Tropical Storm Nestor

Post Tropical Storm Nestor Track 1700 Hours October 19 2019
Post Tropical Storm Nestor Track 1700 Hours October 19 2019

Tropical Storm Nestor Satellite 0700 Hours October 19 2019Tropical Storm Nestor (see Saturday 5:00 pm video below) NWS National Hurricane Center Miami FL 500 PM EDT Sat Oct 19, 2019

The center of Post-Tropical Cyclone Nestor made landfall along on St. Vincent Island, Florida, around 1730 UTC. Since then, that center has moved inland over the Florida Panhandle between Apalachicola and Tallahassee. However, during the past hour, a new center appears to have formed farther west along a quasi-occluded frontal boundary. The earlier 40-45 kt winds over water have moved inland and weakened, and the initial intensity of 35 kt is based on a recent wind report of a sustained wind of 33 kt at 5-meters elevation from NOAA buoy 41008/Gray’s Reef, Georgia.

The initial motion estimate is now northeastward or 055/20 kt. Nestor is forecast to move northeastward over the next 36 hours or so, followed by a turn toward the east once the cyclone reaches the North Carolina Outer Banks. On days 2 an 3, upper-level support is expected to weaken and lift out to the northeast, leaving a weakening extratropical cyclone Nestor behind. The cyclone should then dissipate or merge with another frontal system by 96 h offshore of the U.S. east coast. The new official forecast track is similar to the previous advisory, and lies close to the center of the tightly packed model guidance envelope.Post Tropical Storm Nestor Tropical Wind Speeds October 19 2019

Some slight strengthening is expected on Sunday, mainly due to the robust circulation moving out over the warm waters of the far western Atlantic where less friction will affect the cyclone. The official intensity foreast closely follows an average of the 1200 UTC GFS, UKMET, and ECMWF global model intensity forecasts.

This is the last advisory issued by the National Hurricane Center on Nestor. 

Key Messages:

  • 1. Gale-force winds will gradually develop over the Atlantic waters and along the coasts northeastern Florida and Georgia tonight, and spread northward to the Carolinas on Sunday.
  • 2. Isolated flash flooding is possible across the southeastern United States into Sunday.
  • 3. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 30.4N  84.1W   35 KT  40 MPH - Low (ESE Tallahassee, FL)
 12H  20/0600Z 32.3N  81.4W   40 KT  45 MPH - Low (WSW Guyton, GA)
 24H  20/1800Z 35.0N  76.7W   40 KT  45 MPH - Low (ESE Wiggins Point, NC)
 36H  21/0600Z 36.8N  72.0W   45 KT  50 MPH - Low (ESE Virginia Beach, VA)
 48H  21/1800Z 36.8N  68.0W   40 KT  45 MPH - Low (ESE Virginia Beach, VA)
 72H  22/1800Z 36.5N  65.5W   35 KT  40 MPH - Low (WSW St George's, Bemuda)
 96H  23/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sat Oct 19, 2019

Nestor has made the transition to a post-tropical extratropical cyclone. There has been no significant convection near the low-level center for more than six hours, and satellite and surface observations indicate that the cyclone’s center has merged with a nearby frontal system that lies along the coast of Florida panhandle. The overall cloud pattern more closely resembles that of an occluded low-pressure system now, including a pre-frontal squall line or convergence zone a few hundred nmi east of the low. Sustained tropical-storm-force winds with gusts to near 50 kt have been reported by some of the buoys and coastal marine stations over the northeastern Gulf of Mexico during the past few hours. The initial intensity of 45 kt is based on Doppler velocity values of 50-55 kt between 4000-6000 ft ASL located over Apalachee Bay, which approximately equals surface winds of 40-44 kt.Post Tropical Storm Nestor Arrival Times October 19 2019

The now well-defined low-level center made a brief jog toward the northwest early this morning as an upper-level low passed over the larger cyclonic gyre. However, the motion since that time has been slowly eastward, and the initial motion estimate is now east-northeastward or 075/08 kt. Despite the earlier erratic motion, the latest NHC track model guidance remains in very good agreement on post-tropical Nestor moving northeastward and accelerating over the next 36 hours or so, followed by a turn toward the east once the cyclone reaches the North Carolina Outer Banks. By 48 hours, the parent upper-level low is expected to weaken and open up into a shortwave trough, and leave Nestor behind as a weakening the extratropical cyclone that dissipates by 96 h east of the U.S. east coast. The new official forecast track was only nudged a little to the west of the previous advisory due to the more westward initial position and lies close to an average of the deterministic 0000 UTC and 0600Z GFS, ECMWF, and UKMET model runs.

No strengthening is anticipated before Nestor moves inland later this afternoon. Some slight weakening will occur after the center moves inland, but gale-force winds are expected develop over the Atlantic waters of northeastern Florida to the Carolinas this afternoon and tonight, and across the mid-Atlantic U.S. coastal waters on Sunday. The extratropical cyclone is expected to dissipate or merge with a cold front in about 4 days or sooner.

Given the non-tropical structure of Nestor, dangerous storm surge and tropical-storm-force and gale-force winds will occur along a large portion of the Florida Gulf Coast well east of the track of Nestor’s center today.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 4 feet above ground level along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds will continue across portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible across the southeastern The United States into Sunday morning.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 29.3N  86.3W   45 KT  50 MPH - Low (WSW Port St Joe, FL)
 12H  20/0000Z 31.0N  83.5W   35 KT  40 MPH - Low (WSW Barney, GA)
 24H  20/1200Z 34.1N  79.5W   40 KT  45 MPH - Low (WSW Marion, SC)
 36H  21/0000Z 36.0N  75.1W   40 KT  45 MPH - Low (ESE Kill Devil Hills, NC)
 48H  21/1200Z 36.6N  71.5W   40 KT  45 MPH - Low (ESE Virginia Beach, VA)
 72H  22/1200Z 36.4N  66.6W   35 KT  40 MPH - Low (ESE Virginia Beach, VA)
 96H  23/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 AM CDT Sat Oct 19 2019

Nestor is rapidly losing the few tropical characteristics that it once had. The cloud pattern consists of a large circulation of low clouds with a comma-shaped convective band well to the east of the circulation. This band is already over a large portion of the Florida peninsula. The center of the system or the area of minimum pressure could be anywhere within this gyre, and the precise location is uncertain. Surrounding data and ASCAT measurements suggest that the winds have decreased to 45 kt.

All indications are that no significant strengthening is anticipated before the broad circulation moves inland later today, and guidance suggests that Nestor will lose its tropical characteristics while moving across the southeastern United States. The weaker extratropical cyclone is expected to dissipate or merge with a cold front in about 4 days or sooner.

Since the center is not well defined, the initial motion is highly uncertain. It appears that cyclone has slowed down but it should resume a motion toward northeast or 045 degrees at about 15 kt. Most of the track models are in good agreement that this general motion should continue, and the broad circulation will move inland over the Florida Panhandle later today and across portions of Georgia and the Carolinas later tonight and Sunday.

Given the non-tropical appearance of Nestor, dangerous storm surge and tropical-storm-force winds will occur along a large portion of the Florida Gulf Coast well east of the track of Nestor’s center today.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds are spreading across portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible across the southeastern United States into Sunday morning.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 29.0N  86.0W   45 KT  50 MPH - Tropical Storm (WSW Port St. Joe, FL)
 12H  19/1800Z 30.7N  84.0W   35 KT  40 MPH - Tropical Storm (W Metcalf, GA)
 24H  20/0600Z 33.5N  80.0W   35 KT  40 MPH - Tropical Depression (WSW Greeleyville, SC)
 36H  20/1800Z 36.0N  76.0W   35 KT  40 MPH - Low (WSW Kill Devil Hills, NC)
 48H  21/0600Z 37.0N  71.5W   35 KT  40 MPH - Low (ESE Hog Island. VA)
 72H  22/0600Z 37.5N  65.0W   35 KT  40 MPH - Low (ESE Ocean City, MD)

NWS National Hurricane Center Miami FL 1000 PM CDT Fri Oct 18, 2019

The Air Force and NOAA Hurricane Hunters are investigating Nestor this evening, and they have found that the minimum pressure has dropped to 996 mb, 3 mb lower than this afternoon, but they have not found higher winds yet. Based on preliminary data from both aircraft, the initial wind speed remains 50 kt. The Air Force also reported that there is a lot of lightning occurring in the thunderstorms on Nestor’s east side. Nestor remains a lopsided tropical storm, with very intense deep convection extending well to the east of the center with only small areas of convection near and to the west of the center. This asymmetric cloud pattern is due to strong westerly wind shear associated with a nearby shortwave trough. Doppler radar imagery indicates that rain bands are now spreading inland over much of the eastern portions of the Gulf coast, and surface observations show the winds increasing near the coast, but they are still not quite at tropical storm strength.

Water vapor satellite images show that the shortwave trough is almost co-located with Nestor, which is likely part of the reason why the minimum pressure has fallen. Even though it is not explicitly reflected in the forecast, Nestor could strengthen a little before the storm makes landfall. However, significant intensification seems unlikely as the shortwave trough is expected to bypass the cyclone soon, leaving the storm in a less favorable environment of upper-level confluence and drier air. After landfall, weakening is forecast and the models suggest that Nestor should lose its tropical characteristics on Saturday when it tracks across the southeast U.S. The weaker extratropical cyclone is expected to dissipate or merge with a cold front in about 4 days.

The tropical storm is moving quickly northeastward at about 20 kt. The models are in good agreement that this general motion should continue for the next couple of days, taking the center of the storm inland over the Florida Panhandle on Saturday morning and across portions of Georgia and the Carolinas later Saturday and Sunday. The weakening system is expected to slow down and turn eastward over the western Atlantic early next week before it merges with a cold front. The NHC track forecast is nudged to the west of the previous one to be in better agreement with the latest consensus models.

Given the structure of Nestor, dangerous storm surge and tropical-storm-force winds will occur along a large portion of the Florida Gulf Coast well east of the track of Nestor’s center through Saturday.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds are spreading across portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast and Southeast United States coast into early Sunday morning.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  19/0300Z 28.5N  87.0W   50 KT  60 MPH - Tropical Storm (ESE Pensacola, FL)
 12H  19/1200Z 30.2N  85.2W   50 KT  60 MPH - Tropical Storm (ENE Wewahitchka, FL)
 24H  20/0000Z 32.7N  82.3W   35 KT  40 MPH - Tropical Storm (WSW Blun, GA)
 36H  20/1200Z 34.9N  78.2W   35 KT  40 MPH - Low (WSW Turkey, NC)
 48H  21/0000Z 36.5N  73.7W   35 KT  40 MPH - Low (ESE Knotts Island, NC)
 72H  22/0000Z 37.5N  67.0W   35 KT  40 MPH - Low (ESE Ocean City, MD)
 96H  23/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Fri Oct 18, 2019

Nestor’s structure has evolved quite a bit today. Since the release of the previous advisory, the center has become better defined based on data from aircraft, satellite, and surface observations, and on that basis, the system was classified as a tropical cyclone around 1800 UTC. Since that time, the center has become more separated from the area of deep convection to the east, consistent with 30-40 kt of deep-layer westerly shear analyzed by the SHIPS model and UW-CIMSS. The initial intensity remains 50 kt based on aircraft data and earlier ASCAT data.

The mid/upper-level trough seen in water vapor imagery over southeastern Louisiana is beginning to impinge on Nestor, and the cloud pattern has become more lopsided. It would not be surprising to see Nestor take on a more subtropical appearance overnight, as the GFS and ECMWF show the upper trough becoming superimposed on the low-level circulation, with the pressure continuing to deepen and some increase in the peak winds noted in both those models. This is reflected in the 12-h intensity forecast of 55 kt. After that time, the upper-level pattern becomes less favorable and Nestor should weaken while it moves inland over the southeastern United States and becomes post-tropical. Gale-force winds are shown over the western Atlantic waters, but are not expected over land areas from 24 h onward. The global models show Nestor’s circulation dissipating by 96 hours, and that is reflected in the NHC forecast.

The initial motion estimate is 050/19, but remains somewhat uncertain given the recent formation of a better-defined center. The track forecast reasoning remains unchanged, with Nestor expected to move quickly northeastward ahead of the approaching upper trough and moving inland over the Florida Panhandle early Saturday. The circulation center will move across the southeastern United States before moving back offshore after 48 hours with a slower east-northeastward to eastward motion shown late in the period before dissipation. The new NHC track forecast lies a little to the right of the previous and is close to the middle of the guidance envelope. It should be noted that dangerous storm surge and tropical storm-force winds will occur along a large portion of the Gulf Coast well east of the track of Nestor’s center.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning this evening along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical storm-force winds are likely later today and tonight along portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast and Southeast United States coast from late tonight through Sunday.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 27.0N  88.5W   50 KT  60 MPH - Tropical Storm (WSW Port Eads, LA)
 12H  19/0600Z 28.9N  86.2W   55 KT  65 MPH - Tropical Storm (WSW Port St. Joe, Fl)
 24H  19/1800Z 31.1N  83.7W   35 KT  40 MPH - Tropical Storm (WNW Berlin, GA)
 36H  20/0600Z 33.4N  80.3W   35 KT  40 MPH - Tropical Storm (ENE Eutawville, SC)
 48H  20/1800Z 35.4N  75.9W   35 KT  40 MPH - Low (ESE Engelhard, NC)
 72H  21/1800Z 36.6N  68.6W   35 KT  40 MPH - Low (ESE Virginia Beach, VA)
 96H  22/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Fri Oct 18, 2019

The satellite presentation of the system features an area of very deep convection with cloud tops colder than -80C within the eastern part of a rather broad and elongated surface circulation seen in visible satellite imagery and data from an Air Force Reserve Hurricane Hunter aircraft. A NOAA Hurricane Hunter aircraft found flight-level winds as high as 72 kt and SFMR winds of 45-50 kt southeast of the ill-defined center and based on these data the initial intensity is set to 50 kt. The NOAA aircraft also measured the pressure of around 1001 mb. While the cyclone has deepened, the circulation is still quite elongated and not well defined, so the system is maintained as a Potential Tropical Cyclone for now.

The global models continue to indicate that the circulation will consolidate and the system will strengthen some during the next 12 hours or so, as the low-level circulation will be overtaken by an upper-level trough currently situated over southwest Louisiana. The system is still expected to become a tropical or subtropical storm later today, with the exact phase dependent on the timing of the circulation improving and the interaction with the upper trough. Once the system moves inland, it should become extratropical by 36 hours and slowly weaken once it moves offshore of the Carolinas by 72-96 hours before dissipating by day 5. The new NHC intensity forecast is adjusted upward from the previous one through 24 hours based on the initial intensity and allows for the possibility of at least some additional strengthening later today.

The initial motion is a somewhat uncertain 055/19 given the lack of a well-defined center. The track model guidance remains in good agreement on the system moving quickly northeastward toward the northeastern Gulf Coast during the next 24 hours as it interacts with the upper trough. After moving inland, a northeastward motion is forecast to continue until after 48 hours, when an east-northeastward motion is expected, which will take the circulation offshore over the Atlantic by 72 hours. The new NHC track forecast is similar to, but a bit to the south of the previous one and is close to the various track consensus aids.

Regardless of the exact evolution of the system, portions of the northeastern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge later today and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States on Saturday and Sunday.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning later today along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds are likely later today and tonight along portions of the central and eastern Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast and the southeast United States coast through Saturday night.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  18/1500Z 25.9N  90.0W   50 KT  60 MPH - Potential Tropical Storm (WSW Port Eads, LA)
 12H  19/0000Z 27.8N  88.0W   55 KT  65 MPH - Tropical Storm (ESE Port Eads, LA)
 24H  19/1200Z 29.9N  85.5W   50 KT  60 MPH - Tropical Storm (WSW Mexico Beach, FL)
 36H  20/0000Z 32.2N  82.5W   35 KT  40 MPH - Tropical Storm (WSW Higgston, GA)
 48H  20/1200Z 34.4N  78.5W   35 KT  40 MPH - Tropical Storm (WSW Council, NC)
 72H  21/1200Z 37.0N  71.0W   35 KT  40 MPH - Tropical Storm (ESE Hog Island, VA)
 96H  22/1200Z 37.0N  69.0W   25 KT  30 MPH - Low (ENE Virginia Beach, VA)
120H  23/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 AM CDT Fri Oct 18, 2019

Although the convection associated with the disturbance has increased during the past few hours, there is no evidence that a well-defined center has formed yet. One can observe several swirls of low clouds rotating within a larger gyre. Most of the global models forecast that the system will become better organized later today, and given the current trend, NHC forecasts that a tropical or most likely a subtropical cyclone will form later this morning. A reconnaissance plane will investigate the disturbance in a few hours.

The disturbance is located to the east of an upper trough which is digging along the western Gulf of Mexico, and the upper-level diffluence caused by the trough should induce some strengthening during the next 24 hours or so before the system moves inland. However, the simulated convection by the GFS and the ECMWF models resembles a comma-shaped pattern which is characteristic of a subtropical cyclone. After landfall, the cyclone is expected to become extratropical and gradually weaken while it moves northeastward near the southeast U.S. coast. By day 5, the low is forecast to be absorbed by a front over the western Atlantic.

Since the center is not well defined, the initial motion is highly uncertain. The best estimate is toward the northeast or 045 degrees at 12 kt. The system should accelerate later today and continue toward the northeast embedded within the flow ahead of the trough. Track models are in remarkably good agreement and the NHC forecast is in the middle of the tight guidance envelope.

Regardless of the exact evolution of the system, portions of the northern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge Friday and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States on Saturday and Sunday.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning today along the Florida Gulf Coast from Indian Pass to Clearwater, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical storm-force winds are likely by later today along portions of the central and eastern Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast and the southeastern United States coast from today through Saturday night. Since soils across the southeast are dry, the risk of flash flooding will be confined to the immediate coast where heavier rainfall is possible.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  18/0900Z 24.3N  92.5W   35 KT  40 MPH - Potential Tropical Storm (ESE Brownsville, TX)
 12H  18/1800Z 26.8N  89.8W   40 KT  45 MPH - Tropical Storm (WSW Port Eads, LA)
 24H  19/0600Z 29.0N  87.0W   45 KT  50 MPH - Tropical Storm (ESE Pensacola Beach, FL)
 36H  19/1800Z 31.5N  84.5W   35 KT  40 MPH - Tropical Storm (ENE  Leary, GA)
 48H  20/0600Z 33.5N  80.5W   35 KT  40 MPH - Tropical Storm (WNW Santee, SC)
 72H  21/0600Z 37.0N  72.0W   35 KT  40 MPH - Tropical Storm (ESE Kiptopeke, VA)
 96H  22/0600Z 37.5N  69.5W   30 KT  35 MPH - Low (ESE Chincoteague, VA)
120H  23/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Thu Oct 17, 2019

The disturbance over the southwestern Gulf of Mexico continues to produce a large area of cloudiness and thunderstorms over much of the central and southwestern Gulf of Mexico. The system is not yet a tropical or subtropical cyclone as it still lacks sufficient convective organization and an Air Force reconnaissance aircraft that flew into the disturbance late this afternoon found a broad circulation, but no evidence of a well-defined center. The global models indicate that the circulation will become better defined by early Friday, and that the low will deepen within an area of strong upper-level divergence to the east of an upper-level trough over southeastern Texas. As a result, strengthening is forecast while the system moves over the Gulf of Mexico during the next 24 to 36 hours. While the system is unlikely to develop into a classical tropical cyclone, it is expected to obtain enough organized convection to become a tropical or subtropical cyclone on Friday or Friday night before is reaches the northern Gulf coast. After landfall, the cyclone is expected to become extratropical and gradually weaken while it moves northeastward near the southeast U.S. coast. By day 5, the low is forecast to be absorbed by a front over the western Atlantic.

The disturbance is moving northeastward at about 10 kt. The system should accelerate northeastward ahead of the aforementioned trough on Friday, and the northeastward motion should then continue during the next few days. The low is forecast to slow down and turn east-northeastward after 72 hours when the mid-level flow becomes more zonal. The new NHC track forecast uses a blend of the lastest global model fields and is very similar to the previous advisory.

Regardless of the exact evolution of the system, portions of the northern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge Friday and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States Saturday and Sunday.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning Friday along the Florida Gulf Coast from Indian Pass to Clearwater, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical storm force winds are likely by Friday afternoon along portions of the central and eastern Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast, mainly Friday and Friday night. Since soils across the southeast are dry, the risk of flash flooding will be confined to the immediate coast where heavier rainfall is possible.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 24.1N  93.7W   35 KT  40 MPH - Tropical Storm (ENE Tampico, Mexico)
 12H  18/1200Z 26.0N  91.1W   35 KT  40 MPH - Tropical Storm (ESE Galveston, TX)
 24H  19/0000Z 28.2N  88.5W   45 KT  50 MPH - Tropical Storm (WSW Port Eads, LA)
 36H  19/1200Z 30.2N  86.1W   45 KT  50 MPH - Tropical Storm (ESE Rosemary Beach, FL)
 48H  20/0000Z 32.2N  82.9W   40 KT  45 MPH - Tropical Storm (Cedar Grove, GA)
 72H  21/0000Z 36.1N  74.0W   40 KT  45 MPH - Tropical Storm (ENE Kill Devil Hills, NC)
 96H  22/0000Z 37.0N  69.5W   35 KT  40 MPH - Tropical Storm (ESE Chincoteague, VA)
120H  23/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Thu Oct 17, 2019

The complicated weather situation over the Gulf of Mexico described in the previous advisory continues to evolve. Recent scatterometer data shows that the tropical disturbance in the southwestern Gulf has a circulation elongated north-northeast to south-southwest, with winds of 30-35 kt occurring in the southwestern quadrant. However, the system currently has neither sufficient convection or a well-enough defined center to be designated a tropical or subtropical cyclone. The disturbance remains in close proximity to a mid- to upper-level low moving across southern Texas and northeastern Mexico and a frontal system over the northern and northwestern Gulf. One change from the previous global model guidance is the ECMWF and GFS have backed off of their forecasts of a separate baroclinic low to the north of the disturbance. Instead, the global models are in reasonable agreement that the disturbance, along with whatever vorticity centers form along the front, will be part of a large low-pressure area that will affect portions of the northern Gulf coast and the southeastern United States.

The initial motion of the disturbance is now 020/8. There is little change in the forecast track philosophy, the track guidance, or the NHC forecast track. The system should soon turn northeastward in the southern portion of the mid-latitude westerlies, and the track model guidance agrees on a continued northeastward motion through at least 72 h. The forecast track, which is in best agreement with the HCCA corrected consensus model, brings the system across the southeastern United States between 36-72 h, and then has it moving into the Atlantic east of the mid-Atlantic States.

Gradual strengthening is expected as strong upper-level divergence caused by the trough partly prevails over strong vertical shear. Based on this, the intensity forecast again calls for gradual strengthening until landfall in agreement with the global model forecasts. While it remains unlikely that the system will develop into a classical tropical cyclone, the ECMWF and GFS models suggest enough organized convection will develop before landfall to make the system a tropical or subtropical cyclone. After landfall, the cyclone is forecast to become fully extratropical and gradually weaken.

Regardless of the exact evolution, portions of the northern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge Friday and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States on Saturday and Sunday.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning Friday along the Florida Gulf Coast from Indian Pass to Clearwater, where a Storm Surge Warning is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds are likely by Friday afternoon along portions of the central and eastern Gulf Coast, where tropical storm watches and warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
  • 3. Isolated flash flooding is possible along the central and eastern Gulf Coast, mainly Friday and Friday night. Since soils across the southeast are dry, the risk of flash flooding will be confined to the immediate coast where heavier rainfall is possible.
  • 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 22.9N  95.2W   35 KT  40 MPH - Tropical Storm (ENE Tampico, Mexico)
 12H  18/0600Z 24.5N  92.9W   35 KT  40 MPH - Tropical Storm (ESE Brownsville, TX)
 24H  18/1800Z 26.9N  89.8W   40 KT  45 MPH - Tropical Storm (WSW Port Eads, LA)
 36H  19/0600Z 29.3N  86.9W   45 KT  50 MPH - Tropical Storm (WSW Destin, FL)
 48H  19/1800Z 31.4N  84.1W   40 KT  45 MPH - Tropical Storm (ENE Baconton, GA)
 72H  20/1800Z 35.6N  76.2W   40 KT  45 MPH - Tropical Storm (ENE Fairfield, NC)
 96H  21/1800Z 37.5N  70.0W   35 KT  40 MPH - Tropical Storm (ESE Ocean City, MD)
120H  22/1800Z 38.5N  66.5W   30 KT  35 MPH - Low(ESE Ocean City, MD)

NWS National Hurricane Center Miami FL 1000 AM CDT Thu Oct 17, 2019

A complicated weather situation is evolving in the Gulf of Mexico. The circulation associated with the tropical disturbance over the southwestern Gulf of Mexico is getting better defined, and the associated convection is getting better organized. However, a strong mid- to upper-level trough is moving eastward across southern Texas and northern Mexico, and a frontal system is present over the northern and northwestern Gulf of Mexico.

The ECMWF and GFS models suggest that the trough will spawn a low along the front, with the tropical disturbance merging with that low. On the other hand, the UKMET suggests the tropical disturbance will become the primary low-pressure system. Either way, it is likely that a low-pressure area with gale-force winds and at least some tropical cyclone characteristics will move northeastward and affect portions of the northern Gulf coast during the next 36-48 h. Based on this, advisories are initiated on Potential Tropical cyclone Sixteen, and coastal tropical cyclone and storm surge watches/warnings are being issued.

The system should track generally northeastward in the southern portion of the mid-latitude westerlies, and the track model guidance is in reasonably good agreement through 96 h. The forecast track lies a little to the south of the model consensus, as the UKMET has a somewhat more southerly track. The forecast track brings the system across the southeastern United States between 48-72 h, and then has it moving into the Atlantic east of the mid-Atlantic States. Gradual strengthening is expected as strong upper-level divergence caused by the trough partly prevails over strong vertical shear. Thus, the intensity forecast calls for gradual strengthening along the lines of that in the global models. It is unlikely, though, that the system will develop into a classical tropical cyclone. The system is expected to be fully extratropical by 48 h, with gradual weakening expected after that time.

Regardless of the exact evolution of this weather system, portions of the northern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge Friday and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States Saturday and Sunday.

KEY MESSAGES:

  • 1. Dangerous storm surge inundation of up to 5 feet above ground level is possible along the Florida Gulf Coast from Indian Pass to Clearwater, where a Storm Surge Watch is in effect. Residents in these areas should follow the advice given by local officials.
  • 2. Tropical-storm-force winds are likely along portions of the north-central and northeastern Gulf Coast where tropical storm watches and warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center, and begin well in advance of the arrival of the center.
  • 3. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 22.4N  95.7W   30 KT  35 MPH - Tropical Depression (ENE Tampico, Mexico)
 12H  18/0000Z 23.7N  94.2W   35 KT  40 MPH - Tropical Storm (ESE Brownsville, TX)
 24H  18/1200Z 25.8N  91.0W   40 KT  45 MPH - Tropical Storm (WSW New Orleans, LA)
 36H  19/0000Z 28.5N  88.0W   45 KT  50 MPH - Tropical Storm (ESE Port Eads, LA)
 48H  19/1200Z 30.9N  85.0W   45 KT  50 MPH - Tropical Storm (ENE Two Egg, FL)
 72H  20/1200Z 35.5N  77.2W   35 KT  40 MPH - Tropical Storm (WSW Grimesland, NC)
 96H  21/1200Z 37.5N  70.0W   30 KT  35 MPH - Tropical Depression (ESE Ocean City, MD)
120H  22/1200Z 38.0N  66.5W   25 KT  30 MPH - Tropical Depression (ESE Ocean City, MD)

NWS National Hurricane Center Miami FL 800 AM EDT Thu Oct 17, 2019

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

Showers and thunderstorms associated with a broad area of low pressure located over the southwestern Gulf of Mexico continue to show signs of organization. Environmental conditions are expected to be conducive for additional development, and a tropical or a subtropical storm is likely to form later today or tonight while the system moves generally northeastward over the western Gulf of Mexico.

The low is forecast to approach the northern or northeastern Gulf Coast on Friday or Saturday and regardless of development, the system is likely to produce gusty winds and rough surf over those areas. Locally heavy rainfall is also possible across portions of the southeast U.S. late this week and this weekend. Interests along the northern and northeastern Gulf coast should monitor the progress of this system. For more information about marine hazards while the low moves across the Gulf of Mexico, see products issued by the Tropical Analysis and Forecast Branch of the National Hurricane Center. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system this afternoon, if necessary.

* Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high...80 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Wed Oct 16, 2019

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

Shower and thunderstorm activity associated with a broad area of low pressure located over the Bay of Campeche has increased during the past several hours. This system is forecast to move northward and then northeastward across the western and central Gulf of Mexico during the next couple of days and it could become a tropical or subtropical cyclone during that time.

Regardless of development, the low could produce gusty winds and rough surf when it nears the northern Gulf Coast on Friday and Saturday. Heavy rainfall is also possible across portions of the southeast U.S. late this week and this weekend. For more information about marine hazards while the low moves across the Gulf of Mexico during the next couple of days, see products issued by the Tropical Analysis and Forecast Branch of the National Hurricane Center. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system Thursday afternoon, if necessary.

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

NWS National Hurricane Center Miami FL 200 PM EDT Wed Oct 16, 2019

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

A broad area of low pressure located just offshore of the coast of southern Mexico, in the Bay of Campeche, is producing disorganized showers and thunderstorms. Gradual development is possible, and a tropical or subtropical cyclone could form late this week over the western or central Gulf of Mexico while the system is moving generally northeastward. Regardless of development, this system could produce gusty winds, rainfall, and rough surf along portions of the northern Gulf Coast Friday and Saturday. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system Thursday afternoon, if necessary.

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

NWS National Hurricane Center Miami FL 800 AM EDT Wed Oct 16, 2019

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

The National Hurricane Center has issued the last advisory on Tropical Depression Fifteen, which has degenerated into a trough of low pressure near the northern Cabo Verde Islands. 1.

A trough of low pressure located just offshore of the coast of southern Mexico, in the Bay of Campeche, is producing disorganized showers and thunderstorms. Gradual development is possible, and a tropical or subtropical cyclone could form late this week over the western or central Gulf of Mexico while the system is moving generally northeastward. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system this afternoon, if necessary.

* Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 200 AM EDT Wed Oct 16, 2019

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

The National Hurricane Center is issuing advisories on Tropical Depression Fifteen, located near the northern Cabo Verde Islands. 1. A trough of low pressure located over southern Mexico and the Bay of Campeche is producing disorganized showers and thunderstorms. The system is forecast to emerge over the Bay of Campeche later today and move slowly northward. Gradual development is possible, and a tropical or subtropical cyclone could form late this week over the western or central Gulf of Mexico while the system is moving generally northeastward.

* Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Tue Oct 15, 2019

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

The National Hurricane Center is issuing advisories on Tropical Depression Fifteen, located near the northeastern Cabo Verde Islands.

A trough of low pressure located over southern Mexico is producing disorganized showers and thunderstorms over southeastern Mexico, Guatemala, and the Bay of Campeche. This disturbance and another tropical system over the eastern Pacific Ocean are expected to produce heavy rains across portions of southern Mexico and Central America during the next couple of days, which could cause flooding and mudslides, especially in mountainous areas. By late Wednesday, the disturbance is forecast to move over the Bay of Campeche and gradually turn northward. Some gradual development is possible after the disturbance moves over water and a tropical or subtropical cyclone could form later this week over the western Gulf of Mexico.

* Formation chance through 48 hours…low…20 percent.

If this storm is named, it will be called Tropical Storm Nestor.

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Video: Tropical weather forecast & Nestor update: Oct. 19, 2019

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