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Hurricane Dorian Forecast Discussion Number 43
2019-09-04 04:57:00| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Tue Sep 03 2019 000 WTNT45 KNHC 040256 TCDAT5 Hurricane Dorian Discussion Number 43 NWS National Hurricane Center Miami FL AL052019 1100 PM EDT Tue Sep 03 2019 Dorian's structure has changed significantly during the past day or so. Satellite and Doppler radar images show that the inner core has become rather broad with a large ragged eye of at least 30 n mi diameter. Data from the Air Force Hurricane Hunters indicate that the maximum winds and minimum pressure have held steady since this afternoon, and based on that information, the initial intensity is held at 95 kt, but this could be a little generous. The aircraft data and surface observations indicate that the wind field is expanding in size with tropical-storm-force and hurricane-force winds extending up to 150 n mi and 50 n mi from the center, respectively. NOAA data buoy 41010 just northeast of the center has been reporting sustained winds as high as 60 kt with gusts to 78 kt, and seas over 30 ft. Dorian is finally on the move again, and the latest initial motion estimate is 340 degrees at 5 kt. Dorian is being steered by the flow between a mid-level ridge to the east and broad troughing to its north. A northwest to north motion with some increase in forward speed is expected through Wednesday, taking the core of Dorian just offshore and parallel to the east coast of Florida during that time. Thereafter, a faster motion toward the northeast is predicted as a series of shortwave troughs move across the northeastern U.S. This should take the core of the hurricane very near, or possibly over, the coasts of South and North Carolina on Thursday and Friday. After it passes the Outer Banks, the hurricane is forecast to accelerate northeastward in the stronger mid-latitude flow toward the Canadian Maritimes this weekend. The NHC track forecast is largely unchanged and near the middle of the tightly packed guidance envelope. The hurricane is in a favorable environment of low wind shear, high moisture, and warm SSTs, and it is expected to stay in these conditions until it nears the Carolina coast. Therefore, Dorian is expected to remain about the same intensity during the next couple of days. After that time, an increase in shear from the mid-latitude trough and drier air should cause Dorian to slowly weaken. The GFS and ECMWF models both show Dorian becoming an extratropical system by 96 hours, and the official forecast follows those solutions. As this system gains latitude, the wind field is expected to expand even more. Therefore, even if Dorian does not make landfall, hurricane-force winds are expected to reach portions of the coast from central Florida to North Carolina. Key Messages: 1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia, South Carolina, and North Carolina, regardless of the exact track of Dorian's center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials. 2. The risk of wind and rain impacts along portions of the Virginia coast and the southern Chesapeake Bay are increasing. Residents in these areas should continue to monitor the progress of Dorian. 3. The flash flood threat will increase overnight along the Florida east coast, then spread up the southeast and mid Atlantic coast beginning Wednesday. There is a moderate risk of flash flooding from coastal Georgia through the eastern portions of South and North Carolina Wednesday and Thursday. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 28.4N 79.0W 95 KT 110 MPH 12H 04/1200Z 29.4N 79.6W 95 KT 110 MPH 24H 05/0000Z 30.7N 79.9W 95 KT 110 MPH 36H 05/1200Z 31.9N 79.5W 95 KT 110 MPH 48H 06/0000Z 33.3N 78.2W 90 KT 105 MPH 72H 07/0000Z 37.1N 72.1W 75 KT 85 MPH 96H 08/0000Z 43.3N 62.7W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 09/0000Z 51.5N 52.2W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi
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