ZCZC MIATCPAT4 ALL TTAA00 KNHC DDHHMM BULLETIN Potential Tropical Cyclone Nine Advisory Number 4 NWS National Hurricane Center Miami FL AL092020 500 AM AST Wed Jul 29 2020 ...HEAVY RAINFALL AND GUSTY WINDS LIKELY OVER PORTIONS OF THE LEEWARD ISLANDS THROUGH TONIGHT... SUMMARY OF 500 AM AST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...15.3N 61.3W ABOUT 5 MI...10 KM S OF DOMINICA ABOUT 385 MI...615 KM ESE OF SAN JUAN PUERTO RICO MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...WNW OR 295 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Warning has been issued for the north coast of Haiti from Le Mole St Nicholas eastward to the northern border with the Dominican Republic. The government of the Bahamas has issued a Tropical Storm Watch for the southeastern Bahamas, including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Puerto Rico, Vieques, Culebra * U.S. Virgin Islands * British Virgin Islands * Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and Anguilla * Guadeloupe, Martinique, St. Martin, and St. Barthelemy * Saba and St. Eustatius * St. Maarten * Dominica * Dominican Republic from Cabo Caucedo eastward to Cabo Engano and then westward along the northern coast to the Dominican Republic/Haiti border * North coast of Haiti from Le Mole St Nicholas eastward to the northern border with the Dominican Republic A Tropical Storm Watch is in effect for... * Dominican Republic from the southern Haiti border eastward to Cabo Caucedo * Turks and Caicos Islands * Southeastern Bahamas Interests in the central and northwestern Bahamas and Cuba should monitor the progress of this system. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 AM AST (0900 UTC), the disturbance was centered near latitude 15.3 North, longitude 61.3 West. The system is moving toward the west-northwest near 23 mph (37 km/h), and this general motion with some slight reduction in forward speed is expected over the next few days. On the forecast track, the center will move through the southern Leeward Islands during the next few hours, near or over the Virgin Islands and Puerto Rico tonight, near or over Hispaniola on Thursday, and near or over the southeastern Bahamas on Friday. Maximum sustained winds remain near 45 mph (75 km/h) with higher gusts. Some increase in strength is forecast today, with weakening likely on Thursday due to land interaction, and some restrengthening possible late week. Environmental conditions are expected to be conducive for additional development, and a tropical storm is forecast to form later today. * Formation chance through 48 hours...high...90 percent * Formation chance through 5 days...high...90 percent Tropical-storm-force winds extend outward up to 275 miles (445 km) from the center. Antigua recently reported a wind gust of 47 mph (76 km/h). The estimated minimum central pressure based on Air Force Reserve reconnaissance data and surface observations is 1005 mb (29.68 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Potential Tropical Cyclone Nine can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml. WIND: Tropical storm conditions are moving across portions of the Leeward Islands now and will spread across the U.S. and British Virgin Islands and Puerto Rico this afternoon through Thursday morning. These conditions are forecast to reach portions of the Dominican Republic and Haiti within the warning area early Thursday. Tropical storm conditions are possible in the watch areas on Thursday. RAINFALL: The potential tropical cyclone is expected to produce the following rain accumulations: Across the northern Leeward Islands, British and U.S. Virgin Islands: 3 to 6 inches. Across Puerto Rico: 3 to 6 inches, with isolated maximum totals of 10 inches. Across the Dominican Republic, northern Haiti and the Turks and Caicos: 3 to 6 inches, with isolated maximum totals of 8 inches. Across the Inagua Islands: 4 to 8 inches, with isolated totals of 12 inches. These rainfall amounts could lead to life threatening flash flooding and mudslides, as well as potential riverine flooding. SURF: Swells generated by Potential Tropical Cyclone Nine will be affecting portions of the Leeward Islands, the Virgin Islands and Puerto Rico during the next day or two. These dangerous conditions are forecast to reach the north coast of the Dominican Republic and the Turks and Caicos Islands and the southeastern Bahamas on Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 800 AM AST. Next complete advisory at 1100 AM AST. $$ Forecaster Blake NNNN