766 WTNT34 KNHC 130543 TCPAT4 BULLETIN Tropical Storm Isaac Intermediate Advisory Number 22A NWS National Hurricane Center Miami FL AL092018 200 AM AST Thu Sep 13 2018 ...NOAA HURRICANE HUNTER AIRCRAFT FINDS ISAAC A LITTLE WEAKER... ...HEAVY RAINS AND TROPICAL-STORM-FORCE WINDS EXPECTED OVER PORTIONS OF THE LEEWARD ISLANDS ON THURSDAY... SUMMARY OF 200 AM AST...0600 UTC...INFORMATION ---------------------------------------------- LOCATION...15.3N 58.8W ABOUT 170 MI...275 KM E OF DOMINICA ABOUT 185 MI...300 KM ESE OF GUADELOUPE MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 20 MPH...31 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Martinique * Dominica * Guadeloupe A Tropical Storm Watch is in effect for... * Antigua * Montserrat * St. Kitts and Nevis * Saba and St. Eustatius * St. Martin and St. Maarten A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within 12 hours. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, in this case within 12 hours. Interests elsewhere in the Leeward Islands should monitor the progress of Isaac. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 200 AM AST (0600 UTC), the center of Tropical Storm Isaac was located near latitude 15.3 North, longitude 58.8 West. Isaac is moving toward the west near 20 mph (31 km/h), and this general motion with a decrease in forward is expected to continue through the weekend. On the forecast track, Isaac is forecast to move across the central Lesser Antilles and into the eastern Caribbean Sea later today, and then move across the eastern and central Caribbean Sea through the weekend. Data from a NOAA Hurricane Hunter aircraft indicate that the maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts. A continued gradual decrease in the winds is forecast during the next few days. Tropical-storm-force winds extend outward up to 175 miles (280 km) to the north of the center. Recent data from the NOAA aircraft indicate that the minimum pressure is 1006 mb (29.71 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Isaac is expected to produce total rainfall accumulations of 2 to 4 inches with isolated amounts up to 8 inches across Martinique, Dominica, and Guadeloupe. Rainfall of 1 to 2 inches with isolated amounts to 4 inches are forecast across Puerto Rico and the southern United States Virgin Islands, with up to an inch anticipated across the remaining Windward and Leeward Islands. This rainfall may cause life-threatening flash flooding. WIND: Tropical storm conditions are expected within the tropical storm warning area later this morning through the afternoon. Tropical storm conditions are possible within the tropical storm watch area, beginning later this morning. STORM SURGE: Some coastal flooding is possible in areas of onshore winds. Near the coast, the surge will be accompanied by large waves. SURF: Swells generated by Isaac are affecting portions of the Lesser Antilles. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 500 AM AST. $$ Forecaster Zelinsky