000 WTNT31 KNHC 040854 TCPAT1
Hurricane Irma Advisory Number 20
NWS National Hurricane Center Miami FL AL112017
500 AM AST Mon Sep 04 2017
…TROPICAL-STORM-FORCE WINDS EXPECTED TO BEGIN IN THE LEEWARD ISLANDS LATE TUESDAY…
SUMMARY OF 500 AM AST…0900 UTC…INFORMATION
ABOUT 625 MI…1010 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS…115 MPH…185 KM/H
PRESENT MOVEMENT…WSW OR 255 DEGREES AT 14 MPH…22 KM/H
MINIMUM CENTRAL PRESSURE…961 MB…28.38 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Watch is in effect for…
* Antigua, Barbuda, Anguilla, Montserrat, St. Kitts, and Nevis
* Saba, St. Eustatius, and Sint Maarten
* Saint Martin and Saint Barthelemy
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
Interests in the remainder of the Leeward Islands, the British and U.S. Virgin Islands, Puerto Rico, and the Dominican Republic should monitor the progress of Irma. Additional hurricane and tropical storm watches and warnings will likely be required for portions of this area later today.
For storm information specific to your area, please monitor products issued by your national meteorological service.
DISCUSSION AND 48-HOUR OUTLOOK
At 500 AM AST (0900 UTC), the eye of Hurricane Irma was located near latitude 16.9 North, longitude 52.3 West. Irma is moving toward the west-southwest near 14 mph (22 km/h). A turn toward the west is expected later today, followed by a west-northwestward turn late Tuesday.
On the forecast track, the center of Irma will move closer to the Leeward Islands through Tuesday and then be near the
northern Leeward Islands Tuesday night.
Maximum sustained winds are near 115 mph (185 km/h) with higher gusts. Irma is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Some strengthening is forecast through Tuesday night.
Hurricane-force winds extend outward up to 30 miles (45 km) from the center, and tropical-storm-force winds extend outward up to 140
miles (220 km).
The estimated minimum central pressure is 961 mb (28.38 inches).
HAZARDS AFFECTING LAND
WIND: Hurricane conditions are possible within the watch area by Tuesday night, with tropical storm conditions possible by late
SURF: Swells generated by Irma will begin affecting the northern Leeward Islands today. These swells are likely to cause
life-threatening surf and rip current conditions. Please consult products from your local weather office.
Next intermediate advisory at 800 AM AST.
Next complete advisory at 1100 AM AST.