WTNT31 KNHC 042347
Hurricane Irma Intermediate Advisory Number 22A
NWS National Hurricane Center Miami FL AL112017
800 PM AST Mon Sep 04 2017
…DANGEROUS HURRICANE IRMA HEADING TOWARD THE LEEWARD ISLANDS……PREPARATIONS WITHIN THE WARNING AREA SHOULD BE RUSHED TO COMPLETION…
SUMMARY OF 800 PM AST…0000 UTC…INFORMATION
ABOUT 450 MI…725 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS…140 MPH…220 KM/H
PRESENT MOVEMENT…W OR 270 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…943 MB…27.85 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning 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 is in effect for…
* British Virgin Islands
* U.S. Virgin Islands
* Puerto Rico, Vieques, and Culebra
A Tropical Storm Warning is in effect for…
A Tropical Storm Watch is in effect for…
A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion.
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 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.
Interests in the Dominican Republic, Haiti, the Turks and Caicos Islands, and the southeastern Bahamas should monitor the progress of
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 the United States, please monitor products issued by your national meteorological service.
DISCUSSION AND 48-HOUR OUTLOOK
At 800 PM AST (0000 UTC), the eye of Hurricane Irma was located by NOAA and Air Force Hurricane Hunter aircraft near latitude 16.7 North, longitude 55.0 West. Irma is moving toward the west near 13 mph (20 km/h) and this general motion is expected to continue into Tuesday, followed by a turn toward the west-northwestward late Tuesday. On the forecast track, the center of Irma will move near or over portions of the northern Leeward Islands Tuesday night and early Wednesday.
Reports from the Hurricane Hunter aircraft indicate that the maximum sustained winds have increased to near 140 mph (220 km/h) with higher gusts. Irma is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Additional strengthening is forecast during the next 48 hours.
Hurricane-force winds extend outward up to 40 miles (65 km) from the center and tropical-storm-force winds extend outward up to 140 miles (220 km).
The latest minimum central pressure estimated from the Hurricane Hunter observations is 943 mb (27.85 inches).
HAZARDS AFFECTING LAND
STORM SURGE: The combination of a dangerous storm surge and large breaking waves will raise water levels by as much as 6 to 9 feet above normal tide levels along the coasts of the extreme northern Leeward Islands within the hurricane warning area near and to the north of the center of Irma. Near the coast, the surge will be accompanied by large and destructive waves.
The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water is expected to reach the following heights above ground if the peak surge occurs at the time of high tide…
British and U.S. Virgin Islands except St. Croix…4 to 6 ft
Northern coast of Puerto Rico…2 to 4 ft
Southern coast of Puerto Rico and St. Croix…1 to 2 ft
The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.
WIND: Hurricane conditions are expected within the hurricane warning area by Tuesday night, with tropical storm conditions expected by late Tuesday. Hurricane conditions are possible within the hurricane watch area in the Virgin Islands and Puerto Rico by late Wednesday, with tropical storm conditions possible by early Wednesday. Tropical Storm conditions are expected within the tropical storm warning area by late Tuesday.
RAINFALL: Irma is expected to produce total rainfall accumulations of 3 to 6 inches across the Leeward Islands, with isolated maximum amounts of 10 inches across the northern Leeward Islands. These rainfall amounts may cause life-threatening flash floods and mudslides.
SURF: Swells generated by Irma will affect the northern Leeward Islands during the next several days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
Next complete advisory at 1100 PM AST.