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Tropical Storm Dorian Moves Toward Puerto Rico

Tropical Storm Dorian moved toward Puerto Rico on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Dorian was located at latitude 16.0°N and longitude 63.0°W which put it about 275 miles (440 km) east-southeast of Ponce, Puerto Rico.  Dorian was moving toward the northwest at 13 m.p.h. (20 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 1006 mb.

A Hurricane Watch was issued for Puerto Rico.  Tropical Storm Warnings were in effect for Puerto Rico, Culebra, Vieques, the U.S. Virgin Islands and the British Virgin Islands.  A Tropical Storm Watch was issued for the coast of the Dominican Republic from Isla Saona to Puerto Plata.

The original low level center of Tropical Storm Dorian passed south of Barbados and St. Lucia on Tuesday morning.  Dorian dropped heavy rain and there were reports of flash floods on Martinique.  The original center weakened on Tuesday afternoon and a new low level center formed about 60 miles farther to the north.  The formation of a new center of circulation caused the forecast future track of Tropical Storm Dorian to be shifted northward as well.

Even with the formation of a new center of circulation, the overall circulation around Tropical Storm Dorian did not change much on Tuesday.  The circulation around Dorian remained small.  Winds to tropical storm force only extended out about 45 miles (75 km) from the center of circulation.  A broken ring of thunderstorms surrounded the new low level center.  Bands of showers and thunderstorms were revolving the center of Tropical Storm Dorian.  Storms near the center were producing upper level divergence which was pumping mass away to the north of the tropical storm.

Tropical Storm Dorian will move through an environment somewhat favorable for intensification on Wednesday.  Dorian will move over water where the Sea Surface Temperature is near 29°C.  An upper level low northwest of Puerto Rico will produce southerly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, which will inhibit intensification.  A large mass of drier air is north of Tropical Storm Dorian and the drier air could also inhibit intensification if it gets pulled into the circulation around Dorian.  The small size of the circulation around Tropical Storm Dorian means that it could weaken or strengthen quickly if the environmental conditions change significantly.  Dorian is likely to weaken when it crosses Puerto Rico on Wednesday night.

The upper low northwest of Puerto Rico will help to steer Tropical Storm Dorian toward the northwest on Wednesday.  On its anticipated track Tropical Storm Dorian could reach Puerto Rico by Wednesday evening.  Dorian will bring gusty winds and it will drop locally heavy rain on Puerto Rico.  Locally heavy rain could cause flash floods in some locations.  A high pressure system will build north of Tropical Storm Dorian on Thursday and Friday.  The high will turn Dorian back toward the west-northwest.  Dorian could approach the east coast of Florida on Sunday.

Elsewhere over the Atlantic Ocean, Tropical Depression Six strengthened into Tropical Storm Erin southeast of Cape Hatteras on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Erin was located at latitude 31.9°N and longitude 72.1°W which put it about 300 miles (485 km) southeast of Cape Hatteras, North Carolina.  Erin was moving toward the west at 2 m.p.h. (3 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. (65 km/h).  The minimum surface pressure was 1005 mb.  Tropical Storm Erin is forecast to move northeast toward Nova Scotia.

Category 5 Hurricane Maria Bearing Down on Puerto Rico

Category 5 Hurricane Maria was bearing down on Puerto Rico on Tuesday night.  The eye was very near St. Croix.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Maria was located at latitude 17.3°N and longitude 64.7°W which put it about 30 miles (45 km) south-southeast of St. Croix and about 120 miles (190 km) southeast of San Juan, Puerto Rico.  Maria was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 215 m.p.h. (345 m/h).  The minimum surface pressure was 909 mb.

Hurricane Warnings were in effect for Puerto Rico, Culebra, Vieques, the U.S. Virgin Islands, the British Virgin Islands, and for the portion of the coast from Cabo Engano to Puerto Plata, Dominican Republic.  Hurricane Watches were in effect for the Turks and Caicos, the Southeastern Bahamas, Saba, St. Maarten, St. Martin, St. Eustatius, St. Barthelemy, and the portion of the coast from Isla Saona to Cabo Engano, Dominican Republic.  Tropical Storm Warnings were in effect for Saba, St. Eustatius, St. Maarten, the portion of the coast from Puerto Plata,, Dominican Republic to the northern border with Haiti and for the portion of the coast from Cabo Engano to Punta Palenque, Dominican Republic,

Hurricane Maria is a very well organized powerful hurricane.  It has a small inner eye and a second outer eyewall extends most of the way around the inner eyewall.  The strongest winds are occurring in the inner eyewall.  Additional spiral bands are revolving around the core of the circulation.  The concentric eyewalls have caused the circulation of Hurricane Maria to increase in size.  Winds to hurricane force now extend out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extend out about 160 miles (260 km) from the center.

The Hurricane Intensity Index (HII) for Hurricane Maria is 40.4.  The Hurricane Size Index (HSI) is 19.2 and the Hurricane Wind Intensity Size Index (HWISI) is 59.6.  Those indices indicate that Hurricane Maria is capable of causing regional catastrophic damage.

Hurricane Maria will continue to move through an environment favorable for powerful hurricanes until it reaches Puerto Rico.  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.  If the outer eyewall completely encircles the inner eyewall, then an eyewall replacement cycle could cause some weakening.  Hurricane Maria will weaken more if the center moves directly over Puerto Rico.  The amount of weakening will depend on the stage of the eyewall replacement cycle at the time of landfall.

Hurricane Maria is being steered toward the west-northwest by the subtropical high pressure system over the Atlantic Ocean.  The western end of the high is forecast to weaken during the next several days.  The weakening of the high will allow Hurricane Maria to move more toward the north.  The core of Hurricane Maria will pass near or over St. Croix during the next few hours.  On its anticipated track Hurricane Maria will reach Puerto Rico on Wednesday morning.

Hurricane Maria is a very dangerous hurricane.  It is capable of causing catastrophic damage.  Maria will also drop very heavy rain over Puerto Rico and there is the potential for significant flash flooding.  Maria could also cause a storm surge of up to 12 feet (4 meters) along the coast.

Elsewhere, Hurricane Jose weakened to a tropical storm east of the U.S.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Jose was located at latitude 37.9°N and longitude 70.8°W which put it about 230 miles (375 km) south of Nantucket.  Jose was moving toward the northeast at 9 m.p.h. (15 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 973 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Woods Hole to Sagamore Beach, Massachusetts including Block Island, Martha’s Vineyard, Nantucket and Cape Cod.  A Tropical Storm Watch was in effect for the portion of Long Island from Fire Island Inlet to Port Jefferson.

Maria Becomes a Hurricane, Jose Prompts Watches for Northeast U.S.

A reconnaissance plane found that Tropical Storm Maria had intensified into a hurricane as it moved toward the Leeward Islands on Sunday afternoon.  At the same time Hurricane Jose moved farther north and Tropical Storm Watches were issued for the coast of the northeastern U.S.  At 5:00 p.m. EDT on Sunday the center of Hurricane Maria was located at latitude 13.8°N and longitude 57.5°W which put it about 275 miles (445 km) east-southeast of Dominica.  Maria was moving toward the west-northwest at 15 m.p.h. (24 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. (150 km/h).  The minimum surface pressure was 982 mb.

Hurricane Warnings were in effect for Guadeloupe, Dominica, St. Kitts, Nevis and Montserrat.  Hurricane Watches were in effect for the U.S. Virgin Islands, the British Islands, Saba, St. Eustatius, St. Maarten, St. Martin, St. Barthelemy, and Anguilla.  Tropical Storm Warnings were in effect for Martinique, St. Lucia, Antigua, Barbuda, Saba, and St. Eustatius.  Tropical Storm Watches were in effect for Barbados, St. Vincent and the Grenadines.

A reconnaissance plane found sustained winds to hurricane force when it investigated Hurricane Maria on Sunday afternoon.  The plane reported a circular eye with a diameter of 32 miles (52 km) at the center of circulation.  The eye was surrounded by an almost complete ring of thunderstorms.  The ring was broken south of the center.  The strongest winds wind occurring in that ring of thunderstorms.  Additional bands of showers and thunderstorms were developing in the eastern half of the circulation.  There were fewer showers and thunderstorms in the western half of Maria.  Hurricane Maria was generating upper level divergence which was pumping away mass and allowing the surface pressure to decrease.

Hurricane Maria will move through an environment that will be favorable for intensification.  Maria will move over water where the Sea Surface Temperature is near 29°C.  An upper level low over Caribbean Sea is causing southern winds which are blowing near the eastern side of Hurricane Maria.  Those winds do not appear to be causing significant vertical wind shear.  Hurricane Maria is likely to continue to intensify as it moves toward the Leeward Islands.  Maria could intensify rapidly once a fully closed eye develops.

Hurricane Maria is being steered toward the west-northwest by the subtropical high pressure system over the Atlantic Ocean and that general motion is expected to continue for several more days.  On its anticipated track Hurricane Maria could reach the Leeward Islands by later on Monday.  Maria could be near Puerto Rico by Wednesday.  Hurricane Maria will affect some of the same islands damaged by Hurricane Irma a few days ago.  Strong winds and heavy rain will significantly impact recovery efforts in those areas.

A reconnaissance plane also found that Hurricane Jose was stronger on Sunday afternoon.  At 5:00 p.m. EDT on Sunday the center of Hurricane Jose was located at latitude 31.5°N and longitude 71.8°W which put it about 335 miles (535 km) southeast of Cape Hatteras, North Carolina.  Jose was moving toward the north at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 967 mb.

Tropical Storm Watches have been issued for the portions of the coast from Fenwick Island, Delaware to Sandy Hook, New Jersey and from East Rockaway Inlet, New York to Plymouth, Massachusetts including Long Island Sound, Block Island, Martha’s Vineyard and Nantucket.

Hurricane Jose strengthened on Sunday as it moved over water where the Sea Surface Temperature was near 29°C.  An eye appeared at times on visible satellite imagery.  The circulation of Hurricane Jose increased in size which often happens when hurricanes move north out of the tropics.  Winds to hurricane force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 290 miles (470 km) from the center.

Hurricane Jose will move through an environment which will be marginal for further intensification.  Jose will move over water which is warm enough to support intensification.  However, an upper level trough over the eastern U.S. is producing southerly winds which are blowing toward the top of the circulation.  Those winds are producing strong vertical wind shear and they could weaken Jose during the next several days.  Jose will be moving over warm water until it gets north of the Gulf Stream.  If the upper level winds slow, then Jose could get stronger.

Hurricane Jose is being steered northward by the subtropical high over the Atlantic Ocean and the trough over the eastern U.S.  On its anticipated track the center of Jose is forecast to move toward the northeastern U.S. and turn toward the east before it reaches the coast.  If Jose follows the forecast track, then the core of the hurricane would remain offshore.  However, the circulation of Jose is large enough that even if the center stays offshore, there could still be tropical storm force winds along the coast.