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Subtropical Storm Alberto Forecast Discussion Number 4
2018-05-26 10:53:25| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Sat May 26 2018 000 WTNT41 KNHC 260853 TCDAT1 Subtropical Storm Alberto Discussion Number 4 NWS National Hurricane Center Miami FL AL012018 400 AM CDT Sat May 26 2018 Alberto is not very well organized this morning. Satellite images indicate that the low-level center is located between widespread showers and thunderstorms well to its northeast and patches of deep convection to its south and east. The struggling cyclone continues to battle westerly shear and dry air. A recent ASCAT pass indicated that winds near the center were not particularly strong. The initial intensity is held at a possibly generous 35 kt pending a sampling of the circulation farther east by an Air Force reconnaissance aircraft in a few hours. Alberto remains subtropical given its sprawling structure and involvement with an upper-level trough. The subtropical storm has now turned north-northeastward at an estimated speed of 6 kt. This general motion with a increase in forward speed is expected throughout the day today, taking the center of Alberto through the Yucatan Channel. A turn to the northwest is forecast on Sunday as the storm rotates around a developing mid- to upper-level low in the central Gulf of Mexico. Alberto is predicted to be very near the northern Gulf Coast in about 72 hours, and should then turn northward and northeastward when it moves inland over the eastern U.S. The models are in fairly good agreement this cycle, but they have trended a bit faster from previous runs. The NHC track forecast has been adjusted accordingly, and lies fairly close to the latest consensus aids. Only slow strengthening is expected today due to the broad nature of the system and continued influences of westerly shear and dry air. There is an opportunity for more significant strengthening tonight and Sunday when the shear is expected to lessen and Alberto moves into a region of upper-level diffluence while it remains over warm SSTs. The models also suggest that Alberto will likely make a transition to a tropical storm in about 36 hours, and that is reflected in the official forecast below. The official intensity forecast is fairly similar to the previous one, and is in line with the IVCN and HCCA consensus models. The HMON model is now the only intensity guidance that makes Alberto a hurricane before it reaches the coast. Although a hurricane watch could still be required for a portion of the Gulf Coast later today, the recent intensity guidance trends suggest that this possibility is decreasing. KEY MESSAGES: 1. Regardless of its exact track and intensity, Alberto is expected to produce heavy rainfall and flash flooding over western Cuba, southern Florida and the Florida Keys. Rainfall and flooding potential will increase across the central U.S. Gulf Coast region and over much of the southeastern United States beginning Sunday. 2. Tropical-storm-force winds and hazardous storm surge are possible along portions of the central and eastern U.S. Gulf Coast beginning on Sunday, including areas well east of the track of Alberto's center, and tropical storm and storm surge watches are in effect for portions of these areas. Residents in the watch areas are encouraged not to focus on the details of the forecast track of Alberto and should follow any guidance given by their local government officials. 3. Dangerous surf and rip current conditions are affecting portions of the Yucatan Peninsula and western Cuba and will likely spread along the eastern and central U.S. Gulf Coast later today and tonight. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 19.9N 85.6W 35 KT 40 MPH 12H 26/1800Z 21.6N 85.1W 35 KT 40 MPH 24H 27/0600Z 24.3N 85.0W 40 KT 45 MPH 36H 27/1800Z 26.2N 85.9W 50 KT 60 MPH...TROPICAL STORM 48H 28/0600Z 27.5N 86.8W 55 KT 65 MPH...TROPICAL STORM 72H 29/0600Z 30.4N 87.9W 50 KT 60 MPH...NEAR THE COAST 96H 30/0600Z 33.3N 88.1W 25 KT 30 MPH...INLAND 120H 31/0600Z 38.0N 85.0W 20 KT 25 MPH...INLAND $$ Forecaster Cangialosi/Berg
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