000 AXNT20 KNHC 290559 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU SEP 29 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...SPECIAL FEATURES... TROPICAL STORM OPHELIA IS CENTERED NEAR 19.4N 60.7W AT 29/0300 UTC OR ABOUT 155 NM E-NE OF THE NORTHERN LEEWARD ISLANDS MOVING NW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/ WTNT21 KNHC FOR MORE DETAILS. OPHELIA HAS STRENGTHEN TODAY DESPITE BEING UNDER SOUTHWESTERLY SHEAR WITH SCATTERED MODERATE/ ISOLATED STRONG CONVECTION WITHIN 90 NM OF LINE FROM 16N58W 19N58W TO 21N60W AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVERING THE REMAINDER OF THE AREA FROM 14N-23N BETWEEN 57-62W INCLUDING THE LESSER ANTILLES. TROPICAL STORM PHILIPPE IS CENTERED NEAR 17.4N 40.8W AT 29/0300 UTC OR ABOUT 970 NM W OF THE CAPE VERDE ISLANDS MOVING W-NW AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/ WTNT22 KNHC FOR MORE DETAILS. PHILIPPE REMAINS UNDER SOUTHERLY SHEAR WITH SCATTERED MODERATE/STRONG CONVECTION FROM 17N-21N BETWEEN 38W-42W. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED ALONG 30W BETWEEN 4N-11N MOVING W NEAR 10 KT. WAVE IS DIFFICULT TO DISCERN IN SATELLITE IMAGERY BUT IS EVIDENT IN THE UPPER LEVEL SATELLITE WINDS. NO ASSOCIATED SHOWERS/CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL ATLC NEAR 17N16W TO 14N25W. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 3N-7N BETWEEN 11W-26W AND FROM 1N-4N BETWEEN 32W-42W. ...DISCUSSION... GULF OF MEXICO... THE LARGE UPPER LOW REMAINS CENTERED OVER THE GREAT LAKES EXTENDING A BROAD UPPER TROUGH INTO THE N GULF N OF 29N SUPPORTING A FRONTAL BOUNDARY THAT REMAINS INLAND OVER THE SE CONUS AND PRODUCING AN OUTFLOW BOUNDARY THAT AT 29/0300 UTC EXTENDS FROM 27N89W TO OVER LOUISIANA NEAR LAKE CHARLES GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM ALONG THIS BOUNDARY. A SURFACE TROUGH AT 29/0300 UTC IS OVER FLORIDA EXTENDING FROM JACKSONVILLE TO TAMPA THEN S TO FORT MYERS INTO FLORIDA BAY TO NEAR 25N82W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 30 NM OF THE TROUGH. A BROAD UPPER RIDGE COVERS THE REMAINDER OF THE GULF ANCHORED OVER THE E PACIFIC REGION GIVING THE GULF WATERS NEAR WESTERLY FLOW ALOFT. MOSTLY CLEAR SKIES DOMINATE THE REMAINDER OF THE GULF TONIGHT WITH THE EXCEPTION OF FAST MOVING HIGH CLOUDS. WEAK HIGH PRESSURE WILL DRIFT NW THROUGH FRI. A COLD FRONT WILL MOVE INTO THE N GULF FRI NIGHT EXTENDING FROM TAMPA BAY FLORIDA TO SE TEXAS LATE FRI NIGHT THEN WILL STALL FROM THE STRAITS OF FLORIDA TO THE YUCATAN SUN. STRONG HIGH PRESSURE WILL BUILD SE BEHIND THE FRONT ACROSS THE N CENTRAL GULF. CARIBBEAN SEA... THE PRIMARY CONCERN AGAIN TONIGHT IS TROPICAL STORM OPHELIA NE OF THE LEEWARD ISLANDS AND THE ACTIVITY OVER THE LESSER ANTILLES...SEE SPECIAL FEATURE SECTION ABOVE. THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS OVER THE W CARIBBEAN W OF 70W PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE ISOLATED CLUSTERS OF SHOWERS/THUNDERSTORMS N OF A LINE FROM 17N70W ACROSS JAMAICA TO THE W TIP OF CUBA. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 9N76W ACROSS E PANAMA INTO THE E PACIFIC REGION OVER NICARAGUA NEAR 12N84W BUT IS NOT GENERATING ANY SHOWER ACTIVITY IN THE SW CARIBBEAN. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES AGAIN TONIGHT. A WEAK PRESSURE PATTERN WILL EXIST OVER THE CARIBBEAN THROUGH SUN. ATLANTIC OCEAN... THE PRIMARY CONCERN TONIGHT IS TROPICAL STORM OPHELIA NE OF THE LEEWARD ISLANDS AND TROPICAL STORM PHILIPPE OVER THE CENTRAL ATLC...SEE SPECIAL FEATURE SECTION ABOVE. AN UPPER RIDGE COVERS THE W ATLC EXTENDING FROM THE N COAST OF CUBA NEAR 22N75W TO BEYOND 30N72W PROVIDING A DIFFLUENT ENVIRONMENT ALOFT TO GENERATE ISOLATED SHOWERS/THUNDERSTORMS OVER THE BAHAMA ISLANDS. AN ELONGATED UPPER TROUGH EXTENDS FROM BERMUDA THROUGH AN UPPER LOW NEAR 28N63W TO THE E OF TROPICAL STORM OPHELIA NEAR 21N64W. A WEAK SURFACE RIDGE DOMINATES THE W INTO THE CENTRAL ATLC N OF 26N BETWEEN 55W-80W ANCHORED BY 1019 MB HIGH OVER BERMUDA. AN UPPER TROUGH EXTENDS S INTO THE CENTRAL ATLC N OF 26N BETWEEN 35W-55W SUPPORTING A COLD FRONT N OF THE DISCUSSION AREA AND A PAIR OF SURFACE TROUGHS...THE EASTERN ONE EXTENDING FROM 30N38W TO 25N50W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM E OF THE TROUGH AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF LINE FROM 30N36W TO BEYOND 32N30W. THE WESTERN SURFACE TROUGH EXTENDS FROM 31N45W 29N50W TO 30N53W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60 NM SE OF THE TROUGH E OF 48W. A SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A PAIR OF 1022 MB HIGHS...ONE NNE OF THE MADEIRA ISLANDS AND A SECOND NEAR 29N22W. HIGH PRESSURE OVER THE W ATLC WILL REMAIN STATIONARY THROUGH THU MOVING NE FRI AND SAT. A WEAK FRONT WILL MOVE INTO THE FAR W ATLC THU AND FRI STALLING OFF THE FLORIA COAST ON FRI EVENING. A STRONGER FRONT WILL MOVE INTO THE FAR W ATLC FRI NIGHT RAPIDLY MOVING E AND MERGING WITH THE STALLED FRONT EXTENDING FROM NEAR BERMUDA TO THE SE BAHAMAS SUN THEN STALLING OUT OVER CENTRAL ATLC MON. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW