Tag Archives: Leeward Islands

Tropical Storm Sebastien Speeds East

Tropical Storm Sebastien sped eastward across the Atlantic Ocean on Friday.  At. 4:00 p.m. EST on Friday the center of Tropical Storm Sebastien was located at latitude 26.2°N and longitude 53.7°W which put it about 815 miles (1315 km) northeast of the Leeward Islands.  Sebastien was moving toward the east-northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 999 mb.

An upper level trough over the western Atlantic Ocean was producing strong southwesterly winds which were blowing toward the top of Tropical Storm Sebastien.  Those winds were producing moderate vertical wind shear.  The shear was contributing to an asymmetrical distribution of thunderstorms around Sebastien.  Stronger thunderstorms were occurring in bands north and east of the center of circulation.  Bands south and west of the center consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out 200 miles (325 km) from the center of circulation.

Tropical Storm Sebastien will move through an environment that could permit it to maintain its intensity for another day or so.  Sebastien will move over water where the Sea Surface Temperature is near 25.5°C.  The upper level trough over the western Atlantic will continue to cause moderate vertical wind shear, which will inhibit intensification.  Sebastien will move over cooler water during the weekend and it should start to weaken at that time.

The upper level trough will steer Tropical Storm Sebastien toward the northeast during the weekend.  On its anticipated track Sebastien will move toward the Azores.  Sebastien is forecast to merge with a cold front before it reaches the Azores.

Tropical Storm Sebastien Forms Northeast of the Leeward Islands

Tropical Storm Sebastien formed northeast of the Leeward Islands on Tuesday morning.  At 10:00 a.m. EST on Tuesday the center of Tropical Storm Sebastien was located at latitude 20.1°N and longitude 58.7°W which put it about 275 miles (445 km) northeast of the Leeward Islands.  Sebastien was moving toward the north-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1008 mb.

More thunderstorms developed closer to the center of a low pressure system northeast of the Leeward Islands on Tuesday morning and the National Hurricane Center designated the system as Tropical Storm Sebastien.  There was a distinct low level center of circulation evident on visible satellite imagery.  However, the distribution of thunderstorms was asymmetrical.  The stronger thunderstorms were occurring in bands in the eastern half of the circulation.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  Storms near the center were generating upper level divergence which was pumping mass away to the east of the tropical storm.  Winds to tropical storm force were occurring primarily in the northeastern quadrant of Sebastien.  Those winds extended out 100 miles (160 km) from the center of circulation.

Tropical Storm Sebastien will move through an environment marginally favorable for intensification during the next day or two.  Sebastien will move over water where the Sea Surface Temperature is near 28°C.  So, there will be sufficient energy in the upper ocean to support intensification.  An upper level trough near the east coast of the U.S. will produce southwesterly winds which will blow toward the top of the circulation.  Those winds will create moderate vertical wind shear and they are probably contributing to the asymmetrical distributions of thunderstorms.  Tropical Storm Sebastien could strengthen if the shear does not increase.  However, if the upper level winds get stronger, then wind shear will cause Sebastien to weaken.

The upper level trough near the east coast of the U.S. and a subtropical high pressure system over the Atlantic Ocean will interact to steer Tropical Storm Sebastien toward the north during the next 24 to 36 hours.  On its anticipated track Sebastien will move away from the Leeward Islands and it is forecast to stay southeast of Bermuda.

Low Pressure Developing East of the Leeward Islands

A low pressure system was developing east of the Leeward Islands on Sunday night.  The low pressure system was centered about 550 miles (890 km) east of the Leeward Islands.  The structure of the low pressure system was still organizing.  Thunderstorms were forming in bands southeast of the low level center of circulation.  Bands in the other parts of the circulation consisted primarily of showers and lower clouds.

The low level center appeared to be located east of a small upper level low.  The upper low was causing southerly winds which were creating vertical wind shear over the western half of the surface center.  Some upper level divergence appeared to be occurring over the eastern half of the low level circulation.  The upper level divergence could be contributing to the development of the thunderstorms in that region.

The low pressure system will move through an environment somewhat favorable for development during the next several days.  The low will move over water where the Sea Surface Temperature is near 28°C.  It will move into a region where the upper level winds will not be too strong and there will not be too much vertical wind shear.  The National Hurricane Center is indicating that there is a 50% probability that a tropical or subtropical cyclone forms during the next five days.

The upper level low will steer the developing low pressure system toward the northwest on Monday.  A much large upper level trough off the east coast of the U.S. will steer the low pressure system more toward the north on Tuesday and Wednesday.  On its anticipated track the low pressure system will pass northeast of the Leeward Islands early next week.

Hurricane Jerry Passing North of Leeward Islands

Hurricane Jerry was passing north of the Leeward Islands on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Hurricane Jerry was located at latitude 19.6°N and longitude 62.0°W which put it about 120 miles (195 km) northeast of Anguilla.  Jerry was moving toward the west-northwest at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 991 mb.

Tropical Storm Watches were in effect for St. Maarten, St. Martin and St. Barthelemy.

Hurricane Jerry weakened during much of Friday, but it began to exhibited greater organization again late in the afternoon.  Thunderstorms weakened around the core of Jerry and in the rainbands on Friday morning.  The lack of stronger thunderstorms to transport stronger winds to the surface caused the circulation around the hurricane to weaken.  Northwesterly winds blowing around the eastern side of an upper level ridge over the Caribbean Sea caused more vertical wind shear.  The circulation may have also draw some drier air into the western half of the circulation.  Stronger thunderstorms began to redevelop near the center of circulation late in the afternoon.  Thunderstorms also began to form in a band on the western side of Hurricane Jerry.  The circulation around Jerry was small.  Winds to hurricane force extended out 20 miles (30 km) from the center of circulation.  Winds to tropical storm force extended out about 90 miles (145 km) from the center.

Hurricane Jerry will move through an environment somewhat favorable for intensification during the weekend.  Jerry will move over water where the Sea Surface Temperature is near 28°C.  It will move near the eastern side of an upper level ridge and the ridge will cause some vertical wind shear.  If the shear is greater, the Hurricane Jerry could weaken to a tropical storm.  If the shear is less then Hurricane Jerry could intensify.  It is possible that the wind speed in Hurricane Jerry will fluctuate during the weekend as the strength of the upper level wind changes.

Hurricane Jerry will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Jerry toward the west-northwest during the next 12 to 24 hours.  A portion of the high is forecast to weaken during the weekend and if that happens, then Hurricane Jerry could move northward.  On its anticipated track Hurricane Jerry will pass north of the Leeward Islands and Puerto Rico.

Imelda’s Remnants Cause Flash Floods in Southeast Texas

The remnants of former Tropical Storm Imelda caused flash floods over parts of southeastern Texas on Thursday.  The National Weather Service extended Flash Flood Emergencies for portions of southwestern San Jacinto County, east central Montgomery County, Chambers County and Liberty County.

At 11:00 a.m. EDT on Thursday the center of Tropical Depression Imelda was located at latitude 30.5°N and longitude 95.5°W which put it about 55 miles (90 km) north of Houston, Texas.  Imelda was moving toward the northwest at 6 m.p.h. (9 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1009 mb.

The remnants of former Tropical Storm Imelda remained nearly stationary over southeastern Texas on Thursday morning.  Bands of showers and thunderstorms in the eastern half of the circulation were dropping heavy rain.  There were unofficial reports that some locations had received up to 30 inches (0.9 meters) of rain.  Flash flood were occurring and a portion of Interstate 10 was closed due to high water.  Southeasterly winds were transport very moist air over the region and the heavy rain was forecast to continue.

Elsewhere over the Atlantic Ocean, former Tropical Storm Jerry strengthened into a hurricane and Hurricane Humberto sped away from Bermuda.  At 11:00 a.m. EDT on Thursday the center of Hurricane Jerry was located at latitude 16.8°N and longitude 54.4°W which put it about 490 miles (785 km) east of the Leeward Islands.  Jerry was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 988 mb.  Tropical Storm Watches were in effect for St. Maarten, St. Martin, St. Barthelemy, Barbuda, Anguilla, Saba and St. Eustatius.

At 11:00 a.m. EDT on Thursday the center of Hurricane Humberto was located at latitude 36.8°N and longitude 60.0°W which put it about 415 miles (665 km) northeast of Bermuda.  Humberto was moving toward the northeast at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 110 m.p.h. (185 km/h) and there were gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 955 mb.

Hurricane Humberto Brings Strong Winds to Bermuda

Hurricane Humberto brought strong winds to Bermuda on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Humberto was located at latitude 34.0°N and longitude 63.9°W which put it about 130 miles (215 km) northeast of Bermuda.  Humberto was moving toward the northeast at 23 m.p.h. (37 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 952 mb.

The Hurricane Warning for Bermuda was changed to a Tropical Storm Warning because Hurricane Humberto was moving rapidly away from Bermuda.

Although the center of Hurricane Humberto passed just to the northwest of Bermuda, Humberto did produce hurricane force winds on Bermuda.  The weather station at the L.F. Wade International airport measured a sustained wind speed of 82 m.p.h. (132 km/h) and a wind gust to 114 m.p.h. (184 km/h).  There were reports of power electrical outages and wind damage on Bermuda.  Conditions will improve on Thursday when Hurricane Humberto moves rapidly away from Bermuda.

A trough over the eastern U.S. will steer Hurricane Humberto rapidly toward the northeast on Thursday.  Humberto will move into a less favorable environment.  The upper level trough will cause moderate vertical wind shear.  Hurricane Humberto will start to move over cooler water.  Moderate shear and cooler water will cause Hurricane Humberto to weaken during the next several days.  While Humberto moves into a less tropical environment, it will make a transition to a strong extratropical cyclone.

Elsewhere, Tropical Depression Imelda continued to drop heavy rain over parts of eastern Texas and southwestern Louisiana and Tropical Storm Jerry threatened the northern Leeward Islands.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Imelda was located at latitude 31.2°N and longitude 94.9°W which put it about 110 miles (175 km) north-northeast of Houston, Texas.  Imelda was moving toward the north at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1008 mb.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Jerry was located at latitude 15.4°N and longitude 51.8°W which put it about 675 miles (1085 km) east of the Leeward Islands.  Jerry was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 997 mb.  Tropical Storm Watches were in effect for St. Maarten, St. Martin, St. Barthelemy, Barbuda, Anguilla, Saba and St. Eustatius.

Tropical Storm Jerry Strengthens East of Leeward Islands

Tropical Storm Jerry strengthened east of the Leeward Islands on Wednesday.  At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Jerry was located at latitude 14.6°N and longitude 49.2°W which put it about 855 miles east of the Leeward Islands.  Jerry was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

The circulation around Tropical Storm Jerry exhibited much more organization on Wednesday.  A long band of thunderstorms curved around the western and southern sides of the center of circulations.  Other bands of showers and thunderstorms developed and began to revolve around the center of circulation.  Storms near the center began to generate upper level divergence which was pumping mass away from the tropical storm.  Winds to tropical storm force extended out about 45 miles (75 km) from the center of circulation.

Tropical Storm Jerry will move through an environment favorable for intensification during the next several days.  Jerry will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Jerry is likely to strengthen into a hurricane during the next day or two.  Jerry could rapidly intensify once it develops an inner core with an eye and an eyewall.

Tropical Storm Jerry will move south of a subtropical ridge over the Atlantic Ocean.  The ridge will steer Jerry toward the west-northwest.  On its anticipated track Tropical Storm Jerry could approach the northern Leeward Islands on Friday.  Jerry is likely to be a hurricane by that time.

Elsewhere, Hurricane Humberto was nearing Bermuda and Tropical Depression Imelda was dropping heavy rain over parts of eastern Texas and southwestern Louisiana.  At 2:00 p.m. EDT on Wednesday the center of Hurricane Humberto was located at latitude 32.4°N and longitude 67.2°W which put it about 140 miles (225 km) west of Bermuda.  Humberto was moving toward the east-northeast at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 952 mb.  A Hurricane Warning was in effect for Bermuda.

At 11:00 a.m. EDT on Wednesday the center of Tropical Depression Imelda was located at latitude 30.6°N and longitude 95.6°W which put it about 65 miles (105 km) north of Houston, Texas.  Imelda was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1009 mb.  Flash Flood Watches were in effect for parts of eastern Texas and southwestern Louisiana.

Hurricane Humberto Strengthens to a Major Hurricane, Warning for Bermuda

Hurricane Humberto strengthened into a major hurricane on Tuesday and a Hurricane Warning was issued for Bermuda.  At 11:00 pm. EDT on Tuesday the center of Hurricane Humberto was located at latitude 31.3°N and longitude 71.0°W which put it about 370 miles (595 km) west of Bermuda.  Humberto was moving toward the east-northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 140 m.p.h. (225 km/h).  The minimum surface pressure was 951 mb.

Hurricane Humberto exhibited the structure of a large mature hurricane on Tuesday night.  There was a circular eye at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Hurricane Humberto.  The stronger rainbands were occurring in the northern half of the circulation.  Humberto appeared to be drawing drier air around the southern half of the circulation and bands in that part of the hurricane consisted primarily of showers and lower clouds.

Winds to hurricane force extended out about 45 miles (75 km) from the center of Hurricane Humberto.  Winds to tropical storm force extended out about 150 miles (240 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Humberto was 20.6.  The Hurricane Size Index (HSI) was 16.9 and the Hurricane Wind Intensity Size Index (HWISI) was 37.5.  Hurricane Humberto was capable of causing major wind damage.

Hurricane Humberto will remain in an environment capable of supporting a major hurricane for another 12 to 24 hours.  Humberto will move over water where the Sea Surface Temperature is near 28.5°C.  An upper level trough over the eastern U.S. will produce southwesterly winds which will blow toward the top of the hurricane.  Those winds will cause some vertical wind shear, but the shear may not be strong enough to cause Hurricane Humberto to weaken on Wednesday.

Hurricane Humberto will move around the northern side of a subtropical high pressure system over the Atlantic Ocean.  The high and the upper level trough over the eastern U.S.  will combine to steer Humberto toward the east-northeast on Wednesday.  On its anticipated track the center of Hurricane Humberto could approach Bermuda on Wednesday evening.  Humberto could still be a major hurricane at that time.  If the center of Hurricane Humberto passes just north of Bermuda, then the strongest winds could affect Bermuda.

Elsewhere, Tropical Depression Imelda was dropping heavy rain near Houston, Texas and Tropical Depression Ten was churning toward the northern Leeward Islands.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Imelda was located at latitude 29.8°N and longitude 95.5°W which put it about 10 miles (15 km) northwest of Houston, Texas.  Imelda was moving toward the north at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there  were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1007 mb.

At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Ten was located at latitude 13.7°N and longitude 46.7°W which put it about 1030 miles (1660 km) east of the Leeward Islands.  It was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1006 mb.

Tropical Storm Imelda Forms Along Upper Texas Coast

Tropical Storm Imelda formed along the Upper Texas coast on Tuesday.  At 2:00 p.m. EDT on Tuesday the center of Tropical Storm Imelda was located at latitude 29.0°N and longitude 95.3°W which put it near Freeport, Texas.  Imelda was moving toward the north at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1005 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Sargent to Port Bolivar, Texas.

A small low pressure system over the northwestern Gulf of Mexico exhibited greater organization on satellite and radar images on Tuesday.  When a surface weather station reported a sustained wind speed of 40 m.p.h. (65 km/h), the National Hurricane Center designated the system as Tropical Storm Imelda.  The winds to tropical storm force were occurring southeast of the center of circulation.  Winds to tropical storm force extended out about 45 miles (75 km) in the southeastern quadrant of Tropical Storm Imelda.

Tropical Storm Imelda will move around the western end of a warm high pressure system over the southeastern U.S.  The high will steer Imelda slowly toward the north during the next several days.  On its anticipated track Tropical Storm Imelda will move slowly inland over east Texas.  Although Imelda will cause a small storm surge along the coast around the northwestern Gulf of Mexico, locally heavy rain will pose a much greater risk.  Southeasterly winds blowing around the eastern side of Tropical Storm Imelda will transport very moist air over parts of eastern Texas.  Over a foot of rain (0.33 meters) could fall in some locations where rain bands linger.  Flash Flood Watches have been issued for a number of counties around Houston and Galveston.

Elsewhere over the Atlantic Ocean, Hurricane Humberto moved closer to Bermuda and Tropical Depression Ten formed east of the Lesser Antilles.  At 2:00 p.m. EDT on Tuesday the center of Hurricane Humberto was located at latitude 30.8°N and longitude 72.9°W which put it about 490 miles (785 km) west-southwest of Bermuda.  Humberto was moving toward the east-northeast at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 961 mb.

A Hurricane Watch and a Tropical Storm Warning were in effect for Bermuda.

At 11:00 a.m. EDT on Tuesday the center of Tropical Depression Ten was located at latitude 12.9°N and longitude 44.9°W which put it about 1165 miles (1870 km) east-southeast of the Leeward Islands.  It was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1007 mb.  The depression is forecast to strengthen into a hurricane while it moves toward the northern Leeward Islands.

Tropical Storm Gordon Makes Landfall on the Gulf Coast.

Tropical Storm Gordon made landfall on the Gulf Coast near Pascagoula, Mississippi on Tuesday night.  At 11:30 p.m. EDT on Tuesday the center of Tropical Storm Gordon was located at latitude 30.4°N and longitude 88.4°W which put it about 30 miles (50 km) east of Biloxi, Mississippi.  Gordon was moving toward the northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 997 mb.

A Hurricane Warning was in effect for the portion of the coast from the Mouth of the Pearl River to the Alabama-Florida border.  A Tropical Storm Warning was in effect for the portion of the coast from the Okaloosa-Walton County line to the Alabama-Florida border.

The circulation of Tropical Storm Gordon was asymmetrical.  The strongest bands of showers and thunderstorms were north and east of the center of circulation.  The strongest winds were occurring in those bands.  A C-MAN station on Dauphin Island, Alabama reported a sustained wind speed of 62 m.p.h. (100 km/h) and a wind gust of 72 m.p.h. (117 km/h).  The winds were much weaker south and west of the center of Tropical Storm Gordon and there was little rain in those parts of the tropical storm.

Tropical Storm Gordon will start to weaken as the center moves inland.  Gordon will continue to move around the western end of a high pressure system over the western Atlantic Ocean.  The high will steer Tropical Storm Gordon toward the northwest during the next day or two.  On its anticipated track Tropical Storm Gordon will move across southern Mississippi on Wednesday and over Arkansas on Thursday.  The wind will be strong enough to cause minor damage and it will cause some power outages.  Locally heavy rain and the potential for flash floods are the greater risks.  Flash Flood Warnings were in effect for parts of West Florida and Southwest Alabama.  Flash Flood Watches were in effect for Mississippi and Southeastern Arkansas.

Elsewhere over the tropical Atlantic Ocean, Hurricane Florence was continuing to intensify east of the northern Leeward Islands.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 20.7°N and longitude 43.9°W which put it about 1515 miles (2440 km) east-southeast of Bermuda.  Florence was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 976 mb.