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BULLETIN
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
----------------------------------------------
LOCATION...16.9N 52.3W
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:

None.

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
dangerous.

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
Tuesday.

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 ADVISORY
-------------
Next intermediate advisory at 800 AM AST.
Next complete advisory at 1100 AM AST.

$$
Forecaster Berg

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