE Trinidad and Tobago)
 12H  25/1200Z 11.2N  52.0W   40 KT  45 MPH - Tropical Storm (ENE Trinidad and Tobago)
 24H  26/0000Z 11.7N  54.1W   45 KT  50 MPH - Tropical Storm (ESE St Davids, Grenada)
 36H  26/1200Z 12.5N  56.2W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 48H  27/0000Z 13.2N  58.2W   55 KT  65 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 72H  28/0000Z 15.0N  62.3W   65 KT  75 MPH - Category 1 (Cité Ozanam Bâtelière,Martinique )
 96H  29/0000Z 17.0N  66.5W   70 KT  80 MPH - Category 1 (WSW Frederiksted, USVI)
120H  30/0000Z 19.0N  70.0W   55 KT  65 MPH...INLAND

NWS National Hurricane Center Miami FL 500 PM AST Sat Aug 24, 2019

Tropical Storm Dorian – Visible and passive microwave satellite imagery indicate that the inner-core of the small cyclone has noticeably improved since the previous advisory. The depression has been upgraded to Tropical Storm Dorian on this advisory. The upper-level outflow has been improving to the northwest, but remains slightly restricted to the southeast due to some modest southeasterly vertical wind shear.

The initial motion is 280/11 kt. The latest NHC model guidance remains in excellent agreement that Dorian will generally move west-northwestward for the next 5 days around the southern periphery of the sprawling Bermuda-Azores high-pressure ridge that is located to the north of the Lesser and Greater Antilles. This motion is expected to bring Dorian through the central or northern Lesser Antilles on Tuesday, possibly as a hurricane, and then into the northeastern Caribbean Sea on Wednesday and Thursday. The official forecast track was shifted slightly north of the previous advisory track, and is close to the consensus model TVCN, which remains north of the NOAA HCCA corrected-consensus model.

The moderate to strong vertical wind shear that has been hindering the development of this system for the past several days is forecast to diminish significantly during the next 12 h, and remain near 5 kt through Tuesday. The low shear conditions, along with warm SSTs and the significantly improved small, inner-core structure, should allow for at least slow but steady strengthening despite the abundance of dry mid-level air nearby. However, the low vertical wind shear and tight inner-core wind field are also harbingers of possible rapid intensification. For now, the new intensity forecast remains conservative and similar to the previous advisory, and is above all of the available intensity guidance, including the HWRF model.

Key Messages:

1. Dorian is forecast to strengthen and could be near hurricane strength when it approaches the Lesser Antilles on Tuesday.

2. It is too soon to determine the specific timing or magnitude of impacts in the Lesser Antilles, but tropical storm or hurricane watches may be needed for a portion of the area on Sunday.

FORECAST POSITIONS AND MAX WINDS

INIT  24/2100Z 10.7N  49.1W   35 KT  40 MPH - Tropical Storm (ENE Trinidad and Tobago)
 12H  25/0600Z 11.0N  50.7W   40 KT  45 MPH - Tropical Storm (ENE Trinidad and Tobago)
 24H  25/1800Z 11.4N  52.8W   45 KT  50 MPH - Tropical Storm (ESE St Davids, Grenada)
 36H  26/0600Z 11.9N  54.9W   50 KT  60 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 48H  26/1800Z 12.7N  57.0W   55 KT  65 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 72H  27/1800Z 14.6N  61.1W   65 KT  75 MPH - Category 1 (Cité Ozanam Bâtelière,Martinique )
 96H  28/1800Z 16.5N  65.3W   75 KT  85 MPH - Category 1 (WSW Frederiksted, USVI)
120H  29/1800Z 18.4N  69.0W   70 KT  80 MPH - Category 1 (Villa Hermosa, Dominican Republic) 

NWS National Hurricane Center Miami FL 1100 AM AST Sat Aug 24, 2019

The small low-pressure system that the NHC has been tracking the past several days across the tropical Atlantic Ocean has acquired enough deep convection to be classified as a tropical depression, the fifth tropical cyclone of the 2019 hurricane season.  Two ASCAT passes between 1200-1300Z this morning indicated that the system had a closed circulation and surface winds of at least 30 kt, and that is the intensity set for this advisory. Upper-level outflow is fair to the northwest and restricted to the southeast due to moderate easterly vertical wind shear.

The initial motion estimate is 280/10 kt. The NHC model guidance is in very good agreement that the cyclone will move in a general west-northwestward direction along the southern periphery of a deep-layer ridge for the next 5 days, bring the system through the central or northern Lesser Antilles on Tuesday, and into the northeastern Caribbean Sea on Wednesday and Thursday. The official forecast track is close to the consensus model TVCN, which is a little north of the NOAA HCCA corrected-consensus model.

The small cyclone is currently experiencing easterly to southeasterly shear of about 15 kt. The shear is forecast to steadily decrease over the next 24 h and be around 5 kt in the 24-to-72-hour time period. Although the depression is expected to remain embedded in a fairly dry mid-level environment, the small overall circulation, small radius of maximum winds, low shear regime, and warm SSTs of 28.0-28.5 deg C should allow for slow but steady intensification through the 5-day period despite occasional intrusions of dry air. The NHC intensity forecast is a blend of the statistical-dynamical SHIPS and LGEM models, and the more robust HWRF model.

FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 10.4N  47.9W   30 KT  35 MPH - Tropical Deprerssion (ENE Trinidad and Tobago)
 12H  25/0000Z 10.7N  49.4W   30 KT  35 MPH - Tropical Deprerssion (ESE Charlotteville, Tobago)
 24H  25/1200Z 11.0N  51.4W   35 KT  40 MPH - Tropical Storm (ENE Charlotteville, Tobago)
 36H  26/0000Z 11.4N  53.5W   40 KT  45 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 48H  26/1200Z 12.0N  55.5W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 72H  27/1200Z 13.6N  59.3W   55 KT  65 MPH - Tropical Storm (ESE Vieux Fort, Saint Lucia)
 96H  28/1200Z 15.2N  63.1W   65 KT  75 MPH - Category 1 (WSW Portsmouth, Dominica)
120H  29/1200Z 17.1N  66.7W   75 KT  85 MPH - Category 1 (S Ponce, Puerto Rico)

NWS National Hurricane Center Miami FL 800 PM EDT Fri Aug 23, 2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Depression Chantal, located several hundred miles west of the Azores.

Satellite imagery suggests that the circulation associated with an area of low pressure located about 1100 miles east-southeast of the Windward Islands has become better defined, but the thunderstorm activity is limited at this time. Environmental conditions appear conducive for additional development, and a tropical depression is likely to form over the weekend or early next week while it moves generally westward to west-northwestward near 15 mph.

* Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high...70 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Fri Aug 23,  2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Depression Chantal, located about 765 miles west of the Azores. 2. Recent satellite wind data indicate that a low-pressure area has formed in association with a tropical wave located about 1300 miles east-southeast of the Windward Islands. Additional development of this system is possible during the next few days, and a tropical depression could form late this weekend or early next week as it moves generally westward to west-northwestward near 15 mph.

* Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Fri Aug 23, 2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on Tropical Depression Chantal, located about 765 miles west of the Azores.

Showers and thunderstorms have increased since yesterday in association with a tropical wave located about 1400 miles east-southeast of the Windward Islands. Additional slow development of this system is possible during the next few days as it moves generally westward at about 15 mph.

* Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.

If this storm system is named it will be Tropical Storm Dorian.

Article Resources:

Recent Tropical Cruise Weather:

Video: 1200 ADT Hurricane Dorian – Halifax Nova Scotia

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