[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 212354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 21 2009

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 34W S OF 14N MOVING W 15-20 KT. WAVE IS
EMBEDDED WITHIN THE ITCZ WITH SATELLITE IMAGERY SHOWING CYCLONIC
CURVATURE IN THE LOW LEVEL CLOUD FIELD ALONG THE WAVE AXIS. A
LARGE AREA OF SAHARAN DUST FOLLOWS THE WAVE MAINLY E OF 30W. AN
ISOLATED SHOWER IS N OF THE WAVE AXIS WITHIN A 30/45 NM RADIUS
OF 16N34W.

TROPICAL WAVE IS TILTED FROM 22N42W TO 15N45W MOVING NWW 10-15
KT. WAVE IS BEING GUIDED WNW AROUND A 1010 MB LOW THAT IS
CENTERED NEAR 15N48W. THE ENTIRE AREA SURROUNDING THE WAVE AND
LOW COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE AS OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD LOW LEVEL CYCLONIC
CURVATURE IS OBSERVED ON SATELLITE IMAGERY EXTENDING FROM THE
LOW NE ALONG THE WAVE AXIS. THIS LOW LEVEL CURVATURE AND SURFACE
CONVERGENCE IS GENERATING SCATTERED MODERATE/STRONG CONVECTION
FROM 15N-17N BETWEEN 45W-48W AND SCATTERED MODERATE/ISOLATED
STRONG CONVECTION FROM 16N-20N BETWEEN 40W-45W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N22W 9N36W 8N40W 9N48W
10N62W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 7N-12N BETWEEN 36W-39W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE EXTENDS FROM S/CENTRAL MEXICO INTO THE GULF NEAR
TAMPICO NE TO NEAR 28N87W WITH A SECOND UPPER RIDGE COVERING THE
E GULF W OF 87W AND ANCHORED IN THE W ATLC. SCATTERED SHOWERS/
THUNDERSTORMS ARE INLAND AND WITHIN 45 NM ALONG THE COAST OF
FLORIDA FROM THE FLORIDA KEYS TO TAMPA. DIFFLUENCE ALOFT IS
GENERATING ISOLATED SHOWERS/THUNDERSTORMS DOTTING THE REMAINDER
OF THE GULF. A WEAK COLD FRONT WILL MOVE OFF THE TEXAS COAST
LATE TUE/EARLY WED THEN STALL OVER THE W GULF THU AND FRI.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE W CARIBBEAN EXTENDING FROM COSTA
RICA TO W CUBA COVERING THE AREA W OF 80W WITH A WEAK UPPER
TROUGH EXTENDING FROM THE CENTRAL ATLC ACROSS THE VIRGIN/LEEWARD
ISLANDS TO NEAR 13N76W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE INLAND AND WITHIN 60 NM ALONG THE COAST OF PUERTO RICO TO
CUBA INCLUDING JAMAICA AND N OF 20N W OF 82W TO OVER THE YUCATAN
PENINSULA. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE FROM 11N-16N W OF 81W TO INLAND OVER NICARAGUA AND HONDURAS.
THE ITCZ IS S OF PANAMA IN THE E PACIFIC REGION GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER PANAMA AND COSTA
RICA MOVING INTO THE SW CARIBBEAN WITHIN 60 NM ALONG THE COAST.
THE REMAINDER OF THE CARIBBEAN REMAINS TRANQUIL THIS EVENING.

ATLANTIC OCEAN...
A WEAKENING SURFACE TROUGH IS IN THE FAR W ATLC EXTENDING FROM
31N79W TO INLAND OVER FLORIDA NEAR DAYTONA BEACH WITH A WEAK
1017 MB LOW NEAR 30N75W. AN UPPER RIDGE COVERS THE W ATLC
ANCHORED NEAR 28N77W ENHANCING SCATTERED SHOWERS/THUNDERSTORMS
WITHIN 75 NM RADIUS OF 28.5N73.5W. AN UPPER TROUGH DIPS S INTO
THE W ATLC N OF 26N BETWEEN 62W-71W SUPPORTING A SURFACE TROUGH
THAT EXTENDS FROM 31N63W TO 26N67W AND GENERATING SCATTERED
SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM OF
THE SURFACE TROUGH. AN UPPER TROUGH COVERS THE CENTRAL ATLC
INTO THE CARIBBEAN FROM AN UPPER LOW NEAR 21N61W ACROSS THE
VIRGIN/LEEWARD ISLANDS COVERING THE AREA FROM 16N-27N BETWEEN
55W-70W WITH A SURFACE TROUGH EXTENDING ALONG 59W FROM 17N-22N
AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
19N-23N BETWEEN 49W-62W. A WEAK SURFACE RIDGE DOMINATES THE ATLC
WITH WEAKNESSES IN THE IMMEDIATE VICINITY OF THE SURFACE
TROUGHS.

$$
WALLACE





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