NWS National Hurricane Center Miami FL AL092018
…HURRICANE AND TROPICAL STORM WATCHES ISSUED FOR ISAAC…
SUMMARY OF 1100 AM AST…1500 UTC…INFORMATION
ABOUT 775 MI…1250 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS…70 MPH…110 KM/H
PRESENT MOVEMENT…W OR 270 DEGREES AT 16 MPH…26 KM/H
MINIMUM CENTRAL PRESSURE…996 MB…29.42 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of France has issued a Hurricane Watch for Guadeloupe and Martinique.
The government of Barbados has issued a Hurricane Watch for Dominica.
The meteorological service of Antigua and Barbuda has issued a Tropical Storm Watch for Antigua and Montserrat.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Watch is in effect for…
A Tropical Storm Watch is in effect for…
* Antigua and Montserrat
A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.
A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.
Interests elsewhere in the Leeward Islands should monitor the progress of Isaac as additional watches could be issued this afternoon or evening.
For storm information specific to your area, please monitor products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
At 1100 AM AST (1500 UTC), the centre of Tropical Storm Isaac was located near latitude 14.6 North, longitude 49.7 West. Isaac is moving toward the west near 16 mph (26 km/h) and this motion is expected to continue for the next few days. On the forecast track Isaac is anticipated to move near or over the central Lesser Antilles on Thursday and move into the eastern Caribbean Sea Thursday night.
Maximum sustained winds remain near 70 mph (110 km/h) with higher gusts. Isaac is expected to be near hurricane strength when it moves through the central Lesser Antilles, with some weakening forecast afterward on Friday.
Tropical-storm-force winds extend outward up to 105 miles (165 km) from the centre.
The estimated minimum central pressure is 996 mb (29.42 inches).
HAZARDS AFFECTING LAND
RAINFALL: Isaac is expected to produce total rainfall accumulations of 3 to 5 inches with isolated amounts near 10 inches across the southern Leeward Islands late this week, with 1 to 2 inches anticipated across portions of the Windward Islands.
STORM SURGE: A storm surge of 2 to 4 feet above normal tide levels is possible near and to the north of where the centre moves through the Lesser Antilles. Near the coast, the surge will be accompanied by large and destructive waves.
WIND: Hurricane conditions are possible within the hurricane watch area by Thursday morning, with tropical storm conditions possible early Thursday in both the hurricane and tropical storm watch areas.
SURF: Swells generated by Isaac will begin to affect portions of the Lesser Antilles on Wednesday afternoon. These swells are likely to cause life-threatening surf and rip current conditions.
Please consult products from your local weather office.