000 AXNT20 KNHC 081741 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EDT MON NOV 08 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... AS OF 08/1800 UTC...SUB-TROPICAL STORM SEAN IS NOW TROPICAL STORM SEAN CENTERED NEAR 27.7N 69.5W...OR ABOUT 490 NM SW OF BERMUDA. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 40 KTS WITH GUSTS TO 50 KTS. SEAN IS CURRENTLY STATIONARY. FOR MORE INFORMATION SEE THE FORECAST/ADVISORY UNDER THE AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC...AND THE PUBLIC ADVISORY LISTED UNDER THE AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC. CURRENTLY...SCATTERED MODERATE CONVECTION IS AROUND THE NRN SEMICIRCLE FROM 27N-31N BETWEEN 66W-71W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ONLY TO THE W AFRICAN COAST AND ENDS AT THE COASTLINE. THE ITCZ EXTENDS ALONG 6N23W 7N34W 4N48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-11N BETWEEN 26W-35W. SIMILAR ACTIVITY IS FROM 3N-7N BETWEEN 35W-45W. ANOTHER AREA OF SIMILAR ACTIVITY IS FARTHER W AND E OF THE WINDWARD ISLANDS FROM 7N-13N BETWEEN 49W-58W. ...DISCUSSION... THE GULF OF MEXICO... MOSTLY FAIR WEATHER IS ACROSS THE GULF OF MEXICO TODAY AROUND A SURFACE RIDGE EXTENDING FROM A 1027 MB HIGH OVER VIRGINIA. ANTI-CYCLONIC FLOW OF 15-20 KTS IS AROUND THE RIDGE WITH PATCHES OF STRATOCUMULUS CLOUDS. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM NRN CENTRAL AMERICA ALONG 88W SUPPORTING THE SURFACE RIDGE. A STRONG COLD FRONT CURRENTLY ACROSS THE CENTRAL CONUS WILL ENTER THE NW GULF WITHIN TE NEXT 24 HOURS ACCOMPANIED BY SHOWERS/THUNDERSTORMS AND STRONG WINDS BEHIND THE FRONT. THE CARIBBEAN SEA... AN UPPER LEVEL RIDGE COVERS THE WRN HALF OF THE CARIBBEAN SEA EXTENDING FROM HONDURAS NWD ALONG 88W. THE ERN SIDE OF THE UPPER RIDGE IS ACCOMPANIED BY STRONG DRY AIR WHICH IS PROVIDING MOSTLY FAIR WEATHER ACROSS THIS PORTION OF THE BASIN. A FEW AREAS OF ISOLATED SHOWERS ARE E OF THE YUCATAN PENINSULA AND E OF NICARAGUA. SCATTERED SHOWERS/THUNDERSTORMS ARE IN THE SW CARIBBEAN N OF PANAMA AND ACROSS PORTIONS OF NRN COLOMBIA NEAR THE MONSOON TROUGH THAT EXTENDS ACROSS PANAMA TO NRN COLOMBIA. THE ERN CARIBBEAN IS COVERED BY AN UPPER LEVEL TROUGH THAT EXTENDS ACROSS THE WRN ATLC TO VENEZUELA WITH AXIS ALONG 68W. MOSTLY DRY AIR ACCOMPANIES THE WRN SIDE OF THE UPPER TROUGH MAINTAINING FAIR CONDITIONS BESIDES A FEW ISOLATED SHOWERS S OF HISPANIOLA AND ACROSS PUERTO RICO AS WELL AS W OF THE WINDWARD ISLANDS. DUE TO HIGHER MOISTURE VALUES PRESENT OVER THE ERN CARIBBEAN...THERE IS THE CHANGE FOR MORE PRECIPITATION LATER IN THE DAY AND THE TEMPERATURE RISES. MODEL DATA INDICATES THIS AREA OF MOISTURE WILL GRADUALLY DRIFT WWD. THE ATLANTIC OCEAN... TROPICAL STORM SEAN IS DOMINATING THE WRN ATLC TODAY PRODUCING A LARGE CYCLONIC WIND FIELD. WATER VAPOR IMAGERY INDICATES MOSTLY DRY AIR AROUND THE STORM BESIDES WITHIN 150 NM OF THE CENTRAL AND FARTHER TOT HE N WHERE MOST OF THE SHOWER ACTIVITY LIES. THE STORM LIES UNDERNEATH AN UPPER LEVEL TROUGH ALONG 68W WHICH IS ALSO PROVIDING DIFFLUENT FLOW ALOFT FARTHER E SUPPORTING CLUSTERS OF SHOWERS/THUNDERSTORMS FROM 18N-30N BETWEEN 56W-63W. A SURFACE TROUGH ALSO EXTENDS FROM N OF PUERTO RICO NEAR 19N66W TO 24N64W DEPICTING THE CONVERGENCE OF SW WINDS FROM THE W AND SE WINDS FROM THE E. SCATTERED SHOWERS/THUNDERSTORMS ARE ALONG THE TROUGH AXIS. FARTHER E...AN UPPER LEVEL RIDGE EXTENDS FROM E OF THE WINDWARD ISLANDS NEAR 11N56W TO NEAR 33N40W. AN UPPER LEVEL TROUGH IS THE E CENTERED NEAR 15N37W WHICH MAY BE HELPING ENHANCE CONVECTION NEAR THE ITCZ. TO THE N...A BROAD UPPER TROUGH BETWEEN THE AZORES ISLANDS AND SPAIN IS SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N22W ALONG 27N33W 26N44W BECOMING STATIONARY TO 30N58W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT. EXPECT SEAN TO REMAIN THE DOMINATE WEATHER FEATURE ACROSS THE WRN ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON