000 AXNT20 KNHC 042353 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN DEC 04 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ONLY A SMALL PORTION OVER WATER FROM THE COAST OF GUINEA NEAR 10N14W TO 8N17W. THE ITCZ CONTINUES FROM 8N17W ALONG 3N30W 4N43W 3N51W. ISOLATED MODERATE/STRONG CONVECTION IS WITHIN 250 NM N...100 NM S OF THE AXIS BETWEEN 26W-49W. ...DISCUSSION... GULF OF MEXICO... SURFACE RIDGING CONTINUES TO DOMINATE THE GULF OF MEXICO WITH AXIS FROM THE BIG BEND OF FLORIDA TO THE BAY OF CAMPECHE. THIS PATTERN IS PROVIDING MAINLY 15-20 KT NE-E SURFACE FLOW ACROSS THE BASIN AROUND THE RIDGE WITH LIGHTER WINDS ON THE WRN PERIPHERY. PATCHES OF ISOLATED SHOWERS ARE EMBEDDED WITHIN THE ANTI-CYCLONIC FLOW MAINLY N OF 24N. ALOFT...MOSTLY DRY AIR COVERS THE AREA AROUND AN UPPER LEVEL RIDGE WITH AXIS EXTENDING FROM THE BAY OF CAMPECHE TO CENTRAL FLORIDA AND INTO THE W ATLC. A SWATH OF UPPER LEVEL MOISTURE LIES ON THE WRN SIDE OF THE UPPER RIDGE BETWEEN THE RIDGE AND AN APPROACHING TROUGH OVER THE WRN CONUS. THIS MOISTURE IS SUPPORTING A FEW UPPER LEVEL CLOUDS OVER THE NW GULF ALONG WITH ISOLATED SHOWERS AT THE SURFACE DUE TO AN APPROACHING COLD FRONT. THE AFOREMENTIONED UPPER TROUGH OVER THE WRN CONUS SHOULD BEGIN TO PUSH EWD SUPPORTING THE FRONTAL BOUNDARY NEAR THE TEXAS COASTLINE. THE FRONT IS EXPECTED TO MOVE OVER THE NW GULF WATERS WITHIN 24 HOURS. NLY WINDS UP TO 25 KTS ARE EXPECTED BEHIND THE FRONT. CARIBBEAN SEA... MAINLY NELY FLOW COVERS THE WRN HALF OF THE CARIBBEAN AROUND THE SURFACE RIDGE THAT COVERS THE FAR ERN CONUS...GULF OF MEXICO...AND WRN ATLC. POSSIBLE ISOLATED SHOWERS ARE EMBEDDED WITHIN THIS FLOW AND MORE CONCENTRATED NEAR THE CENTRAL AMERICAN COASTLINE AND INLAND. ALOFT...DRY AIR AND SUBSIDENCE COVER THE AREA W OF 70W AROUND AN UPPER LEVEL TROUGH WITH AXIS FROM HISPANIOLA TO COLUMBIA. E OF 70W...DIFFLUENCE AROUND THE ERN SIDE OF THE UPPER TROUGH IS HELPING SUPPORT SCATTERED SHOWERS/THUNDERSTORMS E OF A LINE FROM THE VIRGIN ISLANDS TO THE NW CORNER OF VENEZUELA. SOME OF THIS ACTIVITY IS ENHANCED BY A SURFACE TROUGH EXTENDING FROM THE CENTRAL ATLC INTO THE NE CARIBBEAN ALONG 19N63W TO 16N64W. THIS AREA INCLUDING MUCH OF THE LEEWARD AND WINDWARD ISLANDS HAVE ALREADY RECEIVED LARGE AMOUNTS OF RAIN OVER THE PAST SEVERAL DAYS. WITH MOISTURE EXPECTED TO REMAIN OVER THIS AREA...THERE IS THE POTENTIAL FOR FLOODING ESPECIALLY IN AREAS OF HIGH TERRAIN. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE IS MOVING OVER THE FAR WRN ATLC WITH AXIS JUST E OF THE ERN UNITED STATES SEABOARD SUPPORTING SURFACE RIDGING AROUND A 1037 MB HIGH S OF NOVA SCOTIA NEAR 42N64W. DRY AIR ALOFT ACCOMPANIES THE UPPER RIDGE PROVIDING MOSTLY FAIR WEATHER. AN UPPER LEVEL TROUGH TO THE E ALONG 32N61W TO HISPANIOLA NEAR 19N69W IS SUPPORTING A FRONTAL BOUNDARY N OF THE DISCUSSION AREA...TRANSITIONING INTO A SURFACE TROUGH ALONG 31N60W 23N63W 19N63W. SURFACE CONVERGENCE ALONG WITH UPPER LEVEL DIFFLUENCE IS HELPING SUPPORT SCATTERED SHOWERS/ISOLATED THUNDERSTORMS MAINLY E OF THE SURFACE TROUGH WITHIN 300 NM. AN UPPER LEVEL RIDGE IS E OF THE SURFACE TROUGH SANDWICHED BETWEEN THE AFOREMENTIONED UPPER TROUGH AND AN UPPER LEVEL LOW NEAR 30N33W. THE UPPER LOW IS SUPPORTING A SECOND SURFACE TROUGH FROM 32N47W TO 27N43W. SCATTERED SHOWERS ARE FARTHER E OF THE TROUGH FROM 24N-30N BETWEEN 31W-40W. TO THE S...ANOTHER SURFACE TROUGH IS ALONG 17N46W TO 11N48W. ISOLATED SHOWERS ARE WITHIN 300 NM EITHER SIDE OF THE AXIS. EXPECT THE SURFACE TROUGH IN THE CENTRAL ATLC TO REMAIN THE MAIN ACTIVE WEATHER MAKER AS IT REMAINS MOSTLY STATIONARY FOR THE NEXT 24 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON