Tropical Storm Elsa

Post Tropical Storm Elsa Track 1700 Hours July 9 2021
Post Tropical Storm Elsa Track 1700 Hours July 9 2021

Tropical Storm Elsa Wind Speed FieldTropical Storm Elsa – NWS National Hurricane Center Miami FL 500 PM AST Fri Jul 09, 2021 (see 5:00 pm video below)

Surface, satellite, and radar data indicate that Elsa’s deep convection remains limited to a shield north of its center and that a front extends through the center of the cyclone. For those reasons, Elsa was designated as a post-tropical cyclone at 1800 UTC. Surface observations of sustained winds a little above 40 kt were reported across portions of southern Massachusetts and the nearby waters as Elsa crossed the state, so the intensity estimate remains 45 kt.

Elsa is moving quickly just off the northeast coast of the U.S. with an initial motion estimate of 040/27 kt. A faster northeastward motion is expected tonight and on Saturday while the system remains embedded within a deep mid-latitude trough. Very little change was made to the NHC track forecast. All available guidance indicates that Elsa will gradually weaken during the next couple of days. The GFS, ECMWF, and CMC global models now indicate the cyclone will open into a trough within the next 48 h or so, and this is reflected in the NHC forecast.

It is estimated that center of Elsa made landfall along the coast of Long Island near Southampton around 1430 UTC (10:30 am EDT), and again near Watch Hill, Rhode Island near 1615 UTC (12:15 pm EDT). Elsa’s classification at the time the center crossed the coast will be determined in the post-storm analysis. It should also be noted that the landfall position had little bearing on the location or timing of the strong winds and heavy rain which were well removed from the cyclone’s center.

Since Elsa is now post-tropical and all coastal tropical storm warnings have been discontinued, this is the last NHC advisory. 

Key Messages:

  • 1. As Elsa moves off the coast of Maine through this evening, heavy rainfall could lead to considerable flash and urban flooding.
  • 2. Gusty winds will continue across portions of the southern New England coast during the next couple of hours. The post-tropical cyclone is also expected to bring gusty winds to portions of Atlantic Canada tonight and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 43.0N  69.5W   45 KT  50 MPH - Post Tropical (ESE Portsmouth, ME)
 12H  10/0600Z 46.2N  64.7W   40 KT  45 MPH - Post Tropical (ENE Moncton, NB Canada)
 24H  10/1800Z 50.3N  56.1W   40 KT  45 MPH - Post Tropical (WNW Western Island, NL Canada)
 36H  11/0600Z 54.7N  46.0W   35 KT  40 MPH - Post Tropical (WSW Nanortalik,Greenland)
 48H  11/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Fri Jul 09, 2021 

The extratropical transition of Elsa is well underway. A frontal boundary located over southern New England nearly wraps into the circulation center, and the primary area of cold cloud tops and heavy rainfall has now shifted to the northwestern portion of the cyclone. Elsa is expected to complete its extratropical transition this afternoon. Buoy and surface observations indicate that the cyclone’s intensity has changed little since early this morning. Based on those data, Elsa’s peak winds and minimum pressure remain 45 kt and 1000 mb for this advisory, respectively.

Elsa continues to move quickly northeastward or 045/27 kt. The post-tropical cyclone is forecast to continue accelerating northeastward over the next day or two as it remains embedded within deep-layer southwesterly flow. After 48 hours, the system is expected to slow before it dissipates over the north Atlantic around day 3. The track guidance remains in good agreement, but has shifted slightly southward after 24 hours and the NHC forecast has been adjusted accordingly.

Little change in strength is anticipated in the short-term as Elsa completes its extratropical transition. After that time, gradual weakening is anticipated and the wind speed forecast calls for the system to weaken below gale-force in a couple of days. The global models show the post-tropical cyclone dissipating over the north Atlantic by early next week, and the official forecast follows suit.

Key Messages:

  • 1. As Elsa moves near southern and coastal New England today, heavy rainfall could lead to considerable flash and urban flooding.
  • 2. Tropical storm conditions are expected to continue in portions of the warning area in Long Island and southern New England through this afternoon. Gusty winds are expected over portions of Atlantic Canada tonight and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 41.0N  72.1W   45 KT  50 MPH - Tropical Storm (WNW Gardner's Bay, NY)
 12H  10/0000Z 44.0N  67.7W   45 KT  50 MPH - Post Tropical (WSW Bar Harbor, ME)
 24H  10/1200Z 48.4N  60.3W   40 KT  45 MPH - Post Tropical (WSW Cape St. George, NF)
 36H  11/0000Z 52.2N  51.0W   35 KT  40 MPH - Post Tropical (WSW Blanc-Sablon, QB)
 48H  11/1200Z 56.5N  41.0W   30 KT  35 MPH - Post Tropical (ESE Nanortalik,Greenland)
 60H  12/0000Z 60.0N  32.5W   30 KT  35 MPH - Post Tropical (WSW Reykjavik,Iceland)
 72H  12/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Thu Jul 08, 2021 

Elsa has become slightly better organized this evening. Convection near the center of Elsa has deepened, and the surface pressures have fallen a few mb since this afternoon based on observations over eastern Virginia. Although there are no wind reports above 40 kt during the past several hours, recent Doppler velocity data shows stronger winds offshore of the mid-Atlantic states, so the initial wind speed will remain 45 kt.

It appears that the early stages of extratropical transition have begun with Elsa, with almost all of the deep convection north of the center. A shortwave moving out of the Great Lakes should cause the storm to deepen on Friday but also expand in size, resulting in the maximum winds staying about the same as they are now. Elsa should transition into an extratropical cyclone within 24 hours due to the shortwave and cold waters south of New England, and then gradually weaken over Atlantic Canada and northeast of Newfoundland after it loses its baroclinic support. The new intensity forecast is similar to the previous one and the consensus of the global models.

The storm is moving faster to the northeast this evening and will gradually accelerate northeastward during the next day or two due to speedy mid-latitude southwesterly flow ahead of a broad mid-tropospheric trough over the eastern North America. Elsa should move over southeastern New England and Atlantic Canada within the next 12-36 hours. The model guidance remains tightly packed on that solution, and the new official track forecast remains close to the previous one.

Key Messages:

  • 1. As Elsa moves across the eastern mid-Atlantic overnight, heavy rainfall may result in limited flash and urban flooding. Heavy rainfall across New England through Friday could lead to considerable flash and urban flooding.
  • 2. Tropical storm conditions should continue along portions of the mid-Atlantic coast overnight. Tropical storm conditions are expected in portions of the southern New England states and New York by Friday. Gusty winds are expected over portions of Atlantic Canada Friday night and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  09/0300Z 37.6N  76.5W   45 KT  50 MPH - Tropical Storm (ENE Locust Hill, VA)
 12H  09/1200Z 40.5N  72.7W   45 KT  50 MPH - Tropical Storm (ESE Bay Shore, NY)
 24H  10/0000Z 44.6N  66.9W   45 KT  50 MPH - Post Tropical (WNW Southern Head Beach, NB)
 36H  10/1200Z 49.4N  59.1W   40 KT  45 MPH - Post Tropical (WSW Trout River, NF)
 48H  11/0000Z 54.5N  48.5W   35 KT  40 MPH - Post Tropical (ENE North River,NF)
 60H  11/1200Z 58.5N  40.5W   30 KT  35 MPH - Post Tropical (ESE Nanortalik,Greenland)
 72H  12/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM EDT Thu Jul 08, 2021

A NOAA NOS observing site at Wrightsville Beach, North Carolina, recently reported a sustained wind of 41 kt, so Elsa’s maximum winds are now estimated to be 45 kt. A number of other observing sites in the vicinity have also reported sustained tropical-storm-force winds. Elsa’s slight strengthening may be the result of baroclinic forcing associated with an approaching short-wave trough. The system’s cloud tops have warmed somewhat during the day, but it is still producing some very heavy rains.

Elsa’s low-level center is a bit elongated from southwest to northeast, but surface synoptic data indicate that it has moved into northern North Carolina. The storm continues to gradually accelerate toward the northeast, and the initial motion estimate is 040/18 kt. A faster northeastward motion is expected over the next 1-2 days as the cyclone moves along with the mid-latitude southwesterly flow ahead of a broad mid-tropospheric trough over the eastern United States and Canada. Elsa should move near or over southeastern New England and Atlantic Canada within the next 24-48 hours. The official track forecast remains close to the previous one and similar to the multi-model consensus, TVCA.

The global models suggest that not much additional strengthening is likely. Simulated satellite imagery from these models show an extratropical appearance in 24-36 hours so the official forecast shows an extratropical transition by late Friday. This is also supported by cyclone phase analyses of the model fields from Florida State University.

Key Messages:

  • 1.As Elsa moves from North Carolina to Virginia today and this evening, heavy rainfall may result in limited flash and urban flooding. Heavy rainfall from the Mid-Atlantic into New England through Friday could lead to considerable flash and urban flooding.
  • 2. Tropical storm conditions should continue along portions of the North Carolina coast this afternoon and spread over the mid-Atlantic coast later today or tonight. Tropical storm conditions are expected in portions of the southern New England states and New York by Friday. Gusty winds are expected over portions of Atlantic Canada Friday night and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 36.3N  78.3W   45 KT  50 MPH - Tropical Storm (ENE Weldons Mill, NC)
 12H  09/0600Z 38.7N  75.1W   45 KT  50 MPH - Tropical Storm (WNW Dewey Beach, DE)
 24H  09/1800Z 42.5N  70.0W   45 KT  50 MPH - Tropical Storm (ESE Rockport, MA)
 36H  10/0600Z 47.0N  63.0W   45 KT  50 MPH - Post Tropical (WSW Havre-Aubert, QC)
 48H  10/1800Z 51.5N  54.5W   40 KT  45 MPH - Post Tropical (ESE St.Lunaire-Griquet, NF)
 60H  11/0600Z 56.0N  45.0W   35 KT  40 MPH - Post Tropical (ESE Nanortalik,Greenland)
 72H  11/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Thu Jul 08, 2021

Surface synoptic observations and high-resolution satellite images indicate that the center of the storm has moved into North Carolina. WSR 88-D Doppler radar data and surface reports indicate that the maximum winds are near 40 kt. These highest winds are likely occurring in some of the stronger convective bands near the coast.

Elsa is gradually accelerating toward the northeast, and the initial motion is about 040/17 kt. A faster northeastward motion is expected over the next couple of days as the cyclone becomes entrained into the mid-latitude southwesterly flow ahead of a broad mid-tropospheric trough over the eastern United States and Canada. Elsa should move near or over southeastern New England and Atlantic Canada during the next 24-48 hours. The official track forecast is basically an update of the previous one and continues to follow the multi-model consensus.

Some slight intensification is possible within the next 24-36 hours due to baroclinic forcing from a mid-latitude short wave trough. Around 36 hours, the simulated satellite imagery from the global models depicts a cloud pattern resembling that of a frontal cyclone. Moreover, the FSU phase analyses of the GFS fields shows the system becoming extratropical at that time. This is also reflected in the official forecast.

Key Messages:

  • 1. As Elsa moves across North Carolina and Virginia today, heavy rainfall may result in limited flash and urban flooding. Heavy rainfall from the Mid-Atlantic into New England through Friday could lead to considerable flash and urban flooding.
  • 2. Tropical storm conditions are expected along portions of the North Carolina coast today and the mid-Atlantic coast by this afternoon or tonight. Tropical storm conditions are expected in portions of the southern New England states and New York by Friday. Gusty winds are expected over portions of Atlantic Canada Friday night and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 35.0N  79.7W   40 KT  45 MPH - Tropical Storm (ENE Rockingham, NC)
 12H  09/0000Z 37.3N  77.0W   40 KT  45 MPH - Tropical Storm (ESE Milton, VA)
 24H  09/1200Z 40.6N  72.5W   45 KT  50 MPH - Tropical Storm (WSW Hampton Bays, NY)
 36H  10/0000Z 44.5N  67.0W   45 KT  50 MPH - Post Tropical (WSW Deep Cove, NB Canada)
 48H  10/1200Z 49.0N  59.0W   45 KT  50 MPH - Post Tropical (WSW York Harbour, NF Canada)
 60H  11/0000Z 53.5N  50.0W   40 KT  45 MPH - Post Tropical (ESE St. John's, NF Canada)
 72H  11/1200Z 59.0N  40.0W   35 KT  40 MPH - Post Tropical (WSW Aappilattoq, Greenland)
 96H  12/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Wed Jul 07, 2021 

Doppler radar and surface observations indicate that Elsa is maintaining its intensity. However, these winds aren’t close to the center but, rather, in a strong band of convection in the eastern semicircle of the storm. The current wind speed is set to 40 kt in accordance with an earlier sustained wind report of 38 kt, and radar velocities reduced to the surface that would support at least 40 kt.

Some weakening is expected overnight while a significant portion of Elsa’s circulation remains over land. However by late Thursday, more of the storm will be moving over water, and a fair number of the models suggest re-intensification could take place. It is a little puzzling why the ECMWF and UKMET models, however, are showing a strengthening tropical storm close to the mid-Atlantic states, especially without a significant trough interaction or warm waters. I’m getting some deja vu in this case after working Claudette from a few weeks ago, with those same models also over-intensifying that storm. The GFS has been relatively consistent in showing only a small intensification of Elsa, and the NHC forecast will continue to be closer to that model’s relatively weaker solution.

The storm has turned north-northeastward tonight and is moving a little faster, about 14 kt. Elsa should move northeastward at an increasing forward speed during the next few days as it becomes embedded within fast southwesterly flow ahead of a mid-latitude trough. No significant changes were made to the previous track forecast since guidance remains in good agreement. Elsa is likely to become absorbed north of Newfoundland by another extratropical low by day 4.

There is greater confidence tonight that some portion of North Carolina and the mid-Atlantic coast will receive tropical-storm force-winds, so the Tropical Storm Watch has been upgraded to a Tropical Storm Warning in those areas. Areas to the north remain less certain, and remain under a Tropical Storm Watch.

Key Messages:

  • 1. As Elsa moves across southeastern Georgia into the Lowcountry of South Carolina tonight, heavy rainfall may result in considerable flash, urban, and minor river flooding. Heavy rainfall, from North Carolina across the mid-Atlantic and into New England Thursday and Friday, could lead to isolated flash and urban flooding.
  • 2. Tropical storm conditions are expected along portions of the coasts of Georgia and South Carolina tonight. Tropical storm conditions are also expected along the coasts of North Carolina on Thursday and the mid-Atlantic by Thursday night. Tropical storm conditions are possible in the southern New England states and New York by Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 32.1N  82.3W   40 KT  45 MPH - Tropical Storm (ESE Santa Claus, GA)
 12H  08/1200Z 34.1N  80.7W   35 KT  40 MPH - Tropical Storm (ESE MeadowView, SC)
 24H  09/0000Z 37.1N  77.3W   35 KT  40 MPH - Tropical Storm (WSW Disputanta, VA)
 36H  09/1200Z 40.4N  72.9W   40 KT  45 MPH - Tropical Storm (WSW Sayville, NY)
 48H  10/0000Z 44.5N  67.0W   40 KT  45 MPH - Post Tropical (WSW Deep Cove, NB Canada)
 60H  10/1200Z 49.0N  60.0W   40 KT  45 MPH - Post Tropical (WSW York Harbour, NF Canada)
 72H  11/0000Z 54.0N  50.0W   35 KT  40 MPH - Post Tropical (ESE North River, NF Canada)
 96H  12/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM EDT Wed Jul 07, 2021

Surface synoptic data indicate that the center of Elsa has moved into extreme southern Georgia and, assuming continued weakening since earlier today, the maximum winds are estimated to be 40 kt. This may be a generous estimate of the current intensity since no surface observations of sustained tropical-storm-force winds have been recently received. Elsa should weaken into a tropical depression on Thursday. By early Friday, the dynamical models show some restrengthening of the cyclone as it moves along the Mid-Atlantic coastline. However, the simulated satellite imagery from the global models at that time depict the system resembling a frontal cyclone, so it is dubious as to whether Elsa will be completely tropical in 48 hours. Due to the uncertainty as to when extratropical transition will occur, tropical storm watches have been issued for Long Island and portions of southern New England at this time.

The initial motion is northward, or 010/12 kt. Elsa is forecast to turn north-northeastward overnight as it moves around the northwestern periphery of an Atlantic subtropical ridge while accelerating northeastward ahead of a broad mid-level trough over the eastern United States and Canada on Thursday. The official forecast is about the same as the previous one and closely follows the multi-model consensus.

Key Messages:

  • 1. Heavy rainfall may result in considerable flash, urban, and isolated moderate river flooding over northern Florida. Heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result inconsiderable flash and urban flooding across southeast Georgia and the Lowcountry of South Carolina. Heavy rainfall across the Northeast and New England Thursday and Friday could lead to isolated flash and urban flooding.
  • 2. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next day or two, tropical storm conditions are expected along portions of the coasts of Georgia and South Carolina tonight. Tropical storm conditions are also possible along the coast of the mid-Atlantic and southern New England states by Thursday night or Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 30.8N  83.4W   40 KT  45 MPH - Tropical Storm (ENE Ousley, GA)
 12H  08/0600Z 32.8N  82.1W   35 KT  40 MPH - Tropical Storm (ESE Herndon, GA)
 24H  08/1800Z 35.6N  79.4W   30 KT  35 MPH - Tropical Storm (WSW Bear Creek, NC)
 36H  09/0600Z 38.8N  75.4W   35 KT  40 MPH - Tropical Storm (ESE Ellendale, DE)
 48H  09/1800Z 42.0N  70.5W   35 KT  40 MPH - Tropical Storm (ENE Plymouth, MA)
 60H  10/0600Z 46.0N  64.5W   40 KT  45 MPH - Post Tropical (ESE Memramcook, NB, Canada)
 72H  10/1800Z 50.0N  57.0W   40 KT  45 MPH - Post Tropical (WNW Jackson's Arm, NF Canada)
 96H  11/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Wed Jul 07, 2021

Corrected Taylor County to Dixie County in the first paragraph. An Air Force

Hurricane Hunter aircraft has made several fixes in Elsa this morning, and recent observations from the plane indicated that the center is now on the coast making landfall. The aircraft found that the central pressure remained about steady with maximum winds of 55 kts up to landfall. Sustained tropical-storm-force winds are being reported from observing sites within the warning area, with an unofficial report of a sustained wind of 54 kt gusting to 62 kt at Horseshoe Beach in Dixie County, Florida during the past half hour.

Center fixes indicate that Elsa has continued northward, with a motion estimate of 360/12 kt. Elsa should turn toward the north-northeast today as it moves along the northwestern periphery of an Atlantic subtropical ridge. On Thursday, the cyclone should begin to accelerate northeastward on the southeast side of a broad mid-tropospheric trough over the eastern United States and Canada. The official track forecast is on top of the latest multi-model consensus, TVCA, solution. This is only slightly to left of the previous NHC track, and shows the center moving near the northeastern U.S. coast within the next 48 hours.

Weakening will occur while the cyclone moves over land during the next 36 hours or so, and the official intensity forecast closely resembles the decay-SHIPS guidance. Since winds of 35 kt are possible near the coast well to the southeast of the center within the next day or two, a tropical storm warning is in effect for a portion of the southeast U.S. coast. Some slight reintensification is shown when the center moves near the coast in 48-60 hours. However, since the water temperatures are rather cool near the northeast coast, strengthening will probably be influenced by baroclinic forcing associated with a 500 mb shortwave trough. The system will likely become extratropical by 72 hours if not sooner while it moves through Atlantic Canada.

Key Messages:

  • 1. As Elsa moves across the western and northern Florida Peninsula today, heavy rainfall may result in considerable flash, urban, and isolated moderate river flooding. Heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across southeast Georgia and the Lowcountry of South Carolina. Heavy rainfall across the Northeast and New England Thursday and Friday could lead to isolated flash and urban flooding.
  • 2. There is still a danger of life-threatening storm surge along portions of the west coast of Florida today, and a Storm Surge Warning is in effect for that area.
  • 3. Tropical storm conditions wile continue today across portions of the northeast Gulf coast today within the warning area.
  • 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next day or two, tropical storm conditions are expected along much of the coasts of Georgia and South Carolina. Tropical storm conditions are also possible along the coast of the mid-Atlantic states by Thursday night or Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 29.9N  83.6W   55 KT  65 MPH - Tropical Storm (WNW Fish Creek, FL)
 12H  08/0000Z 31.7N  82.9W   35 KT  40 MPH - Tropical Storm (ENE Pridgen, GA)
 24H  08/1200Z 34.3N  80.9W   30 KT  35 MPH - Tropical Storm (WSW Ridgeway, SC)
 36H  09/0000Z 37.3N  77.6W   30 KT  35 MPH - Tropical Storm (WSW Winterpock, VA)
 48H  09/1200Z 40.6N  73.3W   35 KT  40 MPH - Tropical Storm (WSW Fire Island, NY)
 60H  10/0000Z 44.5N  68.0W   40 KT  45 MPH - Tropical Storm (ENE Gouldsboro, ME)
 72H  10/1200Z 49.0N  60.9W   40 KT  45 MPH - Post Tropical (WSW Anticosti Island,QC, Can)
 96H  11/1200Z 58.0N  47.0W   35 KT  40 MPH - Post Tropical (WSW Nanortalik, Greenland)
120H  12/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Tue Jul 06, 2021

After an earlier flurry of convective bursting and even the development of a eye in radar imagery, Elsa appears to have leveled off over the past couple of hours. Between 2100 UTC and 0000 UTC, WSR-88D radars from Tampa and Key West indicated areas of average Doppler velocities of 75-85 kt between 8000-13,000 ft, which were co-located with convective bands consisting of 50 dBZ and higher reflectivity values, which equates to at least 65 kt surface winds. Elsa’s center also passed just barely to the east of Buoy 41023 around 2100 UTC, producing a sustained wind of 49 kt at 3-meters elevation, which equals a 10-meter wind speed of 55 kt on the west side of the cyclone. The strongest 850-mb flight-level wind measured by an Air Force reconnaissance aircraft so far has been 74 kt. However, radar data indicate that the aircraft just missed the strongest winds in the convection by only about 5 n mi.

The initial intensity is being held at 65 kt just in case convection redevelops around the ragged eye feature later tonight. Elsa is moving northward, or 360/12 kt. This motion should continue tonight and early Wednesday until landfall occurs across the northwestern Florida peninsula. Thereafter, a gradual turn toward the north-northeast is expected by late Wednesday, followed by some acceleration toward the northeast on Thursday as Elsa rounds the western periphery of a deep-layer subtropical ridge and gets caught up by the southwesterly flow ahead of a mid-level trough. The official track forecast lies between the simple and corrected-consensus tracks models and the previous NHC track forecast.

Elsa’s inner-core convection looks pretty ragged right now, but the vertical structure has improved based on the reconnaissance data, which indicate that the low-, middle- and upper-level circulations are nearly vertically stacked now. Elsa’s ragged eye feature along with the very warm water beneath the cyclone and the upcoming nocturnal convective maximum period could combine to allow convection to redevelop. However, proximity to dry mid-level air just to the west should prevent any significant strengthening from occurring. After landfall, rapid weakening is expected due to increased frictional effects and Elsa’s small size. The pressure gradient, however, is forecast by the GFS and ECMWF models to increase between Elsa and a sprawling surface high pressure system over the western Atlantic, which should act to increase the winds to tropical storm force near the coastal areas from Georgia to North Carolina on Wednesday and Thursday. The new NHC intensity forecast is similar to the previous advisory and follows the consensus intensity models HCCA and IVCN.

Key Messages:

  • 1. Heavy rain will impact Cuba tonight resulting in significant flooding and mudslides. As Elsa moves across the western and northern Florida Peninsula through Wednesday, heavy rainfall may result in considerable flash, urban, and minor to isolated moderate river flooding. Mid to late week, heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina.
  • 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area.
  • 3. Hurricane conditions are expected tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions southwest Florida and will continue to spread northward along the west coast of the state within the warning area through Wednesday morning.
  • 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next couple of days, tropical storm conditions are expected along much of the coasts of Georgia and South Carolina.
FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 27.3N  83.2W   65 KT  75 MPH - Category 1 (WSW Longboat Key, FL)
 12H  07/1200Z 29.0N  83.1W   60 KT  70 MPH - Tropical Storm (WSW Cedar Key, FL)
 24H  08/0000Z 31.4N  82.5W   45 KT  50 MPH - Tropical Storm (ESE Beach, GA)
 36H  08/1200Z 33.9N  80.5W   35 KT  40 MPH - Tropical Storm (ENE Wedgewood, SC)
 48H  09/0000Z 36.4N  77.4W   35 KT  40 MPH - Tropical Storm (ENE Jackson, NC)
 60H  09/1200Z 39.3N  73.3W   40 KT  45 MPH - Tropical Storm (ESE Atlantic City, NJ)
 72H  10/0000Z 42.8N  68.0W   45 KT  50 MPH - Tropical Storm (ESE Portsmouth, NH)
 96H  11/0000Z 51.0N  54.4W   45 KT  50 MPH - Post Tropical (ENE Bell Island, NF Canada)
120H  12/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM EDT Tue Jul 06, 2021 

The Hurricane Hunters completed their mission into Elsa a little while ago, and observations from the aircraft indicate that the storm’s maximum winds are near 60 kt. Elsa is a sheared tropical cyclone, with the low level center situated on the southwest edge of the main area of deep convection. Much of the western half of the circulation continues to lack significant shower or thunderstorm activity. Moderate westerly vertical shear, along with relatively dry mid-level air, should continue to affect the cyclone until landfall within the next day or so. However this environment should not be hostile enough to prevent some slight strengthening, and Elsa is predicted to become a hurricane overnight.

Elsa is moving northward, or 350/9 kt. A continued northward track is likely for the next 24 hours or so as the tropical cyclone moves between the western periphery of an Atlantic subtropical ridge and a broad low pressure area over the northwestern Gulf of Mexico. A turn toward the north-northeast along the northwestern side of the ridge is expected by late tomorrow, followed by an acceleration toward the northeast over the next couple of days ahead of a trough over the eastern United States and eastern Canada. The official track forecast is similar to the previous ones and near or slightly to the right of the model consensus tracks.

Key Messages:

  • 1. Heavy rain will impact Cuba tonight resulting in significant flooding and mudslides. As Elsa moves across the western and northern Florida Peninsula through Wednesday, heavy rainfall may result in considerable flash, urban, and minor to isolated moderate river flooding. Mid- to late-week, heavy rainfall across southeast Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina.
  • 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area.
  • 3. Hurricane conditions are expected tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Warning is in effect. Tropical storm conditions are occurring across portions of the Florida Keys and will spread northward along the west coast of the state within the warning area through Wednesday morning.
  • 4. Although the center of Elsa is expected to remain inland of the coastline from Georgia through the Carolinas during the next couple of days, tropical storm conditions are expected in a portion of southeastern Georgia and are possible elsewhere along much of the coasts of Georgia and South Carolina.
FORECAST POSITIONS AND MAX WINDS

INIT  06/2100Z 25.8N  83.0W   60 KT  70 MPH - Tropical Storm (WSW Marco Island, FL)
 12H  07/0600Z 27.5N  83.1W   65 KT  75 MPH - Category 1 (WSW St.Petersburg, FL)
 24H  07/1800Z 30.0N  82.8W   55 KT  65 MPH - Tropical Storm (WNW Fort White, FL)
 36H  08/0600Z 32.3N  81.5W   35 KT  40 MPH - Tropical Storm (WSW  Hubert, GA)
 48H  08/1800Z 34.8N  78.9W   30 KT  35 MPH - Tropical Storm (WNW Buies Neck, NC)
 60H  09/0600Z 37.4N  75.4W   35 KT  40 MPH - Tropical Storm (ENE Eastville, VA)
 72H  09/1800Z 40.5N  71.0W   40 KT  45 MPH - Tropical Storm (ESE Montauk, NY)
 96H  10/1800Z 48.5N  58.5W   40 KT  45 MPH - Post Tropical (WSW Stephenville Crossing, NF)
120H  11/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM EDT Tue Jul 06, 2021 

Elsa’s overall cloud pattern has changed little in organization since earlier today. There continues to be minimal shower and thunderstorm activity over the western semicircle of the circulation, with some bursting of deep convection near and east of the estimated center. A slightly-elevated observing site on Sand Key, near Key West Florida, recently reported a peak 1-minute wind of 49 kt with a gust to 56 kt. This supports the current intensity estimate of 50 kt. Recent WSR-88D Doppler velocities from the Key West radar suggest that the storm could be a little stronger than that. The Air Force Hurricane Hunter mission into the storm has been delayed due to bad weather at the Keesler base, but is rescheduled to investigate Elsa in a few hours. This flight should provide updated information on the intensity of the system.

Recently, the storm has been moving a little slower toward the north-northwest and the initial motion is about 340/9 kt. Elsa should move generally northward today and tonight between the western periphery of a subtropical ridge and an area of low pressure over the northwestern Gulf of Mexico. A gradual turn toward the north-northeast should occur on Wednesday as the system moves along the northwestern periphery of the ridge. Thereafter, the cyclone is expected to accelerate northeastward ahead of a trough over the eastern United States and eastern Canada. This will take the system across the southeastern United States within the next couple of days, near the coast of New England in about 3 days and near or over Atlantic Canada in 4 days or so. The official forecast is nearly the same as the previous one and, again, very close to the model consensus.

The environment over the eastern Gulf of Mexico is not ideal for strengthening, with moderate westerly shear and some dry mid-level air. However, upper-level divergence ahead of a trough over the east-central Gulf could result in some intensification of the system during the next 12-24 hours. The official forecast continues to show the cyclone nearing hurricane strength while it approaches the north Florida Gulf coast, but this is at the high end of the numerical intensity guidance.

Key Messages:

  • 1. Heavy rain will impact Cuba today resulting in significant flooding and mudslides. As Elsa moves near or along the western Florida Peninsula through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding, with considerable flash and urban flooding possible in southwest and western portions of Florida. Mid to late week, heavy rainfall across coastal Georgia, South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding, with considerable flash and urban flooding possible across coastal Georgia and the Lowcountry of South Carolina.
  • 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida tonight and Wednesday, and a Storm Surge Warning is in effect for that area.
  • 3. Hurricane conditions are possible tonight and early Wednesday along a portion of the west coast of Florida, where a Hurricane Watch is in effect. Tropical storm conditions are occurring across portions of the Florida Keys and are expected to spread northward along much of the west coast of the state through Wednesday morning, where a Tropical Storm Warning is in effect.
  • 4. A Tropical Storm Watch is in effect for the Georgia coast and portions of the South Carolina coast, where tropical storm conditions are possible late Wednesday and early Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 24.9N  82.8W   50 KT  60 MPH - Tropical Storm (WNW Key West, Fl)
 12H  07/0000Z 26.6N  82.9W   55 KT  65 MPH - Tropical Storm (WSW Cayo Costa, FL)
 24H  07/1200Z 28.9N  83.0W   60 KT  70 MPH - Tropical Storm (WNW Crystal River, FL)
 36H  08/0000Z 31.3N  82.0W   35 KT  40 MPH - Tropical Storm (WNW Raybon, GA)
 48H  08/1200Z 33.8N  80.0W   30 KT  35 MPH - Tropical Storm (ESE New Zion, SC)
 60H  09/0000Z 36.7N  76.4W   35 KT  40 MPH - Tropical Storm (WSW Chesapeake, VA)
 72H  09/1200Z 39.5N  72.5W   40 KT  45 MPH - Tropical Storm (ENE Atlantic City, NJ)
 96H  10/1200Z 48.0N  60.0W   40 KT  45 MPH - Post Tropical (WSW Doyles, NF Canada)
120H  11/1200Z...POST-TROP/EXTRATROP

NWS National Hurricane Center Miami FL 1100 PM EDT Mon Jul 05, 2021

Radar data from Cuba and Key West, Florida, along with surface observations, indicate that the center of Elsa is back over water, having emerged off the northern coast of of Cuba around 0200 UTC. Doppler velocity data from the NOAA WSR-88D at Key West indicate values of around 55 t at 10,000 ft, which supports equivalent surface winds of 49 kt. An Air Force reconnaissance aircraft flying just offshore the north coast of Cuba over deep water measured reliable SFMR surface winds of at least 50 kt. Based on these data, the intensity has been increased to 50 kt.

The initial motion estimate is 330/10 kt. Just like over the past three days, no significant changes have been made to the previous track forecast or synoptic reasoning. Elsa is now moving north-northwestward around the southwestern periphery of a deep-layer ridge whose axis extends westward across the Atlantic to central Florida. The cyclone should gradually move around the ridge over the next 36 hours, turning northward on Tuesday and then north-northeastward Tuesday night and Wednesday morning. By late Wednesday, Elsa should accelerate northeastward ahead of a mid-latitude trough and frontal system, moving across the eastern United States to near Atlantic Canada. The new NHC track forecast is very similar to the previous advisory track, but was nudged slightly eastward due to the more eastward initial position, and lies a tad east of of the various tightly clustered track consensus models.

Some additional strengthening is expected over the next 36 hours, with some of the SHIPS and global models showing Elsa possibly reaching 60 kt just before landfall along the northwestern Florida peninsula. This would typically require a Hurricane Watch for a small portion of northwest Florida. However, given that Elsa has been hugging a very tight mid-level moisture gradient — a condition that is expected to continue until landfall occurs in about 36 hours — the new official intensity forecast remains similar to the previous advisory and holds the peak intensity at 55 kt due to expected intermittent dry-air intrusions. Subsequent NHC forecasts can assess the new reconnaissance and model data that will be coming in later tonight, and determine if an increase in the intensity forecast and the issuance of a hurricane watch or warning is required. By 96 hours, the global models suggest that the cyclone will merge with a frontal zone, so the new intensity forecast continues to shows extratropical transition at that time.

Key Messages:

  • 1. Heavy rain will impact the Cayman Islands and Cuba tonight resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and southeast Georgia through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding, with considerable flooding possible in southwest and western portions of Florida. Mid to late week, heavy rains across coastal South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding.
  • 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida Tuesday night and Wednesday, and a Storm Surge Warning has been issued for that area.
  • 3. Tropical storm conditions are expected to continue across portions of central and western Cuba tonight, and spread northward across portions of the Florida Keys and the Florida west coast through Wednesday, where a Tropical Storm Warning is in effect.
  • 4. There is a risk of tropical storm conditions along portions of the coasts of Georgia and the Carolinas Wednesday and Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 23.5N  82.3W   50 KT  60 MPH - Tropical Storm (WNW Havana, Cuba)
 12H  06/1200Z 24.9N  82.9W   55 KT  65 MPH - Tropical Storm (WNW Key West, FL)
 24H  07/0000Z 26.9N  83.3W   55 KT  65 MPH - Tropical Storm (WSW Venice, FL)
 36H  07/1200Z 29.2N  83.1W   55 KT  65 MPH - Tropical Storm (WNW Cedar Key, FL)
 48H  08/0000Z 31.6N  82.0W   30 KT  35 MPH - Tropical Storm (WSW Jesup, GA)
 60H  08/1200Z 34.0N  79.8W   30 KT  35 MPH - Tropical Storm (WNW Coward, SC)
 72H  09/0000Z 36.9N  76.1W   30 KT  35 MPH - Tropical Storm (WNW Virginia Beach, VA)
 96H  10/0000Z 43.3N  66.0W   40 KT  45 MPH - Post Tropical (WSW 

NWS National Hurricane Center Miami FL 500 PM EDT Mon Jul 05, 2021

Satellite and radar imagery along with surface synoptic observations indicate that the tropical cyclone moved inland over west-central Cuba around 1800 UTC, accompanied by very heavy rains. Assuming that some weakening has occurred due to the influence of land, the advisory intensity is set to 45 kt. An Air Force Hurricane Hunter aircraft is scheduled to investigate Elsa this evening after the center moves into the Florida Straits and will provide a better assessment of the system’s intensity.

The storm appears to be continuing on its northwestward track and the initial motion estimate is 315/12 kt. There are no changes to the track forecast reasoning from the previous advisory. Elsa should move between the western portion of a mid-level subtropical ridge extending westward from the Atlantic and a broad low pressure area near the northwestern Gulf of Mexico coast for the next couple of days. Later in the forecast period, the system is likely to accelerate northeastward and move from the eastern United States to near Atlantic Canada. The NHC track forecast over the eastern Gulf of Mexico is practically identical to the one from the previous advisory, and a little to the left of the previous one over the eastern United States and the Atlantic. This is in good agreement with the now tightly-clustered track model guidance.

Some restrengthening of the cyclone is likely after it moves into the Gulf of Mexico, but vertical shear associated with a broad upper-level trough over the Gulf is likely to limit intensification. The official intensity forecast is slightly above the latest model consensus, IVCN. Around 96 hours, the global models suggest that the cyclone will merge with a frontal zone, so the forecast shows extratropical transition at that time.

Key Messages:

  • 1. Heavy rain will impact the Cayman Islands and Cuba through tonight resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and southeast Georgia through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding, with considerable flooding possible in southwest and western portions of Florida. Mid- to late-week, heavy rains across coastal South Carolina, North Carolina, and southeastern Virginia may result in isolated flash and urban flooding.
  • 2. There is a danger of life-threatening storm surge along portions of the west coast of Florida Tuesday night and Wednesday, and a Storm Surge Warning has been issued for that area.
  • 3. Tropical storm conditions are expected to continue across portions of central and western Cuba tonight, and spread northward across portions of the Florida Keys and the Florida west coast through Wednesday, where a Tropical Storm Warning is in effect.
  • 4. There is a risk of tropical storm conditions along portions of the coasts of Georgia and the Carolinas Wednesday and Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 22.7N  81.9W   45 KT  50 MPH - Tropical Storm (WNW Playa del Caimito, Cuba)
 12H  06/0600Z 24.1N  82.7W   50 KT  60 MPH - Tropical Storm (WSW Key West, FL)
 24H  06/1800Z 26.1N  83.4W   55 KT  65 MPH - Tropical Storm (WSW Naples, FL)
 36H  07/0600Z 28.2N  83.6W   55 KT  65 MPH - Tropical Storm (WNW Tarpon Springs, FL)
 48H  07/1800Z 30.6N  83.0W   35 KT  40 MPH - Tropical Storm (ENE Avoca, FL)
 60H  08/0600Z 32.8N  81.4W   30 KT  35 MPH - Tropical Storm (WSW Cohens Bluff Landing, SC)
 72H  08/1800Z 35.5N  78.5W   30 KT  35 MPH - Tropical Storm (WSW Smithfield, NC)
 96H  09/1800Z 41.5N  69.5W   40 KT  45 MPH - Post Tropical (ESE Chatham, MA)
120H  10/1800Z 49.0N  56.0W   40 KT  45 MPH - Post Tropical (ENE Badger, NF Canada)

NWS National Hurricane Center Miami FL 1100 AM EDT Mon Jul 05, 2021 

A NOAA Hurricane Hunter aircraft has been investigating Elsa while it approaches the south coast of Cuba this morning. Based on SFMR-observed surface winds from the aircraft, the intensity is held at 55 kt for this advisory. A center dropsonde from the plane measured 1009 mb with 26 kt at the surface, so the minimum central pressure estimate is 1006 mb, indicating no significant change since yesterday. Tail Doppler wind data from the NOAA plane showed that there is an eastward tilt of the center with height, so the storm continues to have some vertical alignment issues. Satellite imagery continues to depict convective banding features over the eastern portion of the circulation, with the center located near the western edge of the main cloud mass.

Elsa continues its northwestward track with an initial motion estimate of 310/12 kt. Over the next 2-3 days, the tropical cyclone should move between a subtropical ridge over the southwest North Atlantic and a mid-level low over the northern Gulf of Mexico. In the latter part of the forecast period, Elsa is forecast to accelerate northeastward into the westerlies off the eastern United States coast and into the Atlantic, where it should lose its tropical characteristics in the vicinity of Nova Scotia.

Over the eastern Gulf of Mexico, the official track track forecast has been nudged slightly westward toward the model consensus aids, HCCA and TVCA, but not as far west as that guidance. The GFS model track lies a little east of the latest NHC track.

Some slight weakening is likely while Elsa crosses west-central Cuba today. Restrengthening over the Gulf of Mexico is likely to be limited by moderate westerly shear associated with a broad upper-level trough over the Gulf. The official intensity forecast is mostly higher than the numerical model consensus.

Key Messages:

  • 1. Heavy rain will impact the Cayman Islands and Cuba today resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, the Florida Peninsula, and coastal Georgia through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding. Mid to late week, heavy rains across coastal South Carolina and North Carolina may result in isolated flash and urban flooding.
  • 2. Tropical storm conditions and a dangerous storm surge are expected to continue across portions of central and western Cuba today.
  • 3. Tropical storm conditions are expected in portions of the Florida Keys and along the Florida west coast tonight through Tuesday night, where a Tropical Storm Warning is in effect. A Tropical Storm Watch and a Storm Surge Watch are in effect for portions of the west coast of Florida and the Florida Big Bend.
  • 4. There is a risk of tropical storm conditions and storm surge impacts along the coasts of Georgia and the Carolinas Wednesday and Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 21.5N  81.2W   55 KT  65 MPH - Tropical Storm (ESE Playa Blanca Beach, Cuba)
 12H  06/0000Z 23.2N  82.2W   50 KT  60 MPH - Tropical Storm (ENE Havana, Cuba)
 24H  06/1200Z 25.0N  83.2W   55 KT  65 MPH - Tropical Storm (WNW Key West, FL)
 36H  07/0000Z 27.0N  83.6W   55 KT  65 MPH - Tropical Storm (WSW Venice, FL)
 48H  07/1200Z 29.3N  83.4W   55 KT  65 MPH - Tropical Storm (ESE Suwannee, FL)
 60H  08/0000Z 31.5N  82.2W   30 KT  35 MPH - Tropical Storm (ENE Bristol, GA)
 72H  08/1200Z 33.7N  79.8W   30 KT  35 MPH - Tropical Storm (ENE Kingstree, SC)
 96H  09/1200Z 38.5N  72.5W   40 KT  45 MPH - Tropical Storm (ESE Rehoboth Beach, DE)
120H  10/1200Z 44.5N  61.5W   40 KT  45 MPH - Post Tropical (ESE Liscomb, NS Canada)

NWS National Hurricane Center Miami FL 1100 PM EDT Sun Jul 04, 2021 

Similar to this time last night, Elsa has undergone another convective bursting pattern, except that tonight this has translated into at least some slight strengthening. An Air Force Reserve reconnaissance aircraft investigating the cyclone this evening has found maximum 850-mb flight-level winds of 55 kt and reliable SFMR surface winds of about 55 kt. Although there have been SFMR winds of 60 kt or more reported northeast and north of the center, those values appear to be contaminated by shoaling and/or breaking waves owing to the shallow water flowing in and around the offshore Cayo Anclitas and Cayo Pingues archipelagos. The estimated center pressure of 1004 mb based on dropsonde data also does a higher intensity of 60 kt. Therefore, based on the most reliable data, the intensity has been increased to 55 kt.

The initial motion estimate is 310/13 kt. There remains no significant change to the previous few track forecasts and synoptic reasonings. Elsa is expected to move northwestward and then northward around the western periphery of a mid-level subtropical ridge during the next 3 days, followed by acceleration toward the northeast on days 4 and 5 as the cyclone moves near the southeast U.S. coast and then over the northwestern Atlantic. The new NHC track forecast is basically just an update and extension of the previous advisory track, and lies close to a blend of the tightly packed corrected consensus model HCCA and the simple consensus models TVCA and GFEX.

Cuban radar data from Pilan and Camaguey have occasionally revealed an eye-like feature in the low -and mid-levels of the cyclone where cloud top temperatures have been colder than -80C and also where significant lightning activity has been occurring. Given that the circulation centers have become better aligned and the upper-level outflow pattern is well-established and steadily improving, some additional strengthening during the next 12 h is forecast, which calls for Elsa to be near hurricane strength before landfall occurs along the south-central coast of Cuba tomorrow. Over the eastern Gulf of Mexico late Monday and Tuesday, some restrengthening is forecast after Elsa clears Cuba, but southwesterly vertical wind shear is expected to hinder the intensification process. The official intensity forecast remains on the high side of the numerical model guidance, and follows a blend of the HCCA intensity consensus model, and the LGEM and and Decay-SHIPS statistical-dynamical models.

Key Messages:

  • 1. Widespread heavy rain will continue to affect portions of Jamaica tonight where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba tonight into Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and coastal Georgia Monday through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding. Mid to late week, heavy rains across coastal South Carolina may result in isolated flash flooding.
  • 2. Tropical storm conditions and a dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba tonight. Tropical storm conditions are expected in portions of central and western Cuba tonight and Monday, and will spread into portions of the Florida Keys by late Monday.
  • 3. Tropical Storm and Surge Surge Watches are in effect for portions of the west coast of the Florida peninsula where tropical storm conditions and a dangerous storm surge are possible beginning as early as Monday night and continuing into Tuesday.
  • 4. There is a risk of tropical storm conditions, storm surge, and rainfall impacts along the remainder of the Florida Peninsula Tuesday night through Wednesday and the coasts of Georgia and the Carolinas Wednesday and Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 20.6N  79.2W   55 KT  65 MPH -Tropical Storm (WSW Cayos Anclitas, Cuba)
 12H  05/1200Z 21.9N  80.7W   60 KT  70 MPH -Tropical Storm (WSW Jagua, Cuba)
 24H  06/0000Z 23.5N  82.1W   50 KT  60 MPH -Tropical Storm (ENE Havana, Cuba)
 36H  06/1200Z 25.1N  82.9W   50 KT  60 MPH -Tropical Storm (WNW Key West, FL)
 48H  07/0000Z 27.1N  83.2W   50 KT  60 MPH -Tropical Storm (WNW Venice, FL)
 60H  07/1200Z 29.2N  82.8W   45 KT  50 MPH -Tropical Storm (WSW Gulf Hammock, FL)
 72H  08/0000Z 31.5N  81.6W   35 KT  40 MPH -Tropical Storm (ENE Altamaha Park, GA)
 96H  09/0000Z 36.0N  76.0W   35 KT  40 MPH -Tropical Storm (ENE Fort Landing, NC)
120H  10/0000Z 41.0N  66.8W   40 KT  45 MPH -Tropical Storm (ESE Chatham, MA)

NWS National Hurricane Center Miami FL 500 PM EDT Sun Jul 04, 2021

Elsa continues to exhibit some well-defined convective banding features over the northern and eastern portions of the circulation. Dvorak current intensity estimates from TAFB and SAB are 45 and 55 kt respectively,so the advisory intensity remains at 50 kt. Although the cirrus-level outflow over the area looks fairly impressive, the SHIPS output diagnoses about 20 kt of vertical shear over the cyclone, which may be inhibiting strengthening. Another negative factor could be blockage of the low-level inflow by the land masses surrounding the cyclone.

The storm has turned toward the northwest, and the initial motion estimate is now 310/12 kt. There is little change to the track forecast reasoning from the previous advisory package. Elsa should move around the western periphery of a mid-level subtropical high pressure area during the next 3 days or so. Thereafter, the system should accelerate northward to northeastward over the eastern United States and the northwest Atlantic. No significant changes have been made to the NHC track forecast, which remains close to the simple and correct model consensus solutions.

Some strengthening could occur as the storm approaches the south coast of Cuba and although not explicitly shown in the official forecast, Elsa could strengthen to near 60 kt before landfall in that country. Over the eastern Gulf of Mexico, southwesterly shear is expected to limit strengthening. The official intensity forecast remains on the high side of the numerical model guidance.

Key Messages:

  • 1. Widespread heavy rain will continue to affect portions of Jamaica tonight where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba through Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and coastal Georgia Monday through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding.
  • 2. Tropical storm conditions and a dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba tonight. Tropical storm conditions are expected in portions of central and western Cuba tonight and Monday, and will spread into portions of the Florida Keys by late Monday.
  • 3. Tropical Storm and Surge Surge Watches are in effect for portions of the west coast of the Florida peninsula where tropical storm conditions and a dangerous storm surge are possible beginning as early as Monday night and continuing into Tuesday.
  • 4. There is a risk of tropical storm conditions, storm surge, and rainfall impacts along the remainder of the Florida Peninsula Tuesday night through Wednesday and the coasts of Georgia and the Carolinas Wednesday and Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 19.8N  77.9W   50 KT  60 MPH - Tropical Storm (WSW Cabo Cruz, Cuba)
 12H  05/0600Z 21.1N  79.4W   55 KT  65 MPH - Tropical Storm (WNW Cayos Anclitas, Cuba)
 24H  05/1800Z 22.7N  81.2W   50 KT  60 MPH - Tropical Storm (ESE La Isabel, Cuba)
 36H  06/0600Z 24.2N  82.4W   50 KT  60 MPH - Tropical Storm (WSW Key West, FL)
 48H  06/1800Z 25.8N  83.0W   50 KT  60 MPH - Tropical Storm (WSW Marco Island, FL)
 60H  07/0600Z 27.9N  83.0W   50 KT  60 MPH - Tropical Storm (WNW Indian Rocks Beach, FL)
 72H  07/1800Z 30.5N  82.3W   30 KT  35 MPH - Tropical Storm (WSW Moniac, GA)
 96H  08/1800Z 34.9N  78.0W   30 KT  35 MPH - Tropical Storm (ENE Magnolia, NC)
120H  09/1800Z 40.0N  69.0W   35 KT  40 MPH - Tropical Storm (ESE New York City, NY)

NWS National Hurricane Center Miami FL 1100 AM EDT Sun Jul 04, 2021 

A NOAA P-3 Hurricane Hunter aircraft has been investigating Elsa this morning. Flight-level and SFMR surface observations from the aircraft indicate that the maximum winds are near 50 kt and the estimated central pressure, about 1009 mb, is rather high for a system of this intensity. Also, tail Doppler radar data from the aircraft show an eastward tilt of the center with height. Nonetheless, the storm still looks fairly impressive on satellite images with a well-defined convective banding feature over the northern through eastern portions of the circulation. Also, the highest cloud tops are quite cold and near -70C.

Elsa’s forward speed has slowed a little more, and the current motion is around 290/11 kt. There hasn’t been much change to the track forecast or reasoning since the previous advisory. Over the next few days, the tropical cyclone should move around the western periphery of the subtropical ridge. The NHC forecast track is similar to the previous official forecast, and close to the model consensus. The latest GFS and HWRF solutions are to the west of this forecast.

Elsa should remain in a low-shear environment through Monday, and some strengthening is likely before the storm reaches Cuba, assuming the circulation becomes better aligned vertically. The storm should weaken somewhat due to its passage over Cuba. After the cyclone emerges into the southeastern Gulf of Mexico, only slight restrengthening is forecast due to moderate southwesterly shear. The official intensity forecast is on the high end of the numerical intensity guidance suite.

Key Messages:

  • 1. Widespread heavy rain will continue to affect portions of southern Haiti and Jamaica today where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba today into Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys and Florida Peninsula Monday through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding.
  • 2. Tropical storm conditions and dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba later today and tonight. Tropical storm conditions are expected in portions of central and western Cuba tonight and Monday.
  • 3. Tropical storm conditions, storm surge, and rainfall impacts are expected beginning late Monday in the Florida Keys, and are possible along the coast of southwestern Florida beginning Monday night. Tropical Storm Warnings and Watches are in effect in those areas.
  • 4. There is a risk of tropical storm conditions, storm surge, and rainfall impacts along the remainder of the Florida Peninsula Monday night through Wednesday and the coasts of Georgia and the Carolinas Wednesday and Thursday. However, uncertainty in the forecast remains larger than usual due to Elsa’s potential interaction with Cuba.
FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 18.7N  76.8W   50 KT  60 MPH - Tropical Storm (ENE Port Maria, Jamaica)
 12H  05/0000Z 20.2N  78.2W   55 KT  65 MPH - Tropical Storm (WSW Media Luna, Cuba)
 24H  05/1200Z 21.9N  80.0W   60 KT  70 MPH - Tropical Storm (ESE Topes de Collantes, Cuba)
 36H  06/0000Z 23.4N  81.5W   50 KT  60 MPH - Tropical Storm (ENE Matanzas, Cuba)
 48H  06/1200Z 24.7N  82.5W   50 KT  60 MPH - Tropical Storm (WNW Key West, FL)
 60H  07/0000Z 26.5N  83.0W   50 KT  60 MPH - Tropical Storm (WSW Captiva, FL)
 72H  07/1200Z 28.6N  82.8W   50 KT  60 MPH - Tropical Storm (WSW Pine Island, FL)
 96H  08/1200Z 33.5N  79.5W   40 KT  45 MPH - Tropical Storm (ENE Andrews, SC)
120H  09/1200Z 38.5N  71.0W   35 KT  40 MPH - Tropical Storm (ESE Atlantic City, NJ)

NWS National Hurricane Center Miami FL 1100 PM EDT Sat Jul 03, 2021

Elsa is undergoing a convective bursting pattern the past few hours, with some cold overshooting tops of -90 deg C east and northeast of the center. However, data from an Air Force Reserve reconnaissance aircraft indicate that this convective increase has not translated into an intensity increase. To the contrary, 5000-ft flight-level and SFMR surface winds have decreased while the central pressure has increased to 1004 mb. Based on the latest recon data, the intensity has been lowered to 55 kt. The aircraft has now climbed to 10,000 ft for safety reasons and will be penetrating the area of intense convection to check for stronger winds there.

The initial motion estimate is now 295/15 kt. Elsa is forecast to gradually move around the western periphery of a deep-layer subtropical ridge over the next 96 hours, accompanied by an additional decrease in forward speed. The latest model guidance has continued to converge along the previous advisory track, with the corrected-consensus models HCCA and FSSE nearly on top of each other. The TCVA simple consensus model is also similar to the HCCA and FSSE models. However, out of respect for the slightly more westward GFS and GFS-ensemble models, which have performed admirably thus far with Elsa, the new official forecast lies a tad west of the aforementioned consensus models and lies nearly on top of the previous advisory track.

After interacting with the mountainous terrain of southwestern Haiti, which could have caused some disruption in the low-level field despite the center remaining offshore, little change in intensity is expected tonight. However, some slight restrengthening could occur by Sunday afternoon as Elsa approaches the south-central coast of Cuba where the sea-surface temperatures are quite warm at more than 30 deg C and the water is deep. Weakening is expected after the cyclone moves across west-central Cuba, followed again by some slight restrengthening after Elsa emerges over the warm Gulf Stream in the Straits of Florida. Westerly vertical wind shear increasing to near 20 kt by 96 hours should prevent any significant strengthening from occurring. Elsa should become a very asymmetrical tropical cyclone late on day 3 and on day 4 with most of the heavy rain and strongest winds displaced along and to the east of the forecast track. The initial intensity is similar to the previous advisory and closely follows the simple and corrected consensus models.

Given the remaining uncertainty in the track forecast and the degree of land interaction with Hispaniola and Cuba, users are urged to factor in some of this uncertainty. For reference, average NHC track errors at days 3 and 4 are 125 miles and 150 miles, respectively. The average NHC intensity errors are around 15 mph for both days 3 and 4.

Key Messages:

  • 1. Widespread heavy rain will move across southern Haiti and Jamaica tonight into Sunday where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba Sunday into Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys and Florida Peninsula early next week, isolated flash flooding and minor river flooding will be possible.
  • 2. Tropical storm conditions and dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba beginning early Sunday, with tropical storm conditions possible in central and western Cuba Sunday night and Monday.
  • 3. There is an increasing risk of tropical storm conditions, storm surge, and rainfall impacts beginning Monday in the Florida Keys and the southern Florida Peninsula, and a Tropical Storm Watch is now in effect for portions of the Florida Keys. This risk will spread northward along the Florida Peninsula through Wednesday and reach the coasts of Georgia and the Carolinas Wednesday and Thursday, however uncertainty in the forecast remains larger than usual due to Elsa’s potential interaction with the islands of Hispaniola and Cuba. Interests elsewhere in Florida and along the southeast U.S. coast should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 17.9N  75.3W   55 KT  65 MPH - Tropical Storm (WSW Port-Salut, Haiti)
 12H  04/1200Z 19.2N  77.3W   55 KT  65 MPH - Tropical Storm (WNW Cayos Anclitas, Cuba)
 24H  05/0000Z 20.9N  79.4W   60 KT  70 MPH - Tropical Storm (WNW Cayos Anclitas, Cuba)
 36H  05/1200Z 22.5N  81.0W   50 KT  60 MPH - Tropical Storm (WNW Cayos Anclitas, Cuba)
 48H  06/0000Z 24.1N  82.2W   45 KT  50 MPH - Tropical Storm (WSW Key West, FL)
 60H  06/1200Z 26.0N  82.8W   50 KT  60 MPH - Tropical Storm (WSW Naples, FL)
 72H  07/0000Z 28.0N  83.0W   50 KT  60 MPH - Tropical Storm (WNW Clearwater, FL)
 96H  08/0000Z 32.7N  81.0W   45 KT  50 MPH - Tropical Storm (ENE Grays, SC)
120H  09/0000Z 37.7N  74.9W   35 KT  40 MPH - Tropical Storm (ESE Wallops Island, VA)

NWS National Hurricane Center Miami FL 500 PM EDT Sat Jul 03, 2021 

Satellite imagery shows that Elsa looks ragged and disorganized at this time, with bursts of convection occuring near the low-level center and poorly-defined convective banding. Some of this is likely due to the the proximity of the system to Hispaniola. Air Force Reserve and NOAA Hurricane Hunter aircraft have reported reliable 55-60 kt surface wind estimates from the SFMR, along with the latest central pressure report of 1000 mb. The initial intensity remains 60 kt based mainly on the SFMR data.

The initial motion is now 295/24. There is little change in the forecast philosophy from the previous advisory. Elsa is approaching a weakness in the subtropical ridge caused by a large baroclinic trough over the eastern United States. The global models forecast this trough to move eastward into the Atlantic, but the southern portion is likely to split off and become an upper-level low pressure area over the western Gulf of Mexico, with the subtropical ridge over the Atlantic situated to the east of the this low. In response, Elsa should slow its forward motion and turn northwestward during the next 48 h, followed by a general northward motion from 60-96 h and recurvature into the westerlies after that time. The forecast track takes the center near or over southwestern Haiti, Cuba, and the eastern Gulf of Mexico or the Florida Peninsula during the next 3 days or so. After that, the system is likely to cross portions of the southeastern United States on its way into the Atlantic. The new forecast track is changed little from the previous advisory, and it lies near the center of the now reasonably-agreeing track guidance envelope.

In addition to land interaction, Elsa continues to be affected by northwesterly shear that is at least partly due to the fast low-level flow that the storm is embedded in. Some shear is expected to continue through the next 72 h. However, once the system passes the southwestern peninsula of Haiti, there may be less land interaction than previously forecast. The intensity guidance is in good agreement on weakening during the next 48 h, and the GFS, UKMET, and ECMWF show Elsa as a not very vertically aligned system with some separation between the low- and mid-level centers over the southeastern Gulf of Mexico. After that, despite the shear, upper-level divergence associated with the aforementioned upper-level low could allow for some re-intensification as forecast by the HWRF and other models. The new NHC intensity forecast calls for some weakening in the first 48 h and then shows re- intensification over the Gulf of Mexico. Through the first 72 h, the forecast remains at the upper edge of the intensity guidance.

Hurricane warnings remain in effect for portions of Haiti at this time, as there is still the possibility that a short-lived re-intensification might occur due to a convective burst.

Given the remaining uncertainty in the track forecast and the degree of land interaction with Hispaniola and Cuba, users are urged to factor in some of this uncertainty. For reference, average NHC track errors at days 3 and 4 are 125 miles and 150 miles, respectively. The average NHC intensity errors are around 15 mph for both days 3 and 4.

Key Messages:

  • 1. A hurricane warning remains in effect for portions of Haiti, where near-hurricane conditions and dangerous storm surge are expected through this evening.
  • 2. Widespread heavy rain will move across southern Hispaniola and Jamaica tonight into Sunday where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba Sunday into Monday resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys and Florida Peninsula early next week, isolated flash flooding and minor river flooding will be possible.
  • 3. Tropical storm conditions and dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba beginning early Sunday, with tropical storm conditions possible in central and western Cuba Sunday night and Monday.
  • 4. There is an increasing risk of tropical storm conditions, storm surge, and rainfall impacts beginning Monday in the Florida Keys and the southern Florida Peninsula, and a Tropical Storm Watch is now in effect for portions of the Florida Keys. This risk will spread northward along the Florida Peninsula through Wednesday and reach the coasts of Georgia and the Carolinas Wednesday and Thursday, however uncertainty in the forecast remains larger than usual due to Elsa’s potential interaction with the islands of Hispaniola and Cuba. Interests elsewhere in Florida and along the southeast U.S. coast should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 17.5N  73.9W   60 KT  70 MPH - Tropical Storm (ESE Les Cayes, Haiti)
 12H  04/0600Z 18.7N  75.9W   60 KT  70 MPH - Tropical Storm (ENE Port Antonio, Jamaica)
 24H  04/1800Z 20.2N  78.3W   60 KT  70 MPH - Tropical Storm (WNW Media Luna, Cuba)
 36H  05/0600Z 21.6N  80.1W   55 KT  65 MPH - Tropical Storm (WNW Playa Ancon, Cuba)
 48H  05/1800Z 23.1N  81.6W   45 KT  50 MPH - Tropical Storm (WNW Matanzas, Cuba)
 60H  06/0600Z 24.9N  82.6W   50 KT  60 MPH - Tropical Storm (WNW Key West, FL)
 72H  06/1800Z 26.9N  83.1W   55 KT  65 MPH - Tropical Storm (WSW Englewood, FL)
 96H  07/1800Z 32.0N  82.0W   45 KT  50 MPH - Tropical Storm (WSW Mendes, GA)
120H  08/1800Z 36.5N  77.0W   35 KT  40 MPH - Tropical Storm (ENE Como, NC)

NWS National Hurricane Center Miami FL 1100 AM EDT Sat Jul 03, 2021 

Reports from an Air Force Reserve Hurricane Hunter aircraft and satellite imagery indicate that Elsa has weakened some since the last advisory. The aircraft reported maximum 700-mb flight-level winds of 64 kt well to the northeast of the center, and maximum surface winds estimates from the SFMR of about 55 kt. The aircraft-reported central pressure is near 999 mb and gradually rising, In addition, the center was exposed for a few hours, although it is now located at the northwestern edge of a new convective burst. Based on the aircraft data, the initial intensity is reduced to 60 kt.

The initial motion is now 295/25. Elsa is approaching a weakness in the subtropical ridge caused by a large baroclinic trough over the eastern United States. The global models forecast this trough to move eastward into the Atlantic, but the southern portion is likely to split off and become an upper-level low-pressure area over the western Gulf of Mexico, with the subtropical ridge over the Atlantic situated to the east of the this low. This evolution should cause Elsa to slow its current breakneck forward speed during the next day or so, then turn northwestward between 36-60 h, followed by a general northward motion from 72-96 h and recurvature into the westerlies after that time. The track guidance is in much better agreement than this time yesterday, and Elsa is expected to pass near or over southwestern Haiti, Cuba, and the eastern Gulf of Mexico or the Florida Peninsula during the next 3 days or so. After that, the system is likely to cross portions of the southeastern United States on its way into the Atlantic. The new NHC forecast track has only minor adjustments from the previous one, and it lies near the various consensus models.

Elsa continues to be affected by northwesterly shear that is at least partly due to the fast forward motion. While the forward speed is forecast to decrease over the next few days, continued westerly shear and land interaction are expected to cause additional weakening. Indeed, by 60 h, the GFS, UKMET, and ECMWF show Elsa as a weak system with some separation between the low- and mid-level centers. While some shear is likely to continue when the storm is near or over the eastern Gulf of Mexico, upper-level divergence associated with the aforementioned upper-level low could allow for some re-intensification. The new NHC intensity forecast calls for more weakening in the first 48 h than previously forecast and then shows re-intensification over the Gulf of Mexico. Through the first 72 h, the forecast is at the upper edge of the intensity guidance.

Although Elsa is now a tropical storm, hurricane warnings remain in effect for portions of the Dominican Republic and Haiti at this time, as conditions have not yet reached their worst there and the possibility that a short-lived re-intensification might occur due to a convective burst. Given that there is still uncertainty in the track forecast and the degree of land interaction with Hispaniola and Cuba, users are urged to factor in some of this uncertainty. For reference, average NHC track errors at days 3 and 4 are 125 miles and 150 miles, respectively. The average NHC intensity errors are around 15 mph for both days 3 and 4.

Key Messages:

  • 1. A hurricane warning remains in effect for portions of Haiti and the Dominican Republic, where near-hurricane conditions and dangerous storm surge are expected through this evening.
  • 2. Widespread heavy rain will move across southern Hispaniola and Jamaica today into Sunday where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will impact the Cayman Islands and Cuba Sunday into Monday, resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys and southern Florida early next week, isolated flash flooding and minor river flooding will be possible.
  • 3. Tropical storm conditions and dangerous storm surge are expected with hurricane conditions possible in portions of eastern Cuba beginning early Sunday, with tropical storm conditions possible in central Cuba Sunday night and Monday.
  • 4. There is an increasing risk of tropical storm conditions, storm surge, and rainfall impacts beginning Monday in the Florida Keys and the southern Florida Peninsula. This risk will spread northward along the Florida Peninsula through Wednesday and reach the coasts of Georgia and the Carolinas Wednesday and Thursday, however uncertainty in the forecast remains larger than usual due to Elsa’s potential interaction with the islands of Hispaniola and Cuba. Interests in Florida and along the southeast U.S. coast should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 17.0N  71.6W   60 KT  70 MPH - Tropical Storm (WSW Cabo Rojo, DR)
 12H  04/0000Z 18.1N  74.0W   60 KT  70 MPH - Tropical Storm (WSW Port Salut, Haiti)
 24H  04/1200Z 19.6N  76.7W   60 KT  70 MPH - Tropical Storm (WSW Uvero, Cuba)
 36H  05/0000Z 21.2N  78.9W   55 KT  65 MPH - Tropical Storm (WSW Playa Santa María, Cuba)
 48H  05/1200Z 22.7N  80.5W   45 KT  50 MPH - Tropical Storm (ESE Cascajal, Cuba)
 60H  06/0000Z 24.0N  81.8W   50 KT  60 MPH - Tropical Storm (WSW Key West, FL)
 72H  06/1200Z 25.9N  82.5W   55 KT  65 MPH - Tropical Storm (WSW Naples, FL)
 96H  07/1200Z 30.0N  82.5W   50 KT  60 MPH - Tropical Storm (WSW Lake Butler, FL)
120H  08/1200Z 35.0N  78.0W   35 KT  40 MPH - Tropical Storm (ESE Warsaw, NC)

NWS National Hurricane Center Miami FL 1100 PM AST Fri Jul 02, 2021 

Data from an Air Force Reserve hurricane hunter aircraft indicate that Elsa has weakened slightly, and that the flight-level and surface centers are not vertically aligned. The maximum 700-mb wind speed measured was 75 kt and the highest SFMR surface wind sampled was 61 kt in the northeastern quadrant. However, these data were collected outside of the strongest convection that was occurring just east of the flight track, so the intensity has only been lowered to 70 kt, which is supported by the slightly higher central pressure of 995 mb sampled by a dropsonde.

The initial motion estimate now is 285/25 kt. There remains little significant change to the previous track forecast or reasoning. The latest 00Z model guidance has become more convergent and now lies nearly on top of the previous advisory track. Over the last 48 h, the ECMWF model has steadily shifted Elsa’s track westward by about 1 degree of longitude each model cycle, with the latest ECMWF forecast track now being located about 240 nmi west of its forecast track two days ago. As a result, less weight has been placed on the ECMWF solution for this advisory. However, even its latest solution no longer takes Elsa over the heart of Hispaniola. Elsa should continue to move generally west-northwestward for the next 48 h, accompanied by a slow but steady decrease in forward speed. By the time the hurricane nears southern Cuba, the forward speed should be less than 15 kt. Thereafter, Elsa should gradually turn northwestward and eventually northward through a developing weakness in the subtropical ridge This motion should take Elsa across Cuba and over the eastern Gulf of Mexico or the nearby Florida Peninsula on day 4, followed by a motion over the coastal regions of the southeastern United States on day 5. The new NHC forecast track is essentially just an update of the previous advisory, and closely follows a blend of the GFS, UKMET, and HWRF models, and the TVCA simple consensus model.

Elsa’s fast forward speed and recent entrainment of dry mid-level air into the western semicircle has eroded some of the inner-core convection, resulting in the aforementioned weakening. In fact, NOAA G-IV dropsondes launched around 2100 UTC northwest of Elsa indicated a significant dry-air layer between 400-500-hPa that may have been imported by moderate northwesterly mid-level shear. However, as the cyclone’s forward speed steadily decreases, the low-, mid-, and upper-level circulations should become more vertically aligned, which should allow for at least some slight re-strengthening during the next 24 h or so. Possible interaction with the landmasses of Haiti, southeastern Cuba, and Jamaica is the primary reason for not showing a more robust intensity forecast given the very warm water beneath the hurricane and a very favorable upper-level wind flow regime. The latest GFS and UKMET models indicate that Elsa will be moving into the center of a 300-200-mb synoptic-scale anticyclone, which would produce enhanced outflow jets to the north and south of the cyclone, resulting in significant strengthening. If Elsa ends up ‘threading-the-needle’ between Haiti, Jamaica, and Cuba, then subsequent intensity forecasts may have to be increased similar to the much stronger HWRF model. For now, the official NHC intensity forecast maintains continuity with the previous advisory, and shows only slight re-strengthening due to possible interaction with land.

It should be noted that the average NHC track errors are 175 miles and 200 miles at days 4 and 5, respectively. Given the larger-than-normal uncertainty and because hazards will extend well away from the center of the storm, users are urged to not focus on the exact forecast points.

Key Messages:

  • 1. Hurricane conditions and dangerous storm surge are expected within the Hurricane Warning areas in Haiti and the Dominican Republic beginning Saturday and in Jamaica beginning Sunday.
  • 2. The outer rain bands from Elsa will impact Puerto Rico by late tonight, with widespread heavy rain moving into southern Hispaniola and Jamaica Saturday into Sunday. Isolated to scattered flash flooding and mudslides are possible. Through early next week, heavy rain is expected to impact the Cayman Islands and Cuba resulting in significant flooding with mudslides possible in Cuba.
  • 3. Hurricane conditions and dangerous storm surge are possible in portions of eastern Cuba beginning early Sunday where a Hurricane Watch is in effect. There is an increasing risk of wind, storm surge, and rainfall impacts elsewhere in Cuba Sunday and Monday.
  • 4. There is an increasing risk of storm surge, wind, and rainfall impacts beginning Monday in the Florida Keys and spreading northward along the Florida Peninsula through Tuesday. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the islands of Hispaniola and Cuba this weekend. Interests throughout Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 14.8N  66.3W   70 KT  80 MPH - Category 1 (ESE Ponce, PR USA)
 12H  03/1200Z 16.1N  69.8W   70 KT  80 MPH - Category 1 (WSW Santo Domingo, DR)
 24H  04/0000Z 17.6N  73.5W   75 KT  85 MPH - Category 1 (ESE Port-Salut, Haiti)
 36H  04/1200Z 19.0N  76.2W   75 KT  85 MPH - Category 1 (ESE Chivirico, Cuba)
 48H  05/0000Z 20.5N  78.5W   70 KT  80 MPH - Category 1 (ESE Cayo Anclitas, Cuba) 
 60H  05/1200Z 22.1N  80.4W   55 KT  65 MPH - Tropical Storm (ESE Cayo Corojo, Cuba)
 72H  06/0000Z 23.7N  81.7W   55 KT  65 MPH - Tropical Storm (ENE Havana, Cuba)
 96H  07/0000Z 27.7N  82.9W   50 KT  60 MPH - Tropical Storm (WSW St Pete Beach, FL)
120H  08/0000Z 32.4N  80.7W   35 KT  40 MPH - Tropical Storm (ENE Port Royal, SC)

NWS National Hurricane Center Miami FL 500 PM AST Fri Jul 02, 2021 

Reports from a NOAA Hurricane Hunter aircraft indicate that Elsa has strengthened a little more since the last advisory, with a combination of flight-level winds, SFMR surface wind estimates, and dropsonde data showing that the maximum winds are near 75 kt. The aircraft also reported that the 700-mb circulation remains somewhat disorganized, and that the 700-mb center is not vertically aligned with with the surface center. The former issue is likely due to the rapid motion, and the latter may be due to the effects of westerly shear.

The initial motion now is 290/26. There is again little change to the forecast track or the forecast guidance. The guidance is in good agreement on a rapid west-northwestward notion to near the south coast of the Dominican Republic and Haiti by 24-30 h, followed by a continued west-northwestward motion at a slower forward speed through 48 h. After that time, Elsa should gradually turn northwestward and eventually northward as it moves through a weakness in the subtropical ridge created by a mid-latitude trough over the eastern United States. This motion should take the cyclone across Cuba and over the eastern Gulf of Mexico or the nearby Florida Peninsula, eventually moving into the southeastern United States by the end of the period. The track guidance is a little less divergent than earlier, but there is still enough spread in the potential tracks that this part of the forecast remains low confidence.

The latest global model runs and the associated intensity guidance are forecasting a less favorable environment for Elsa during the next several days. The SHIPS model now calls for 10-20 kt of northwesterly shear during the next 48 h, and 15-25 kt of shear after 60 h. In addition, the 12Z GFS forecasts a considerably weaker storm than its last several runs. The intensity forecast thus calls for little change in strength during the first 24 h, although it is possible the hurricane could strengthen a little more during that time. After that, land interaction and shear are likely to cause weakening until Elsa emerges into the Gulf of Mexico. However, the HWRF still calls for Elsa to intensify into a Category 3 hurricane, and like the track forecast the intensity forecast remains of low confidence due to the spread in the guidance.

It should be noted that the average NHC track errors are 175 miles and 200 miles at days 4 and 5, respectively. Given the larger-than-normal uncertainty and because hazards will extend well away from the center of the storm, users are urged to not focus on the exact forecast points.

Key Messages:

  • 1. Hurricane conditions and dangerous storm surge are expected within the Hurricane Warning areas in Haiti and the Dominican Republic beginning Saturday and in Jamaica beginning Sunday.
  • 2. Heavy rainfall will gradually subside across the Windward and southern Leeward Islands tonight, including Barbados. Outer rain bands will impact Puerto Rico by late tonight, and affect southern Hispaniola and Jamaica Saturday into Sunday. Isolated to scattered flash flooding and mudslides are possible. By early next week, heavy rain will impact the Cayman Islands and Cuba. Significant flooding and mudslides are possible.
  • 3. Hurricane conditions and dangerous storm surge are possible in portions of eastern Cuba beginning early Sunday where a Hurricane Watch is in effect. There is an increasing risk of wind, storm surge, and rainfall impacts elsewhere in Cuba Sunday and Monday.
  • 4. There is an increasing risk of storm surge, wind, and rainfall impacts beginning Monday in the Florida Keys and spreading northward along the Florida Peninsula through Tuesday. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the islands of Hispaniola and Cuba this weekend. Interests throughout Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  02/2100Z 14.2N  63.7W   75 KT  85 MPH - Category 1 (WNW Castries, St Lucia)
 12H  03/0600Z 15.4N  67.5W   75 KT  85 MPH - Category 1 (WSW Ponce, PR USA)
 24H  03/1800Z 17.0N  71.7W   75 KT  85 MPH - Category 1 (ESE Jacmel, Haiti)
 36H  04/0600Z 18.3N  74.8W   70 KT  80 MPH - Category 1 (WSW Tiburon, Haiti)
 48H  04/1800Z 19.9N  77.3W   70 KT  80 MPH - Category 1 (ESE Pilon, Cuba)
 60H  05/0600Z 21.4N  79.4W   65 KT  75 MPH - Category 1 (WSW El Toro, Cuba)
 72H  05/1800Z 22.9N  81.1W   55 KT  65 MPH - Tropical Storm (ESE Cardenas, Cuba)
 96H  06/1800Z 26.5N  83.0W   55 KT  65 MPH - Tropical Storm (WNW Captiva, FL)
120H  07/1800Z 31.6N  82.0W   40 KT  45 MPH - Tropical Storm (WSW Jesup, GA)

NWS National Hurricane Center Miami FL 830 AM AST Fri Jul 02, 2021

Surface observations from Barbados indicate that Elsa has become a hurricane, and this special advisory is being issued to update the first 36 h of the intensity and wind radii forecasts. More revisions of the intensity forecast are likely on the next regular advisory. An Air Force Reserve Hurricane Hunter aircraft is currently entering the hurricane, and a NOAA aircraft is scheduled to investigate the system this afternoon.

There are no changes to the forecast track at this time. It should be noted that the average NHC track errors are 175 miles and 200 miles at days 4 and 5, respectively. Given the larger-than-normal uncertainty and because hazards will extend well away from the center of the storm, users are urged to not focus on the exact forecast points.

Key Messages:

  • 1. Hurricane conditions are occurring on Barbados and are expected elsewhere in the Hurricane Warning area in the next few hours. Tropical storm conditions are expected to begin later this morning in other portions of the Windward and Leeward Islands. Tropical storm conditions are expected and hurricane conditions are possible over southern portions of Hispaniola on Saturday. Tropical storm conditions are possible over Jamaica beginning Saturday night.
  • 2. Heavy rainfall from Elsa will move quickly across the Windward and southern Leeward Islands today, including Barbados. Outer rain bands will impact Puerto Rico late today into Saturday, and southern Hispaniola and Jamaica Saturday into Sunday. Flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of Cuba, the Turks and Caicos, and the Bahamas through early next week. Interests in these areas should monitor Elsa’s progress and updates to the forecast.
  • 4. There is a risk of storm surge, wind, and rainfall impacts in the Florida Keys and portions of the Florida Peninsula early next week. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the Greater Antilles this weekend. Interests in Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  02/1230Z 13.1N  60.1W   65 KT  75 MPH - Category 1 (WNW Bridgetown, Barbados)
 12H  02/1800Z 13.8N  62.4W   65 KT  75 MPH - Category 1 (WSW Castries, St. Lucia)
 24H  03/0600Z 15.4N  67.4W   65 KT  75 MPH - Category 1 (WSW Ponce, PR USA)
 36H  03/1800Z 17.1N  71.7W   65 KT  75 MPH - Category 1 (ESE Cabo Rojo, DR)
 48H  04/0600Z 18.7N  75.2W   60 KT  70 MPH - Tropical Storm (WSW Dame Marie, Haiti)
 60H  04/1800Z 20.2N  77.8W   55 KT  65 MPH - Tropical Storm (WSW Media Luna, Cuba)
 72H  05/0600Z 21.7N  79.7W   55 KT  65 MPH - Tropical Storm (WSW La Unión, Cuba)
 96H  06/0600Z 25.2N  82.2W   55 KT  65 MPH - Tropical Storm (WNW Key West, FL)
120H  07/0600Z 29.2N  82.6W   55 KT  65 MPH - Tropical Storm (ESE Cedar Key, FL)

NWS National Hurricane Center Miami FL 1100 PM AST Thu Jul 01, 2021

The convective structure with Elsa tonight appears to be somewhat better organized than earlier, with a bursting type pattern of cold -75 to -80 C cloud top temperatures just to the northeast of the estimated center. However, a SSMIS microwave pass at 2130 UTC revealed that, underneath the cirrus, the deeper convection is still struggling to rotate up-shear as the system moves quickly to the west-northwest. Despite that fact, an ASCAT-A pass clipped the northeastern edge of Elsa and showed several wind retrievals of 44-46 kt. In addition, the most recent subjective Dvorak satellite classification from TAFB was T3.0/45 kt. In support of these data, the current estimated intensity was raised to 45 kt for this advisory.

Elsa continues to move quickly to the west-northwest at 290/23 kt. A continued rapid motion to the west-northwest is expected for the next 36 hours as the storm remains steered by a strong subtropical ridge to its north, and the guidance has trended a bit faster once again tonight. Thereafter, Elsa will reach the western extent of this ridge which will be eroded by a strong mid-latitude trough centered off the eastern US. Once again, the guidance spread increases greatly by this time, with the GFS/UKMET on the slow and left side of the guidance envelope, the ECMWF and its ensembles on the fast and right side, and the Canadian roughly in the middle. Interestingly, the latest GFS ensembles show some bifurcation within the larger guidance envelope, with the strongest members further south and west. The latest NHC track forecast is close to the previous track early on but somewhat faster, and in the latter period was nudged just slightly eastward towards the TVCN consensus. However, the track forecast in the latter time period remains low confidence.

The intensity forecast with Elsa also continues to be challenging this evening. While the GFS-based SHIPS guidance indicates that the current 200-850-hPa vertical wind shear is only 5-10 kt, the strong east-southeasterly low-level flow Elsa is embedded in is resulting in stronger 15-20 kt of west-northwesterly mid-level shear. This mid-level shear has thus far prevented deep convection from wrapping around the circulation and helping to align the low- and mid-level vortex like the GFS/HWRF models have been forecasting over the past day. Despite this convective structure, the fast east-southeasterly low-level flow will likely continue to enhance the winds on the north side of the circulation. For this reason, the intensity forecast still shows intensification in the short term to 55 kt. However, additional intensification beyond that will likely require a better vertically aligned vortex. This structure may be difficult to achieve as moderate mid-level shear continues, counter to the motion vector of the storm. After 48 hours, the intensity forecast shows slight weakening given the possibility of land interaction over the Greater Antilles. The latest intensity forecast continues remain on the conservative side relative to the guidance, especially the HWRF/HMON regional hurricane models, and is also low confidence.

Key Messages:

  • 1. Tropical storm conditions are expected to begin early Friday in portions of the Windward and southern Leeward Islands, and are possible over portions of southern Hispaniola on Saturday, and are also possible over Jamaica beginning Saturday night.
  • 2. Heavy rainfall from Elsa will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Outer rain bands will impact Puerto Rico on Friday and southern Hispaniola by early Saturday. Flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of Cuba, the Turks and Caicos, and the Bahamas through early next week. Interests in these areas should monitor Elsa’s progress and updates to the forecast.
  • 4. There is a risk of storm surge, wind, and rainfall impacts in the Florida Keys and portions of the Florida Peninsula early next week. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the Greater Antilles this weekend. Interests in Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 11.8N  55.9W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 12H  02/1200Z 12.8N  59.7W   55 KT  65 MPH - Tropical Storm (WSW Bridgetown, Barbados)
 24H  03/0000Z 14.5N  64.8W   55 KT  65 MPH - Tropical Storm (WSW Le Carbet, Martinique)
 36H  03/1200Z 16.2N  69.8W   55 KT  65 MPH - Tropical Storm (ESE Santo Domingo, DR)
 48H  04/0000Z 17.7N  73.3W   55 KT  65 MPH - Tropical Storm (ESE Les Cayes, Haiti)
 60H  04/1200Z 19.4N  76.5W   50 KT  60 MPH - Tropical Storm (WSW Pilón, Cuba)
 72H  05/0000Z 21.2N  78.8W   50 KT  60 MPH - Tropical Storm (WNW Alazán, Cuba)
 96H  06/0000Z 23.9N  81.7W   50 KT  60 MPH - Tropical Storm (ESE Key West, FL)
120H  07/0000Z 28.2N  83.1W   50 KT  60 MPH - Tropical Storm (WNW Holiday, FL)

NWS National Hurricane Center Miami FL 500 PM  AST Thu Jul 01, 2021 

The structure of Elsa has changed little since the last advisory, with the low-level center partly exposed to the northwest of the somewhat-ragged primary convective band. Various subjective and objective satellite intensity estimates have changed little during the last 6 h, so the initial intensity is held at 40 kt.

The initial motion is now 285/25. There is little change to the track forecast philosophy from the previous advisory. A rapid west-northwestward motion is likely for the next 48 h or so as Elsa is steered by the strong subtropical ridge to the north. After that time, the storm is expected to approach a weakness in the ridge caused by a mid-latitude trough over the eastern United states. The guidance becomes rather divergent as this happens, as the ECWMF and the ECMWF ensembles forecast a turn toward the north while the GFS and UKMET are forecasting a continued west- northwestward to northwestward motion. In addition, the GFS ensemble members are spread from a continued west-northwestward motion toward the Yucatan Peninsula on one side to a northward motion east of the northern Bahamas on the other. The latter part of the new NHC forecast track will still lean more toward the deterministic GFS/UKMET solutions, but the confidence remains low. The new official forecast track again has only minor adjustments from the previous forecast.

The intensity forecast and its high uncertainty are also little changed from the last advisory. Some strengthening is expected during the next day or so as Elsa is expected to be in an environment of warm sea-surface temperatures, light vertical wind shear, and high mid-level relative humidity. However, as mentioned earlier, the fast forward motion could result in the upper and lower parts of the storm being unable to stay together, and this could limit strengthening. The latter part of the intensity forecast also has the issues of possible land interaction and disagreements among the global models on how favorable the upper-level winds will be, although the latest model runs trended toward less favorable conditions north of about 22N. This uncertainty is highlighted by the UKMET forecasting Elsa to weaken to a trough near western Cuba while the GFS forecasts it to be a hurricane in the same area and time. Based on these factors, the NHC intensity forecast continues to be on the lower end of the intensity guidance suite.

Key Messages:

  • 1. Tropical storm conditions are expected beginning early Friday in portions of the Windward and southern Leeward Islands, and are possible over portions of southern Hispaniola on Saturday.
  • 2. Heavy rainfall from Elsa will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Outer rain bands will impact Puerto Rico on Friday and southern Hispaniola by early Saturday. Flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of Cuba, Jamaica, the Turks and Caicos, and the Bahamas through early next week. Interests in these areas should monitor Elsa’s progress and updates to the forecast.
  • 4. There is a risk of storm surge, wind, and rainfall impacts in the Florida Keys and portions of the Florida Peninsula early next week. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the Greater Antilles this weekend. Interests in Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 11.2N  53.8W   40 KT  45 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 12H  02/0600Z 12.1N  57.5W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 24H  02/1800Z 13.5N  62.4W   50 KT  60 MPH - Tropical Storm (WSW Vieux Fort, St Lucia)
 36H  03/0600Z 15.1N  67.3W   50 KT  60 MPH - Tropical Storm (WSW Ponce, PR USA)
 48H  03/1800Z 16.7N  71.6W   50 KT  60 MPH - Tropical Storm (WSW Cabo Rojo, DR)
 60H  04/0600Z 18.3N  75.0W   50 KT  60 MPH - Tropical Storm (WSW Navassa Island, Haiti)
 72H  04/1800Z 19.8N  77.9W   50 KT  60 MPH - Tropical Storm (WSW Cabo Cruz, Cuba)
 96H  05/1800Z 22.5N  82.0W   50 KT  60 MPH - Tropical Storm (Gulf of Batabano, Cuba)
120H  06/1800Z 26.5N  83.5W   50 KT  60 MPH - Tropical Storm (WSW Cape Coral, FL)

NWS National Hurricane Center Miami FL 1100 AM AST Thu Jul 01, 2021

Just-received scatterometer data showed 35-40 kt winds to the northeast of the center, so the initial intensity is increased to 40 kt. Some slight revisions were also made to the initial and forecast wind radii. Over all, the organization of the storm has changed little during the past several hours, with the low-level center partly exposed to the north and northwest of the primary convective band. Elsa continues to move a little faster with the initial motion now 280/24. A rapid west-northwestward motion is likely for the next 48 h or so as Elsa is steered by the strong subtropical ridge to the north. After that time, the storm is expected to approach a weakness in the ridge caused by a mid-latitude trough over the eastern United states. The guidance becomes rather divergent as this happens, as the ECWMF and ECMWF ensemble mean forecast a turn toward the north while the GFS and UKMET are forecasting a west-northwestward to northwestward motion. The latter part of the new NHC forecast track will lean more toward the GFS/UKMET solutions at this time, but the large spread in both the deterministic models and the ensembles make this part of the forecast of low confidence. The new official forecast track has only minor adjustments from the previous forecast.

Some additional strengthening is expected during the next day or so as Elsa is expected to be in an environment of warm sea-surface temperatures, light vertical wind shear, and high mid-level relative humidity. However, as mentioned earlier, the fast forward motion could result in some decoupling of the lower and upper parts of the storm, and this could limit strengthening. The latter part of the intensity forecast also has high uncertainty due to the possibility of land interaction and disagreements among the global models on how favorable the upper-level winds will be. Based on these factors, the NHC intensity forecast continues to be on the lower end of the intensity guidance suite.

Key Messages:

  • 1. Tropical storm conditions are expected beginning early Friday in portions of the Windward and southern Leeward Islands.
  • 2. Heavy rainfall from Elsa will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday, with outer rain bands impacting Puerto Rico Friday into Saturday. Isolated flash flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of Hispaniola, Cuba, the Turks and Caicos and the Bahamas through early next week. Interests in these areas should monitor Elsa’s progress and updates to the forecast.
  • 4. There is a risk of storm surge, wind, and rainfall impacts in the Florida Keys and portions of the southern Florida Peninsula early next week. However, the forecast uncertainty remains larger than usual due to Elsa’s potential interaction with the Greater Antilles this weekend. Interests in Florida should monitor Elsa’s progress and updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 10.1N  51.4W   40 KT  45 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 12H  02/0000Z 11.2N  54.9W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 24H  02/1200Z 12.6N  59.9W   50 KT  60 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 36H  03/0000Z 14.1N  64.9W   50 KT  60 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 48H  03/1200Z 15.9N  69.8W   50 KT  60 MPH - Tropical Storm (ESE Santo Domingo, DR)
 60H  04/0000Z 17.6N  73.6W   50 KT  60 MPH - Tropical Storm (WSW Les Cayes, Haiti)
 72H  04/1200Z 19.3N  76.5W   45 KT  50 MPH - Tropical Storm (ESE Pilón, Cuba)
 96H  05/1200Z 22.0N  80.5W   50 KT  60 MPH - Tropical Storm (WSW Jagua, Cuba)

NWS National Hurricane Center Miami FL 1100 PM AST Wed Jun 30, 2021

The satellite presentation of the system over the last 6-12 hours has continued to gradually improve, with a prominent banding feature to the west of the estimated center. An ASCAT-A pass received at 2323 UTC revealed that the low-level circulation has become a bit better defined compared to earlier today, though still somewhat elongated to the south and west. The peak wind retrievals from this instrument were 30-32 kt. While subjective satellite estimates from TAFB and SAB were a bit higher, the latest estimated intensity was held at 30 kt for this advisory in agreement with the slightly lower scatterometer data.

The initial motion has accelerated a bit tonight at 280/20 kt. A strong subtropical ridge is situated poleward of the tropical depression and this feature should steer the system quickly to the west-northwest over the next several days. After 72 hours, the tropical cyclone will reach the westward extent of the ridge and begin to move more poleward and slow down as the ridge also becomes eroded by a mid-latitude trough to over the eastern US. The track guidance in the latter portion of the forecast continues to exhibit large spread, with the GFS and HWRF/HMON models along the left side of the guidance envelop, while the ECMWF and its ensemble mean on the right side. The latest NHC track forecast is a shade right of the previous one, and also slightly faster, but given the spread in the models, the latter portion of the track is more uncertain than usual.

While the depression is currently in a favorable environment of low vertical wind shear, warm sea-surface temperatures, and high mid-level relative humidity, the expected acceleration in forward motion could cause the system to outrun the favorable upper-level easterlies currently overhead, after 36 hours. In addition, the system could be near or over some of the Greater Antilles in the latter portions of the forecast. For these reasons, the intensity remained capped at 50 kt after 36 hours, and is still on the lower end of the intensity guidance suite, though this forecast could be somewhat conservative.

Key Messages:

  • 1. The tropical depression is expected to become a tropical storm before reaching the Lesser Antilles and tropical storm conditions are expected beginning late Thursday night in portions of the Windward and southern Leeward Islands.
  • 2. Heavy rainfall will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Isolated flash flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of the Virgin Islands, Puerto Rico, Hispaniola, Cuba, the Turks and Caicos and the southeastern Bahamas through early next week. Interests in these areas should monitor the system’s progress and updates to the forecast.
  • 4. Interests in Florida should monitor updates to the forecast for this system, but it is too soon to determine what if any impacts could occur there next week given the uncertainty in the long-range forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  01/0300Z  9.6N  46.3W   30 KT  35 MPH - Depression (ESE Bridgetown, Barbados)
 12H  01/1200Z 10.5N  49.6W   40 KT  45 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 24H  02/0000Z 11.7N  54.4W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 36H  02/1200Z 13.0N  59.6W   50 KT  60 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 48H  03/0000Z 14.7N  65.0W   50 KT  60 MPH - Tropical Storm (WSW Roseau,Dominica)
 60H  03/1200Z 16.5N  69.8W   50 KT  60 MPH - Tropical Storm (WSW Santo Domingo, DR)
 72H  04/0000Z 18.3N  73.8W   50 KT  60 MPH - Tropical Storm (WSW La Borde, Haiti)
 96H  05/0000Z 20.9N  78.6W   50 KT  60 MPH - Tropical Storm (WSW Alazán, Cuba)
120H  06/0000Z 24.5N  82.0W   50 KT  60 MPH - Tropical Storm (WSW Key West, FL)

NWS National Hurricane Center Miami FL 500 PM AST Wed Jun 30, 2021

Satellite imagery indicates that the convection associated with the low-pressure area over the central tropical Atlantic is becoming better organized. However, earlier scatterometer data showed that the circulation was elongated and not well defined. Since the system is about 48 h away from the Lesser Antilles and is expected to become a tropical storm before reaching the islands, advisories are being initiated at this time on Potential Tropical Cyclone Five. The initial intensity is set to 30 kt based on the scatterometer data and satellite intensity estimates from TAFB and SAB.

The initial motion is 285/18. The disturbance is currently on the south side of a strong subtropical ridge, and for the next 72 h the system should move rapidly west-northwestward. Indeed, the forward speed may exceed 25 kt as the system moves through the Lesser Antilles. There is excellent agreement in the guidance on this part of the forecast track. After 72 h, the system is expected to approach a weakness in the ridge caused by a mid-latitude trough over the eastern United States. The should cause the system to slow its forward speed and turn more northwestward. The track guidance become more diverse during this time in regards to how far north the system will turn, and this part of the NHC forecast track is most similar to the GFS and UKMET forecasts. Note that the track forecast is more uncertain than usual since the system does not yet have a well-defined center.

The disturbance is currently in a favorable upper-level wind pattern. However, most Atlantic systems in this area moving near 25 kt have trouble strengthening, and there are indications that the fast forward speed may produce some westerly shear. Thus, the NHC intensity forecast for the first 72 h is near the lower edge of the intensity guidance. After 72 h, the intensity forecast becomes highly uncertain due to possible land interaction and differences in the model forecasts of the upper-level winds. This portion of the NHC intensity forecast maintains a constant 50-kt intensity due to the level of uncertainty.

Key Messages:

  • 1. The system is expected to become a tropical storm before reaching the Lesser Antilles and tropical storm conditions are possible beginning Friday in portions of the Windward and southern Leeward Islands.
  • 2. Heavy rainfall will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Isolated flash flooding and mudslides are possible.
  • 3. There is a risk of wind and rainfall impacts in portions of the Virgin Islands, Puerto Rico, Hispaniola, Cuba, the Turks and Caicos and the southeastern Bahamas through early next week, although the forecast is more uncertain than usual since the system does not have a well-defined center. Interests in these areas should monitor the system’s progress and updates to the forecast.
  • 4. Interests in Florida should monitor updates to the forecast for this system, but it is too soon to determine what if any impacts could occur there next week given the uncertainty in the long-range forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z  9.6N  43.7W   30 KT  35 MPH - Potential TS (ESE Bridgetown, Barbados)
 12H  01/0600Z 10.2N  46.6W   35 KT  40 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 24H  01/1800Z 11.1N  51.0W   40 KT  45 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 36H  02/0600Z 12.4N  56.0W   45 KT  50 MPH - Tropical Storm (ESE Bridgetown, Barbados)
 48H  02/1800Z 13.8N  61.2W   45 KT  50 MPH - Tropical Storm (WSW Palmiste, St Lucia)
 60H  03/0600Z 15.4N  66.3W   50 KT  60 MPH - Tropical Storm (ESE Ponce, PR USA)
 72H  03/1800Z 17.0N  70.9W   50 KT  60 MPH - Tropical Storm (ESE Enriquillo, DR)
 96H  04/1800Z 20.0N  77.0W   50 KT  60 MPH - Tropical Storm (WSW Bartolome Maso, Cuba)
120H  05/1800Z 22.5N  81.5W   50 KT  60 MPH - Tropical Storm (WNW Playa Larga, Cuba)

NWS National Hurricane Center Miami FL 200 PM EDT Wed Jun 30, 2021

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

  • 1. Showers and thunderstorms associated with a broad low-pressure area and tropical wave located about 1300 miles east-southeast of the Windward Islands have become better organized since yesterday. However, recent satellite wind data indicates that the disturbance does not have a well-defined circulation. Environmental conditions appear generally favorable for continued development, and a tropical depression or storm is likely to form during the next day or two while the system moves west-northwestward at 20 to 25 mph. Interests in the Lesser Antilles should closely monitor the progress of this system, as advisories on a potential tropical cyclone, accompanied by tropical storm watches for portions of this area, are likely to be issued later today. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent. [NHC will initiate advisories on Potential Tropical Cyclone Five, located over the central Tropical Atlantic, at 500 PM AST (2100 UTC).]
  • 2. Showers and thunderstorms continue in association with a tropical wave located over the Lesser Antilles. This system has become less organized since yesterday, and significant development is no longer expected while it moves quickly westward across the Caribbean Sea. The wave should continue to produce locally heavy rains over portions of the Lesser Antilles through tonight. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…near 0 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Wed Jun 30, 2021 

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

  • 1. A broad area of low pressure, associated with a tropical wave, is located about midway between the west coast of Africa and the Windward Islands. This system is producing a large area of showers and thunderstorms that continues to show some signs of organization. Environmental conditions appear generally favorable for development, and a tropical depression is likely to form during the next few days while the system moves west-northwestward at about 20 mph. Interests in the Windward and Leeward Islands should closely monitor this system as it will likely be moving through that region on Friday. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…80 percent.
  • 2. Disorganized showers and thunderstorms continue in association with a tropical wave located just east of the Lesser Antilles. Significant development of this system is unlikely while it moves quickly westward to west-northwestward at 20 to 25 mph, passing through the Lesser Antilles today and then across the eastern and central Caribbean Sea later this week. Regardless of development, this system could bring locally heavy rainfall to portions of the Lesser Antilles during the next day or two. * Formation chance through 48 hours…low…10 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Tue Jun 29, 2021

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

  • 1. A broad area of low pressure, associated with a tropical wave, is located about midway between the west coast of Africa and the Windward Islands. This system is producing a large area of showers and thunderstorms that are starting to show some signs of organization. Environmental conditions appear generally favorable for development, and a tropical depression could form during the next few days while the system moves west-northwestward at about 20 mph. Interests in the Windward and Leeward Islands should closely monitor this system as it will likely be moving through that region on Friday. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium...60 percent.
  • 2. Disorganized showers and thunderstorms continue in association with a tropical wave located a few hundred miles east of the Lesser Antilles. Development, if any, of this system should be slow to occur as the tropical wave moves quickly westward to west-northwestward at 20 to 25 mph, passing through the Lesser Antilles on Wednesday and then across the eastern and central Caribbean Sea later this week. Regardless of development, this system could bring locally heavy rainfall to portions of the Lesser Antilles during the next couple of days. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Tue Jun 29, 2021

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

The National Hurricane Center has issued the last advisory on the remnants of Tropical Depression Danny, located inland over eastern Georgia.

  • 1. Disorganized showers and thunderstorms continue in association with a tropical wave located over the tropical Atlantic, about 850 miles east of the Lesser Antilles. Some slow development of this disturbance is possible later this week and this weekend while the system moves westward to west-northwestward at 15 to 20 mph, likely reaching the Lesser Antilles by Wednesday night. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. Shower activity associated with a tropical wave located about 800 miles southwest of the Cabo Verde islands has become a little better organized since yesterday. Additional slow development of this system is possible during the next several days as it moves generally west-northwestward at about 20 mph. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 PM EDT Mon Jun 28, 2021

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

The National Hurricane Center is issuing advisories on Tropical Storm Danny, located near the southern South Carolina coast.

  • 1. Disorganized showers and a few thunderstorms continue in association with a tropical wave located over the central Atlantic Ocean. Some slow development of this disturbance is possible later this week and this weekend while the system moves westward to west-northwestward at 15 to 20 mph, likely reaching the Lesser Antilles by Wednesday night. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.

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