Hurricane Dorian strengthened to a category-5 hurricane overnight and is moving over Abaco Island on a slow path west toward the United States. The Northern Bahamas Islands are experiencing a storm surge of 15 to 20 feet above tide level in areas of onshore winds, coupled with destructive waves, rainfall in excess of 20 inches, and hurricane force winds. Much uncertainty remains in the longer term forecast, as the timing of a turn northward will determine potential impacts in the southeastern United States. The National Hurricane Center (NHC) best forecast continues to keep Dorian offshore of Florida, however the latest model runs support Dorian approaching more closely than previous forecasts. Although the official forecast does not show a landfall in the Continental United States, the level of uncertainty is very high and a landfall anywhere from Florida through the Carolinas is still a distinct possibility. Status (11AM EDT NHC Advisory)
- Location: Pass over Abaco Island; 205 miles east of West Palm Beach
- Maximum sustained winds: 180 mph
- Motion: west at 7 miles per hour
- Minimum central pressure: 913 mb
- Extent of hurricane-force winds: 45 miles
- Extent of tropical-storm-force winds: 140 miles
- Status: Category-5 hurricane
Position and Best Forecast. Source: NHC Discussion A very strong category-5 Hurricane Dorian is currently moving directly across the Northern Bahamas Islands, with the eyewall impacting Abaco Island this morning. Sustained winds of 180 mph, with gusts to over 200 mph are being experienced. The system is moving slowly through an environment that is favorable for maintaining this intensity through the next 12 hours. The Bahamas Islands can expect to experience hurricane conditions throughout the day on Sunday and Monday as the system continues to slow down on a path to the west. Hurricane warnings are in place for the Northern Bahamas, while a tropical storm warning has been issued for portions of the south-central Florida coast in response to a shift westward in the official track. This westward shift in the track has meaningful implications for the Florida coast. The entire east coast of Florida is well within the NHC cone of uncertainty, and mere miles shift in track could mean major hurricane conditions inland.
Satellite image of Dorian (infrared) ending 13:22 UTC September 1. Source: tropicaltidbits.com The satellite presentation of Dorian is impressive, with a very well defined eye approaching Abaco Island. The storm has strengthened significantly in the past 24 hours, and also grown in size. Hurricane force winds extend 45 miles from the center. The environment is supportive for maintaining category-5 status through the short term, with deep ocean heat content and weak shear. However, due to the overall slowing down of the system and relatively shallow waters in the Bahamas, the available heat content will eventually limit the intensity of the storm. Most of the ensemble intensity guidance times this weakening to occur later today. The NHC best intensity forecast is on the high side of model guidance, and keeps Dorian a major hurricane (category-3 or higher) through the 72 hour forecast.
Intensity model guidance for Dorian. Source: tropicaltidbits.com Model track guidance has necessitated a shift to the west in the NHC best track estimate. The European Model below illustrates the concensus in track forecast for the next 12-24 hours as the storm is being steered slowly west by a high pressure ridge to the north. A weakening of the ridge and a slowing down of the system has been forecast for the past several days, however models are maintaining westward motion for slightly longer than previous runs, which brings Dorian closer to the Florida Atlantic coast. The 51 member ensemble suite of tracks show varying scenarios, including landfalls in Florida, Georgia and the Carolinas, although the mean of the ensemble remains offshore. Information like this from several global and hurricane models, in addition to the European model, is informing the official NHC track forecast. The large-scale weather environment is continually being observed by instruments and satellite, and these observations are being ingested into the models to inform steering currents. Each model run today and tomorrow should bring increased clarity to the ultimate path and progress of the storm.
European weather model 51 member ensemble project for Dorian. Source: Dr. Brian Tang / UAlbany The NHC official track forecast predicts the onset of tropical storm force winds early Monday in south central Florida. With the increased size of the storm and westward shift in track, it is increasingly likely that the east coast of Florida will experience hurricane force winds. The storm is expected to progress to the north and bring wind and surge from Florida to the Carolinas. Regardless of a potential landfall location or the bypassing distance, there will be significant local impacts along the entire coastline. Of note, background tides are running at some of the highest levels of the year, known as king tides. Additionally, the slow moving nature of the storm will create a very significant storm surge. In areas where the coastal geography and bathymetry are conducive to storm surge, these combined effects could inundate low lying areas and cause significant coastal erosion.
Earliest reasonable arrival time of tropical-storm-force winds and probabilities. Source: NHC The NHC and Local Offices maintain watches and warnings for areas under potential or immediate threat. Specifics can be found at www.nhc.noaa.gov, www.weather.gov, and official government agencies. Official watches and warnings, and statements from emergency management agencies supersede this update, and should be closely followed concerning matters of personal safety. Next Update The next Weather Sentinel update will be issued on Monday, September 2. For up to date, official information, the following websites are recommended: National Hurricane Center National Weather Service, Melbourne, FL National Weather Service, Jacksonville, FL National Weather Service, Charleston, SC National Weather Service, Newport/Morehead City, NC Florida Evacuation Orders Georgia Emergency Management South Carolina Emergency Management North Carolina Emergency Management Subscribe to Guy Carpenter Email Alerts on Real Time Activity To receive email notifications of Weather Sentinel updates, please click on this link to update your preferences. https://go.guycarp.com/preferencecenter Additionally, in response to client demand, we are pleased to offer daily email alerts for any tropical cyclone occurring globally. The GC Global Tropical Cyclone Alert discusses active tropical cyclones across the globe, portraying a graphical forecast and brief commentary on intensity forecast changes expected over a 24 hour period. Fill out the form at the link below to start receiving our key insights. https://go.guycarp.com/hurricanealerts