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Tropical Storm Laura Forecast Discussion Number 7
2020-08-21 16:56:22| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Fri Aug 21 2020 000 WTNT43 KNHC 211456 TCDAT3 Tropical Storm Laura Discussion Number 7 NWS National Hurricane Center Miami FL AL132020 1100 AM AST Fri Aug 21 2020 A NOAA Hurricane Hunter aircraft has been investigating the system this morning and found that the maximum winds have increased to near 40 kt, and therefore the cyclone is being named. The Hurricane Hunters also found that the center of the storm is located somewhat to the south of previous estimates. The system is better organized than it was yesterday, but still lacks well-defined banding features. However, some upper-level outflow is now noted over the southern portion of the circulation. The official forecast calls for some slow strengthening during the next couple of days, but the intensity forecast is quite uncertain and depends on how much interaction with land will occur. For now, we will assume that the northern part of the circulation will remain over water so that the system will not be too disrupted by Hispaniola and Cuba. The official intensity forecast remains close to the model consensus except at days 4 and 5 where it is a little lower due to these uncertainties. With the repositioning of the center, the motion is very uncertain but is estimated to be 270/16 kt. Laura is expected to move mainly west-northwestward on the south side of a subtropical high pressure system over the next couple of days. Later in the forecast period, the tropical cyclone should turn toward the northwest as it moves around the western periphery of the high. The official track forecast has been adjusted to the south of the previous one and is on the northern side of the guidance suite. Tropical storm warnings have been issued for the northern Leeward Islands, Puerto Rico, and the Virgin Islands. Key Messages: 1. Tropical storm conditions are expected across portions of the northern Leeward Islands, the Virgin Islands, and Puerto Rico today through Saturday, and Tropical Storm Warnings are in effect. Heavy rainfall is likely across this area beginning today and could cause mudslides and flash and urban flooding through Sunday. 2. Tropical storm conditions are possible along the northern coasts of the Dominican Republic and Haiti, the southeastern Bahamas, and the Turks and Caicos islands Saturday and Sunday, and Tropical Storm Watches are in effect. 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 northeast U.S. Gulf Coast by the middle of next week. Interests there should monitor the progress of Laura and updates to the forecast over the next few days. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 17.0N 60.2W 40 KT 45 MPH 12H 22/0000Z 17.4N 62.7W 40 KT 45 MPH 24H 22/1200Z 18.3N 66.0W 45 KT 50 MPH 36H 23/0000Z 19.2N 69.5W 45 KT 50 MPH 48H 23/1200Z 20.2N 73.4W 45 KT 50 MPH 60H 24/0000Z 21.6N 77.1W 50 KT 60 MPH 72H 24/1200Z 23.2N 80.7W 55 KT 65 MPH 96H 25/1200Z 26.5N 85.5W 65 KT 75 MPH 120H 26/1200Z 29.5N 87.5W 65 KT 75 MPH $$ Forecaster Pasch
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