[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 6N9W 3N30W 4N48W 4N52W. SCATTERED
MODERATE CONVECTION IS FROM THE EQUATOR TO 4N BETWEEN 19W-25W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD DEEP LAYERED TROUGH IS ADVANCING QUICKLY EWD ACROSS THE
CENTRAL CONUS WITH ITS ASSOCIATED COLD FRONT EXTENDING ACROSS
THE GULF FROM PENSACOLA FLORIDA SW TO 25N96W AND S TO INLAND
OVER COASTAL MEXICO NEAR TAMPICO. NWS DOPPLER RADAR MOSAIC SHOWS
SCATTERED SHOWERS AND ISOLATED TSTMS ALONG THE FRONT...WHILE
AREAS OF POSSIBLE SHOWERS EMBEDDED IN OVERCAST LOW AND MID
CLOUDS ARE TO THE NW OF THE FRONT. TO THE E OF THE FRONT...THE
ERN GULF IS UNDER BROAD/MID UPPER LEVEL RIDGING EXTENDING FROM
THE WRN CARIBBEAN. WATER VAPOR IMAGERY INDICATES MODERATE TO
STRONG SUBSIDENCE AND DRY STABLE AIR COVERING THE GULF TO THE SE
OF THE FRONT. THE RIDGE IS FORECAST TO SHIFT EWD OVER THE NEXT
FEW DAYS AS THE FRONT PROGRESSES E ACROSS THE GULF. LOW LEVEL
MOISTURE IN THE FORM OF SCATTERED PATCHES OF LOW CLOUDS WITH
POSSIBLE ISOLATED SHOWERS MARK A NARROW ZONE OF CONVERGENCE
AHEAD OF THE FRONT WITHIN 30 NM ON EITHER SIDE OF A LINE 25N88W
28N87W NE TO ACROSS THE FLORIDA PANHANDLE. THIS MOISTURE IS
EXPECTED TO BE ABSORBED BY THE FRONT THROUGH THE NEXT 24 HOURS.

CARIBBEAN SEA...
A STRONG 1029 MB SURFACE HIGH IS CENTERED JUST N OF AREA NEAR
33N66W AND CONTINUES TO PRODUCE STRONG ELY TRADES AND LOW-LEVEL
MOISTURE ACROSS THE BASIN. THE SURFACE HIGH IS SUPPORTED BY MID-
UPPER LEVEL RIDGING THAT EXTENDS FROM COLOMBIA NW TO 18N82W AND
THEN N INTO THE ERN GULF OF MEXICO. WITH THE PRESSURE GRADIENT
CREATED BY THIS HIGH AND LOW PRESSURE OVER S AMERICA...MAXIMUM
WIND SPEEDS OF 20-30 KT WILL CONTINUE TO BE OBSERVED OVER THE SW
CARIBBEAN SEA NEAR THE COAST OF COLOMBIA THROUGH MON. THESE
WINDS ARE ADVECTING PATCHES OF LOW LEVEL MOISTURE WITH SCATTERED
SHOWERS WWD ACROSS THE SEA WITHIN 60 NM ON EITHER SIDE OF A LINE
FROM 13N67W TO 17N80W. THE HIGH CENTER IS FORECAST TO MOVE SE
OVER THE NEXT 24-48 HOURS ALLOWING FOR THE WINDS TO DECREASE. TO
THE E OF THE MID/UPPER LEVEL RIDGE...THE BROAD BASE OF A CENTRAL
ATLC TROUGH IS OBSERVED COVERING THE AREA N OF 12N AND E OF 67W.
ASSOCIATED STRONG SUBSIDENCE AND DRY STABLE AIR IS OVER THE ERN
CARIBBEAN SEA MAINLY N OF 16N AND E OF 76W.

ATLANTIC OCEAN...
THE MID/UPPER LEVEL PATTERN HERE IS VERY PROGRESSIVE WITH LARGE
AMPLITUDE FEATURES TRANSLATING EWD AS THEY PUSH OFF THE SE
CONUS. THE FIRST FEATURE IS A CONTINUATION OF THE ERN CARIBBEAN
MID/UPPER LEVEL TROUGH WHICH EXTENDS NE THROUGH 20N50W TO BEYOND
32N38W. A CONFLUENT FLOW PATTERN INTO THE BACK SIDE OF THE
TROUGH IS RESULTING IN STABLE ATMOSPHERIC CONDITIONS OVER THE
WRN PORTION OF THE ATLC. THE SURFACE COLD FRONT ASSOCIATED WITH
THE MID/UPPER LEVEL TROUGH ENTERS THE REGION AT 32N22W AND
EXTENDS ALONG 27N30W SW TO 23N45W WHERE IT BECOMES A DIFFUSE
SURFACE TROUGH TO 23N59W. THE FRONT IS CHARACTERIZED BY MAINLY
BROKEN/OVERCAST LOW AND MID CLOUDS WITH ISOLATED SHOWERS ALONG
THE FRONT. TO THE SE OF THE FRONTAL BOUNDARY OVER THE FAR E
ATLC...VERY STRONG SW UPPER LEVEL FLOW RESIDES E OF THE UPPER
TROUGH AXIS AND EXTENSIVE BROKEN TO OVERCAST CLOUDINESS IS
ACROSS THE ERN TROPICAL ATLC SE OF A LINE FROM TRINIDAD TO
WESTERN SAHARA OVER WRN AFRICA. SCATTERED SHOWERS AND TSTMS ARE
IN AN AREA OF UPPER DIFFLUENCE FROM 6N-15N BETWEEN 34W-46W.

$$
HUFFMAN





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