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Hurricane Dorian Forecast Discussion Number 42
2019-09-03 22:49:55| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Tue Sep 03 2019 000 WTNT45 KNHC 032049 TCDAT5 Hurricane Dorian Discussion Number 42 NWS National Hurricane Center Miami FL AL052019 500 PM EDT Tue Sep 03 2019 Dorian has finally begun a more definitive northwestward motion this afternoon. The satellite presentation of the hurricane is slightly better in one-minute GOES 16 imagery with the large eye becoming a little more apparent. The eye has also become better defined in NWS Doppler radar from Melbourne, Florida. Reconnaissance aircraft data continue to show an expansion of the tropical-storm and 50-kt wind radii, and it is likely that the area of hurricane-force winds will also increase somewhat during the next 24-36 hours. The initial intensity remains 95 kt, and is a blend of the earlier reconnaissance data and the latest satellite estimates. Dorian will be moving northwestward over untapped waters east of the Florida peninsula, which may lead to some structural re-organization, but little overall change in intensity is expected during the next couple of days. After that time, a gradual decrease in the peak wind speed and an increase in storm size are predicted while the vertical shear increases and the storm moves farther north. An approaching mid-latitude trough and front will begin interacting with the hurricane on Saturday and Dorian is forecast to become a powerful extratropical low by 120 hours. Dorian is now moving northwestward or 325/5 kt. The deep-layer trough along the east coast of the United States is expected to amplify on Wednesday, which should cause Dorian to move at a slightly faster north-northwestward motion tonight and Wednesday. After that time, Dorian should turn northward, and then north- northeastward ahead of a shortwave trough moving into the eastern United States. Once Dorian is offshore of eastern North Carolina, it should accelerate northeastward within the mid-latitude westerlies. The track envelope has edged closer to the coasts of South Carolina and North Carolina and the NHC track has been adjusted in that direction. A track that close to the coast, even if landfall does not occur, is likely to bring dangerous winds, life-threatening storm surge, and flooding rains across the eastern portions of the Carolinas. 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 tonight along the Florida east coast and then spread up the southeast and mid-Atlantic coast during the middle and latter part of the week. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 27.7N 78.7W 95 KT 110 MPH 12H 04/0600Z 28.7N 79.4W 95 KT 110 MPH 24H 04/1800Z 30.0N 80.0W 95 KT 110 MPH 36H 05/0600Z 31.4N 80.0W 95 KT 110 MPH 48H 05/1800Z 32.6N 79.2W 90 KT 105 MPH 72H 06/1800Z 36.1N 74.0W 80 KT 90 MPH 96H 07/1800Z 42.0N 65.0W 75 KT 85 MPH 120H 08/1800Z 50.0N 55.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown
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