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Hurricane Irma Advisory Number 23
NWS National Hurricane Center Miami FL AL112017
1100 PM AST Mon Sep 04 2017
...HURRICANE WARNINGS ISSUED FOR PUERTO RICO AND THE VIRGIN
SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
ABOUT 410 MI...660 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:
The Hurricane Watch for the U.S. Virgin Islands, Puerto Rico,
Vieques, and Culebra has been changed to a Hurricane Warning.
The government of Antigua has changed the Hurricane Watch for the
British Virgin Islands to a Hurricane Warning.
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
* British Virgin Islands
* U.S. Virgin Islands
* Puerto Rico, Vieques, and Culebra
A Hurricane Watch is in effect for...
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, Cuba, and the southeastern and central Bahamas should
monitor the progress of Irma.
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 1100 PM AST (0300 UTC), the eye of Hurricane Irma was located
by an Air Force Hurricane Hunter aircraft near latitude 16.7 North,
longitude 55.6 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-northwest 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.
Maximum sustained winds are 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 45 miles (75 km) from the
center and tropical-storm-force winds extend outward up to 140 miles
The minimum central pressure estimated from 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
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 with isolated maximum amounts of 10 inches across
the northern Leeward Islands, the British and U.S. Virgin Islands,
and Puerto Rico. These rainfall amounts may cause life-threatening
flash floods and mudslides.
SURF: Swells generated by Irma will affect the northern Leeward
Islands, Puerto Rico, and the U.S. and British Virgin 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 200 AM AST.
Next complete advisory at 500 AM AST.