000 AXNT20 KNHC 281753 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... ITCZ IS CENTERED ALONG 7N10W 4N20W 3N30W 4N40W 4N45W 4N52W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS OCCURRING FROM 4N-8N BETWEEN 36W-40W...AND WITHIN 180 NM S OF THE AXIS BETWEEN 19W-23W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF A LINE FROM 11N44W TO 1013N40W. ...DISCUSSION... GULF OF MEXICO... BROAD DEEP LAYERED TROUGH IS SEEN ON WATER VAPOR SATELLITE IMAGERY ADVANCING QUICKLY EASTWARD ACROSS THE MID-WEST SECTION OF CONUS. ITS ASSOCIATED COLD FRONT EXTENDS FROM MOBILE BAY SW TO 27N92W TO INLAND THE MEXICAN COAST JUST N OF TAMPICO. NWS DOPPLER RADAR SHOWS SCATTERED SHOWERS AND ISOLATED TSTMS ALONG THE FRONT...WHILE AREAS OF POSSIBLE LIGHT RAIN EMBEDDED IN OVERCAST LOW AND MID CLOUDS ARE TO THE NW OF THE FRONT. TO THE E OF THE FRONT...THE AREA IS UNDER BROAD/MID UPPER LEVEL RIDGING WITH THE WESTERN EXTENSION OF THE ATLANTIC RIDGE PROTRUDING WESTWARD INTO THE FAR NE GULF. WATER VAPOR IMAGERY INDICATES MODERATE TO STRONG SUBSIDENCE AND RESULTANT DRY STABLE AIR COVERING THE GULF TO THE SE OF THE FRONT. THE RIDGE IS FORECAST TO SHIFT EASTWARD OVER THE NEXT 2 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 ARE WITHIN 30 NM EITHER SIDE OF LINE 23N88W 26N87W NE TO ACROSS THE WESTERN FLORIDA PANHANDLE. THESE CLOUDS AND SHOWERS ARE EXPECTED TO BECOME ABSORBED BY THE FRONT THROUGH THE NEXT 24 HOURS. CARIBBEAN SEA... STRONG SURFACE HIGH PRES OF 1030 MB CENTERED JUST N OF AREA NEAR 33N64W CONTINUES TO DOMINATE THE THE WEATHER PATTERN ACROSS THIS AREA IN TERMS OF INTENSITY OF ELY TRADES AND LOW LEVEL MOISTURE FOUND THROUGHOUT THE AREA. THE SURFACE HIGH IS SUPPORTED BY MID/UPPER LEVEL RIDGING THAT EXTENDS FROM COLOMBIA NW TO 15N80W AND THEN N INTO THE EASTERN GULF OF MEXICO. WITH THE PRES GRADIENT CREATED BY THIS HIGH AND LOW PRES OVER S AMERICA BEING RATHER TIGHT...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 WESTWARD ACROSS THE SEA N OF 13N E OF 77W...AND ALSO TO THE S OF 20N W OF 80W WHERE CLUSTERS OF THESE LOW LEVEL MOISTURE PATCHES ARE BRINGING ISOLATED SHOWERS TO THE COAST OF CENTRAL AMERICA. THIS ACTIVITY IS PRIMARILY ATTRIBUTED TO LOW LEVEL CONVERGENCE AS FAST ELY WINDS DECREASE NEAR THE COAST. THE HIGH CENTER IS FORECAST TO DROP S 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 EVIDENT ON WATER VAPOR IMAGERY TO COVER THE THE AREA N OF 14N E OF 73W. ASSOCIATED STRONG SUBSIDENCE AND DRY STABLE AIR IS BEING NUDGED SWD OVER THE EASTERN CARIBBEAN SEA WITH THE TROUGH WHERE A POCKET RATHER CLOUD FREE SKIES IS SEEN FROM 14N-17N E OF 68W. ATLANTIC OCEAN... THE MID/UPPER LEVEL PATTERN HERE IS VERY PROGRESSIVE LARGE AMPLITUDE FEATURES TRANSLATING EASTWARD AS THEY PUSH OFF THE SE CONUS. THE FIRST FEATURE IS A CONTINUATION OF THE EASTERN CARIBBEAN MID/UPPER LEVEL TROUGH WHICH EXTENDS NORTHEASTWARD THROUGH 21N58W TO 25N48W TO NE OF THE AREA AT 32N43W. CONFLUENT FLOW PATTERN INTO THE BACK SIDE OF THE TROUGH IS RESULTING IN STABLE ATMOSPHERIC CONDITIONS OVER THE WESTERN PORTION OF THE ATLC. A RIDGE CREST EXISTS N OF THE AREA W OF 70W. UPPER LEVEL MOISTURE IS SPILLING SWD AROUND THE CREST AXIS...AND INTO THE AREA BEHIND THE TROUGH N OF 25N E OF 64W. THE SURFACE COLD FRONT ASSOCIATED WITH MID/UPPER LEVEL TROUGH ENTERS THE REGION AT 32N25W AND EXTENDS ALONG 27N34W SW TO ABOUT 24N49W WHERE IT BECOMES A DIFFUSE CLOUD LINE (REMNANT CLOUD BAND) TO 22N60W TO NEAR TO NEAR 23N70W. THE FRONT IS CHARACTERIZED BY MAINLY BROKEN/OVERCAST LOW AND MID CLOUDS WITH ISOLATED SHOWERS ALONG THE FRONT...EXCEPT FOR AN ENHANCED AREA OF SCATTERED SHOWERS AND TSTMS WITHIN 90 NM S AND 60 NM N OF THE FRONT BETWEEN 34W-41W DUE TO THE SUPPORT FROM THE MID/UPPER LEVEL TROUGH. TO THE SE OF THE FRONTAL BOUNDARY OVER THE FAR E ATLC...VERY STRONG SW-W UPPER LEVEL FLOW REIGNS HERE WITH THE CULPRIT OF THIS FLOW PATTERN BEING A VERY PRONOUNCED JET STREAM BRANCH THAT EXTENDS FROM 17N49W ENE THROUGH 21N35W TO 23N22W TO INLAND THE COAST OF AFRICA OVER THE WESTERN SAHARA SECTION. A MID/UPPER LEVEL RIDGE EXTENDS FROM AN ANTICYCLONE CENTERED NEAR 7N16W WESTWARD TO 7N31W. THE UPPER SW-W STRONG FLOW BECOMES LIGHTER ALONG AND S OF THE RIDGE AXIS. UPPER LEVEL MOISTURE IN THE FORM OF EXTENSIVE BROKEN TO OVERCAST LAYERS OF CIRRUS CLOUDS IS RAPIDLY STREAMING NE TOWARDS WESTERN AFRICA IN THE SW-W FLOW GENERALLY FROM 13N-24N E OF 30W...AND FROM 9N-18N W OF 30W. $$ AGUIRRE