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WTNT21 KNHC 040853
TCMAT1

HURRICANE IRMA FORECAST/ADVISORY NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112017
0900 UTC MON SEP 04 2017

CHANGES IN WATCHES AND WARNINGS 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.

HURRICANE CENTER LOCATED NEAR 16.9N  52.3W AT 04/0900Z
POSITION ACCURATE WITHIN  15 NM

PRESENT MOVEMENT TOWARD THE WEST-SOUTHWEST OR 255 DEGREES AT  12 KT

ESTIMATED MINIMUM CENTRAL PRESSURE  961 MB
EYE DIAMETER  10 NM
MAX SUSTAINED WINDS 100 KT WITH GUSTS TO 120 KT.
64 KT....... 25NE  20SE  20SW  25NW.
50 KT....... 40NE  40SE  30SW  40NW.
34 KT.......120NE  80SE  50SW  90NW.
12 FT SEAS..270NE 150SE 180SW 330NW.
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 16.9N  52.3W AT 04/0900Z
AT 04/0600Z CENTER WAS LOCATED NEAR 17.0N  51.7W

FORECAST VALID 04/1800Z 16.7N  53.9W
MAX WIND 105 KT...GUSTS 130 KT.
64 KT... 25NE  25SE  20SW  25NW.
50 KT... 50NE  50SE  30SW  50NW.
34 KT...130NE  90SE  60SW 100NW.

FORECAST VALID 05/0600Z 16.6N  56.2W
MAX WIND 110 KT...GUSTS 135 KT.
64 KT... 30NE  30SE  25SW  30NW.
50 KT... 60NE  50SE  40SW  60NW.
34 KT...130NE 100SE  70SW 110NW.

FORECAST VALID 05/1800Z 17.0N  58.6W
MAX WIND 115 KT...GUSTS 140 KT.
64 KT... 35NE  35SE  30SW  35NW.
50 KT... 70NE  60SE  50SW  70NW.
34 KT...140NE 110SE  80SW 120NW.

FORECAST VALID 06/0600Z 17.8N  61.2W
MAX WIND 120 KT...GUSTS 145 KT.
50 KT... 70NE  70SE  50SW  70NW.
34 KT...150NE 130SE  90SW 130NW.

FORECAST VALID 07/0600Z 19.6N  66.8W
MAX WIND 120 KT...GUSTS 145 KT.
50 KT... 80NE  70SE  60SW  80NW.
34 KT...170NE 150SE 100SW 140NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 08/0600Z 21.0N  72.0W
MAX WIND 115 KT...GUSTS 140 KT.

OUTLOOK VALID 09/0600Z 22.0N  76.5W
MAX WIND 110 KT...GUSTS 135 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 16.9N  52.3W

NEXT ADVISORY AT 04/1500Z

$$
FORECASTER BERG