Hurricane Irma

Forecast Advisory 20

---

457
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