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HURRICANE HARVEY FORECAST/ADVISORY NUMBER  18
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092017
2100 UTC THU AUG 24 2017

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE HURRICANE WARNING HAS BEEN EXTENDED NORTHEAST OF MATAGORDA TO
SARGENT TEXAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A STORM SURGE WARNING IS IN EFFECT FOR...
* PORT MANSFIELD TO HIGH ISLAND TEXAS

A STORM SURGE WATCH IS IN EFFECT FOR...
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A HURRICANE WARNING IS IN EFFECT FOR...
* PORT MANSFIELD TO SARGENT TEXAS

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* NORTH OF SARGENT TO HIGH ISLAND TEXAS
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A HURRICANE WATCH IS IN EFFECT FOR...
* SOUTH OF PORT MANSFIELD TEXAS TO THE MOUTH OF THE RIO GRANDE

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* SOUTH OF THE MOUTH OF THE RIO GRANDE TO BOCA DE CATAN MEXICO

A STORM SURGE WARNING MEANS THERE IS A DANGER OF LIFE-THREATENING
INUNDATION...FROM RISING WATER MOVING INLAND FROM THE COASTLINE...
DURING THE NEXT 36 HOURS IN THE INDICATED LOCATIONS. FOR A
DEPICTION OF AREAS AT RISK...PLEASE SEE THE NATIONAL WEATHER
SERVICE STORM SURGE WATCH/WARNING GRAPHIC...AVAILABLE AT
HURRICANES.GOV.  THIS IS A LIFE-THREATENING SITUATION.  PERSONS
LOCATED WITHIN THESE AREAS SHOULD TAKE ALL NECESSARY ACTIONS TO
PROTECT LIFE AND PROPERTY FROM RISING WATER AND THE POTENTIAL FOR
OTHER DANGEROUS CONDITIONS.  PROMPTLY FOLLOW EVACUATION AND OTHER
INSTRUCTIONS FROM LOCAL OFFICIALS.

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA.  A WARNING IS TYPICALLY ISSUED
36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-
FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT
OR DANGEROUS.  PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE
RUSHED TO COMPLETION.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A STORM SURGE WATCH MEANS THERE IS A POSSIBILITY OF LIFE-
THREATENING INUNDATION...FROM RISING WATER MOVING INLAND FROM THE
COASTLINE...IN THE INDICATED LOCATIONS DURING THE NEXT 48 HOURS.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA.

IN ADDITION...INTERESTS IN SOUTHWESTERN LOUISIANA SHOULD CONTINUE
TO MONITOR THE PROGRESS OF THIS SYSTEM.

HURRICANE CENTER LOCATED NEAR 24.7N  93.9W AT 24/2100Z
POSITION ACCURATE WITHIN  15 NM

PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 330 DEGREES AT   9 KT

ESTIMATED MINIMUM CENTRAL PRESSURE  976 MB
EYE DIAMETER  20 NM
MAX SUSTAINED WINDS  75 KT WITH GUSTS TO  90 KT.
64 KT....... 20NE   0SE   0SW   0NW.
50 KT....... 30NE  20SE  20SW  30NW.
34 KT....... 80NE  40SE  30SW  60NW.
12 FT SEAS..120NE  75SE  75SW  75NW.
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 24.7N  93.9W AT 24/2100Z
AT 24/1800Z CENTER WAS LOCATED NEAR 24.4N  93.6W

FORECAST VALID 25/0600Z 25.5N  94.8W
MAX WIND  95 KT...GUSTS 115 KT.
64 KT... 30NE  15SE  10SW  15NW.
50 KT... 50NE  40SE  30SW  40NW.
34 KT...110NE  70SE  50SW  80NW.

FORECAST VALID 25/1800Z 26.7N  96.0W
MAX WIND 110 KT...GUSTS 135 KT.
64 KT... 35NE  30SE  20SW  30NW.
50 KT... 60NE  50SE  40SW  50NW.
34 KT...130NE 100SE  70SW 100NW.

FORECAST VALID 26/0600Z 27.8N  96.7W
MAX WIND 105 KT...GUSTS 130 KT.
64 KT... 35NE  30SE  30SW  35NW.
50 KT... 60NE  60SE  50SW  60NW.
34 KT...140NE 110SE  80SW  90NW.

FORECAST VALID 26/1800Z 28.5N  97.1W...INLAND
MAX WIND  85 KT...GUSTS 105 KT.
50 KT... 50NE  50SE  40SW  40NW.
34 KT...130NE 110SE  80SW  80NW.

FORECAST VALID 27/1800Z 28.7N  97.2W...INLAND
MAX WIND  45 KT...GUSTS  55 KT.
34 KT... 90NE  70SE  60SW  50NW.

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 28/1800Z 28.5N  96.5W...INLAND
MAX WIND  35 KT...GUSTS  45 KT.

OUTLOOK VALID 29/1800Z 29.0N  95.0W...OVER WATER
MAX WIND  35 KT...GUSTS  45 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 24.7N  93.9W

NEXT ADVISORY AT 25/0300Z

$$
FORECASTER BERG


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