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Hurricane Irma Advisory Number 22
NWS National Hurricane Center Miami FL AL112017
500 PM AST Mon Sep 04 2017
...IRMA STRENGTHENS AS IT HEADS TOWARD THE LEEWARD ISLANDS...
...PREPARATIONS WITHIN THE WARNING AREA SHOULD BE RUSHED TO
SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
ABOUT 490 MI...790 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H
PRESENT MOVEMENT...W OR 265 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...944 MB...27.88 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of France has issued a Tropical Storm Warning for
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
DISCUSSION AND 48-HOUR OUTLOOK
At 500 PM AST (2100 UTC), the center of Hurricane Irma was located
near latitude 16.7 North, longitude 54.4 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.
Data from an Air Force Reserve Hurricane Hunter aircraft indicate
that the maximum sustained winds have increased to near 130 mph
(215 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
The latest minimum central pressure reported by reconnaissance
aircraft is 944 mb (27.88 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
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
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 intermediate advisory at 800 PM AST.
Next complete advisory at 1100 PM AST.