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TROPICAL STORM ISAAC FORECAST/ADVISORY NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092018
1500 UTC WED SEP 12 2018

CHANGES IN WATCHES AND WARNINGS 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

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA... IN THIS CASE WITHIN
24 TO 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA... IN THIS CASE WITHIN 24 TO 36
HOURS.

INTERESTS ELSEWHERE IN THE LEEWARD ISLANDS SHOULD MONITOR THE
PROGRESS OF ISAAC.

TROPICAL STORM CENTER LOCATED NEAR 15.0N  54.7W AT 12/1500Z
POSITION ACCURATE WITHIN  15 NM

PRESENT MOVEMENT TOWARD THE WEST OR 275 DEGREES AT  15 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1000 MB
MAX SUSTAINED WINDS  50 KT WITH GUSTS TO  60 KT.
50 KT....... 40NE   0SE   0SW   0NW.
34 KT.......120NE 100SE  20SW 150NW.
12 FT SEAS..180NE  60SE  60SW 180NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT.  RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 15.0N  54.7W AT 12/1500Z
AT 12/1200Z CENTER WAS LOCATED NEAR 14.7N  53.6W

FORECAST VALID 13/0000Z 15.1N  56.7W
MAX WIND  50 KT...GUSTS  60 KT.
50 KT... 20NE   0SE   0SW   0NW.
34 KT...100NE  90SE   0SW 120NW.

FORECAST VALID 13/1200Z 15.3N  59.4W
MAX WIND  45 KT...GUSTS  55 KT.
34 KT... 90NE  60SE   0SW  90NW.

FORECAST VALID 14/0000Z 15.3N  62.6W
MAX WIND  45 KT...GUSTS  55 KT.
34 KT... 80NE  40SE   0SW  70NW.

FORECAST VALID 14/1200Z 15.4N  65.6W
MAX WIND  40 KT...GUSTS  50 KT.
34 KT... 80NE  40SE   0SW  70NW.

FORECAST VALID 15/1200Z 15.5N  71.0W
MAX WIND  40 KT...GUSTS  50 KT.
34 KT... 70NE  30SE   0SW  50NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 16/1200Z 15.5N  75.0W
MAX WIND  35 KT...GUSTS  45 KT.

OUTLOOK VALID 17/1200Z...DISSIPATED

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 15.0N  54.7W

NEXT ADVISORY AT 12/2100Z

$$
FORECASTER BLAKE


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