000 AXNT20 KNHC 051147 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST MON DEC 05 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 7N12W TO 5N15W. THE ITCZ AXIS CONTINUES FROM 5N15W ALONG 4N18W 5N35W 7N46W TO SOUTH AMERICA NEAR 5N54W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 1N-9N BETWEEN 28W-43W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE ITCZ BETWEEN 45W-50W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH IS OVER THE CENTRAL PLAIN STATES TO OVER MEXICO APPROACHING THE GULF WATERS SUPPORTING A STATIONARY FRONT ENTERING THE GULF AT 05/0900 UTC JUST N OF GALVESTON TEXAS CONTINUING OFF THE COAST OF TEXAS TO A 1010 MB LOW NEAR 29N95W TO 27N97W WHERE IT BECOMES A COLD FRONT AS IT CROSSES S TEXAS BETWEEN CORPUS CHRISTI AND BROWNSVILLE TO OVER NE MEXICO. A SURFACE RIDGE DOMINATES THE REMAINDER OF THE GULF ANCHORED IN THE W ATLC S OF NOVA SCOTIA ACROSS NE FLORIDA TO 24N91W. THIS SURFACE RIDGE IS GIVING THE GULF E OF THE FRONT SOUTHERLY RETURN FLOW. PATCHES OF SCATTERED SHOWERS ARE WITHIN 120 NM OF THE TEXAS COAST WITH ISOLATED SHOWERS WITHIN 90/120 NM OF LINE FROM THE STRAITS OF FLORIDA NEAR 25N80W ALONG 25N87W TO THE N GULF COAST NEAR THE MISSISSIPPI/LOUISIANA BORDER. THE REMAINDER OF THE UPPER LEVELS ARE DOMINATED BY AN UPPER RIDGE WITH AN AXIS EXTENDING FROM THE BAY OF CAMPECHE TO ACROSS NE FLORIDA COVERING THE W CARIBBEAN AND INTO THE W ATLC. THE COLD FRONT WILL EXTEND FROM SE LOUISIANA TO TAMPICO MEXICO TONIGHT THEN FROM MOBILE ALABAMA TO W BAY OF CAMPECHE TUE NIGHT. FRONT WILL THEN BRIEFLY STALL WED BEFORE ADVANCING E THU MOVING OUT OF THE GULF LATE THU OR EARLY FRI. CARIBBEAN SEA... THE UPPER RIDGE OVER THE GULF OF MEXICO COMBINED WITH AN UPPER TROUGH OVER THE CENTRAL CARIBBEAN IS GIVING THE W CARIBBEAN NW FLOW ALOFT. A NARROW CENTRAL CARIBBEAN UPPER TROUGH AXIS EXTENDS FROM THE CENTRAL ATLC ACROSS THE DOMINICAN REPUBLIC NEAR 19N70W ALONG 13N76W TO PANAMA NEAR 9N79W. STRONG SUBSIDENCE AND DRY STABLE AIR ARE W OF A LINE FROM E PUERTO RICO NEAR 18N66W TO PANAMA NEAR 9N78W WHILE MOIST TROPICAL AIR IS TO THE E OF THIS LINE. EMBEDDED WITH THE MOIST AREA IS A SURFACE TROUGH THAT EXTENDS FROM 17N64W THROUGH THE VIRGIN ISLANDS NEAR 18N64W INTO THE CENTRAL ATLC. SCATTERED SHOWERS AND CLUSTERS OF ISOLATED THUNDERSTORMS ARE IN THE MOIST SECTOR OF THE CARIBBEAN WHILE THE REMAINDER OF THE CARIBBEAN IS UNDER FAIR CONDITIONS THIS MORNING. THE LESSER ANTILLES CONTINUE TO RECEIVE RAIN AS THEY HAVE FOR THE PAST SEVERAL OF DAYS AND WITH THESE SHOWERS/ THUNDERSTORMS TRAINING NE MAINLY ACROSS THE LEEWARD ISLANDS HAVE THE POTENTIAL FOR FLOODING ESPECIALLY IN MOUNTAINOUS REGIONS. THESE RAINS ARE FORECASTED TO CONTINUE THROUGH TONIGHT. ATLANTIC OCEAN... AN UPPER RIDGE EXTENDS AN AXIS FROM THE GULF OF MEXICO ACROSS NE FLORIDA INTO THE W ATLC TO BEYOND 32N75W COVERING THE FAR W ATLC. A SURFACE RIDGE COVERS THE W ATLC W OF 65W INTO THE GULF OF MEXICO. A NARROW UPPER TROUGH IS IN THE CENTRAL ATLC EXTENDING FROM AN UPPER LOW NEAR 29N62W INTO THE CENTRAL CARIBBEAN ACROSS THE DOMINICAN REPUBLIC NEAR 19N70W SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 28N60W ALONG 23N63W INTO THE NE CARIBBEAN THROUGH THE VIRGIN ISLANDS NEAR 18N64W. THE TIGHT PRESSURE GRADIENT BETWEEN THIS SURFACE TROUGH AND THE SURFACE RIDGE OVER THE NW ATLC IS PRODUCING GALE FORCE WINDS THAT ARE EXPECTED TO LAST LESS THAN 24 HOURS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ASSOCIATED WITH THE UPPER LOW COVERING THE AREA WITHIN 120 NM W OF THE SURFACE TROUGH BETWEEN 25N-28N. MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR COVERS THE REMAINDER OF THE W ATLC W OF THE SURFACE TROUGH GIVING THE AREA FAIR WEATHER THIS MORNING. A BROAD UPPER RIDGE IS TO THE E OF THE UPPER TROUGH EXTENDING FROM NEAR 10N50W ALONG 22N52W TO BEYOND 32N48W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 15N-31N BETWEEN 50W AND THE SURFACE TROUGH. AN UPPER LOW IS TO THE E CENTERED NEAR 28N30W AND COVERS THE AREA N OF 16N BETWEEN 20W-40W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-27N BETWEEN 30W-35W. A SECOND WEAK SURFACE TROUGH IS IN THE TROPICAL ATLC ALONG 48W/49W FROM 11N-16N. W ATLC SURFACE RIDGE WILL WEAKEN THROUGH MIDWEEK AS THE HIGH PRESSURE CENTER SHIFTS SE AND WEAKENS. A COLD FRONT WILL MOVE OFF THE SE COAST LATE THU. THE SURFACE TROUGH IN THE CENTRAL ATLC/E CARIBBEAN IS EXPECTED TO DRIFT EASTWARD. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW