Tag Archives: Andros Island

Isaias Crosses Andros Island, Weakens to Tropical Storm

The center of former Hurricane Isaias crossed Andros Island on Saturday afternoon and it weakened to a tropical storm.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Isaias was located at latitude 25.1°N and longitude 78.7°W which put it about 115 miles (185 km) southeast of Ft. Lauderdale, Florida.  Isaias was moving toward the northwest at 10 m.p.h. (16 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 993 mb.

A Hurricane Warning was in effect for the portion of the coast from Boca Raton, Florida to the Flagler/Volusia County Line.  A Hurricane Waning was also in effect for the Northwestern Bahamas including Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island, and Bimini.

Tropical Storm Warnings were in effect for the portions of the coast from Ocean Reef to Boca Raton, Florida and from the Flagler/Volusia County Line to Ponte Vedra Beach, Florida.  A Tropical Storm Warning was also in effect for Lake Okeechobee.  A Tropical Storm Watch was in effect for the portion of the coast from Ponte Vedra Beach, Florida to South Santee River, South Carolina.

The center of former Hurricane Isaias crossed over Andros Island on Saturday afternoon.  Normally, Andros Island does not have much of an impact on hurricanes, but combined with a less favorable environment it contributed to a temporary weakening of Isaias.   Tropical Storm Isaias consisted primarily of bands of showers and lower clouds after crossing Andros Island.  However, new thunderstorms began to develop northeast of the center of circulation during the past several hours and part of the eyewall appeared to be reforming.  Bands in the western and southern parts of Isaias still consisted primarily of showers and lower clouds.  Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation.

Tropical Storm Isaias will move through an environment somewhat favorable for intensification during the next 36 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the central U.S. will produce westerly winds which blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear, but they are likely to only affect the very top of the tropical storm.  Tropical Storm Isaias will move into a region where there is drier air in the middle and upper troposphere.  The circulation around Tropical Storm Isaias will reorganize and it is likely to strengthen back into a hurricane.

Tropical Storm Isaias will move around the western end of a subtropical high pressure system over the Atlantic Ocean.  The high will steer Isaias toward the northwest during the next 24 hours.  Isaias will move more toward the north later on Sunday.  The upper level trough will turn Isaias toward the northeast on Monday.  On its anticipated track Tropical Storm Isaias is will approach the southeast coast of Florida near Ft. Lauderdale and West Palm Beach on Sunday.  Isaias is likely to be a hurricane when it approaches the coast.

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.