000 WTNT45 KNHC 030854 TCDAT5 Hurricane Dorian Discussion Number 40 NWS National Hurricane Center Miami FL AL052019 500 AM EDT Tue Sep 03 2019 Dorian continues to pound Grand Bahama Island early this morning while moving little. The eyewall has become a little less defined over the past few hours on radar. On infrared satellite images, the eye remains fairly well defined, but the surrounding deep convection is somewhat fragmented. Upper-level outflow is a bit restricted over the western semicircle of the circulation. The initial intensity is held at 105 kt, which is a blend of subjective Dvorak data-T numbers from TAFB and SAB. Dorian is expected to more or less maintain its intensity for about 36 hours. After that time period, increasing vertical shear should cause gradual weakening. However, the system is likely to remain a major hurricane for the next few days. The official forecast is closest to the latest LGEM guidance. Dorian has been nearly stationary for the past 18 hours, as steering currents in its vicinity have collapsed. The global models indicate that a weakness in the subtropical ridge will develop in response to a trough that will amplify along the east coast of the United States within the next day or so. Dorian should respond to these changes by beginning to move north-northwestward toward the weakness in the ridge a little later today. The system should turn northward with a gradual increase in forward speed as it moves through the weakness in around 48 hours. Later in the period, the cyclone should accelerate northeastward on the southern side of the trough. The official track forecast is similar to the previous one, and is fairly close to the model consensus. Although the official forecast does not show Dorian making landfall along the Florida east coast, users are reminded not to forecast on the exact forecast track. A relatively small deviation to the left of this track could bring the core of the hurricane near or over the coastline. Key Messages: 1. Devastating winds and storm surge will continue to affect Grand Bahama Island for several more hours. Everyone there should remain in shelter. 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast and the coasts of Georgia and South Carolina, regardless of the exact track of Dorian's center. Water levels could begin to rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials. 3. The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coast of North Carolina. Residents in these areas should follow advice given by local emergency officials. 4. The flash flood threat will increase today and tonight along the Florida peninsula, then spread up the southeast and mid-Atlantic coast during the middle and latter part of the week. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 26.9N 78.4W 105 KT 120 MPH 12H 03/1800Z 27.5N 78.8W 105 KT 120 MPH 24H 04/0600Z 28.5N 79.3W 105 KT 120 MPH 36H 04/1800Z 29.9N 79.7W 105 KT 120 MPH 48H 05/0600Z 31.4N 79.4W 100 KT 115 MPH 72H 06/0600Z 34.3N 76.6W 85 KT 100 MPH 96H 07/0600Z 39.0N 69.3W 75 KT 85 MPH 120H 08/0600Z 46.5N 59.5W 70 KT 80 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch