000 AXNT20 KNHC 291136 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... TROPICAL STORM OPHELIA IS CENTERED NEAR 20.0N 61.1W AT 29/0900 UTC OR ABOUT 156 NM NE OF THE NORTHERN LEEWARD ISLANDS MOVING N-NW AT 6 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. CONVECTION IS NOW TO THE N AND WRAPPING AROUND TO THE E INDICATING OPHELIA MAY BE STRENGTHENING AGAIN. SCATTERED STRONG CONVECTION IS WITHIN A 45/60 NM RADIUS OF 20N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE AREA FROM 15N-20N BETWEEN 56W-60W AND FROM 20N-23N BETWEEN 57W-62W. ISOLATED SHOWERS REMAIN ACROSS THE LESSER ANTILLES BETWEEN SAINT LUCIA TO ANGUILLA. TROPICAL STORM PHILIPPE IS CENTERED NEAR 17.8N 41.7W AT 29/0900 UTC OR ABOUT 1020 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/ISOLATED STRONG CONVECTION FROM 18N-22N BETWEEN 39W-42W. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED ALONG 31W BETWEEN 3N-8N MOVING W NEAR 10 KT. WAVE IS DIFFICULT TO DISCERN IN SATELLITE IMAGERY AND BECOMING LESS 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 ALONG 13N21W TO 10N25W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 3N-7N BETWEEN 19W-29W AND FROM 7N-11N BETWEEN 40W-44W. ...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. A SHORTWAVE UPPER TROUGH IS EMBEDDED WITHIN THIS FLOW EXTENDING ALONG THE LOWER MISSISSIPPI VALLEY INTO THE GULF TO 29N91W PRODUCING AN OUTFLOW BOUNDARY THAT AT 29/0900 UTC EXTENDS FROM 26N91W TO OVER HOUSTON TEXAS GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS WITHIN 75 NM W OF THIS BOUNDARY. A SECOND SURFACE TROUGH EXTENDS AT 29/0900 UTC FROM JACKSONVILLE FLORIDA INTO THE GULF NEAR 29N84W W INTO SE LOUISIANA TO JUST S OF NEW ORLEANS WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 30 NM OF THE THIS 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 WITH A WEAK 1014 MB HIGH LOCATED NEAR 25N88W. THIS FLOW IS GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 26N INTO THE BAY OF CAMPECHE BETWEEN 90W-97W. WEAK HIGH PRESSURE WILL DRIFT NW THROUGH FRI. A COLD FRONT WILL MOVE INTO THE N GULF FRI EXTENDING FROM TAMPA BAY FLORIDA TO SE TEXAS FRI NIGHT THEN WILL STALL FROM THE STRAITS OF FLORIDA TO THE YUCATAN SAT NIGHT. STRONG HIGH PRESSURE WILL BUILD SE BEHIND THE FRONT ACROSS THE N CENTRAL GULF. CARIBBEAN SEA... THE PRIMARY CONCERN AGAIN THIS MORNING IS TROPICAL STORM OPHELIA NE OF THE LEEWARD ISLANDS...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 17N BETWEEN 68W-80W. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N76W ALONG 10N81W INTO THE E PACIFIC REGION OVER NICARAGUA NEAR 11N84W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF THE MONSOON TROUGH TO INLAND OVER COLOMBIA AND PANAMA. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES AGAIN THIS MORNING. A WEAK PRESSURE PATTERN WILL EXIST OVER THE CARIBBEAN THROUGH SUN. ATLANTIC OCEAN... THE PRIMARY CONCERN THIS MORNING 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 22N78W TO BEYOND 30N73W PROVIDING A DIFFLUENT ENVIRONMENT ALOFT TO GENERATE ISOLATED SHOWERS/THUNDERSTORMS OVER THE BAHAMA ISLANDS. THE ELONGATED UPPER TROUGH TO THE E IS BEGINNING TO BREAK DOWN AS TROPICAL STORM OPHELIA BEGINS TO STRENGTHEN. AN UPPER TROUGH EXTENDS S INTO THE CENTRAL ATLC N OF 26N BETWEEN 35W-50W SUPPORTING A COLD FRONT THAT EXTENDS ALONG THE N PERIPHERY OF THE DISCUSSION AREA FROM 32N36W 31N42W TO 31N44W WHERE IT BECOMES STATIONARY TO BEYOND 32N53W. THE PAIR OF SURFACE TROUGHS REMAIN IN THE DISCUSSION AREA...THE EASTERN ONE EXTENDING FROM 30N38W TO 26N48W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM E OF THE TROUGH AND CONTINUING N OF 30N WITHIN 60 NM OF LINE FROM 30N34W TO BEYOND 32N28W. THE WESTERN...WEAKER SURFACE TROUGH EXTENDS FROM 31N45W TO 28N50W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 45 NM E OF THE TROUGH. A SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A 1019 MB HIGH NEAR 27N23W. HIGH PRESSURE OVER THE W ATLC WILL MOVE 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