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Hurricane Dorian Hammers the Northwestern Bahamas

Hurricane Dorian hammered the Northwestern Bahamas on Monday.  After pounding the Abacos on Sunday night, Hurricane Dorian moved slowly across Grand Bahama Island before stalling over that island for much of Monday.  There were reports of significant storms surges, numerous injuries and some fatalities.  Dorian was still battering Grand Bahama Island on Monday night.

At 11:00 p.m. EDT on Monday the center of Hurricane Dorian was located at latitude 26.9°N and longitude 78.5°W which put it about 30 miles (50 km) north-northeast of Freeport, Bahamas and about 100 miles (160 km) east of West Palm Beach, Florida.  Dorian was essentially stationary.  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 946 mb.

Hurricane Warnings were in effect for the Abacos and Grand Bahama Island.  A Hurricane Warning was also in effect for the portion of the Florida coast from Jupiter Inlet to Ponte Vedra Beach.  Hurricane Watches were in effect for the portions of the coast from Deerfield Beach to Jupiter Inlet and from Ponte Vedra Beach, Florida to South Santee River, South Carolina.  A Tropical Storm Warning was also in effect for the portion of the coast from Deerfield Beach to Jupiter Inlet.  Tropical Storm Watches were in effect for the portion of the coast from Golden Beach to Deerfield Beach and for Lake Okeechobee.

Hurricane Dorian weakened slowly on Monday.  As it remained nearly stationary the winds around Dorian mixed cooler water to the surface.  Hurricane Dorian was unable to extract enough energy from the ocean to maintain its extreme intensity,  The circulation in core of Dorian developed two concentric eyewalls.  The concentric eyewalls suggested that the hurricane had started an eyewall replacement cycle which may have also contributed to the reduction of the wind speed.

The concentric eyewalls also produced an increase in the size of the circulation around Hurricane Dorian.  Winds to hurricane force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out abou 150 miles from the center.  The Hurricane Intensity Index (HII) was 25.1.  The Hurricane Size Index (HSI) was 15,2 and the Hurricane Wind Intensity Size Index (HWISI) was 40.3.

Hurricane Dorian was south of a high pressure system over the western Atlantic Ocean.  The high was blocking Dorian and preventing the hurricane from moving toward the north.  The western end of the high is forecast to weaken on Tuesday.  When the end of the high weakens, it will allow Hurricane Dorian to move toward the northwest.  An upper level trough over the U.S. will approach Dorian on Wednesday.  The trough is forecast to turn Dorian toward the northeast.  On its anticipated track Hurricane Dorian could approach the Central Florida coast by Tuesday night.  Dorian could approach the Carolinas on Wednesday night.

Hurricane Dorian will move into an environment favorable for intensification when it starts moving again on Tuesday.  Dorian will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  However, Hurricane Dorian could still be in the weakening part of the eyewall replacement cycle and Dorian may not intensify despite the favorable environment.  The upper level trough will produce southwesterly winds which will cause wind shear to increase on Wednesday.  The increase in wind shear will likely cause Hurricane Dorian to weaken when it approaches the Carolinas.

Hurricane Dorian Pounds Northwest Bahamas, Warning Issued for Florida

Hurricane Dorian pounded the Northwestern Bahamas on Sunday afternoon and a Hurricane Warning was issued for a portion of the southeast Florida coast.  Dorian was one of the strongest Atlantic hurricanes on record.  At 5:00 p.m. EDT on Sunday the center of Hurricane Dorian was locate at latitude 26.6°N and longitude 77.3°W which put it about 175 miles (280 km) east of West Palm Beach, Florida.  Dorian was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 185 m.p.h. (295 km/h) and there were wind gusts to 220 m.p.h. (355 km/h).  The minimum surface pressure was 910 mb.

A Hurricane Warning was issued for the portion of the coast of Florida from Jupiter Inlet to the Volusia/Brevard County Line.  Hurricane Warnings were also in effect for the Northwestern Bahamas including the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  Hurricane Watches were in effect for the portion of the coast from Deerfield Beach to Jupiter Inlet, Florida and from the Volusia/Brevard County Line to the Flagler/Volusia County Line.  A Hurricane Watch was also in effect for Andros Island.  A Tropical Storm Warning was in effect for the portion of the coast from Deerfield Beach to Jupiter Inlet, Florida.  Tropical Storm Watches were in effect for the portion of the coast from  Golden Beach to Deerfield Beach, Florida and for Lake Okeechobee.

The core of Hurricane Dorian moved over Great Abaco Island on Sunday afternoon.  Dorian intensified rapidly to an intense Category 5 hurricane on the Saffir-Simpson Scale when it reached the warm water around the Bahamas.  The pressure decreased rapidly to 910 mb and the winds increased to 185 m.p.h. (295 km/h).  There was a circular eye with a diameter of 12 miles (19 km) at the center of Hurricane Dorian.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Dorian.  Storms near the core were generating strong upper level divergence which was pumping mass away from the hurricane.

The circulation around Hurricane Dorian increased in size on Sunday.  Winds to hurricane force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 140 miles (220 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Dorian was 44.1.  The Hurricane Size Index (HSI) was 14,3 and the Hurricane Wind Intensity Size Index (HWISI) was 58.4.  Hurricane Dorian was capable of causing regional catastrophic damage.  Dorian was stronger than Hurricane Andrew was when Andrew hit southeast Florida in 1992.

Hurricane Dorian will remain in a favorable environment for intense hurricanes for another 24 to 36 hours.  Dorian 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.  It appeared that an inner rainband may have wrapped around the existing eye and eyewall.  Radar images indicated that there could be two concentric eyewalls.  If there are two eyewalls, then an eyewall replacement cycle is underway.  Hurricane Dorian will weaken, at least temporarily when the inner eyewall dissipates.  However, Dorian will get larger when the strongest winds occur in the outer eyewall.

Hurricane Dorian will move near the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Dorian slowly toward the west-northwest during the next 24 to 36 hours.  Eventually, Hurricane Dorian will move more toward the north when it moves around the western end of the high.  On its anticipated track Hurricane Dorian will linger over the Northwestern Bahamas on Sunday night.  The core of Dorian will pass over or very near Grand Bahama Island.  It could cause catastrophic damage on the Abacos and Grand Bahama Island.  Hurricane Dorian could approach the east coast of Florida on Tuesday.

Hurricane Dorian Strengthens to Cat. 5 Near Great Abaco

Hurricane Dorian strengthened to Category 5 on the Saffir-Simpson Scale near Great Abaco Island on Sunday morning.  At 9:30 a.m. EDT on Sunday the center of Hurricane Dorian was located at latitude 26.5°N and longitude 76.5°W which put it about 35 miles (55 km) east of Great Abaco Island, Bahamas and about 225 miles (360 km) east of West Palm Beach, Florida.  Dorian was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 220 m.p.h. (355 km/h).  The minimum surface pressure was 927 mb.

A Hurricane Warning was in effect for the Northwestern Bahamas including the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island, and New Providence.  A Hurricane Watch was in effect for Andros Island.  A Tropical Storm Warning was in effect for the portion of the coast from Deerfield Beach to Sebastian Inlet, Florida.  A Tropical Storm Watch was issued for the portion of the coast from Golden Beach to Deerfield Beach, Florida.

A reconnaissance plane found that Hurricane Dorian had strengthened to Category 5 on Sunday morning.  Dorian exhibited the structure of a classic intense hurricane.  There was a circular eye with a diameter of 15 miles (24 km) at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Storms near the core of Hurricane Dorian were generating strong upper level divergence which was pumping mass away from the hurricane.  Bands of showers and thunderstorms were revolving around the core of the hurricane.

Winds to hurricane force extended out about 30 miles from the center of Hurricane Dorian.  Winds to tropical storm force extended out about 110 miles (180 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Dorian was 40.4.  The Hurricane Size Index (HSI) was 11.7 and the Hurricane Wind Intensity Size Index (HWISI) was 52.1.  Hurricane Dorian was very similar in size and strengthen to what Hurricane Michael was when Michael hit northwest Florida in 2018.

Hurricane Dorian will remain in an environment very favorable for intense hurricanes during the next several days.  Dorian will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Dorian is likely to remain a very strong hurricane for several more days.  At some point a rainband is likely to wrap around the existing eye and eyewall.  When that happens, an eyewall replacement cycle will cause fluctuations in the intensity of Dorian.

Hurricane Dorian will move south of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Dorian toward the west on Sunday.  Hurricane Dorian could slow on Sunday night when it nears the western end of the ridge.  On its anticipated track Hurricane Dorian will move over the Abacos and New Providence on Sunday.  Dorian is capable of causing catastrophic damage over portions of the Northwestern Bahamas.  It could generate a storm surge of 15 feet (4.5 meters) where the strongest winds push water toward the coastline.  Hurricane Dorian could eventually approach the coast of southeast Florida as a very strong hurricane.

Dangerous Hurricane Dorian Nears Northwestern Bahamas

Dangerous Hurricane Dorian neared the Northwestern Bahamas on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Dorian was located at latitude 26.3°N and longitude 75.1°W which put it about 125 miles (200 km) east of Great Abaco and about 310 miles (500 km) east of West Palm Beach, Florida.  Dorian was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h)  and there were wind gusts to 185 m.p.h. (315 km/h).  The minimum surface pressure was 940 mb.

Hurricane Warnings were in effect for the Northwestern Bahamas including the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A Hurricane Watch was in effect for Andros Island.  A Tropical Storm Watch has been issued for the portion of the coast from Deerfield Beach to Sebastian Inlet, Florida.

Hurricane Dorian remains a very dangerous, well organized storm.  Dorian has maintained Category 4 intensity on the Saffir-Simpson Scale for 24 hours.  A circular eye with a diameter of 15 miles (24 km) was clearly visible on conventional and microwave satellite imagery.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  The maximum sustained wind speed at the surface was 150 m.p.h. (240 km/h) and data from dropsondes indicated that the wind was stronger a few hundred feet above the surface.  Bands of showers and thunderstorms were revolving around the core of Hurricane Dorian.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.

Winds to hurricane force extended out about 30 miles (50 km) from the center of Hurricane Dorian.  Winds to tropical storm force extended out about 105 miles (170 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Dorian was 33.3.  The Hurricane Size Index (HSI) was 11.7and the Hurricane Wind Intensity Size Index (HWISI) was 45.0.  Hurricane Dorian is capable of causing regional significant damage.

Hurricane Dorian will remain in an environment capable of supporting a very strong hurricane for several more days.  Dorian will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  There will be a potential for Hurricane Dorian to strengthen to Category 5 on the Saffir-Simpson Scale.  At some point eyewall replacement cycles are likely to cause fluctuations in intensity.

Hurricane Dorian will move around the western end of a subtropical high pressure system during the next 24 to 48 hours.  The high will steer Dorian slowly toward the west.  Hurricane Dorian could move very slowly when it reaches the western end of the ridge.  Eventually, Dorian will turn toward the north when it moves around the end of the ridge.  On its anticipated track Hurricane Dorian will reach the Northwestern Bahamas by Sunday evening.  The core of Dorian will move very close to the Abacos and Grand Bahama Island.  Hurricane Dorian could cause significant wind damage.  Dorian could also produce a storm surge of up to 15 feet (4.5 meters) in places where the wind blows water toward the shoreline.

Hurricane Dorian Rapidly Intensifies to Cat. 4

Hurricane Dorian rapidly intensified to Category 4 on the Saffir-Simpson Scale on Friday night and Hurricane Warnings were issued for the Northwestern Bahamas.  At 11:00 p.m. EDT on Friday the center of Hurricane Dorian was located at latitude 25.5°N and longitude 71.4°W which put it about 545 miles (880 km) east of West Palm Beach, Florida,  Dorian was moving toward the west-northwest at 10 m.p.h.  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 948 mb.

Hurricane Warnings were issued for the Northwestern Bahamas including the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A Hurricane Watch was in effect for Andros Island.

When reconnaissance aircraft reached the core of Hurricane Dorian on Friday night they discovered that Dorian has intensified rapidly since Friday afternoon.  The minimum surface pressure had decreased by more than 20 mb and the maximum sustained wind speed was 140 m.p.h. (220 km/h).  Dorian was a very symmetrical, if small hurricane.  There was a circular eye with a diameter to 14 miles (22 km) at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Hurricane Dorian.  Storms around the core were generating upper level divergence which was pumping mass away from the hurricane.

The circulation around Hurricane Dorian was still relatively small.  Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 110 miles (170 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Dorian was 28.3.  The Hurricane Size Index (HSI) was 12.0 and the Hurricane Wind Intensity Size Index (HWISI) was 40.3.  Hurricane Dorian was capable of causing regional significant damage.

Hurricane Dorian will remain in an environment favorable for strong hurricanes for several more days.  Dorian 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.  Hurricane Dorian could intensify to Category 5 hurricane on the Saffir-Simpson Scale.  At some point a rainband will wrap around the existing eye and eyewall.  That will begin an eyewall replacement cycle that will weaken Hurricane Dorian, at least temporarily.

Hurricane Dorian will move south of a subtropical ridge of high pressure over the western Atlantic Ocean.  The high will steer Dorian toward the west during the next 48 to 72 hours.  Dorian will move much more slowly when it reaches the western end of the ridge.  On its anticipated track Hurricane Dorian could reach the Northwestern Bahamas on Sunday.  Dorian could approach the southeast coast of Florida on Tuesday.

Dorian Strengthens to Major Hurricane

Hurricane Dorian strengthened to a major hurricane on Friday afternoon.  Data from a reconnaissance plane indicated that Hurricane Dorian had strengthened to Category 3 on the Saffir-Simpson Scale on Friday afternoon, which meant it was a major hurricane.  At 2:00 p.m. EDT on Friday the center of Hurricane Dorian was located at latitude 24.8°N and longitude 70.3°W which put it about 625 miles (1005 km) east of West Palm Beach, Florida.  Dorian was moving toward the northwest at 10 m.p.h. (16 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 970 mb.

Hurricane Watches had been issued for the Northwestern Bahamas.

The circulation around Hurricane Dorian exhibited much more impressive organization on satellite images and radar products generated by reconnaissance aircraft.  Clouds cleared out of the eye and it became even more circular.  The diameter of the eye was 21 miles (34 km).  The eye was surround by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  The overall appearance of Hurricane Dorian was more symmetrical.  Bands of showers and thunderstorms were revolving around the core of the circulation.  Storms around the core generating upper level divergence which was pumping mass away from the hurricane.

The circulation around Hurricane Dorian was still small.  Winds to hurricane force extended out about 25 miles from the center of circulation.  Winds to tropical storm force extended out about 100 miles from the center.  The Hurricane Intensity Index (HII) for Dorian was 20.6.  The Hurricane Size Index (HSI) was 9.0 and the Hurricane Wind Intensity Index (HWISI) was 29.6.  Hurricane Dorian was already capable of causing major damage.

Hurricane Dorian will move through an environment that is favorable for intensification.  Dorian 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.  Hurricane Dorian could start a period of rapid intensification at any time.  Dorian will almost certainly intensify to Category 4 and there is the potential for it to strengthen to Category 5.  After Hurricane Dorian strengthens, eyewall replacement cycles could cause fluctuations in intensity.

A ridge of high pressure north of Hurricane Dorian is starting to turn Dorian more toward the west.  The high is forecast to steer Dorian toward the west during the next two to three days.  On its anticipated track Hurricane Dorian will be near the Northwestern Bahamas on Sunday and it will approach the southeast coast of Florida on Monday.  Dorian will reach the western end of the high when it gets close to the Florida coast.  Hurricane Dorian could slow down and turn northward on Tuesday.

Hurricane Dorian Strengthens East of the Bahamas

Hurricane Dorian resumed strengthening east of the Bahamas on Thursday night after exhibiting little change of intensity during much of the day.  At 11:00 p.m. EDT on Thursday the center of Hurricane Dorian was located at latitude 23.3°N and longitude 68.4°W which put it about 580 miles (930 km) east of the Northwestern Bahamas.  Dorian was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 977 mb.

The structure of Hurricane Dorian exhibited little change for much of Thursday.  Storms around the core of Dorian grew stronger on Thursday evening.  An eye with a diameter of 10 miles (16 km) developed at the center of circulation.  A nearly complete ring of 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 Dorian.  Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.  The removal of mass allowed the surface pressure to start decreasing again.  The circulation around Dorian was still relatively small.  Winds to hurricane force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) from the center.

Hurricane Dorian will move through an environment favorable for intensification during the next 24 to 48 hours.  Dorian 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.  Hurricane Dorian is likely to intensify to major hurricane status on Friday.  There is the potential for Dorian to strengthen to Category 5 on the Saffir-Simpson Scale during the weekend.  When Hurricane Dorian becomes a major hurricane, eyewall replacement cycles could cause fluctuations in its intensity.

A ridge of high pressure will build north of Hurricane Dorian on Friday.  The high will block Dorian from moving toward the north and it will turn the hurricane toward the west.  On its anticipated track Hurricane Dorian could approach the Northwestern Bahamas on Sunday and the east coast of Florida on Monday.  Dorian is likely to be a small, but very dangerous hurricane.

Hurricane Dorian Strengthens North of Puerto Rico

Hurricane Dorian strengthened north of Puerto Rico on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Hurricane Dorian was located at latitude 19.7°N and longitude 66.0°W which put it about 90 miles (145 km) north of San Juan, Puerto Rico.  Dorian was moving toward the northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 110 m.p.h. (170 km/h).  The minimum surface pressure was 986 mb.

The circulation around Hurricane Dorian strengthened steadily on Wednesday.  A circular eye with a diameter of 14 miles (22 km) formed at the center of circulation.  A closed ring of thunderstorms surrounded the eye and the strongest winds were occurring in the northeastern part of that ring.  Bands of showers and thunderstorms were revolving around the core of Hurricane Dorian.  Storms near the core were generating upper level divergence which was pumping mass away to the north and northeast of the hurricane.  The circulation around Hurricane Dorian remained fairly small.  Winds to hurricane force extended out about 20 miles (30 km) in the northeastern quadrant of Dorian.  Winds to tropical storm force extended out about 70 miles from the center of circulation.

Hurricane Dorian will move through an environment favorable for intensification during the next several days.  Dorian will move over water where the Sea Surface Temperature is near 29°C.  It will move into an area where the upper level winds are relatively weak and there will be little vertical wind shear.  Hurricane Dorian is very likely to intensify during the next 48 hours and it could intensify rapidly at times.  Dorian is likely to strengthen into a major hurricane.

An upper level low near the Bahamas will pull Hurricane Dorian toward the northwest during the next 24 to 36 hours.  A strong ridge of high pressure will build north of Dorian on Friday.  The high will block Dorian from moving north and it will turn it toward the west-northwest.  On its anticipated track Hurricane Dorian could be near the northern Bahamas on Saturday night.  Dorian could approach the east coast of Florida by later on Sunday.  Dorian is likely to be a major hurricane when it approaches Florida.

Tropical Storm Dorian Strengthens, Hurricane Warnings for Virgin Islands

Tropical Storm Dorian strengthened on Wednesday morning and it was on the verge of becoming a hurricane.  Hurricane Warnings were issued for Vieques, Culebra, the U.S. Virgin Islands and the British Virgin Islands. At 11:00 a.m. EDT on Wednesday the center of Tropical Storm Dorian was located at latitude 17.5°N and longitude 64.5°W which put it about 25 miles (40 km) south of St. Croix.  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 999 mb.

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

The circulation around Tropical Storm Dorian exhibited much greater organization on Wednesday morning.  A ring of strong thunderstorms wrapped almost completely around the center of circulation.  The strongest winds were occurring in the northeastern part of that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Dorian.  Storms near near the core were generating upper level divergence which was pumping mass away to the north and northeast of the tropical storm.  The circulation also increased in size on Wednesday morning.  Winds to tropical storm force extended out about 70 miles (110 km) from the center of circulation.

Tropical Storm Dorian will move through an environment favorable for intensification during the next few days.  Dorian will move over water where the Sea Surface Temperature is near 29°C.  It will move northeast of an upper level low during the next 24 hours.  The low will produce some southerly winds which will blow toward the top of the circulation, but the winds will not be strong enough to prevent intensification.  The wind shear will decrease on Friday and Dorian could strengthen into a major hurricane near the Bahamas.

The upper level low will help to steer Tropical Storm Dorian toward the northwest during the next 24 to 36 hours.  A ridge of high pressure will build north of Dorian on Friday.  The ridge will block Dorian from moving north and it will steer Dorian toward the west-northwest.  On its anticipated track Tropical Storm Dorian will pass over the Virgin Islands near the eastern end of Puerto Rico today.  Dorian will be near the northern Bahamas on Saturday and it could approach the east coast of Florida by Sunday night.  Dorian could be a major hurricane when it approaches the east coast of the U.S.

Elsewhere over the Atlantic Ocean, former Tropical Storm Erin weakened to a tropical depression.  At 11:00 a.m. EDT on Wednesday the center of Tropical Depression Erin was located at latitude 33.6°N and longitude 72.8°W which put it about 190 miles (305 km) southeast of Cape Hatteras, North Carolina.  Erin was moving toward the 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 wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1006 mb.

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.