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Nicole Transitions to Tropical Storm, Hurricane Warning Issued for Florida

Former Subtropical Storm Nicole completed a transition to a tropical storm on Tuesday morning and a Hurricane Warning was issued for a portion of the east coast of Florida. At 10:00 a.m. EST on Tuesday the center of Tropical Storm Nicole was located at latitude 27.8°N and longitude 72.7°W which put it about 460 miles (740 km) east of West Palm Beach, Florida. Nicole was moving toward the west at 9 m.p.h. (15 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 994 mb.

A Hurricane Warning was in effect for the portion of the coast from Boca Raton to the Flagler/ Volusia County Line, Florida. The Hurricane Warning included West Palm Beach, Ft. Pierce, Melbourne and Daytona Beach. A Hurricane Warning was in effect for the Abacos, Berry Islands, Bimini and Grand Bahama Island. A Hurricane Watch was in effect for the portion of the coast from the Flagler/Volusia County Line to Ponte Vedra Beach, Florida. A Hurricane Watch was in effect for the portion of the coast from Hallandale Beach to Boca Raton, Florida. A Hurricane Watch was in effect for Lake Okeechobee. Tropical Storm Warnings were in effect for Andros Island, New Providence and Eleuthera. A Tropcial Storm Warning was in effect for the portion of the coast from Hallandale Beach to Boca Raton, Florida. A Tropical Storm Warning was in effect for the portion of the coast from Altamaha Sound, Georgia to the Flagler/Volusia County Line, Florida. The Tropical Storm Warning includes Jacksonville. A Tropical Storm Watch was in effect for the portion of the coast from Hallandale Beach to Ocean Reef, Florida. The Tropical Storm Watch included Miami. A Tropical Storm Watch was in effect for the portion of the coast from Bonita Beach to the Ochlockonee River, Florida. A Tropical Storm Watch was in effect for the portion of the coast from Altamaha Sound to Savannah River, Georgia.

More thunderstorms formed near the center of former Subtropical Storm Nicole’s circulation. Thunderstorms near the center of circulation is one of the characteristics of a tropical storm. When the thunderstorms near the center persisted, the National Hurricane Center indicated that Nicole had complete a transition to a tropical storm. There was still a large area of tropical storm force winds around Nicole. Winds to tropical storm force extended out about 380 miles (615 km) in the northern side of Tropical Storm Nicole. Those winds were not entirely being produced by Nicole’s circulation. A large surface high pressure system was over the northeastern U.S. The high pressure system was interacting with the northern side of Nicole’s circulation to generate the large area of tropical storm force winds.

Tropical Storm Nicole will move through an environment that is favorable for intensification during the next 24 hours. Nicole will move over water where the Sea Surface Temperatures are near 28˚C. It will move into a region where the upper level winds are weaker and the vertical wind shear will diminish. Tropical Storm Nicole is likely to intensify gradually during the next 12 hours. Nicole will move over warmer water when it moves over the Gulf Stream on Wednesday. Nicole will extract more energy from the warmer water and it is likely to strengthen more rapidly on Wednesday. Tropical Storm Nicole could intensify to a hurricane when it moves over the warmer water.

The surface high pressure system currently over the northeastern U.S. will block Tropical Storm Nicole from moving toward the north. The high pressure system will steer Nicole toward the west-southwest during the next 18 hours. On its anticipated track Tropical Storm Nicole will reach the Northwestern Bahamas on Wednesday morning. Nicole will move toward the west-northwest on Wednesday when it reaches the southwestern part of the high pressure system. Nicole will reach the east coast of Florida on Wednesday night. Nicole could be a hurricane when it reaches Florida. Nicole is likely to bring strong, gusty winds and locally heavy rain to the Northwestern Bahamas and to central and northern Florida. The winds in the northern side of Nicole will blow water toward the coast of Florida and the Southeast U.S. Those winds will cause a storm surge and serious beach erosion when Nicole moves toward the coast.

Subtropical Storm Nicole Strengthens

Subtropical Storm Nicole strengthened on Tuesday morning as it moved over the Western Atlantic Ocean east of the Bahamas. At 7:00 a.m. EST on Tuesday the center of Subtropical Storm Nicole was located at latitude 27.7°N and longitude 72.0°W which put it about 385 miles (615 km) east of the Northwestern Bahamas. Nicole was moving toward the west-northwest at 8 m.p.h. (13 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 992 mb.

A Hurricane Warning was in effect for the Abacos, Berry Islands, Bimini and Grand Bahama Island. A Hurricane Watch was in effect for the portion of the coast from the Volusia/Brevard County Line to Hallandale Beach, Florida. The Hurricane Watch included Melbourne, West Palm Beach and Ft. Lauderdale. A Hurricane Watch was in effect for Lake Okeechobee. Tropical Storm Warnings were in effect for Andros Island, New Providence and Eleuthera. A Tropical Storm Warning was in effect for the portion of the coast from Altamaha Sound, Georgia to Hallandale Beach, Florida. The Tropical Storm Warning includes Jacksonville and Daytona Beach. A Tropical Storm Watch was in effect for the portion of the coast from Hallandale Beach to Ocean Reef, Florida. The Tropical Storm Watch included Miami. A Tropical Storm Watch was in effect for the portion of the coast from Bonita Beach to the Ochlockonee River, Florida.

Subtropical Storm Nicole began a transition to a tropical storm on Tuesday morning as it gradually strengthened. More thunderstorms formed near the center of Nicole’s circulation. Thunderstorms near the center of circulation is one of the characteristics of a tropical storm. There was still a large area of tropical storm force winds around Nicole, which is one of the characteristics of a subtropical storm. Winds to tropical storm force extended out almost 400 miles (645 km) in the northern side of Subtropical Storm Nicole. Those winds were not entirely being produced by Nicole’s circulation. A large surface high pressure system was over the northeastern U.S. The high pressure system was interacting with the northern side of Nicole’s circulation to generate the large area of tropical storm force winds.

Subtropical Storm Nicole will move through an environment that is favorable for a transition to a tropical storm during the next 24 hours. Nicole will move over water where the Sea Surface Temperatures are near 28˚C. It will move into a region where the upper level winds are weaker and the vertical wind shear will diminish. Subtropical Storm Nicole is likely to complete the transition to a tropical storm during the next 24 hours. Nicole will move over warmer water when it moves over the Gulf Stream on Wednesday. Nicole could intensify to a hurricane when it moves over the warmer water.

The surface high pressure system currently over the northeastern U.S. will block Subtropical Storm Nicole from moving toward the north. The high pressure system will steer Nicole toward the west-southwest during the next 24 hours. On its anticipated track Subtropical Storm Nicole will reach the Northwestern Bahamas on Wednesday morning. Nicole will move toward the west-northwest on Wednesday when it reaches the southwestern part of the high pressure system. Nicole will reach the coast of Southeast Florida on Wednesday night. Nicole could be a hurricane when it reaches Florida. Nicole is likely to bring strong, gusty winds and locally heavy rain to the Northwestern Bahamas and to central and northern Florida. The winds in the northern side of Nicole will blow water toward the coast of Florida and the Southeast U.S. Those winds will cause a storm surge and serious beach erosion when Nicole moves toward the coast.

Tropical Storm Humberto Develops East of the Bahamas

Former Tropical Depression Nine strengthened into Tropical Storm Humberto east of the Bahamas on Friday night.  At 11:00 p.m. EDT on Friday night the center of Tropical Storm Humberto was located at latitude 25.6°N and longitude 75.2°W which put it about 130 miles (210 km) east-southeast of Great Abaco, Bahamas.  Humberto was moving toward the northwest at 6 m.p.h. (10 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 1008 mb.

Tropical Storm Warnings were in effect for the Abacos, the Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.

A NOAA research aircraft flying through former Tropical Depression Nine on Friday night determined that the depression had strengthened into Tropical Storm Humberto.  The aircraft reported that the maximum sustained wind speed had increased to 40 m.p.h. (65 km/h).  The circulation around Tropical Storm Humberto was still poorly organized.  A few thunderstorms developed just to the north of the center of circulation.  A band of showers and thunderstorms curved around the eastern side of the circulation.  Bands in the other parts of Tropical Storm Humberto consisted primarily of showers and lower clouds.

Tropical Storm Humberto will move through an environment somewhat favorable for intensification during the next few days.  Humberto will move over water where the Sea Surface Temperature is near 29°C.   A large upper level low over the Gulf of Mexico will produce southerly winds which will blow toward the top of the tropical storm. Those winds will cause moderate vertical wind shear and they will inhibit intensification.  The upper low is forecast to move westward away from Humberto and the wind shear could decrease during the weekend. Tropical Storm Humberto is forecast to slowly become more organized and it could strengthen into a hurricane.

The upper low over the Gulf of Mexico will help to steer Tropical Storm Humberto toward the northwest during the next day or two.  A strong upper level trough over the Great Lakes will start to turn Humberto toward the east later in the weekend.  On its anticipated track the center of Tropical Storm Humberto could move near the Northwestern Bahamas.  If Humberto brings wind and rain to that region, it will hinder efforts to recover from Hurricane Dorian.

Tropical Depression Nine Develops Near the Bahamas

Tropical Depression Nine developed near the Bahamas on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Tropical Depression Nine was located at latitude 25.6°N and longitude 75.0°W which put it about 140 miles (225 km) east-southeast of Great Abaco, Bahamas.  It was moving toward the northwest at 8 m.p.h. (13 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.

Tropical Storm Warnings were in effect for the Abacos, the Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A Tropical Storm Watch was in effect for the portion of the Florida coast from Jupiter Inlet to the Volusia/Brevard County Line.

An Air Force Reserve Hurricane Hunter plane was able to identify a low level center of circulation in a tropical disturbance near the Bahamas on Friday afternoon and the National Hurricane Center designated the system as Tropical Depression Nine.  The center of circulation developed on the southwestern side of a cluster of thunderstorms just east of the Bahamas.  The circulation around the depression was still in the early stages of organization.  Most of the stronger thunderstorms were occurring in the eastern half of the tropical depression.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.

Tropical Depression Nine will move through an environment somewhat favorable for intensification during the next few days.  The tropical depression will move over water where the Sea Surface Temperature is near 29°C.  A large upper level low over the Gulf of Mexico will produce southerly winds which will blow toward the top of the depression.  Those winds will cause moderate vertical wind shear and they will inhibit intensification.  The upper low is forecast to move westward away from the  tropical depression and the wind shear could decrease during the weekend.  Tropical Depression Nine is forecast to slowly become more organized and it could strengthen into a tropical storm.

The upper low over the Gulf of Mexico will help to steer Tropical Depression Nine toward the northwest during the next day or two.  A strong upper level trough over the Great Lakes will start to turn the depression toward the east later in the weekend.  On its anticipated track the center of the depression could move near the Northwestern Bahamas.  If Tropical Depression Nine brings wind and rain to that region, it will hinder efforts to recover from Hurricane Dorian.

Tropical Storm Warnings Issued for Northwestern Bahamas

The government of the Bahamas issued Tropical Storm Warnings for the Northwestern Bahamas on Friday afternoon.  Tropical Storm Warnings were issued for the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.  A tropical disturbance over the Southeastern Bahamas was forecast to strengthen into a tropical storm, which prompted the issuance of the Tropical Storm Warnings.  The National Hurricane Center (NHC) initiated advisories on the disturbance at 5:00 p.m. EDT on Thursday and NHC designated the system at Potential Tropical Cyclone Nine.

At 5:00 p.m. EDT on Thursday the broad center of Potential Tropical Cyclone Nine was located at latitude 23.7°N and longitude 74.8°W which put it about 235 miles (380 km) southeast of Great Abaco.  It was moving toward the northwest at 8 m.p.h. (13 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 1008 mb.

The circulation around Potential Tropical Cyclone Nine was very poorly organized.  There was a very broad center around which the air was turning cyclonically.  An Air Force Reserve Hurricane Hunter reconnaissance plane was finding weak winds near the broad center.  Most of the strong thunderstorms were northeast of the broad center of the disturbance.  The stronger winds here occurring near those thunderstorms.  There did not appear to be any significant banding of the showers and thunderstorms.

A large upper level low over the Gulf of Mexico was producing moderate southerly winds which were blowing across the western side of Potential Tropical Cyclone Nine.  Those winds were causing moderate vertical wind shear.  A small upper level ridge was developing between the upper low over the Gulf and another smaller upper low near Bermuda.  Winds were weaker under the ridge and that was the likely reason the stronger thunderstorms were in the northeastern part of the disturbance.  It is possible that a new center of circulation could develop near one of the clusters of thunderstorms.

Potential Tropical Cyclone Nine will move through an area somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 29°C.  The upper low over the Gulf of Mexico is forecast to move westward which would cause the vertical wind shear to decrease.  If the shear decreases, then a distinct low level center of circulation could develop.  If a distinct center forms, then the system would be designated as a tropical depression.  Potential Tropical Cyclone Nine has the potential to strengthen into a tropical storm during the next 24 to 48 hours.

The future track of Potential Tropical Cyclone Nine will depend on the place where a center of circulation forms and how strong the system becomes.  A stronger tropical cyclone would be steered by winds higher in the atmosphere.  If Potential Tropical Cyclone Nine strengthens significantly then the upper level low over the Gulf of Mexico and the developing upper level ridge will combine to the system toward the northwest during the next day or two.  A cold front moving southeast across the Great Lakes and Ohio River Valley could turn the system toward the northeast later in the weekend.  Under that scenario Potential Tropical Cyclone Nine would move across the Northwestern Bahamas on Friday.  It could approach southeast Florida on Saturday.

On the other hand, if Potential Tropical Cyclone Nine does not develop, or if it remains a weak tropical cyclone, then it would be steered by winds lower in the atmosphere.  In that case the system could be steered more toward the west-northwest and it could move across Florida into the Gulf of Mexico.   The guidance from numerical models is very divergent about the predicted future track of Potential Tropical Cyclone Nine.  In any case the system will bring some wind and rain to the Northwestern Bahamas and that will hinder efforts to recover from Hurricane Dorian.

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.