[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 270559
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED AUG 27 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURES...
HURRICANE GUSTAV WAS DOWNGRADED TO TROPICAL STORM AT 27/0300
UTC. GUSTAV IS CENTERED NEAR 18.6N 73.5W AT 27/0600 UTC OR ABOUT
70 NM WEST OF PORT AU PRINCE HAITI AND ABOUT 117 NM SOUTHEAST OF
GUANTANAMO CUBA MOVING WEST-NORTHWEST AT 4 KT. LATEST MINIMUM
CENTRAL PRESSURE AS REPORTED BY AN AIR FORCE RECONNAISSANCE
PLANE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED HAS DECREASED TO
50 KT WITH GUSTS TO 65 KT. PLEASE SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND/OR THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR MORE
DETAILS. GUSTAV IS EXPECTED TO MOVE BACK OVER WATER AND IS
EXPECTED TO REGAIN HURRICANE STRENGTH LATER TODAY OR TOMORROW
ONCE IT CLEARS THE SW PENINSULA OF HAITI. UPPER-LEVEL OUTFLOW IS
SLIGHTLY RESTRICTED BUT IMPROVING IN THE NORTHWESTERN QUADRANT
AND IS EXCELLENT IN THE OTHER THREE QUADRANTS. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE
SE QUADRANT AND WITHIN 45/60 NM OF 17N FROM 73W-77W WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ELSEWHERE FROM 16N-21N
BETWEEN 70W-77W. GUSTAV IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 6 TO 12 INCHES OVER HISPANIOLA...EASTERN
CUBA...JAMAICA...AND THE CAYMAN ISLANDS...WITH ISOLATED MAXIMUM
AMOUNTS OF UP TO 25 INCHES POSSIBLE. THESE RAINS WILL LIKELY
PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W S OF 21N MOVING W 10-15 KT. THIS WAVE
IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYERED MOISTURE WITH A
BROAD LOW/MID LEVEL CYCLONIC TURNING EVIDENT ON SATELLITE
IMAGERY. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 16N-20N BETWEEN 29W-34W.

TROPICAL WAVE IS ALONG 42W S OF 16N MOVING W NEAR 20 KT. LOW
AMPLITUDE WAVE IS EMBEDDED WITHIN SOME RATHER DRIER AIR.
THUS...NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IN THE S/CENTRAL CARIBBEAN IS ALONG 76W S OF 13N
MOVING W 15-20 KT. ALTHOUGH THIS WAVE REMAINS EMBEDDED WITHIN
DEEP LAYERED MOISTURE IT IS MOSTLY INLAND OVER SOUTH AMERICA AND
PRODUCING NO ASSOCIATED CONVECTION IN THE CARIBBEAN WATERS.

TROPICAL WAVE IN THE GULF OF MEXICO IS ALONG 92W S OF 20N
MOVING W 15-20 KT. WAVE IS MOSTLY OVER S MEXICO AND THE E
PACIFIC REGION PRODUCING NO ASSOCIATED CONVECTION IN THE GULF
WATERS.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 19N15W 17N25W 12N36W 8N50W 9N55W
8N62W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE WITHIN 90 NM ALONG THE W AFRICAN COAST S OF 11N W OF 8W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 7N-11N
BETWEEN 27W-33W.

...DISCUSSION...

GULF OF MEXICO...
THE REMNANT LOW OF FAY REMAINS INLAND OVER NE ALABAMA MOVING NE
WITH A SURFACE TROUGH TRAILING INTO THE GULF WATERS JUST E OF
PANAMA CITY FLORIDA SW TO 28N90W GENERATING ISOLATED SHOWERS N
OF 28N BETWEEN APALACHICOLA BAY FLORIDA AND THE MISSISSIPPI
DELTA OF LOUISIANA. WEAK UPPER TROUGHING DIPS INTO THE NW GULF
EXTENDING SW FROM W LOUISIANA TO THE TEXAS/MEXICO BORDER. UPPER
HIGH REMAINS ANCHORED IN THE FLORIDA STRAITS NEAR 24N80W
COVERING THE REMAINDER OF THE GULF ACROSS THE FLORIDA PENINSULA.
UPPER DIFFLUENCE IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM TUXPAN MEXICO TO BROWNSVILLE TEXAS W OF 95W
AND IN THE E BAY OF CAMPECHE S OF 21NE OF 92W TO INLAND OVER THE
YUCATAN PENINSULA. THE REMAINDER OF THE GULF IS QUIET AGAIN
TONIGHT.

CARIBBEAN SEA...
THE MAIN CONCERN FOR THE CARIBBEAN IS T.S. GUSTAV OVER SW
HAITI...SEE SPECIAL FEATURES ABOVE. AN UPPER HIGH CENTERED OVER
THE FLORIDA STRAITS COVERS THE NW CARIBBEAN AND IS PROVIDING
UPPER LEVEL DIFFLUENCE TO PRODUCE CLUSTERS OF SCATTERED SHOWERS/
THUNDERSTORMS FROM 17N-21N BETWEEN 77W-80W AND CLEARING THE
REMAINDER OF THE NW CARIBBEAN. AN UPPER LOW IS LOCATED IN THE W
ATLC N OF PUERTO RICO EXTENDS AN UPPER TROUGH TO THE E OF GUSTAV
AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
16N-22N BETWEEN THE VIRGIN ISLANDS AND THE DOMINICAN REPUBLIC.
THE ITCZ AXIS CROSSES THE EXTREME S CARIBBEAN/N PORTION OF SOUTH
AMERICA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF
13N TO INLAND OVER SOUTH AMERICA BETWEEN 65W-73W. OTHERWISE THE
SE CARIBBEAN REMAINS CLEAR TONIGHT.

ATLANTIC OCEAN...
AN UPPER RIDGE ANCHORED IN THE FLORIDA STRAITS NEAR 24N80W
COVERS THE W ATLC W OF 72W. BROAD UPPER TROUGH ENCOMPASSES THE
REMAINDER OF THE W ATLC FROM 57W-72W WITH AN EMBEDDED UPPER LOW
N OF PUERTO RICO NEAR 23N67W GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 16N-22N BETWEEN 60W-72W. A SURFACE
TROUGH IS TO THE E OF THE UPPER TROUGH EXTENDING ALONG 30N61W TO
23N64W GENERATING ISOLATED SHOWERS/THUNDERSTORMS FROM 22N-27N
BETWEEN 60W-66W. AN UPPER RIDGE EXTENDS FROM NEAR 18N53W E TO
20N42W WITH SOUTHERLY UPPER FLOW BETWEEN 53W AND THE LEEWARD
ISLANDS. BENEATH ALL OF THIS IS A WEAK 1011 MB SURFACE LOW NEAR
21N58W AND COUPLED WITH THE UPPER LEVEL DIFFLUENCE IS GENERATING
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
16N-22N BETWEEN 50W-62W. A SECOND BUT BENIGN UPPER LOW COVERS
THE E/CENTRAL ATLC CENTERED NEAR 29N44W EXTENDING S TO 23N. AN
UPPER RIDGE COVERS THE REMAINDER OF THE E ATLC ANCHORED JUST S
OF THE CANARY ISLANDS. BROAD SURFACE RIDGE REMAINS OVER THE ATLC
N OF 25N AND E OF 54W ANCHORED BY A SERIES OF HIGHS N OF THE
REGION WITH A NARROW RIDGE EXTENDING THROUGH 32N54W TO A 1017 MB
HIGH SW OF BERMUDA NEAR 30N70W.

$$
WALLACE





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