000 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