000 AXNT20 KNHC 142343 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED DEC 14 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 2315 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA WITH THE ITCZ ENTERING THE E TROPICAL ATLC NEAR 9N13W CONTINUING ALONG 9N17W 6N26W 6N40W TO 7N51W. ISOLATED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE ITCZ BETWEEN 25W-34W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE DOMINATES THE GULF THIS EVENING EXTENDING AND AXIS FROM THE CARIBBEAN OVER W CUBA ALONG 83W TO OVER THE SE GULF COAST. THE STRONG SURFACE RIDGE HAS SHIFTED E OVER THE PAST 24 HOURS BUT REMAINS OVER MUCH OF THE GULF AND ANCHORED BY A 1029 MB HIGH OVER E VIRGINIA. STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT COVERS THE GULF. HOWEVER THE FRESH EASTERLY SURFACE FLOW COUPLED WITH REMNANT LOW LEVEL MOISTURE IS GIVING A PORTION OF THE GULF PARTLY CLOUDY SKIES WITH ISOLATED SHOWERS WITHIN 60/75 NM OF LINE FROM 24N80W THROUGH THE STRAITS OF FLORIDA ALONG 23N88W THEN N TO THE LOUISIANA COAST NEAR 29N91W. REMARKABLY CLEAR SKIES ARE WITHIN 120 NM ALONG THE COAST OF THE FLORIDA PENINSULA. SURFACE RIDGE ACROSS THE GULF WILL MOVE E AS A COLD FRONT WILL MOVE OFF TEXAS THU EXTENDING FROM SW LOUISIANA TO TAMPICO MEXICO FRI BEFORE STALLING FRI AFTERNOON AND THEN DISSIPATING SAT. SURFACE RIDGE WILL THEN BUILD N OF THE AREA SUN MOVING E ON MON. CARIBBEAN SEA... AN UPPER TROUGH OVER THE W ATLC DIPS S TO ALONG THE GREATER ANTILLES SUPPORTING A WEAKENING COLD FRONT THAT ENTERS THE CARIBBEAN ACROSS N HAITI NEAR 20N72W N OF JAMAICA TO 18N80W. ISOLATED SHOWERS ARE WITHIN 60 NM SE OF THE FRONT. THE UPPER LEVELS OF THE CARIBBEAN ARE DOMINATED BY A BROAD UPPER RIDGE WITH THE AXIS EXTENDING FROM COLOMBIA NEAR 11N74W TO ACROSS W CUBA INTO THE GULF OF MEXICO. THIS UPPER RIDGE IS DRAWING TROPICAL MOISTURE N OVER THE S/CENTRAL CARIBBEAN AND COUPLED WITH THE MONSOON TROUGH THAT EXTENDS FROM COLOMBIA NEAR 11N74W ALONG 10N77W TO ACROSS PANAMA/COSTA RICA NEAR 10N83W INTO THE E PACIFIC REGION ARE GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 12N W OF 72W TO INLAND OVER COLOMBIA TO COSTA RICA. A SURFACE TROUGH IS ANALYZED FROM THE CENTRAL ATLC INTO THE E CARIBBEAN OVER GUADELOUPE TO 13N67W WITH SCATTERED SHOWERS WITHIN 45 NM EITHER SIDE OF THE TROUGH AXIS. THE REMAINDER OF THE CARIBBEAN IS UNDER MOSTLY FAIR CONDITIONS THIS EVENING WITH THE POSSIBLE ISOLATED LOW LEVEL SHOWER USHERED IN ON THE EASTERLY TRADE WINDS. THE COLD FRONT WILL DISSIPATE LATER TONIGHT. THE SURFACE RIDGE OVER THE GULF OF MEXICO AND SE US IS PRODUCING FRESH TO STRONG NE TRADE WINDS ACROSS THE NW CARIBBEAN. THESE CONDITIONS WILL GRADUALLY SHIFT E INTO THE CENTRAL CARIBBEAN TONIGHT THROUGH THE WEEKEND ENCOMPASSING THE MOST OF THE CARIBBEAN FRI AND SAT. WINDS WILL DIMINISH IN THE NW CARIBBEAN THIS WEEKEND AS THE PRESSURE GRADIENT WEAKENS OVER THAT REGION. ATLANTIC OCEAN... A BROAD UPPER TROUGH COVERS THE W ATLC TO THE GREATER ANTILLES BETWEEN 55W-77W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N53W ALONG 24N61W TO 20N72W WHERE IT WEAKENS AS IT ENTERS THE CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE FRONT N OF 26N WITH SCATTERED SHOWERS WITHIN 90 NM SE OF THE REMAINDER OF THE FRONT. STRONG SUBSIDENCE AND DRY STABLE AIR COVER THE W ATLC W OF THE FRONT GIVING THAT AREA FAIR CONDITIONS THIS EVENING. A SURFACE TROUGH IS AHEAD OF THE FRONT EXTENDING FROM 25N57W ALONG 20N58W INTO THE E CARIBBEAN ACROSS GUADELOUPE WITH SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. BROAD UPPER RIDGE COVERS THE CENTRAL AND E ATLC ANCHORED NEAR 31N33W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150/175 NM OF LINE FROM 12N51W TO 26N53W. A SURFACE RIDGE DOMINATES THE E ATLC N OF 20N E OF THE 45W ANCHORED BY A 1030 MB HIGH E OF THE AZORES. THE COLD FRONT WILL MOVE INTO THE CENTRAL ATLC LATER THIS EVENING AS THE SURFACE RIDGE BUILDS IN FROM THE NW. THE RIDGE WILL MOVE SE THROUGH LATE SAT AS ANOTHER COLD FRONT MOVES INTO THE W ATLC REACHING FROM 31N71W TO THE NORTHERN BAHAMAS SUN MORNING THEN FROM 31N62W TO THE CENTRAL BAHAMAS LATE SUN WHILE WEAKENING. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW