Hurricane Dorian Strengthens Further, Winds of 285 KM/H, Gusts to 350 KM/H.

As of 11:00 AM, Hurricane Dorian continues to show no signs of weakening, with frequent lightning still ongoing in its eyewall, indicative of strengthening. Over the last several hours, Dorian’s peak winds from 260 KM/H to 285 KM/H and its pressure dropped a significant 14 millibars between 8:00 AM and 11:00 AM.

Air force reconnaissance planes, i.e. Hurricane Hunters, continue to find lower pressures within the eye of Dorian, as it bears down on Abaco Islands, northwestern Bahamas.

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

Hazards:

  • Wind Gusts over 350 KM/H, winds up to 285 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 Watch is in effect for North of Deerfield Beach to the Volusia/Brevard County Line, Florida. 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 Northwestern Bahamas excluding Andros Island. 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 Andros Island and North of Deerfield Beach to the Volusia/Brevard County Line, Florida. 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

At 11:00 AM, the extremely distinct eye of Hurricane Dorian was located near latitude 26.5 North, longitude 76.8 West. Dorian is moving toward the west near 11 KM/H. A slower westward motion should continue for the next day or two, followed by a gradual turn toward the northwest. On this track, the core of extremely dangerous Hurricane Dorian will continue to move over Great Abaco and move near or over Grand Bahama Island later tonight and Monday. The hurricane should move closer to the Florida east coast late Monday through Tuesday night.

Maximum sustained winds have increased to near 285 KM/H with higher gusts. Dorian is an extremely dangerous category 5 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some fluctuations in intensity are likely, but Dorian is expected to remain a powerful hurricane during the next few days.

Dorian has grown larger in size. Hurricane-force winds extend outward up to 75 kilometers from the center and tropical-storm-force winds extend outward up to 220 kilometers. Ham radio reports indicate that Hope Town in the Abacos just reported wind gust to 100 mph.

The minimum central pressure measured by both NOAA and Air Force reconnaissance plane was 913 millibars.

Hazards Affecting Land

Hurricane Dorian nearing the Bahamas, with the eyewall moving across Abacos Island. Credit: Weathernerds
Hurricane Dorian nearing the Bahamas, with the eyewall moving across Abacos Island. Credit: Weathernerds

Wind: Catastrophic hurricane conditions are occurring in the Abacos Islands and will spread across Grand Bahama Island later today and tonight.

Hurricane conditions are possible within the hurricane watch area in Florida by late Monday or early Tuesday. Tropical storm conditions are expected within the tropical storm warning area on Monday and Tuesday. Tropical storm conditions are possible within the tropical storm watch area by Monday night.

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 the Abaco Islands and Grand Bahama Island. Near the coast, the surge will be accompanied by large and destructive waves.

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.

Volusia/Brevard County Line to Jupiter Inlet FL – 4 to 7 ft
North of Deerfield Beach to Jupiter Inlet FL – 2 to 4 ft

The surge will be accompanied by large and destructive waves. Surge-related flooding depends on the 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).
Coastal Carolinas – 5 to 10 inches (125-250 mm), isolated 15 inches (375 mm).
Central Bahamas and the Atlantic Coast from the Florida peninsula through Georgia – 2 to 4 inches (50-100 mm), isolated 6 inches (150 mm).

This rainfall may cause life-threatening flash floods.

Seas: Large swells are already affecting east-facing shores of the Bahamas, 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. Please consult products from your local weather office.

Hurricane Dorian’s Strength

With winds now estimated at 180 mph, only 7 storms – of the 1,869 recorded in the Atlantic in 169 years- have been as strong or stronger than Hurricane Dorian

Dorian’s pressure (913mb) is now stronger than Irma’s (914mb). The winds of 180 mph and it’s low pressure both place in the top five strongest Atlantic storms on record.

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

Air Force and NOAA reconnaissance planes penetrated the distinct eye of Dorian, and found that the hurricane has become extremely intense with a stadium effect in the eye. The NOAA plane reported a peak flight-level wind of 159 kt, while the SFMR from both planes have measured winds between 155 and 170 kt. A dropsonde from the NOAA plane measured a wind gust of 176 kt at the surface. A blend of these measurements yields to an initial intensity of 155 kt, making Dorian the strongest hurricane on record in the northwestern Bahamas.

For the next few days, Dorian should experience some fluctuations in intensity, and in addition to eyewall replacement cyclone, the interaction with the northwestern Bahamas should weaken the hurricane slightly. After 3 days, as Dorian moves northward along or offshore of southeast United States coast, the shear is forecast to increase, resulting in a more distinct gradual weakening.

Reconnaissance plane and satellite fixes indicate that Dorian, as anticipated, has slowed down and is moving toward the west or 270 degrees at 6 kt. The steering currents are collapsing and Dorian is expected to slow down, even more, prolonging its catastrophic effects in the northwestern Bahamas. The NHC forecast calls for a slow west to west-northwest motion during the next 48 hours, with a turn to the north and an increase in forward speed as the mid-level trough along the eastern United States deepens and becomes the dominant steering feature.

The current forecast is only a few miles west of the previous one and is basically on top of the multi-model consensus. Both the deterministic and consensus tracks have shown the usual variability to the right or to the left from run to run, but the overall trend is for the hurricane to turn northward offshore but very close to the Florida peninsula.

Given the uncertainty in the track forecast and the anticipated increase in the size of the hurricane, a Hurricane Watch, and Storm Surge Watch have been issued for a portion of the east Florida coast. It is emphasized that although the official track forecast does not show landfall, users should not focus on the exact track. A small deviation to the left of the track could bring the intense core of the hurricane its dangerous winds closer to or onto the coast.

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