000 WTNT45 KNHC 312052 TCDAT5 Hurricane Dorian Discussion Number 30 NWS National Hurricane Center Miami FL AL052019 500 PM EDT Sat Aug 31 2019 Dorian's satellite presentation continues to be outstanding. The eye has remained very distinct and is surrounded by a ring of very deep convection. The latest information from the Air Force plane before it departed Dorian supports keeping an initial intensity of 130 kt. Dorian is forecast to move over a deep layer of very warm waters, and with the prevailing low shear along the hurricane's path, some additional strengthening is possible during the next day or so. Most likely, however, the hurricane will experience some fluctuations in intensity due to eyewall replacement cycles that are difficult to predict. Beyond 3 days, as the hurricane begins to gain latitude and encounters increasing shear, gradual weakening is anticipated, but Dorian will remain a dangerous hurricane through 5 days. The best estimate of the initial motion is toward the west or 280 degrees at 8 kt. The hurricane is being steered by the weak flow to the south of the ridge of high pressure over the western Atlantic. In about a day or two, most of the global models shift the high eastward and deepen a trough over the eastern United States. Consequently, the steering currents should collapse and Dorian is anticipated to drift toward the northwest and north-northwest while is moving over the northwestern Bahamas and near the east coast of Florida. After that time, the hurricane should begin to move a little faster northward as the trough over the eastern U.S deepens and should then steer the hurricane toward the northeast by the end of the forecast period. The guidance has not changed significantly since the earlier run, so it has not been necessary to adjust the NHC forecast in this advisory. The uncertainty in the track is high while the hurricane is moving slowly across the northwestern Bahamas and near the east coast of Florida. Any deviation of Dorian's core to the left would result in an increase in the winds along the east coast of Florida. Given that the area of tropical storm force winds could expand, and taking into account the uncertainty in the track forecast, a tropical storm watch was issued for the east of Florida from Deerfield Beach to Sebastian Inlet. Key Messages: 1. A prolonged period of life-threatening storm surge, devastating hurricane-force winds, and heavy rains capable of life-threatening flash floods are expected on the Abaco Islands and Grand Bahama Sunday through Monday, and a hurricane warning is in effect for these areas. 2. A tropical storm watch is in effect for a portion of the Florida east coast. Since Dorian is forecast to slow down and turn northward as it approaches the coast, life-threatening storm surge and dangerous hurricane-force winds are still possible along portions of the Florida east coast by the early to middle part of next week. Residents should have their hurricane plan in place, know if they are in a hurricane evacuation zone, and listen to advice given by local emergency officials. 3. There is an increasing risk of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina during the middle of next week. Residents in these areas should continue to monitor the progress of Dorian. 4. Heavy rains, capable of life-threatening flash floods, are possible over coastal sections of the southeastern United States from Sunday through much of next week. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 26.2N 74.4W 130 KT 150 MPH 12H 01/0600Z 26.4N 75.7W 135 KT 155 MPH 24H 01/1800Z 26.6N 77.0W 130 KT 150 MPH 36H 02/0600Z 26.8N 78.0W 125 KT 145 MPH 48H 02/1800Z 27.2N 78.5W 120 KT 140 MPH 72H 03/1800Z 28.3N 79.1W 110 KT 125 MPH 96H 04/1800Z 31.0N 80.0W 95 KT 110 MPH 120H 05/1800Z 34.0N 77.0W 85 KT 100 MPH $$ Forecaster Avila/Brennan