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#980519 (Received by flhurricane at: 10:54 AM 02.Sep.2019) TCDAT5 Hurricane Dorian Discussion Number 37 NWS National Hurricane Center Miami FL AL052019 1100 AM EDT Mon Sep 02 2019 Satellite and radar imagery show that Dorian is moving very slowly over Grand Bahama Island this morning. The hurricane remains quite symmetric and still exhibits a very well-defined eye, but there is somewhat less evidence of concentric eyewalls in Bahamas radar imagery. Satellite intensity estimates from UW/CIMSS, SAB, and TAFB are slightly lower this morning, and the initial intensity has been reduced to 135 kt. As Dorian moves very slowly during the next 24 hours, some upwelling in the deeper waters around the Bahamas could cause some gradual weakening. After that time, the hurricane is expected to experience a gradual increase in southwesterly shear, which should lead to a slow decrease in wind speed. However, Dorian is forecast to remain a very powerful hurricane while it moves near the southeastern United States coast. The NHC intensity forecast is close to the statistical guidance during the first day or so, then near the HFIP corrected consensus model later in the period. As anticipated, the ridge to the north of the storm has weakened and the eye of Dorian has only been inching westward this morning. The hurricane is expected to drift westward or west-northwestward over the next 24 hours, which will cause a prolonged period of devastating winds and storm surge over Grand Bahama Island. By late Tuesday, the weakness in the ridge becomes more pronounced and Dorian should turn northwestward near the east coast of the Florida. By day 3, the hurricane is expected to make a northeastward turn ahead of a broad mid-latitude trough. The overall track envelope has not changed much, and little adjustment to the previous NHC forecast was required. It cannot be stressed enough that only a small deviation to the left of the NHC forecast could bring the core of the extremely dangerous hurricane onshore of the Florida east coast within the hurricane warning area. In addition, Dorian`s wind field is predicted to expand, which would bring hurricane-force winds closer to the east coast of Florida even if the track does change. Key Messages: 1. A prolonged period of catastrophic winds and storm surge will continue to affect Grand Bahama Island through today and tonight. Everyone there should remain in shelter and not venture into the eye. 2. Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of the Florida east coast and Georgia coast, 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 coasts of South Carolina and North Carolina. Residents in these areas should follow advice given by local emergency officials. 4. Heavy rains, capable of producing life-threatening flash floods, are expected over northern portions of the Bahamas and coastal sections of the Southeast and lower Mid-Atlantic regions of the United States into Friday. FORECAST POSITIONS AND MAX WINDS INIT 02/1500Z 26.8N 78.3W 135 KT 155 MPH 12H 03/0000Z 26.9N 78.7W 130 KT 150 MPH 24H 03/1200Z 27.2N 79.1W 125 KT 145 MPH 36H 04/0000Z 28.1N 79.6W 115 KT 130 MPH 48H 04/1200Z 29.3N 80.2W 110 KT 125 MPH 72H 05/1200Z 32.0N 79.4W 95 KT 110 MPH 96H 06/1200Z 35.4N 75.1W 85 KT 100 MPH 120H 07/1200Z 40.7N 66.8W 75 KT 85 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown |