[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221252
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE MAR 22 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
XXXX UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 6N10W
CONTINUING SW ALONG 3N20W 1S30W INTO SOUTH AMERICA ALONG 4N39W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 6S TO 3N BETWEEN
14W AND 31W. ISOLATED MODERATE TO STRONG CONVECTION IS WITHIN
170 NM S OF THE AXIS E OF 12W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE COVERS THE GULF OF MEXICO THIS MORNING...
SUPPORTING A 1022 MB HIGH OFF THE COAST OF TAMPA FLORIDA NEAR
28N83W. THIS FEATURE ALONG WITH VERY DRY AIR AND STRONG
SUBSIDENCE ALOFT IS PROVIDING FAIR WEATHER CONDITIONS ACROSS THE
AREA. WINDS ARE LIGHT AND VARIABLE AROUND THE HIGH PRESSURE
CENTER...WITH MODERATE TO FRESH EASTERLY WINDS W OF 86W S OF 28N
AND SOUTHEASTERLY RETURN FLOW N OF 24N W OF 90W. THE SURFACE
RIDGE IS EXPECTED TO REMAIN IN THE FAR EAST GULF MAINTAINING
FAIR CONDITIONS ACROSS THE BASIN FOR THE NEXT 24 TO 36 HOURS.

CARIBBEAN SEA...
THE CARIBBEAN IS UNDER THE INFLUENCE OF A BROAD UPPER LEVEL
RIDGE WITH ASSOCIATED DRY AIR AND STRONG SUBSIDENCE ACROSS THE
MAJORITY OF THE BASIN. THIS SCENARIO IS LIMITING DEEP CONVECTION
ACROSS THE AREA...LEAVING JUST A FEW AREAS OF WEAK SHOWERS
SCATTERED ACROSS THE REGION...MOST NOTICED ACROSS THE CENTRAL
AND FAR SE BASIN. THESE AREAS OF SHOWERS ARE MOVING WITH THE NE
FRESH TO STRONG TRADE WIND FLOW. THIS FLOW ALSO GAINS A CYCLONIC
TENDENCY AROUND THE COAST OF COLOMBIA WITH WINDS REACHING UP TO
25 KT. THIS IS GENERATING SOME OROGRAPHIC SHOWER ACTIVITY ALONG
THE COAST OF COLOMBIA S OF 11N BETWEEN 72W-77W. COMPUTER MODELS
SUGGEST SOME WEAK CONVECTION DEVELOPING OVER THE FAR SE BASIN IN
WITHIN THE NEXT 24 HOURS...WITH NO OTHER SIGNIFICANT CHANGES
EXPECTED DURING THE FORECAST PERIOD.

ATLANTIC OCEAN...
THE MAIN FEATURE OF INTEREST IN THE ATLC IS A COLD FRONT THAT
EXTENDS FROM 32N38W SOUTHWESTWARD TO 22N45W AND WESTWARD TO
20N60W. FROM THAT POINT THE BOUNDARY CONTINUES AS A DISSIPATING
COLD FRONT TO NEAR 21N71W NEAR THE TURKS AND CAICOS. A PRE
FRONTAL TROUGH ENTERS THE REGION NEAR 31N36W AND CONTINUES SSW
ALONG 24N37W TO 17N42W. THIS SYSTEM IS SUPPORTED ALOFT BY A DEEP
LAYER TROUGH/LOW MOVING ACROSS THE N CENTRAL ATLC. SCATTERED
SHOWERS ARE FOUND ALONG THE FRONTAL BOUNDARY WITH ISOLATED
SHOWERS UP TO 40 NM BEHIND THE COLD FRONT. STRONGER AND HEAVIER
SHOWERS ALONG WITH ISOLATED THUNDERSTORMS ARE WITHIN 170 NM
EAST OF THE PRE FRONTAL TROUGH SEEN IN THE GEOSTATIONARY
SATELLITE IMAGERY. EARLIER ASCAT SCATTEROMETER PASSES INDICATED
NORTHERLY GUSTY WINDS UP TO 30 KT BEHIND THE COLD FRONT. WINDS
EAST OF THE TROUGH ARE ENHANCED WITH 20 TO 30 KT SE WINDS. THE
FAR W ATLC W OF 60W IS EXPERIENCING FAIR WEATHER CONDITIONS DUE
TO AN UPPER LEVEL RIDGE SUPPORTING A 1022 MB NEAR 29N73W. THE
REMAINDER OF THE E ATLC IS DOMINATED BY A WEAK 1016 MB HIGH NEAR
28N26W SUPPORTING FAIR WEATHER ACROSS THE AREA E OF 33W.
COMPUTER MODELS SUGGEST THE FRONTAL BOUNDARY WILL CONTINUE TO
SLOWLY MOVIE SOUTHEASTWARD WITH THE PRE-FRONTAL TROUGH RETAINING
ITS IDENTITY AHEAD OF THE FRONT. AS THE COLD FRONT WEAKENS...A
FEW SHOWERS MAY LINGER NEAR THE BOUNDARY DURING THE NEXT 24 TO
36 HOURS.

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

$$

FG/PAW




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