Tag Archives: Lesser Antilles

Tropical Storm Beryl Weakens East of the Lesser Antilles

Tropical Storm Beryl weakened on Saturday as it move closer to the Lesser Antilles.  At 11:00 p.m. EDT on Saturday the center of circulation was located at latitude 13.1°N and longitude 54.3°W which put it about 495 miles (795 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west-northwest at 18 m.p.h. (30 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 1005 mb.

Tropical Storm Warnings were in effect for Dominica and Guadeloupe.  Tropical Storm Watches were in effect for Saba, St. Eustatius, St. Maarten, Martinique, St. Martin, St. Barthelemy, Barbados and St. Lucia.

Tropical Storm Beryl moved into a region where the easterly winds in the lower level were stronger and the increased vertical wind shear started to blow the lower part of the circulation to the west of the upper part of Beryl.  It also seemed to move into an area of drier air, which caused most of the stronger thunderstorms to weaken.  There was still a well organized circulation in the lower levels, but it weakened on Saturday.  More thunderstorms developed near the center of circulation and on the eastern side of Tropical Storm Beryl in recent hours.  If those storms persist then Beryl could strengthen again, but if they dissipate quickly, then the tropical storm could weaken again on Sunday.

Tropical Storm Beryl will move through an environment that contains factors that are favorable for intensification and other factors that are unfavorable.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It will move through an area where the lower level winds are stronger and so there will be more vertical wind shear.  There will be areas of moister air within a larger area of drier air.  If the recently developed thunderstorms persist on Sunday, then the Beryl could strengthen again.  However, if the storms dissipate in a few hours, then Tropical Storm Beryl could weaken further.  The small size of the circulation means that rapid changes in intensity can occur.

Tropical Storm Beryl was moving south of the subtropical high over the Atlantic Ocean.  The high was steering Beryl toward the west-northwest and that general motion is forecast to continue for the next several days.  On its anticipated track Tropical Storm Beryl could reach the Lesser Antilles on Sunday night.  There is a lot of uncertainty about how strong Beryl may be when it reaches those islands.

Elsewhere over the Atlantic Ocean Tropical Depression Three spun south of Cape Hatteras.  At 11:00 p.m. EDT on Saturday the center of Tropical Depression Three was located at latitude 32.9°N and longitude 75.1°W which put it about 160 miles (260 km) south of Cape Hatteras, North Carolina.  It was nearly stationary.  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 1014 mb.

Hurricane Beryl Prompts Watches for Lesser Antilles, TD 3 Forms Southeast of Carolinas

The potential approach of Hurricane Beryl prompted the issuance of Watches for some of the Lesser Antilles on Friday afternoon, while at the same time Tropical Depression Three formed southeast of the Carolinas.  At 5:00 p.m. EDT on Friday the center of Hurricane Beryl was located at latitude 10.6°N and longitude 47.8°W which put it about 965 miles (1555 km) east-southeast of the Leeward Islands.  Beryl was moving toward the west at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 994 mb.

A Hurricane Watch has been issued for Dominica.  Tropical Storm Watches have been issued for Martinique, Guadeloupe, St. Martin and St. Barthelemy.

The circulation of Hurricane Beryl remains very small.  The pinhole is no longer visible on satellite imagery, although strong thunderstorms continue to develop near the center of circulation.  Short narrow bands or showers and thunderstorms are revolving around the core of Hurricane Beryl.  Winds to hurricane force only extend out about 10 miles (15 km) from the center of circulation.  Winds to tropical storm force extend out about 40 miles (65 km) from the center.

Hurricane Beryl will move through an environment favorable for intensification during the next 24 hours.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It is moving south of an upper level ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  However, the wind speeds are similar at all levels and there is currently little vertical wind shear.  Tropical Storm Beryl could intensify on Saturday, but the circulation is so small that any increase in wind shear could cause rapid weakening.

The subtropical ridge over the Atlantic Ocean is north of Hurricane Beryl and the ridge has been steering Beryl toward the west.  A motion more toward the west-northwest is forecast during the weekend.  On its anticipated track Hurricane Beryl will approach the Lesser Antilles later on Sunday.  That is the reason why the Watches were issued for some of those islands.  Beryl could still be a hurricane when it gets to the Lesser Antilles, but there is a lot of uncertainty about the intensity forecast because the hurricane is so small.

Elsewhere over the Atlantic Ocean, the National Hurricane Center designated an area of low pressure southeast of the coast of the Carolinas as Tropical Depression Three.  At 5:00 p.m. EDT on Friday the center of Tropical Depression Three was located at latitude 32.2°N and longitude 73.8°W which put it about 230 miles (370 km) south-southeast of Cape Hatteras, North Carolina.  It was moving toward the north-northwest 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 1016 mb.  Tropical Depression Three is forecast to meander off the coast of the Carolinas during the weekend.  It could strengthen into a tropical storm and there is a chance it could intensify into a hurricane next week.

Beryl Strengthens to a Hurricane East of the Lesser Antilles

Former Tropical Storm Beryl strengthened into a hurricane east of the Lesser Antilles on Friday morning.  At 11:00 a.m. EDT on Friday the center of Hurricane Beryl was located at latitude 10.7°N and longitude 46.5°W which put it about 1045 miles (1685 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 994 mb.

The circulation of Hurricane Beryl remains very small.  There is an eye with a diameter of 6 miles (9 km) at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the hurricane force winds are occurring in this ring of storms.  Several short, narrow bands of showers and thunderstorms are revolving around the core of the circulation.  Storms near the core are generating upper level divergence which is pumping mass away from the hurricane.  Winds to hurricane force only extend out about 10 miles (15 km) from the center of circulation.  Winds to tropical storm force only extend out about 40 miles (65 km) from the center.

Hurricane Beryl will move through an environment favorable for intensification during the next 24 to 48 hours.  Beryl will move over water where the Sea Surface Temperature is near 27°C.  It is moving south of an upper level ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  However, the wind speeds are similar at all levels and there will be little vertical wind shear.  Hurricane Beryl is likely to intensify during the next day or so.  There is less mass in motion in a very small hurricane and so it can intensify quickly, but a small hurricane can also weaken quickly if vertical wind shear increases.

Hurricane Beryl is moving south of the subtropical high pressure system over the Atlantic Ocean and the high is steering Beryl toward the west.  A general motion toward the west-northwest is forecast for the next several days.  On its anticipated track Hurricane Beryl could approach the Lesser Antilles later on Sunday.  Beryl could be a hurricane when it nears the Lesser Antilles and watches and warnings may be issued later on Friday or on Saturday.

TD 2 Quickly Strengthens Into Tropical Storm Beryl

Tropical Depression 2 which was designated earlier on Thursday quickly strengthened into Tropical Storm Beryl.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Beryl was located at latitude 10.3°N and longitude 42.8°W which put it about 1295 miles (2080 km) east-southeast of the Lesser Antilles.  Beryl was moving toward the west at 16 m.p.h. (26 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 1004 mb.

The circulation of very small Tropical Storm Beryl organized very quickly on Thursday afternoon.  There was evidence of a tiny eye on some microwave satellite images.  A small tight ring of thunderstorms surrounded the center of circulation and the strongest winds were occurring in that ring of storms.  Several short bands of thunderstorms were revolving around the core of the circulation.  Winds to tropical storm force only extended out 35 miles (55 km) from the center of circulation.  Storms near the core of Beryl were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Beryl will move through an environment somewhat favorable for intensification during the next day or two.  Beryl will move over water where the Sea Surface Temperature is near 26.5°C.  There is cooler water north of the expected track of Beryl, which would limit intensification if the tropical storm wobbles toward the north.  An upper level ridge north of Tropical Storm Beryl will generate easterly winds which will blow toward the top of the circulation.  The wind speed is similar at all level and the vertical wind shear will be modest.  Small tropical cyclones can intensify or weaken rapidly.  Beryl is likely strengthen on Friday and it could intensify into a hurricane.

Tropical Storm Beryl was moving south of the subtropical high over the Atlantic Ocean.  The high was steering Beryl toward the west.  A general motion toward the west-northwest is forecast during the next two to three days.  On its anticipated track Tropical Storm Beryl could be east of the Lesser Antilles on Sunday.

Tropical Depression Two Forms East of the Lesser Antilles

Tropical Depression Two formed east of the Lesser Antilles on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Tropical Depression Two was located at latitude 10.2°N and longitude 41.4°W which put it about 1385 miles (2230 km) east-southeast of the Lesser Antilles.  It was moving toward the west at 16 m.p.h. (26 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 1009 mb.

A distinct area of low pressure developed in the northern end of a tropical wave on Thursday and the National Hurricane Center designated the system as Tropical Depression Two.  The circulation of the depression was quite small.  Several short bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the center were beginning to generate upper level divergence which was pumping mass away from the depression.

Tropical Depression Two will move through an environment somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 26.5°C.  However, there is cooler water to the north of the anticipated track and the depression will not intensify if it moves over the cooler water.  An upper level ridge north of the tropical depression will produce easterly winds which will blow toward the top of the circulation.  The wind speeds will be similar at all levels and there will be little vertical wind shear.  Tropical Depression Two is forecast to strengthen into a tropical storm during the next day or two.

Tropical Depression Two was moving around the southern side of the subtropical ridge over the Atlantic Ocean and the ridge was steering the depression toward the west.  The ridge is forecast to steer the depression toward the west-northwest during the next two or three days.  On its anticipated track Tropical Depression Two could be east of the Lesser Antilles on Sunday.

Hurricane Irma Strengthens Rapidly Over Atlantic

Hurricane Irma strengthened rapidly as it moved over the tropical Atlantic Ocean.  At 11:00 a.m. EDT on Thursday the center of Hurricane Irma was located at latitude 16.9°N and longitude 33.8°W which put it about 1845 miles (2975 km) east of the Leeward Islands.  Irma was moving toward the west-northwest at 10 m.p.h. (16 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 979 mb.

Hurricane Irma intensified rapidly on Thursday morning.  A circular eye developed at the center of circulation and a ring of strong thunderstorms surrounded the eye.  Numerous bands of showers and thunderstorms developed outside the core of Irma.  Hurricane Irma has a very circular, symmetrical shape.  Thunderstorms in the core of Irma were generating strong upper level divergence which was pumping mass away in all directions from the hurricane.

Hurricane Irma will move through an environment favorable for intensification during the next few days.  Irma will move over water where the Sea Surface Temperature is near 28°C.  Irma is under the western end of an upper level ridge, but the upper level winds are weak and there is not much vertical wind shear.  Irma is likely to intensify during the next few days and it is forecast to become a major hurricane.  Hurricanes that intensify rapidly often develop concentric eyewalls, which cause fluctuations in their intensity.  It is highly likely that Hurricane Irma will go through one of more eyewall replacement cycles which will cause temporary fluctuations in the wind speed.  Eyewall replacement cycles often result in a larger hurricane and Hurricane Irma has the potential to develop into a big classic Cape Verde hurricane.

Hurricane Irma is nearing a weaker region in the subtropical ridge to its north.  The weakness is allowing Irma to move toward the west-northwest.  The ridge is expected to strengthen and steer Hurricane Irma more toward the west or west-southwest during the next few days.  On its anticipated track Hurricane Irma is forecast to be a major hurricane east of the Leeward Islands in five days.  The uncertainty about the future track of Hurricane Irma increases after that time.  People around the western Atlantic need to monitor the progress of Hurricane Irma.

Tropical Storm Harvey Moves Into Louisiana, Irma Strengthens Quickly

Tropical Storm Harvey finally moved into Louisiana on Wednesday after lingering for several days over the northwestern Gulf of Mexico.  Harvey weakened to a tropical depression after it moved inland.  At the same time a new tropical storm named Irma strengthened quickly over the eastern Atlantic Ocean.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Harvey was located at latitude 31.7°N and longitude 92.3°W which put it about 30 miles (50 km) north-northeast of Alexandria, Louisiana.  Harvey was moving toward the north-northeast at 9 m.p.h. (15 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 998 mb.

After dropping record rainfall and causing destructive floods of parts of southeastern Texas and western Louisiana, Tropical Depression Harvey finally started to move steadily toward the north-northeast on Wednesday.  Harvey was still producing heavy rain over parts of western Louisiana, but the fact that it was moving should limit the total rainfall at any location.  Bands of showers and thunderstorms on the far eastern periphery of Harvey’s circulation were also dropping heavy rain.  Some of those thunderstorms were strong enough to approach severe criteria.  Tropical Depression Harvey is forecast to move toward the Ohio River Valley during the next several days and it will bring windy, wet weather to the Middle Mississippi and Ohio River Valleys.  Rain associated with the circulation of Tropical Depression Harvey could also reach the Mid-Atlantic States later this week.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Irma was located at latitude 16.4°N and longitude 32.2°W which put it about 545 miles (875 km) west of the Cabo Verde Islands.  Irma was moving toward the west at 12 m.p.h. (19 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 999 mb.

The circulation of Tropical Storm Irma organized quickly on Wednesday.  Numerous bands of showers and thunderstorms formed and began to revolve around a well organized center of circulation.  Thunderstorms in the core of Irma generated well developed upper level divergence which pumped away mass in all direction.  There were occasional satellite images which hinted that an eye could be forming at the center of Tropical Storm Irma.

Tropical Storm Irma will be moving through an environment that will be favorable for intensification.  Irma will move over water where the Sea Surface Temperature is near 28°C.  The upper level winds are weak and there is little vertical wind shear.  Irma is likely to become a hurricane on Thursday and it could intensify rapidly if an eye forms.  Tropical Storm Irma is forecast to become a major hurricane and it could become one of the big classic Cape Verde hurricanes.

A strong subtropical high to the north of Irma is steering the tropical storm toward the west and a general westerly motion is forecast to continue for the next few days.  There is more divergence in the model guidance after a few days and the future track of Irma when it nears the Lesser Antilles is more uncertain.  Tropical Storm Irma has the potential to become a big dangerous hurricane and it will need to be watched carefully.

Hurricane Gert Intensifies to Cat. 2 South of Nova Scotia

Hurricane Gert intensified to Category 2 on the Saffir-Simpson Scale as it sped over the Gulf Stream south of Nova Scotia on Wednesday afternoon.  At 5:00 p.m. EDT on Wednesday the center of Hurricane Gert was located at latitude 38.7°N and longitude 62.4°W which put it about 410 miles (665 km) south of Halifax, Nova Scotia.  Gert was moving toward the northeast at 31 m.p.h. (50 km/h).  The maximum sustained wind speed was 100 mp.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 970 mb.

Although Hurricane Gert is at a fairly high latitude, it has the classic structure of a Hurricane.  There is a fairly small eye at the center of circulation.  The eye is surround by a ring of strong thunderstorm and the strongest winds are occurring in this ring of thunderstorms.  There are additional bands of showers and thunderstorms revolving around the core of the hurricane.  The circulation is symmetrical and thunderstorms in the core are producing upper level divergence which is pumping away mass to the northeast of the hurricane.  Winds to hurricane force extend out about 40 miles (65 km) primarily to the east of the center of circulation.  Winds to tropical storm force extend out about 140 miles (225 km) from the center.

Hurricane Gert is moving over the Gulf Stream which means it is moving over water where the Sea Surface Temperature (SST) is near 28.5°C.  An upper level trough west of Gert is producing southwesterly winds which are blowing toward the top of the hurricane.  However, there is not much change of wind speed with height, which means that there is little vertical wind shear.  The combination of the warm water of the Gulf Stream and little vertical shear, allowed Hurricane Gert to strengthen on Wednesday.

Hurricane Gert could intensify during the next few hours, but it will soon move into a much less favorable environment.  Gert will soon move north of the Gulf Stream where the SSTs are much cooler.  The upper level trough is moving closer to Hurricane Gert and the winds are the upper level are forecast to get stronger.  When those winds increase, there will be much more vertical wind shear.  Colder water and more wind shear will cause Hurricane Gert to weaken on Thursday.  Gert could make a transition to an extratropical cyclone in colder environment of the North Atlantic.

Southwesterly winds in the upper level trough are steering Hurricane  Gert quickly toward the northeast and that general motion is expected to continue.  On its anticipated track, Hurricane Gert will move south of Labrador and Greenland.

Even as Hurricane Gert speeds away over the North Atlantic three new tropical waves over the tropical Atlantic have the potential to develop into tropical cyclones.  A tropical wave about 800 miles (1290 km) east of the Lesser Antilles designated as Invest 91L showed signs of organization on Wednesday.  A few more thunderstorms developed closed to the center of circulation.  A reconnaissance plane is scheduled to investigate this system on Thursday.  A little farther to the east another tropical wave designated Invest 92L was also showing evidence or more organization.  A third tropical wave just west of Africa also has the potential to develop during the next few days.

Tropical Depression Four Develops East of the Lesser Antilles

Tropical Depression Four developed east of the Lesser Antilles on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Four was located at latitude 12.8°N and longitude 38.4°W which put it about 1545 (2485 km) east of the Lesser Antilles.  The depression was moving toward the west-northwest at 14 m.p.h. (22 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.

A larger area of thunderstorms formed and persisted on the western side of a tropical disturbance formerly designated as Invest 94L on Wednesday and the National Hurricane Center classified the system as Tropical Depression Four.  The distribution of thunderstorms is still asymmetrical.  Most of the stronger storms are developing in the western half of the circulation.  The thunderstorms in the western part of the circulation were beginning to generate upper level divergence.  There were few thunderstorms in the eastern half of the depression and the vertical structure of the circulation could be tilted to the west with height.

Tropical Depression Four will be moving through an environment that contains both positive and negative factors for intensification.  The depression will move over water where the Sea Surface Temperature is near 27°C.  So, there is sufficient energy in the upper ocean to support intensification.  An upper level ridge is producing easterly winds which are blowing toward the top of the circulation.  Those winds could be causing the circulation to tilt toward the west with height.  Moderate vertical wind shear could inhibit intensification.  Drier air is north of the tropical depression.  If the depression remains south of the drier air and if the vertical wind shear does not become too strong, then the depression could strengthen.  Alternatively, if the depression pulls in drier air and/or the vertical shear increases, then the depression could weaken back to a tropical wave.

The subtropical ridge over the Atlantic Ocean is steering Tropical Depression Four toward the west-northwest.  A general west-northwesterly motion is expected for the next several days.  The actual track will also have a significant effect on the future intensity of Tropical Depression Four. If the depression moves on a more southerly track, it will stay south of the drier air and it would have a greater opportunity to intensify.  If the depression moves farther to the north, it will move into the drier air and will be more likely to weaken,

Invest 94L Likely to Develop East of Lesser Antilles

A tropical disturbance currently designated as Invest 94L is likely to develop into a tropical cyclone east of the Lesser Antilles.  The National Hurricane Center’s probability of formation of a tropical cyclone from this system during the next five days is 70%.  At 2:00 p.m. EDT on Monday the center of Invest 94L was located at latitude 8.7°N and longitude 32.7°W which put it about 1830 miles (2950 km) east of the Lesser Antilles.  It was moving toward the west at 4 m.p.h. (6 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 1011 mb.

Invest 94L consists of a broad area of low pressure, but it has not developed a well organized inner core.  The initial area of low pressure consisted of a counterclockwise rotation associated with a tropical wave that moved over the eastern Atlantic Ocean.  The initial low slowed down as it was moving westward and a second tropical wave caught up to it.  The thunderstorms from the two waves appear to be merging into a single system.  An area of showers and thunderstorms on the northern and western sides of the surface low was part of the first tropical wave.  Other bands of showers and thunderstorms south and east of the low are associated with the second tropical wave.  If the broad low pressure system can collect the rotation from the two tropical waves, it could strengthen the surface low.

Invest 94L will move through an environment that will be favorable for the development of a tropical cyclone.  It will move over water where the Sea Surface Temperature (SST) is near 28°C.  There are easterly winds blowing at multiple levels in the atmosphere and there is little vertical winds shear.  The existence of a surface low pressure system, warm SSTs and little vertical wind shear are the primary ingredients for the development of a tropical cyclone.  That is the reason why there is strong probability that Invest 94L will develop into a tropical depression or a tropical storm.

Invest 94L will be steered by the subtropical high pressure system over the Atlantic Ocean.  A general westerly or west-northwesterly track is forecast during the next few days.  There is still significant uncertainty about the ultimate track and intensity of this system beyond that time frame.  It will need to be monitored closely as it moves west.