000 AXNT20 KNHC 192339 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN DEC 19 2010 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 2330 UTC. ...ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE COAST OF GUINEA NEAR 10N14W CONTINUING WEST ALONG 7N20W 8N30W 6N37W 11N50W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 12N BETWEEN 30W AND 44W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM ON EITHER SIDE OF THE ITCZ BETWEEN 18W AND 30W. A SURFACE TROUGH IS EMBEDDED IN THE ITCZ EXTENDING FROM 13N51W TO A WEAK 1006 MB LOW NEAR 10N52W CONTINUING S TO 7N51W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 10N TO 13N BETWEEN 48W AND 53W. ...DISCUSSION... GULF OF MEXICO... THE COLD FRONT THAT WAS IMPACTING THE GULF FROM A FEW DAYS AGO HAS NOW MOVED OUT OF THE DISCUSSION AREA INTO THE WEST ATLC AND NW CARIBBEAN. IN RESPONSE...A COLD AIRMASS IS IN PLACE ACROSS THE GULF. LOW LEVEL STRATOCUMULUS CLOUDS ARE CONCENTRATED OVER THE EASTERN HALF OF THE BASIN E OF 90W...EMBEDDED IN THE NNW FLOW. A MORE PRONOUNCED CLEARING AND NNE FLOW IS OBSERVED W OF 90W. LAST SATELLITE IMAGES OF THE DAY INDICATED LOW LEVEL OVERCAST CONDITIONS OVER THE FAR NE BASIN N OF 27N E OF 84W...INCLUDING THE FLORIDA PENINSULA. A WEAK SURFACE TROUGH IS WHITING 65 NM ALONG THE COAST OF MEXICO FROM N OF TAMPICO NEAR 23N96W TO SE OF VERACRUZ 19N95W GENERATING SCATTERED SHOWERS WITHIN 20 NM OF THE AXIS. LOOK FOR ANTICYCLONIC FLOW TO DEVELOP ACROSS THE GULF AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE SETTLES OVER THE REGION OVER THE NEXT 24 HOURS. CARIBBEAN SEA... THE BASE OF AN UPPER LEVEL TROUGH/LONGWAVE SWINGS BY THE NW CARIBBEAN...NOTED BY STRONG SUBSIDENCE AND DRY AIR ALOFT ON WATER VAPOR IMAGERY N OF 11N W OF 72W. THIS UPPER FEATURE SUPPORTS A DISSIPATING COLD FRONT EXTENDING FROM EASTERN CUBA NEAR 20N75W WESTWARD TO THE YUCATAN PENINSULA NEAR 19N87W. THE CONVECTION WITH THIS SYSTEM IS VERY LIMITED DUE TO THE DRY UPPER LEVEL ENVIRONMENT PRODUCED BY THE LONGWAVE. THE SAME UPPER LEVEL FEATURE SUPPORTS A SURFACE TROUGH THAT ENTERS THE NORTHERN CARIBBEAN ACROSS HISPANIOLA NEAR 19N70W TO THE CENTRAL BASIN NEAR 14N71W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 70 NM ON EITHER SIDE OF THE AXIS. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY AN UPPER RIDGE ANCHORED NEAR THE ABC ISLANDS. 15-20 KT TRADE WINDS ARE OVER THE EASTERN BASIN E OF 67W WITH ISOLATED SHOWERS EMBEDDED IN THE FLOW. EXPECT THE SURFACE TROUGH TO MOVE EASTWARD SUPPORTING SHOWER ACTIVITY OVER THE NE CARIBBEAN OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... THE UPPER LEVEL LONGWAVE/TROUGH IS MOVING OFF THE EASTERN CONUS SEABOARD SUPPORTING A FAST MOVING LOW PRESSURE SYSTEM AROUND 28N69W AND ASSOCIATED COLD FRONT EXTENDING WSW TO THE NORTHERN CARIBBEAN ALONG 24N71W 20N75W. A PRE-FRONTAL TROUGH EXTENDS ESE FROM THE LOW CENTER TO HISPANIOLA ALONG 25N67W 19N70W. WHILE THE COLD FRONT LACKS OF CONVECTION DUE TO THE DRY UPPER LEVEL ENVIRONMENT PRODUCED BY THE LONGWAVE...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 70 NM ON EITHER SIDE OF THE TROUGH AXIS. HOWEVER...WIDESPREAD SHOWERS AND THUNDERSTORMS ARE ACROSS MUCH OF THE WESTERN ATLC N OF 25N BETWEEN 60W AND 72W. THIS AREA OF CONVECTION/TROUGHINESS IS UNDER STRONG DIFFLUENCE ALOFT BETWEEN THE UPPER TROUGH ACROSS THE EASTERN CONUS AND AN UPPER LEVEL RIDGE ACROSS THE CENTRAL ATLC. THIS UPPER LEVEL RIDGE IS SUPPORTING SURFACE RIDGING ACROSS THE REMAINDER OF THE CENTRAL ATLC ANCHORED BY A 1016 MB HIGH NEAR 25N51W PROVIDING MOSTLY FAIR WEATHER CONDITIONS BETWEEN 40W AND 60W. A COLD FRONT ENTERS THE EASTERN ATLC NEAR 32N20W CONTINUING SW ALONG 25N25W 21N33W BECOMING STATIONARY TO 18N46W. ISOLATED SHOWERS ARE WITHIN 100 NM AHEAD OF THE FRONT N OF 25N. SIMILAR ACTIVITY IS WITHIN 60 NM ON EITHER SIDE OF THE STATIONARY FRONT. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL LOW/TROUGH CENTERED AROUND 34N20W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA