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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.

Tropical Storm Dorian Brings Wind and Rain to Barbados

Tropical Storm Dorian brought wind and rain to Barbados on Monday night.  Observations made by a U.S. Air Force Reserve Hurricane Hunter aircraft indicated that the center of Tropical Storm Dorian passed just south of Barbados on Monday night.  Dorian brought winds to tropical storm force and locally heavy rain.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Dorian was located at latitude 13.2°N and longitude 59.7°W which put it about 95 miles (155 km) east-southeast of St. Lucia.  Dorian was moving toward the west-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 1003 mb.

Tropical Storm Warnings were in effect for Barbados, St. Lucia, Martinique, St. Vincent and the Grenadines. Tropical Storm Watches have been issued for Puerto Rico, Grenada, Dominica, Saba and St. Eustatius.

The circulation around Tropical Storm Dorian remained fairly small on Monday.  Winds to tropical storm force only extended out about 45 miles (75 km) from the center of circulation.  Thunderstorms were occurring primarily in bands in the northern half of the circulation.  Bands in the southern half of the circulation consisted primarily of showers and lower clouds.  Storms near the center of Dorian were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Dorian will move through an environment somewhat favorable for intensification.  Dorian will move over water where the Sea Surface Temperature is near 29°C.  Tropical Storm Dorian will move south of an upper level ridge.  The ridge will produce easterly winds which will cause some vertical wind shear, but the shear should not be strong enough to prevent intensification.  Dorian will move just south of a large mass of drier air.  It appears that some drier air will get pulled into circulation at times and the drier air will interrupt periods of intensification.  Since the circulation around Tropical Storm Dorian is very small, Dorian could strengthen or weaken very quickly if environmental conditions change.

Tropical Storm Dorian will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Dorian toward the west-northwest during the next several days.  On its anticipated track the center of Tropical Storm Dorian will pass near St. Lucia on Tuesday morning.  Dorian could approach Puerto Rico on Wednesday.

Elsewhere over the Atlantic Ocean, Tropical Depression Six formed off the southeast coast of the U.S.  At 11:00 p.m. EDT on Monday the center of Tropical Depression Six was located at latitude 31.5N and longitude 72.2W which put it about 320 miles southeast of Cape Hatteras, North Carolina. It was moving toward the east at 3 m.p.h. The maximum sustained wind speed was 35 m.p.h. and the minimum surface pressure was 1010 mb.

Stronger Tropical Storm Dorian Causes Warnings for Lesser Antilles

Tropical Storm Dorian strengthened on Sunday and the threat it posed caused warnings and watches to be issued for some of the Lesser Antilles.  Tropical Storm Warnings were in effect for Barbados, St. Lucia, and St. Vincent and the Grenadines.  Tropical Storm Watches were issued for Grenada and Martinique.

At 5:00 p.m. EDT on Sunday the center of Tropical Storm Dorian was located at latitude 11.5°N and longitude 54.2°W which put it about 375 miles (605 km) east-southeast of Barbados.  Dorian was moving a little to the north of due west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1003 mb.

The circulation around Tropical Storm Dorian exhibited greater organization on Sunday afternoon.  The inner end of a band of showers and thunderstorms wrapped tightly around the northern and western sides of the center of circulation.  The strongest winds were occurring in that band.  Several other bands of showers and storms were revolving around the small core of Dorian.  Storms near the center of circulation were generating upper level divergence which was pumping mass away to the north of the tropical storm.  The circulation around Tropical Storm Dorian was small.  Winds to tropical storm force extended out about 35 miles (55 km) from the center of circulation.

Tropical Storm Dorian will move through an environment mostly favorable for intensification.  Dorian will move over water where the Sea Surface Temperature is near 28.5°C.  It will move through a region where the upper level winds are relatively weak and there will be little vertical wind shear.  A large area of drier air is north of Tropical Storm Dorian.  If the circulation draws drier air into the tropical storm, it would interrupt intensification.  Tropical Storm Dorian is likely to strengthen during the next 24 to 48 hours.  Since Dorian has a small circulation, it could intensify or weaken quickly if the environmental conditions change.

Tropical Storm Dorian will move south of the subtropical high pressure system over the North Atlantic Ocean.  The high will steer Dorian toward the west-northwest during the next few days.  On its anticipated track Tropical Storm Dorian could approach Barbados late on Monday.  It could be a hurricane by that time.  Dorian could reach the southern and central Lesser Antilles on Tuesday.  Tropical Storm Dorian could bring strong winds and heavy rain to those islands.

Tropical Depression Five Strengthens Into Tropical Storm Dorian

Former Tropical Depression Five strengthened into Tropical Storm Dorian east of the Lesser Antilles on Saturday afternoon.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Dorian was located at latitude 10.7°N and longitude 49.1°W which put it about 725 miles (1165 km) east southeast of Barbados.  Dorian was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1008 mb.

The circulation around former Tropical Depression Five exhibited greater organization on Saturday afternoon and the National Hurricane Center determined that the system had strengthened to Tropical Storm Dorian.  A band of thunderstorms close to the center of circulation wrapped around the western and southern sides of the center.  The strongest winds were occurring in that band of storms.  Other bands in the western half of the circulation started to revolve around the center of circulation.  Storms near the center began to generate upper level divergence which was pumping mass away to the west of the tropical storm.  The circulation around Tropical Storm Dorian was small.  Winds to tropical storm force extended out about 25 miles (40 km) from the center of circulation.

Tropical Storm Dorian will move through an environment that will be favorable for intensification during the next several days.  Dorian will move over water where the Sea Surface Temperature is near 28°C.  It will move south of an upper level ridge.  The ridge will produce easterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear.  The shear will slow the rate of intensification.  Tropical Storm Dorian will move south of a region of drier air.  If drier air is pulled into the circulation, it will interrupt intensification.  Since Tropical Storm Dorian is so small, it could strengthen or weaken very quickly if the environment changes.  Dorian could strengthen into a hurricane in two or three days.

Tropical Storm Dorian will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Dorian toward the west-northwest during the next few days.  On its anticipated track Tropical Storm Dorian could approach the Lesser Antilles on Tuesday.  Dorian could strengthen into a hurricane by that time.  Watches and/or warnings could be issued for parts of the Lesser Antilles on Sunday.

Tropical Depression Five Forms East of Lesser Antilles

Tropical Depression Five formed east of the Lesser Antilles on Saturday morning.  At 11:00 a.m. EDT on Saturday the center of Tropical Depression Five was located at latitude 10.4°N and longitude 47.9°W which put it about 805 miles (1300 km) east-southeast of Barbados.  It was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1010 mb.

Data from satellites indicated that there was a closed circulation around an area of low pressure east of the Lesser Antilles on Saturday morning and the National Hurricane Center designated the system as Tropical Depression Five.  The circulation around Tropical Depression Five was still organizing.  Many of the stronger thunderstorms were occurring in bands west of the center of circulation.  Bands in the eastern half of the circulation consisted primarily of showers and lower clouds.  The circulation around Tropical Depression Five was relatively small.

Tropical Depression Five will move through an environment favorable for slow intensification.  It will move over water where the Sea Surface Temperature is near 28°C.  The depression will move south of an upper level ridge over the western north Atlantic Ocean.  The ridge will produce easterly winds which will cause some vertical wind shear.  There will be some drier air just to the north of the depression.  If the depression pulls some of the drier air into the circulation, that could also interrupt intensification.  The combination of some wind shear and intrusions of drier air will limit the rate at which Tropical Depression Five strengthens.  The depression is forecast to strengthen into a tropical storm.

Tropical Depression Five will move south of a subtropical high pressure system over the Atlantic Ocean.  The high will steer the depression toward the west-northwest during the next few days.  On its anticipated track Tropical Depression Five could approach the Lesser Antilles on Monday night or Tuesday.  The depression could be a tropical storm by that time.

Ernesto Makes Transition to Tropical Storm

Former Subtropical Storm Ernesto made a transition to a tropical storm on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Ernesto was located at latitude 43.0°N and longitude 41.0°W which put it about 645 miles (1035 km) east-southeast of Cape Race, Newfoundland.  Ernesto was moving toward the northeast 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 1007 mb.

Even though now Tropical Storm Ernesto moved over water where the Sea Surface Temperature was between 24°C and 25°C, there was enough energy in the upper ocean to cause more thunderstorms to develop.  In addition, many of the thunderstorms developed close to the center of circulation.  The inner bands of showers and thunderstorms became stronger and the bands in the outer parts of the circulation weakened.  Ernesto exhibited a structure like a tropical cyclone and the National Hurricane Center classified the system as a tropical storm in the 5:00 p.m. EDT advisory.

Tropical Storm Ernesto will move over much cooler water during the next 24 hours.  It is likely to make a transition to an extratropical cyclone when it moves over the cooler water.  Ernesto could strengthen when colder air is pulled into the western half of the circulation and a cold front forms south of the center.  The development of the cold front and upper level divergence could strengthen the pressure gradient force which would give the air a stronger push.  An upper level trough east of the U.S. is forecast to steer Ernesto in the general direction of Ireland and the United Kingdom.

Subtropical Storm Ernesto Forms West of the Azores

Subtropical Storm Ernesto formed west of the Azores on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Subtropical Storm Ernesto was located at latitude 38.1°N and longitude 46.0°W which put it about 695 miles (1120 km) southeast of Cape Race, Newfoundland.  Ernesto was moving toward the north at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1008 mb.

More thunderstorms formed closer to the center of a low pressure system west of the Azores on Wednesday morning and the National Hurricane Center designated the system as Subtropical Storm Ernesto.  Several bands of showers and thunderstorms wrapped around the eastern and northern portions of the circulation.  Bands northwest of the center of Ernesto consisted primarily of showers and lower clouds.  The circulation may have been transporting some cooler, drier, more stable air into that part of the circulation.  Showers and thunderstorms around the center of Ernesto were generating upper level divergence which was pumping mass away to the northeast of the subtropical storm.

Subtropical Storm Ernesto will move through an environment that could support some intensification during the next day or so.  Ernesto will move over water where the Sea Surface Temperature is near 26°C.  It will move through a region where the upper level winds are not too strong and there will not be much vertical wind shear.  Subtropical Storm Ernesto could strengthen during the next 12 to 24 hours.  Ernesto will move over cooler water later on Thursday and it will start to weaken.  An upper level trough east of the U.S. will approach Subtropical Storm Ernesto from the west.  Southwesterly winds ahead of the trough will cause more vertical wind shear and Ernesto could make a transition to an extratropical cyclone.

The southwesterly winds ahead of the upper level trough will steer Subtropical Storm Ernesto in a general northeasterly direction.  On its anticipated track Subtropical Ernesto will pass between the Azores and Greenland.