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Tropical Storm Laura Forecast Discussion Number 8
2020-08-21 23:25:29| National Hurricane Center (Atlantic)
Issued at 500 PM AST Fri Aug 21 2020 000 WTNT43 KNHC 212125 CCB TCDAT3 Tropical Storm Laura Discussion Number 8...Corrected NWS National Hurricane Center Miami FL AL132020 500 PM AST Fri Aug 21 2020 Corrected formatting and initial intensity A poorly-defined convective band has become evident over the southeastern portion of the circulation. However, there is little or no deep convection near the estimated center. Overall, the system's cloud pattern still has a ragged appearance. Dvorak intensity estimates range from 35 to 45 kt, and the current intensity is held at 40 knots based on continuity from Hurricane Hunter observations from earlier today. There is a fairly well-defined upper-level outflow pattern at this time, but an upper-level trough to the west of Laura could be an impediment to future strengthening. The official intensity forecast is a little below the intensity consensus mainly due to the influences of the land masses of the Greater Antilles. At days 4-5, the intensity forecast is also a bit below the consensus due to uncertainties at these longer forecast ranges. The center is not very easy to see, even on visible or radar images, but the best guess at an initial motion is 275/15 kt. The track forecast reasoning has not changed much from the previous advisory package. Laura should move generally west-northwestward along the southern periphery of a subtropical ridge for about the next 72 hours. Later in the forecast period, the cyclone is expected to turn northwestward as it begins to move around the western side of the ridge. The track guidance has shifted westward at days 4-5 and so has the official forecast, which is mostly close to the model consensus, but not quite as far west as that guidance in the latter part of the forecast period. Another NOAA Hurricane Hunter Aircraft is scheduled to investigate Laura shortly. KEY MESSAGES: 1. Tropical storm conditions are expected across portions of the northern Leeward Islands, the Virgin Islands, and Puerto Rico today through Saturday, Tropical Storm conditions are also expected along the northern coasts of the Dominican Republic and Haiti from Saturday into Sunday. Heavy rainfall is likely across these areas beginning today and could cause mudslides and flash and urban flooding through Sunday. 2. Tropical storm conditions are possible over portions of the southeastern Bahamas and the Turks and Caicos Islands on Sunday. 3. The details of the long-range track and intensity forecasts remain more uncertain than usual since Laura is forecast to move near or over Portions of the Greater Antilles through Monday. However, Laura could bring storm surge, rainfall, and wind impacts to portions of Cuba, the Bahamas, and Florida early next week and the northern U.S. Gulf Coast by the middle of next week. Interests there should monitor the progress of Laura and updates to the forecast during the next few days. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 17.1N 61.2W 40 KT 45 MPH 12H 22/0600Z 17.7N 63.9W 40 KT 45 MPH 24H 22/1800Z 18.6N 67.3W 45 KT 50 MPH 36H 23/0600Z 19.6N 70.7W 50 KT 60 MPH...INLAND 48H 23/1800Z 20.5N 74.3W 55 KT 65 MPH...OVER WATER 60H 24/0600Z 22.0N 77.9W 55 KT 65 MPH 72H 24/1800Z 23.5N 81.5W 55 KT 65 MPH 96H 25/1800Z 26.3N 86.5W 65 KT 75 MPH 120H 26/1800Z 29.0N 89.0W 65 KT 75 MPH $$ FORECASTER PASCH
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