Tag Archives: Bermuda

Hurricane Maria Strengthens to Cat. 5 Near Leeward Islands

Hurricane Maria quickly strengthened to a Category 5 hurricane on the Saffir-Simpson Scale on Monday.  At 8:00 p.m. EDT on Monday the center of Hurricane Maria was located at latitude 15.3°N and longitude 61.1°W which put it about 15 miles (25 km) east-southeast of Dominica.  Maria was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 925 mb.

Hurricane Warnings were in effect for Puerto Rico, Culebra, Vieques, Dominica, Guadeloupe, St. Kitts, Nevis, Martinique, Montserrat, the U.S. Virgin Islands and the British Virgin Islands.  Hurricane Watches were in effect for Saba, St. Eustatius, St. Maarten, Anguilla, St. Martin, St. Barthelemy and the portion of the coast from Isla Saona to Puerto Plata, Dominican Republic.  Tropical Storm Warnings were in effect for Anguilla, St. Lucia, Antigua, Barbuda, Saba, St. Eustatius and St. Maarten.  Tropical Storm Watches were in effect for St. Vincent, the Grenadines and the portion of the coast from Puerto Plata to the Haiti/Dominican Republic border.

Hurricane Maria has a tight compact circulation.  There is a small eye with a diameter of 10 miles (16 km) at the center of circulation.  The eye is surround by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Additional bands of showers and thunderstorms are revolving around the core of Maria.  The overall circulation of Hurricane Maria is small.  Winds to hurricane force only extend out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force only extend out about 125 miles (200 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Maria is 35.0.  The Hurricane Size Index (HSI) is 9.1 and the Hurricane Wind Intensity Size Index (HWISI) is 44.1.

Hurricane Maria will continue to move through an environment very favorable for strong hurricanes.  Maria will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Hurricane Maria could strengthen further.  Since the eye of Hurricane Maria is so small, it would be easy for a rainband to wrap around the eye.  If that happens, then an eyewall replacement cycle could begin and the cycle could result in a temporary weakening of the hurricane.

Hurricane Maria is being steered to the west-northwest by the subtropical high pressure system over the Atlantic Ocean.  That high is forecast to weaken and Maria is likely to move more toward the northwest during the next several days.  On its anticipate track the center of Hurricane Maria will pass very close to Dominica and Guadeloupe on Monday night.  Maria could pass near Montserrat, St. Kitts and Nevis on Tuesday.  It could be near the U.S. Virgin Islands on Tuesday night and Hurricane Maria will approach Puerto Rico on Wednesday.

Hurricane Maria is a small but very dangerous hurricane.  The winds in the core of Hurricane Maria are capable of causing extensive damage.  In addition, heavy rain falling over steep terrain will likely produce flash floods.  Hurricane Maria will affect some of the same islands that were severely damaged by Hurricane Irma.  Maria will significantly hamper efforts in some places to recover from the effects of Hurricane Irma.

Elsewhere over the Atlantic Ocean, Hurricane Jose has begun the transition to an extratropical cyclone as it moves northward off the east coast of the U.S.  At 5:00 p.m. EDT on Monday the center of Hurricane Jose was located at latitude 34.8°N and longitude 71.1°W which put it about 445 miles (720 km) south of Nantucket, Massachusetts.  Jose was moving toward the north at 10 m.p.h. (16 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 977 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Watch Hill, Rhode Island to Hull, Massachusetts including Block Island, Martha’s Vineyard and Nantucket.  Tropical Storm Watches were in effect for the portion of the coast of Long Island from Fire Island Inlet to Port Jefferson and from New Haven, Connecticut to Watch Hill, Rhode Island.

The structure of Hurricane Jose began to change on Monday from the more circular shape of a purely tropical hurricane to an asymmetrical shape seen more commonly in extratropical cyclones.  Drier air wrapped around the western and southern sides of the circulation.  Most of the strong thunderstorms and heavy rain were occurring in the northern half of Jose.  Winds to hurricane force extended out about 60 miles (95 km) north of the center, but there were few if any winds to hurricane force south of the center.  The circulation of Hurricane Jose is much larger than the circulation of Hurricane Maria.  Winds to tropical storm force extend out about 320 miles (515 km) from the center of Jose.

The Hurricane Intensity Index for Hurricane Jose was 10.4.  The Hurricane Size Index for Jose was 15.6 and the Hurricane Wind Intensity Size Index was 26.0.

Hurricane Jose will move into an environment that is unfavorable for hurricanes on Tuesday.  Jose will stay over warm Sea Surface Temperatures until it moves north of the Gulf Stream.  Once Jose moves north of latitude 38°N, it will start to move over cooler water.  An upper level trough over the eastern U.S. is producing southerly winds which are causing moderate vertical wind shear over Jose.  Cooler water and moderate shear would normally cause a hurricane to weaken.  However, as Hurricane Jose makes the transition to an extratropical cyclone, it will start to be powered by the temperature difference between warm and cold air.  The transition to an extratropical cyclone can sometimes produce a stronger storm when it occurs.

Hurricane Jose is moving around the western end of the subtropical high.  Another surface high pressure system is forecast to move north of Jose when the hurricane approaches the northeastern U.S.  The second high will block the northward motion and it will force Hurricane Jose to move toward the east.  Some models are forecasting that Jose could make a clockwise loop southeast of Cape Cod.  Hurricane Jose could bring gusty winds and high waves to sections of the coast in the northeastern U.S. during the next few days.

Tropical Storm Maria Spins Up Quickly, Watches Issued for Leeward Islands

Tropical Storm Maria spun up quickly on Saturday and Watches were issued for the Northern Leeward Islands.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Maria was located at latitude 12.3°N and longitude 52.6°W which put it about 620 miles (1000 km) east-southeast of the Lesser Antilles.  Maria was moving toward the west at 20 m.p.h. (32 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.

A Hurricane Watch was in effect for Antigua, Barbuda, St. Kitts, Nevis and Montserrat.  A Tropical Storm Watch was in effect for St. Lucia, Martinique, Guadeloupe, Dominca, Barbados, St. Vincent and the Grenadines.

The circulation of Tropical Storm Maria organized quickly on Saturday.  A primary rainband wrapped most of the way around the center of circulation.  Thunderstorms in the core of the circulation generated upper level divergence which pumped mass away from the tropical storm.  Numerous additional bands of showers and thunderstorms developed outside the core of the circulation.

Tropical Storm Maria will move through and environment that will be favorable for intensification.  Maria will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Storm Maria could intensify rapidly during the next day or two.  Maria is likely to become a hurricane on Sunday.  Maria could strengthen into a major hurricane early next week.

The subtropical ridge over the Atlantic Ocean has been steering Tropical Storm Maria quickly toward the west.  The ridge is forecast to weaken slightly during the next several days and Tropical Storm Maria will move more toward the west-northwest.  Maria could reach the northern Leeward Islands within 48 hours.  Maria could be near Puerto Rico in about three days.  Maria will move over some of the same places that were seriously damaged by Hurricane Irma.  Maria could severely impact recovery efforts in that region.

Elsewhere over the tropical Atlantic Hurricane Jose moved slowly toward the north southeast of the U.S. and Tropical Storm Lee formed over the eastern Atlantic Ocean.  At 5:00 p.m. EDT on Saturday the center of Hurricane Jose was located at latitude 28.9°N and longitude 71.9°W which put it about 485 miles (780 km) south-southeast of Cape Hatteras, North Carolina.  Jose was moving toward the north at 6 m.p.h. (10 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 973 mb.

At 5:00 p.m. EDT on Saturday the center of Tropical Storm Lee was located at latitude 12.6°N and longitude 34.2°W which put it about 720 miles (1160 km) west-southwest of the Cabo Verde Islands.  Lee was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1007 mb.

Hurricane Jose Turns Back Toward U.S.

Hurricane Jose completed the long slow clockwise loop it made this week over the Atlantic Ocean and it turned back toward the U.S.  At 5:00 p.m. EDT on Friday the center of Hurricane Jose was located at latitude 27.1°N and longitude 70.3°W which put it about 640 miles (1025 km) southeast of Cape Hatteras, North Carolina.  Jose was moving toward the northwest at 10 m.p.h. (16 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 983 mb.

An eye appeared to be forming at the center of Hurricane Jose as the primary rainband wrapped around the eastern and northern portions of the developing eye.  The strongest winds were occurring in that rainband.  Additional bands of showers and thunderstorms were revolving around the eastern half of the circulation.  There were fewer showers and thunderstorms in the western half of the circulation.

Hurricane Jose is moving over the part of the Atlantic Ocean that the hurricane traversed several days ago.  So, Jose is moving over cooler water that it mixed to the surface when it moved over the area the first time.  Hurricane Jose will soon move northwest of its previous track and it will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds will be weak and there will be little vertical wind shear.  Hurricane Jose will strengthen during the weekend and it could intensify rapidly once the eye and eyewall are fully formed.

After a few days of weak steering currents the large subtropical high pressure system over the Atlantic Ocean has started to steer Hurricane Jose toward the northwest.  A general northwesterly motion is forecast to continue for another 24 to 36 hours.  At that time Jose will reach the western end of the high and it will turn more toward the north.  On its anticipated track Hurricane Jose could be near the Outer Banks of North Carolina in two or three days.  It is still too early to know if the center of Hurricane Jose will move into the U.S.

Hurricane Jose Makes Loop East of the Bahamas

Hurricane Jose made a slow clockwise loop east of the Bahamas during the past several days.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Jose was located at latitude 25.2°N and longitude 66.0°W which put it about 935 miles (1510 km) east of Nassau, Bahamas.  Jose was moving toward the west at 3 m.p.h. (5 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 985 mb.

Hurricane Jose was in an area of weaker winds between an upper level ridge to the west and an upper level trough to the east.  The weaker steering winds pushed Jose around a slow clockwise loop.  The ridge is forecast to move north of Jose on Thursday and it should steer the hurricane toward the west.  The ridge is forecast to move east of Jose on Friday and the hurricane is expected to start moving more toward the north.

Hurricane Jose has been moving through an environment that was somewhat unfavorable for intensification.  Jose was moving over water where the Sea Surface Temperature was near 29°C.  However, the upper level ridge was producing northerly winds which were causing moderate vertical wind shear.  Hurricane Jose maintained its intensity despite the moderate shear, although there were fewer showers and thunderstorms in western half of the circulation.  The wind shear could decrease as the upper level ridge moves north of Jose and the hurricane could strengthen.

It is still too early to know if Hurricane Jose will have much of an impact on the U.S.  Most of the guidance from numerical models keeps Jose out over the Atlantic Ocean, but its actual track will depend on where and when the clockwise loop ends.

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.

Gert Intensifies to a Hurricane West of Bermuda

Gert intensified to a hurricane west of Bermuda on Monday.  Gert became the second Atlantic hurricane of 2017 and it is the second hurricane to form during the past six days.  Hurricane Franklin developed over the southern Gulf of Mexico last week.  At 11:00 p.m. EDT on Monday the center of Hurricane Gert was located at latitude 31.2°N and longitude 72.3°W which put it about 445 miles (720 km) west of Bermuda.  Gert was moving toward the north at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 986 mb.

An eye appeared on satellite images of Hurricane Gert at various times on Monday and it looked more like a hurricane.  There was a somewhat elliptical eye at the center of Hurricane Gert on Monday night.  The ring of thunderstorms around the eye did not completely surround the eye.  There was a large break on the northwest side of the eye.  Additional bands of showers and thunderstorms were occurring in the southeastern half of Gert.  There were fewer showers and thunderstorms in the northwestern half of the hurricane.  Thunderstorms near the core of Gert were generating upper level divergence which was pumping out mass to the south of the hurricane.

Hurricane Gert will be an environment that will be favorable for intensification for another 24 to 48 hours.  Gert will move over water where the Sea Surface Temperature is near 28.5°C.  An upper level ridge centered northwest of Gert is producing northerly winds which are blowing toward the top of the circulation.  Those winds are producing some vertical wind shear and they may be responsible for the asymmetrical distribution of showers and thunderstorms.  However, the vertical wind shear should not be strong enough to prevent Hurricane Gert from intensifying further.  An upper level trough will approach Gert from the west, but before the trough reaches the hurricane, the wind shear will decrease and a period of rapid intensification could occur.

Hurricane Gert is moving around the western end of a subtropical high over the Atlantic Ocean.  The high is steering Gert slowly toward the north.  When the upper level trough approaches Gert, southwesterly winds will start to steer the hurricane toward the northeast.  On its anticipated track Hurricane Gert should pass northwest of Bermuda.

TD 8 Strengthens to Tropical Storm Gert

Tropical Depression Eight strengthened to Tropical Storm Gert on Sunday afternoon.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Gert was located at latitude 28.1°N and longitude 71.7°W which put it about 505 miles (810 km) west-southwest of Bermuda.  Gert was moving toward the north-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1011 mb.

The structure of Tropical Storm Gert improved on Sunday.  Numerous bands of showers and thunderstorms developed and began to rotate around the center of circulation.  The thunderstorms began to produce upper level divergence which was pumping out mass in all directions.  The circulation of Tropical Storm Gert became more circular and symmetrical.

Tropical Storm Gert will move through an environment that will be favorable for intensification during the next 24 hours.  Gert will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds over Tropical Storm Gert are weak and there is not much vertical wind shear.  There is an upper level ridge northwest of Tropical Storm Gert and the ridge is producing northeasterly winds west of Bermuda.  So, the vertical wind shear could increase when Gert moves farther north.  Tropical Storm Gert will continue to intensify during the next 24 hours.

Tropical Storm Gert is moving around the western end of the subtropical high pressure system over the Atlantic Ocean.  The high is steering Gert toward the north-northwest and a northerly motion is  expected to continue for another 24 hours.  When Gert moves west of Bermuda, it will start to encounter the westerly winds in the middle latitudes.  Those winds should turn Tropical Storm Gert toward the northeast in a day or so.  On its anticipated track Tropical Storm Gert is expected to move east of the U.S. and west of Bermuda.

Tropical Depression Eight Forms East of the Bahamas

Tropical Depression Eight formed east of the Bahamas on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Depression Eight was located at latitude 25.3°N and longitude 70.3°W which put it about 470 miles (755 km) east of Nassau, Bahamas.  It was moving toward the north-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1011 mb.

Data from satellites and NOAA buoy 41046 indicated that a low level center of circulation formed within former Invest 99L.  Based on those data the National Hurricane Center classified the system as Tropical Depression Eight.  Bands of showers and thunderstorms began to develop in Invest 99L on Saturday afternoon.  There were more bands in the eastern half of the circulation than there were in the western half.  Thunderstorms in the bands began to generate upper level divergence which was pumping away mass.  The circulation took on a more circular appearance and they system exhibited the characteristics of a tropical depression.

Tropical Depression Eight will move through an environment favorable for intensification during the next 36 to 48 hours.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper low that was inhibiting the development of Invest 99L dissipated on Saturday.  When the upper low dissipated, the upper level winds weakened.  Tropical Depression Eight will move through an area where there is little vertical wind shear.  It will likely strengthen into Tropical Storm Gert on Sunday.  It could eventually intensify into a hurricane.

Tropical Depression Eight is moving around the western end of the subtropical high over the Atlantic Ocean.  The high is steering the depression toward the north-northwest and it is forecast to move primarily toward the north during the next 24 to 48 hours.  Tropical Depression Eight will eventually reach the westerly winds in the middle latitudes and it will turn toward the northeast when that happens.  On its anticipated track Tropical Depression Eight will remain east of the Bahamas.

Tropical Storm Emily Makes Landfall on West Coast of Florida

Tropical Storm Emily made landfall on the west coast of Florida at Anna Maria Island late Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Emily was located at latitude 27.5°N and longitude 82.7°W which put it about 10 miles (15 km) northwest of Bradenton, Florida.  Emily was moving toward the east at 9 m.p.h. (15 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.  A Tropical Storm Warning was in effect for the portion of the coast from Anclote River to Bonita Beach, Florida.

Thunderstorms developed near the center of the non-tropical low pressure system over the eastern Gulf of Mexico.  Latent energy released higher in the atmosphere by condensation in those storms created a warm core and the low pressure system made a transition to Tropical Storm Emily.  Thunderstorms near the core of Emily were generating a small area of upper level divergence.  Thunderstorms near the core, a warm core and upper level divergence are part of the typical structure of a tropical cyclone, which is why the National Hurricane Center classified the system as Tropical Storm Emily.  Emily has a well developed circulation, but most of the bands of showers and thunderstorms are in the eastern half of the tropical storm.  Drier air northwest of Emily and vertical wind shear are the probable causes of the asymmetrical distribution of precipitation.

Tropical Storm Emily is bringing gusty winds and heavy rain to parts of Central Florida.  A surface weather station in Sarasota (KSRQ) reported a sustained wind of 39 m.p.h. (63 km/h) and a wind gust of 49 m.p.h. (80 km/h).  The Skyway Bridge over Tampa Bay was closed due to strong winds.

Tropical Storm Emily is likely to weaken as it moves eastward across Central Florida.  When Emily moves over the Atlantic Ocean, it will move over water where the Sea Surface Temperature is near 29°C.  Emily could strengthen back into a tropical storm at that time.

Emily is being steered toward the east by a high pressure system north of the tropical storm.  An upper level trough over the Midwestern U.S. is forecast to move southeastward.  When Emily reaches the Atlantic Ocean southwesterly winds ahead of the trough will turn the tropical storm toward the northeast.

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,