ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM Hurricane Dorian Discussion Number 35 NWS National Hurricane Center Miami FL AL052019 1100 PM EDT Sun Sep 01 2019 Dorian remains an incredibly powerful hurricane and it is currently making landfall on the eastern end of Grand Bahama Island. Satellite images show an symmetrical cyclone with a circular 10 n mi diameter eye and intense eyewall convection with lots of lightning being detected. Doppler radar data from Miami and the Bahamas show that Dorian has developed concentric eyewalls, and this feature is also noted by a double wind maximum that is evident in data from the Air Force Hurricane Hunters. The initial intensity of Dorian is set at 155 kt based mostly on the SFMR winds from the aircraft. The aircraft data also indicated that the radii of tropical-storm-force winds are a little larger than they were earlier today. Dorian is still moving slowly westward at about 5 kt. The ridge to the north of Dorian is gradually weakening and shifting eastward in response to a mid- to upper-level trough that is moving across the eastern U.S. This change in the steering pattern should cause Dorian to slow down even more and perhaps stall, before it turns to the northwest late Monday or early Tuesday. This expected slow motion will likely be devastating to the Great Abaco and Grand Bahama Islands since it would prolong the catastrophic winds, storm surge, and rainfall over those areas. The timing of the northwest or north turn is very critical in determining how close Dorian will get to the Florida peninsula on Tuesday and Wednesday. In general, the track models have changed little from the previous cycle, and the NHC forecast continues to show the core of Dorian very near, but offshore, of the Florida peninsula on Tuesday and Wednesday. The hurricane is then expected to track near the Georgia and Carolina coasts late this week. This forecast is in best agreement with the various consensus models, which typically have the lowest errors. It is once again emphasized that although the official track forecast does not show landfall, users should not focus on the exact track. A small deviation to the left of the track could bring the intense core of the hurricane and its dangerous winds closer to or onto the Florida coast. Category 5 hurricanes like Dorian usually don't hold that intensity for very long, and it is expected that Dorian will weaken slowly during the next few days. However, the observed eyewall replacement cycle will likely cause fluctuations in strength, both up and down, while the system is near Florida. The models show an increase in shear when Dorian tracks near Georgia and the Carolinas, which should cause more notable weakening. This forecast is near the high end of the latest model guidance. Based on this forecast, the hurricane watch has been extended northward to the Florida-Georgia line. Key Messages: 1. A prolonged period of catastrophic winds and storm surge will affect the Abaco Islands and Grand Bahama Island for several more hours. Everyone there should take immediate shelter and not venture into the eye. 2. Life-threatening storm surges and dangerous hurricane-force winds are expected along portions of the Florida east coast through mid-week, and storm surge and hurricane warnings are in effect. Only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the Florida east coast. Residents should listen to advice given by local emergency officials. 3. There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week. Residents in these areas should continue to monitor the progress of Dorian and listen to 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 through late this week. FORECAST POSITIONS AND MAX WINDS INIT 02/0300Z 26.6N 77.9W 155 KT 180 MPH 12H 02/1200Z 26.8N 78.5W 145 KT 165 MPH 24H 03/0000Z 26.9N 79.0W 135 KT 155 MPH 36H 03/1200Z 27.3N 79.3W 125 KT 145 MPH 48H 04/0000Z 28.2N 79.8W 120 KT 140 MPH 72H 05/0000Z 30.6N 80.2W 105 KT 120 MPH 96H 06/0000Z 33.5N 77.7W 85 KT 100 MPH 120H 07/0000Z 37.5N 71.8W 75 KT 85 MPH $$ Forecaster Cangialosi NNNN