000 AXNT20 KNHC 091759 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EDT WED NOV 09 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 FEATURES... TROPICAL STORM SEAN IS CENTERED NEAR 28.3N 70.6W AT 09/1800 UTC OR 390 NM SW OF BERMUDA MOVING N-NW AT 4 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. SCATTERED MODERATE CONVECTION IS FROM 26N-30N BETWEEN 67W-72W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 10N14W TO 09N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N16W TO 06N30W TO 06N53W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 05N-10N BETWEEN 10W-18W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 04N-10N BETWEEN 21W-37W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 37W-55W. ...DISCUSSION... GULF OF MEXICO... A SHORTWAVE UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY MOVING ACROSS THE GREAT LAKES REGION THAT SUPPORTS A COLD FRONT EXTENDING FROM THE SE CONUS ACROSS THE NW GULF WATERS FROM 30N91W TO 26N94W TO THE NE MEXICO COAST NEAR 25N98W. WHILE MOST OF THE ENERGY ASSOCIATED WITH THE UPPER LEVEL TROUGH IS LOCATED NORTH OF THE BASIN...THE FRONT LACKS ANY SIGNIFICANT DEEP CONVECTION...HOWEVER...WIDELY SCATTERED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE COLD FRONT. A SURFACE TROUGH IS ANALYZED FROM THE COLD FRONT NEAR 26N93W TO SOUTHERN MEXICO NEAR 19N94W. RECENT SHIP...BUOY...AND OFFSHORE OIL RIG OBSERVATIONS NW OF THE COLD FRONT INDICATE STRONG N TO NE WINDS TO 30 KT. ELSEWHERE...THE EASTERN GULF WATERS ARE UNDER THE INFLUENCE OF A WEAKENING SURFACE RIDGE AXIS EXTENDING FROM NORTHERN FLORIDA NEAR 30N84W TO NORTH OF THE YUCATAN PENINSULA NEAR 23N90W. THE RIDGE IS EXPECTED TO DISSIPATE AS THE FRONT MOVES EASTWARD INTO THE SW NORTH ATLC THROUGH EARLY FRIDAY. BEHIND THE FRONT A RIDGE IS FORECAST TO INFLUENCE THE GULF OVER THE WEEKEND WITH STRONG N-NE WINDS GRADUALLY DIMINISHING BY SATURDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER GUATEMALA AND HONDURAS NEAR 15N89W THAT IS PROVIDING MUCH OF THE CARIBBEAN BASIN WITH NW FLOW ALOFT. WATER VAPOR IMAGERY INDICATES THAT MUCH OF THIS FLOW IS ACCOMPANIED BY STABLE DRY AIR AND STRONG SUBSIDENCE. SATELLITE IMAGERY SHOWS THAT POSSIBLE ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF A LINE FROM 14N82W TO 18N88W. FARTHER SOUTH...A 1009 MB LOW IS CENTERED NEAR 11N77W ALONG THE MONSOON TROUGH EXTENDING FROM THE EAST PACIFIC REGION ALONG 10N TO 74W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING S OF 14N BETWEEN 75W-84W. THE REMAINDER OF THE EASTERN CARIBBEAN IS UNDER THE INFLUENCE OF AN UPPER LEVEL TROUGH EXTENDING OVER THE SW NORTH ATLC...OF WHICH TROPICAL STORM SEAN IS EMBEDDED WITHIN...WITH AXIS FROM 27N70W TO A BASE NEAR 14N61W. LOW-LEVEL CONVERGENCE OF SOUTHEASTERLY WINDS ACROSS THE NE CARIBBEAN AND UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE UPPER LEVEL TROUGH ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-20N BETWEEN 62W-72W. ATLANTIC OCEAN... THE INFLUENCE OF TROPICAL STORM SEAN ENCOMPASSES MUCH OF THE SW NORTH ATLC N OF 20N W OF 66W...WITH ONGOING CONVECTION MENTIONED ABOVE...A BROAD CYCLONIC 20 KT WIND FIELD...AND SEAS TO 20 FT WITH LONG AND PERSISTENT N TO NE FETCH NORTHWEST OF THE STORM CENTER. SWELLS GENERATED BY SEAN ARE EXPECTED TO AFFECT PORTIONS OF THE SOUTHEASTERN U.S. COAST AND BERMUDA DURING THE NEXT COUPLE OF DAYS...CAUSING LIFE-THREATENING SURF AND RIP CURRENTS. EAST OF 66W...AN UPPER LEVEL LOW IS NEARLY COLLOCATED OVER SEAN NEAR 27N71W WITH TROUGH AXIS EXTENDING SE TO 14N61W. MIDDLE TO UPPER LEVEL DIFFLUENCE AND CONVERGENT SE LOW-LEVEL WINDS ARE GENERATING SCATTERED SHOWERS AND TSTMS FROM 18N-33N BETWEEN 58W-66W. FARTHER EAST...OVER THE CENTRAL AND EASTERN ATLC...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM 12N54W TO 20N48W TO 29N38W. MOST OF THE ACTIVE WEATHER IS LOCATED NORTH AND EAST OF THIS RIDGE WITH A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N16W TO 27N24W WHERE THE FRONT BECOMES STATIONARY ALONG 28N34W TO 26N39W TO 27N44W. A WEAK 1015 MB LOW IS LOCATED NEAR THE TAIL END OF THE FRONT NEAR 28N49W WITH A SURFACE TROUGH EXTENDING SW FROM THE LOW TO 23N54W. LOW-LEVEL MOISTURE CONTINUES TO CONVERGE AND LIFT ALONG AND NORTH OF THE FRONTAL BOUNDARY WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 120 NM SOUTH...AND 240 NM NORTH OF THE STATIONARY FRONT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN