000 AXNT20 KNHC 011126 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST THU DEC 01 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL ATLC NEAR 11N15W TO 9N18W. THE ITCZ NEAR 9N18W EXTENDING ALONG 6N26W 9N37W TO SOUTH AMERICA NEAR 6N57W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-10N E OF 30W TO JUST INLAND OVER SW AFRICA NEAR 11W AND WITHIN 90 NM S O F THE ITCZ BETWEEN 36W-42W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH IS DIGGING S OVER THE E GULF TO 25N MAINLY E OF 88W WITH ZONAL WESTERLY FLOW ALOFT PREVAILING ACROSS THE REMAINDER OF THE AREA. DRY STABLE AIR AND STRONG SUBSIDENCE CONTINUES TO DOMINATE THE AREA WITH SCATTERED COLD AIR STRATOCUMULUS CLOUDS OVER THE FAR E GULF E OF 85W. MOSTLY CLEAR SKIES ARE OVER THE REMAINDER OF THE GULF. A SURFACE RIDGE COVERS THE GULF ANCHORED BY A 1026 MB HIGH OVER S OHIO. SURFACE RIDGE WILL PERSIST THROUGH SAT. A COLD FRONT WILL MOVE INTO THE NW GULF LATE SUN WITH GALE CONDITIONS EXPECTED IN SW GULF W OF THE FRONT LATE MON. CARIBBEAN SEA... THE STATIONARY FRONT HAS WEAKEN INTO A SHEAR LINE EXTENDING FROM CUBA NEAR CABO CRUZ OVER W OF JAMAICA TO 11N81W. ISOLATED SHOWERS ARE POSSIBLE OVER THE NW CARIBBEAN W OF THE SHEAR LINE. AN UPPER RIDGE DOMINATES THE NW CARIBBEAN W OF 70W WHILE A NARROW UPPER TROUGH FROM THE W/CENTRAL ATLC EXTENDS S ACROSS THE VIRGIN ISLANDS TO THE ABC ISLANDS. DRY STABLE AIR ALOFT AND STRONG SUBSIDENCE COVERS ALL BUT THE FAR SE CARIBBEAN. THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA NEAR 11N75W TO ACROSS COSTA RICA INTO THE E PACIFIC REGION NEAR 10N84W AND IS POSSIBLY GENERATING ISOLATED SHOWERS WITHIN 75 NM ALONG THE COAST OF COLOMBIA AND S OF 13N W OF 81W. A SURFACE TROUGH IS E OF LESSER ANTILLES BUT CONTINUES TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF A LINE FROM THE ISLAND OF SAINT LUCIA TO THE COAST OF VENEZUELA NEAR 11N64W TO OVER THE WINDWARD ISLANDS. THIS IS LEAVING THE CENTRAL CARIBBEAN WITH FAIR WEATHER AGAIN THIS MORNING. SHEAR LINE WILL DISSIPATE LATE TONIGHT. SURFACE TROUGH LINGER E OF THE LESSER ANTILLES THROUGH MON. ATLANTIC OCEAN... AN UPPER TROUGH IS MOVING INTO THE W ATLC N OF 25N W OF 75W WITH RE-INFORCING SHOT OF COLD AIR OVER THE SE CONUS AND E GULF OF MEXICO. A COLD FRONT REMAINS ACROSS THE W ATLC SUPPORTED BY AN UPPER TROUGH WELL N OF THE DISCUSSION AREA ENTERING THE REGION NEAR 32N67W 24N73W WHERE IT BECOMES STATIONARY CONTINUING ACROSS THE S BAHAMA ISLANDS TO CUBA NEAR SAINT LUCIA. ISOLATED SHOWERS ARE WITHIN 60 NM W OF THE COLD FRONT. A NARROWING UPPER TROUGH IS IN THE W/CENTRAL ATLC EXTENDING AN AXIS THROUGH 32N66W SE ALONG 24N57W THEN SW ACROSS THE VIRGIN ISLANDS INTO THE CARIBBEAN SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM A 1006 MB SURFACE LOW NEAR 29N60W S TO 20N63W. A SECOND SURFACE TROUGH IS IN THE W TROPICAL ATLC EXTENDING FROM 20N58W OVER BARBADOS TO E TRINIDAD WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120/150 NM E OF THE SURFACE TROUGH S OF 14N. DRY STABLE AIR IS W OF THE UPPER TROUGH WITH MOSTLY CLEAR SKIES W TO THE W ATLC FRONT. A NARROW HIGH AMPLITUDE UPPER RIDGE TO THE E OF THE UPPER TROUGH IS BEGINNING TO WEAKEN AND NOW EXTENDS AN AXIS FROM THE W TROPICAL ATLC NEAR 14N44W TO BEYOND 32N56W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM THE TROPICS NEAR 5N46W 13N54W TO 20N56W. DENSE CLOUD COVER WITH POSSIBLE ISOLATED SHOWERS ARE WITHIN 150/200 NM OF LINE FROM 18N52W 27N54W TO BEYOND 32N59W. AN UPPER TROUGH COVERS THE E ATLC N OF 20N E OF 40W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N23W TO 27N34W. SCATTERED SHOWERS ARE WITHIN 45 NM SE OF THE FRONT. THE REMAINDER OF THE E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1034 MB HIGH ABOUT 550 NM W-NW OF THE AZORES. WEAKENING COLD FRONT WILL DISSIPATE TONIGHT AS THE SURFACE TROUGH TO THE E WILL MOVE N EARLY FRI AS THE LOW DISSIPATES. A SURFACE RIDGE WILL BUILD BEHIND THE FRONT THROUGH MON. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW