[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111034
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED MAY 11 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED FROM 8N12W 5N21W 2N29W 1N34W THEN ALONG
THE EQUATOR W OF 43W TO INLAND OVER SOUTH AMERICA NEAR 51W.
SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF SCATTERED/NUMEROUS
STRONG CONVECTION COVERS THE AREA WITHIN 60/75 NM OF 3N BETWEEN
22W-35W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
FROM 2N TO S OF THE EQUATOR BETWEEN 36W-50W AND FROM 2N-5N
BETWEEN 44W-49W.

...DISCUSSION...

GULF OF MEXICO...
A NARROWING UPPER RIDGE COVERS MUCH OF THE GULF EXTENDING FROM
THE W YUCATAN PENINSULA TO INLAND OVER THE N GULF COAST NEAR
CENTRAL LOUISIANA. THIS RIDGE IS BEING FORCED BETWEEN A
SHORTWAVE UPPER TROUGH OVER THE CENTRAL PLAIN STATES TO TEXAS
AND A BROAD UPPER TROUGH DIGGING S OVER THE W ATLC TO THE FLORIA
PENINSULA. A WEAK SURFACE RIDGE REMAINS OVER THE E GULF ANCHORED
BY A 1015 MB HIGH NEAR 30N86W. SE RETURN FLOW AROUND THE HIGH
COUPLED WITH LINGERING LOW LEVEL MOISTURE CONTINUES TO BANK LOW
LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS WITHIN 60/75 NM
ALONG THE COAST OF FROM VERACRUZ MEXICO TO GALVESTON TEXAS
LEAVING THE REMAINDER OF THE GULF WITH MOSTLY CLEAR SKIES AGAIN
THIS MORNING. MODERATE TO FRESH SE RETURN FLOW IN THE W GULF
WILL BE MAINTAINED BY HIGH PRESSURE THAT WILL MEANDER OVER THE
NE GULF THROUGH THU THEN SHIFT SLIGHTLY S AND WEAKEN BY FRI
NIGHT AHEAD OF THE NEXT COLD FRONT THAT WILL ENTER THE NW GULF
SAT MORNING AND REACH FROM NEAR APALACHICOLA BAY TO NE MEXICO
SUN MORNING.

CARIBBEAN SEA...
A BROAD UPPER RIDGE EXTENDS FROM THE TROPICAL ATLC ACROSS THE S
CARIBBEAN WITH NEAR ZONAL WESTERLY FLOW ACROSS THE N CARIBBEAN.
A SURFACE TROUGH IS OVER THE NE CARIBBEAN EXTENDING FROM THE
TROPICAL ATLC ACROSS THE VIRGIN ISLANDS NEAR 18N63W TO 17N71W
WITH SCATTERED SHOWERS WITHIN 120 NM N OF THE SURFACE TROUGH
AND ISOLATED SHOWERS WITHIN 120 NM S OF THE TROUGH AXIS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE SW
CARIBBEAN S OF 14N W OF 75W TO OVER CENTRAL AMERICA. THIS IS
LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES
THIS MORNING. THE SURFACE TROUGH WILL REMAIN STATIONARY THROUGH
SAT. A WEAK COLD FRONT OVER THE SW ATLC WILL SLOWLY MOVE SE AND
GRADUALLY DISSIPATE THROUGH THU WHEN IT WILL MERGE WITH THE
SURFACE TROUGH. FRESH EASTERLIES ARE EXPECTED IN THE GULF OF
HONDURAS AND WINDWARD PASSAGE TONIGHT THROUGH THU.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH COVERS THE W ATLC N OF 21N BETWEEN 50W AND
THE FLORIDA PENINSULA SUPPORTING A COLD FRONT THAT ENTERS THE
REGION NEAR 32N52W EXTENDING ALONG 25N59W TO 23N68W WHERE IT
DISSIPATES OVER THE BAHAMAS NEAR 23N76W. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 90 NM E OF FRONT N OF
30N AND ISOLATED SHOWERS ARE WITHIN 90 NM E OF THE FRONT N OF
25N. NEAR ZONAL WESTERLY FLOW ALOFT DOMINATES THE REMAINDER OF
THE ATLC WATERS BETWEEN 20N-30N. AN UPPER LOW IS N OF 32N
SUPPORTING A WEAKENING SURFACE TROUGH THAT EXTENDS THROUGH
32N28W TO 26N28W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 90 NM E
OF THE SURFACE TROUGH. THE REMNANTS OF A SURFACE TROUGH ARE IN
THE CENTRAL TROPICAL ATLC EXTENDING FROM 21N38W TO 17N42W WITH
ISOLATED SHOWERS POSSIBLE WITHIN 60 NM EITHER SIDE OF THE
SURFACE TROUGH. A SURFACE TROUGH IS OVER THE W TROPICAL ATLC
INTO THE NE CARIBBEAN EXTENDING FROM 21N55W ACROSS THE VIRGIN
ISLANDS NEAR 18N63W. SCATTERED SHOWERS ARE BEING ENHANCED BY THE
UPPER RIDGE THAT DOMINATES THE TROPICAL ATLC AND ARE WITHIN
90/120 NM N OF THE TROUGH WITH ISOLATED SHOWERS COVERING THE
AREA FROM 17N-23N BETWEEN 45W-55W. THE W ATLC COLD FRONT WILL
CONTINUE TO SINK SE AND GRADUALLY DISSIPATE ON THU. A GALE
CENTER N OF THE DISCUSSION AREA IN THE NW ATLC WILL PASS JUST NE
OF BERMUDA TODAY...INCREASING NORTHERLY FLOW OVER THE WATERS E
OF THE BAHAMAS AND GENERATING LONG PERIOD NORTHERLY SWELL ACROSS
THE REGIONAL WATERS. A NEW COLD FRONT WILL APPROACH THE N
FLORIDA COAST LATE SUN.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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