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BULLETIN
Tropical Storm Isaac Advisory Number  22
NWS National Hurricane Center Miami FL       AL092018
1100 PM AST Wed Sep 12 2018

...NOAA HURRICANE HUNTER AIRCRAFT FINDS ISAAC A LITTLE WEAKER...
...HEAVY RAINS AND TROPICAL-STORM-FORCE WINDS EXPECTED OVER PORTIONS
OF THE LEEWARD ISLANDS ON THURSDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.3N 58.0W
ABOUT 220 MI...355 KM E OF DOMINICA
ABOUT 235 MI...380 KM ESE OF GUADELOUPE
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 20 MPH...31 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Martinique
* Dominica
* Guadeloupe

A Tropical Storm Watch is in effect for...
* Antigua
* Montserrat
* St. Kitts and Nevis
* Saba and St. Eustatius
* St. Martin and St. Maarten

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case within 24
hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 24 hours.

Interests elsewhere in the Leeward Islands should monitor the
progress of Isaac.

For storm information specific to your area, please monitor
products issued by your national meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM AST (0300 UTC), the center of Tropical Storm Isaac was
located near latitude 15.3 North, longitude 58.0 West.  Isaac is
moving toward the west near 20 mph (31 km/h), and this general
motion with a decrease in forward is expected to continue through
the weekend.  On the forecast track, Isaac is forecast to move
across the central Lesser Antilles and into the eastern Caribbean
Sea on Thursday, and then move across the eastern and central
Caribbean Sea through the weekend.

Data from a NOAA Hurricane Hunter aircraft and satellite-derived
wind data indicate that the maximum sustained winds have decreased
to near 50 mph (85 km/h) with higher gusts.  A gradual decrease in
the winds is forecast during the next 48 hours.

Tropical-storm-force winds extend outward up to 175 miles (280 km)
to the north of the center.

Data from the aircraft indicate that the minimum central pressure is
1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
RAINFALL:  Isaac is expected to produce total rainfall accumulations
of 2 to 4 inches with isolated amounts up to 8 inches across
Martinique, Dominica, and Guadeloupe.  Rainfall of 1 to 2 inches
with isolated amounts to 4 inches are forecast across Puerto Rico
and the southern United States Virgin Islands, with up to an inch
anticipated across the remaining Windward and Leeward Islands.  This
rainfall may cause life-threatening flash flooding.

WIND:  Tropical storm conditions are expected within the tropical
storm warning area on Thursday.  Tropical storm conditions are
possible within the tropical storm watch area on Thursday.

STORM SURGE:  Some coastal flooding is possible in areas of onshore
winds.  Near the coast, the surge will be accompanied by large
waves.

SURF:  Swells generated by Isaac are affecting portions of the
Lesser Antilles.  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 200 AM AST.
Next complete advisory at 500 AM AST.

$$
Forecaster Berg

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