[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED MAR 09 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE SOUTHERN COAST OF LIBERIA
NEAR 6N9W...WESTWARD ALONG 2N20W TO BELOW THE EQUATOR AT 28W
AND TO THE COAST OF BRAZIL NEAR 3S43W. SCATTERED STRONG
CONVECTION IS WITHIN 120 NM S OF THE AXIS E OF 13W...AND ALSO
ALONG THE AXIS W OF 40W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH MOVING ACROSS
THE MIDWEST...WITH A LONG WAVE EMBEDDED IN THE SOUTHERN
EXTENSION OF THE TROUGH MOVING THROUGH THE EASTERN AND CENTRAL
TEXAS EARLY THIS AFTERNOON. THE ASSOCIATED SURFACE COLD FRONT
HAS JUST PUSHED OFF THE TEXAS COAST...PRECEDED BY A PRE-FRONTAL
TROUGH THAT EXTENDS FROM S/CENTRAL LOUISIANA TO JUST SE OF
BROWNSVILLE TEXAS. ISOLATED SHOWERS AND TSTMS ARE OVER THE NW
PORTION OF THE GULF ALONG THE TROUGH...WHILE NUMEROUS STRONG TO
SEVERE TSTMS ARE QUICKLY MOVING EASTWARD FROM ACROSS SE
LOUISIANA NE TO OVER THE FAR WESTERN FLORIDA PANHANDLE. DENSE
FOG EARLIER NOTED OVER THE FAR WESTERN GULF COAST HAS JUST ABOUT
DISSIPATED. THE COMBINATION BETWEEN RELATIVELY LOWER PRESSURES
OVER THE WESTERN GULF AND HIGH PRESSURES OVER THE EASTERN
PORTION IS RESULTING IN A FAIRLY TIGHT SURFACE PRESSURE GRADIENT
ACROSS THE AREA WITH ESE 15-20 KT WINDS ACROSS THE AREA...EXCEPT
FOR SE-S 20-25 KT IN THE MIDDLE SECTION N OF 25N AND NLY WINDS
OF 20-30 KT BEHIND THE COLD FRONT. AS THE COLD FRONT PROGRESSES
EASTWARD DURING THE NEXT 24 HOURS...EXPECT MINIMAL GALE
CONDITIONS IN THE SW GULF S OF 20N AND W OF 95W TONIGHT INTO
THU. MODELS INDICATE THAT THE COLD FRONT WILL EXIT THE GULF THU
NIGHT AS HIGH PRES BUILDS ESE ACROSS EASTERN TEXAS AND WESTERN
LOUISIANA. THIS WILL ALLOW FOR WINDS AND SEAS TO SLOWLY SUBSIDE
THROUGHOUT.

CARIBBEAN SEA...
A DRY AND STABLE ATMOSPHERE IS NOTED IN THE UPPER LEVELS ACROSS
THE CARIBBEAN SEA THIS AFTERNOON MAINTAINING FAIR WEATHER
CONDITIONS ACROSS THE BASIN...WITH THE EXCEPTION OF SMALL
BATCHES OF LOW LEVEL MOISTURE MOVING WSW WITH WIDELY SCATTERED
TO ISOLATED SHOWERS N OF 15N...AND OVER THE SE PORTION. GENTLE
TO MODERATE TRADE WINDS ARE OBSERVED THROUGHOUT THE AREA...WITH
THE STRONGEST WINDS TURNING CYCLONICALLY AROUND THE COASTAL
WATERS NEAR THE COLOMBIA COAST WHERE SPEEDS ARE IN THE 20-25 KT
RANGE AND UP 30 KT RIGHT ALONG THE COAST. THE GULF OF MEXICO
COLD FRONT DESCRIBED ABOVE IS FORECAST TO MOVE THROUGH THE
YUCATAN CHANNEL IN ABOUT 48 HOURS FOLLOWED BY N-NE WINDS OF
20-25 KT. UNTIL THEN...NO SIGNIFICANT CHANGES ARE EXPECTED
ACROSS THE REGION.

ATLANTIC OCEAN...
IN THE UPPER LEVELS...BROAD MID/UPPER LEVEL RIDGING COVERS THE
AREA N OF 22N W OF 64W. E OF THIS FEATURE...THE FLOW IS ZONAL
THROUGHOUT EXCEPT N OF 28N BETWEEN 51W AND 59W WHERE A RATHER
SHARP UPPER TROUGH IS NOTED...AND NEAR 28N43W WHERE A DEVELOPING
MID/UPPER LEVEL CYCLONIC CIRCULATION IS VISIBLE. A STATIONARY
FRONT EXTENDS FROM 24N39W TO 28N47W TO N OF THE AREA AT 32N48W.
OVERCAST TO BROKEN...AT TIMES...LOW AND MID LEVEL CLOUDS WITH
EMBEDDED SCATTERED SHOWERS AND A FEW TSTMS ARE NE OF THE FRONT.
THE STATIONARY FRONT IS EXPECTED TO PERSIST INTO THE NEXT 24
HOURS. A GALE WARNING WITH E-SE WINDS OF 30-35 KT IS IN EFFECT
TO THE E OF THE STATIONARY FRONT N OF 30N BETWEEN 45W AND
47W...BUT IS FORECAST TO DIMINISH IN ABOUT 18 HOURS. A WEAK
SURFACE TROUGH EXTENDS FROM 32N66W TO 27N66W TO NEAR 23N70W.
ISOLATED SHOWERS ARE WITHIN 60 NM OF THE TROUGH MAINLY S OF 26N.

ELSEWHERE...RATHER STRONG SURFACE RIDGING IS UNDER THE AREA OF
MID/UPPER LEVEL RIDGING DESCRIBED ABOVE...BUT IS FORECAST TO
GRADUALLY SLIDE E AND WEAKEN OVER THE NEXT 24 HOURS. RIDGING IS
ALSO NOTED OVER THE EASTERN ATLANTIC N OF 21N AND E TO NEAR 23W.
VISIBLE IMAGERY FROM THROUGHOUT THE MORNING AND EARLY AFTERNOON
SHOW AN AREA OF SAL (SAHARAN DUST) OVER THE FAR EASTERN ATLANTIC
S OF 20N AND E OF 27W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE N OF THE ITCZ WITHIN 60 NM OF LINE FROM
1N30W TO 3N37W.

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

$$
AGUIRRE




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