Hurricane Dorian Continues to Batter the Northern Bahamas

As of 9:00 AM, Hurricane Dorian continues to maintain its strength as it pummels Grand Bahama. Dorian has been near stationary over the last several hours. In fact, Hurricane Dorian has traveled only ~40 miles (~3.3 miles per hour) across Grand Bahama island. It is now moving west at only 1 mph. The long-duration impacts of Category 5 Dorian on Grand Bahama Island have been and will continue to be devastating.

The eyewall of catastrophic Hurricane Dorian is currently across the Grand Bahama. This is a life-threatening situation. Residents there should continue to take immediate shelter. Do not venture into the eye if it passes over your location.

Hazards:

  • Wind Gusts over 270 KM/H, winds up to 320 KM/H for sustained, prolonged periods
  • Storm Surge 18 to 23 feet (5.5-7 meters) above normal tide levels with higher destructive waves.

These hazards will cause extreme destruction in the affected areas and will continue for several hours.

A Storm Surge Warning is in effect for Lantana to the Volusia/Brevard County Line, Florida. A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations.

This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Storm Surge Watch is in effect for North of Deerfield Beach to the south of Lantana, Florida and Volusia/Brevard County Line to the Mouth of the St. Mary’s River, Georgia. A Storm Surge Watch means there is a possibility of life-threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours.

A hurricane warning remains in effect for Grand Bahama and the Abacos Islands in the northwestern Bahamas and Jupiter Inlet to the Volusia/Brevard County Line, Florida. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion.

A hurricane watch remains in effect for North of Deerfield Beach to Jupiter Inlet, Florida and Volusia/Brevard County Line to the Mouth of the St. Mary’s River, Georgia. A Hurricane Watch means that hurricane conditions are possible within the watch area.

A tropical storm warning is in effect for North of Deerfield Beach to Sebastian Inlet, Florida. A Tropical Storm Warning means that tropical storm conditions are expected within the warning area within 36 hours.

A tropical storm watch is in effect for north of Golden Beach to Deerfield Beach and Lake Okeechobee, Florida. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

Hurricane Dorian Update

Hurricane Dorian across the Bahamas, with the eyewall moving across the Grand Bahama Island. Credit: Weathernerds

At 9:00 AM, the eye of Hurricane Dorian was located by NOAA Doppler radar near latitude 26.7 North, longitude 78.3 West. Dorian is moving toward the west near 2 KM/H. A slow westward to west-northwestward motion is forecast during the next day or so, followed by a gradual turn toward the northwest and north.

On this track, the core of extremely dangerous Hurricane Dorian will continue to pound Grand Bahama Island through much of today and tonight. The hurricane will move dangerously close to the Florida east coast tonight through Wednesday evening.

Maximum sustained winds are near 270 KM/H with higher gusts. Dorian is a category 5 hurricane on the Saffir-Simpson Hurricane Wind Scale. Although gradual weakening is forecast, Dorian is expected to remain a powerful hurricane during the next couple of days.

Hurricane-force winds extend outward up to 75 kilometers from the center, and tropical-storm-force winds extend outward up to 220 kilometers. The estimated minimum central pressure is 916 millibars.

Hazards Affecting Land

Wind: Catastrophic hurricane conditions continue on Grand Bahama Island. Do not venture out into the eye, as winds will suddenly increase after the eye passes.

Hurricane conditions are expected within the Hurricane Warning area in Florida by late tonight or Tuesday. Hurricane conditions are possible in the Hurricane Watch area on Wednesday.

Tropical storm conditions are expected within the Tropical Storm warning area today and Tuesday and are possible in the Tropical Storm watch area by tonight.

Storm Surge: A life-threatening storm surge will raise water levels by as much as 18 to 23 feet above normal tide levels in areas of onshore winds on Grand Bahama Island. Near the coast, the surge will be accompanied by large and destructive waves. Water levels should very slowly subside on the Abaco Islands during the day.

The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide:

Lantana to the Mouth of the St. Mary’s River – 4 to 7 ft
North of Deerfield Beach to Lantana – 2 to 4 ft

The surge will be accompanied by large and destructive waves. Surge-related flooding depends on how close the center of Dorian comes to the Florida east coast and can vary greatly over short distances.

Rainfall: Dorian is expected to produce the following rainfall totals through late this week:

Northwestern Bahamas – 12 to 24 inches (300-600 mm), isolated 30 inches (750 mm).
Central Bahamas – Additional 1 to 3 inches (25-75 mm), isolated storm totals
of 6 inches (150 mm).
Coastal Carolinas – 5 to 10 inches (125-250 mm), isolated 15 inches (375 mm).
Atlantic Coast from the Florida peninsula through Georgia – 4 to 8
inches (100-200 mm), isolated 10 inches (250 mm).

This rainfall may cause life-threatening flash floods.

Seas: Large swells are affecting east-facing shores of the Bahamas and the Florida east coast, and will spread northward along the southeastern United States coast during the next few days. These swells are likely to cause life-threatening surf and rip current conditions.

Tornadoes: Isolated tornadoes are possible this afternoon into tonight along the immediate coast of east-central Florida.

Hurricane Dorian’s Strength

At Category 5 strength, with winds in excess of 157 MPH (252 KM/H), catastrophic damage is expected.

Category 5 is the highest category of the Saffir–Simpson scale. These storms cause complete roof failure on many residences and industrial buildings and some complete building failures with small utility buildings blown over or away. The collapse of many wide-span roofs and walls, especially those with no interior supports, is common. Very heavy and irreparable damage to many wood frame structures and total destruction to mobile/manufactured homes is prevalent.

Only a few types of structures are capable of surviving intact, and only if located at least 3 to 5 miles (5 to 8 km) inland. They include office, condominium, and apartment buildings and hotels that are of solid concrete or steel frame construction, multi-story concrete parking garages, and residences that are made of either reinforced brick or concrete/cement block and have hipped roofs with slopes of no less than 35 degrees from horizontal and no overhangs of any kind, and if the windows are either made of hurricane-resistant safety glass or covered with shutters. Unless all of these requirements are met, the absolute destruction of a structure is certain.

The storm’s flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened or washed away by the storm surge. Virtually all trees are uprooted or snapped and some may be debarked, isolating most affected communities. Massive evacuation of residential areas may be required if the hurricane threatens populated areas. Total and extremely long-lived power outages and water losses are to be expected, possibly for up to several months.

Dorian’s Forecast Intensity & Track

Satellite imagery continues to show that Dorian has an extremely well-defined eye embedded within very cold cloud tops. The diameter of the eye appears to have expanded to near 20 n mi, and radar data, especially from the Bahamas Department of Meteorology radar, show that there are concentric eyewalls.

The hurricane also continues to exhibit strong upper-tropospheric outflow. The initial intensity estimate has been reduced to 145 kt, which lies between earlier Hurricane Hunter estimates and satellite intensity estimates from TAFB and SAB. This lowering of intensity is consistent with the development of a concentric eyewall. During the next few days,

Dorian should be encountering some increase in shear, which will likely result in weakening. However, it is anticipated that the system will remain a dangerous major hurricane for the next several days. The official intensity forecast lies between the statistical-dynamical guidance and the corrected multi-model consensus.

Steering currents have weakened, and Dorian has almost come to a standstill over eastern Grand Bahama Island, with an initial motion of 270/1 kt. The mid-tropospheric high to the north of the hurricane that had been steering Dorian westward has collapsed. Global models indicate that, in a couple of days, a weakness in the ridge will develop along 75W-80W. This would likely cause Dorian to move northwestward to northward toward and through this weakness.

Later in the forecast period, the system is expected to accelerate northeastward on the southern side of a broad mid-tropospheric trough. The official track forecast is very close to the previous one and to the corrected dynamical model consensus, HCCA. Although the official forecast does not show Dorian making landfall along the Florida east coast, it is still possible for the hurricane to deviate from this forecast, and move very near or over the coast. Users are reminded not to focus on the exact forecast track.

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