000 AXNT20 KNHC 281151 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED SEP 28 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 PHILIPPE IS CENTERED NEAR 16.5N 38.0W AT 28/0900 UTC OR ABOUT 810 NM W OF THE CAPE VERDE ISLANDS MOVING W-NW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/ WTNT22 KNHC FOR MORE DETAILS. PHILIPPE REMAINS SHEARED WITH THE DEEP CONVECTION TO THE N OF THE LOW LEVEL CENTER. SCATTERED MODERATE/STRONG CONVECTION IS FROM 16N-20N BETWEEN 35W-39W. TROPICAL DEPRESSION OPHELIA IS CENTERED NEAR 18.6N 60.0W AT 28/0900 UTC OR ABOUT 180 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING NW AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. OPHELIA APPEARS TO BE GRADUALLY ORGANIZING. SCATTERED MODERATE/STRONG CONVECTION IS FROM 14N-20N BETWEEN 57W-60W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE LESSER ANTILLES FROM SAINT LUCIA TO ANGUILLA. TROPICAL DEPRESSION OPHELIA IS FORECAST TO INTENSITY TO HURRICANE STRENGTH AS IT MOVES THROUGH THE CENTRAL ATLC THROUGH FRI THEN N OF THE DISCUSSION AREA EARLY SAT. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED ALONG 28W BETWEEN 5N-11N MOVING W NEAR 20 KT. WAVE IS DIFFICULT TO DISCERN IN SATELLITE IMAGERY BUT IS EVIDENT IN LOW LEVEL STREAMLINE ANALYSIS AND 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 16N20W. SCATTERED MODERATE CONVECTION IS OFF SW AFRICA WITHIN 60/75 NM OF A LINE FROM 6N12W TO 9N17W WITH SMALL CLUSTERS FROM 6N-10N BETWEEN 36W-45W. ...DISCUSSION... GULF OF MEXICO... THE LARGE UPPER LOW IS CENTERED OVER THE GREAT LAKES EXTENDING A BROAD UPPER TROUGH INTO THE NE GULF AND W ATLC N OF 27N E OF 86W SUPPORTING A FRONTAL BOUNDARY THAT REMAINS INLAND OVER THE SE CONUS AND PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM ALONG THE N GULF COAST FROM THE FLORIDA/ALABAMA BORDER TO THE MISSISSIPPI DELTA. A SURFACE TROUGH AT 28/0900 UTC IS OVER SE FLORIDA EXTENDING FROM LAKE OKEECHOBEE ACROSS THE UPPER FLORIDA KEYS TO 25N81W. A BROAD UPPER RIDGE COVERS THE REMAINDER OF THE GULF ANCHORED OVER S MEXICO PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER THE SW GULF S OF 25N W OF 90W. WEAK HIGH PRESSURE COVERS THE GULF E OF 94W WITH A 1015 MB HIGH LOCATED NEAR 27N88W AT 28/0900 UTC. CLEAR SKIES DOMINATE THE REMAINDER OF THE GULF THIS MORNING. WEAK HIGH PRESSURE WILL PERSIST THROUGH TONIGHT THEN SHIFT TO THE NW GULF THU AND FRI. A COLD FRONT WILL MOVE INTO THE NW GULF FRI REACHING FROM NEAR TAMPA FLORIDA TO NE MEXICO SAT AND FROM S FLORIDA TO THE BAY OF CAMPECHE SUN. STRONG HIGH PRESSURE WILL THEN BUILD SE BEHIND THE FRONT ACROSS THE N/CENTRAL GULF. CARIBBEAN SEA... THE PRIMARY CONCERN THIS MORNING IS TROPICAL DEPRESSION OPHELIA NE OF THE LEEWARD ISLANDS...SEE SPECIAL FEATURE SECTION ABOVE. THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS OVER THE W CARIBBEAN N OF 12N W OF 70W PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE ISOLATED CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF A LINE FROM 15N68W TO 20N83W AND WITHIN 60 NM ALONG THE COAST OF NICARAGUA N OF 13N. THE MONSOON TROUGH EXTENDS FROM COLOMBIA AND PANAMA GENERATING ISOLATED SHOWERS/ THUNDERSTORMS S OF 12N TO OVER PANAMA BETWEEN 79W-82W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES THIS MORNING. A WEAK PRESSURE PATTERN WILL EXIST OVER MUCH OF THE AREA THROUGH SUN. ATLANTIC OCEAN... THE PRIMARY CONCERN THIS MORNING IS TROPICAL DEPRESSION OPHELIA NE OF THE LEEWARD ISLANDS...SEE SPECIAL FEATURE SECTION ABOVE. THE UPPER TROUGH OVER THE GULF OF MEXICO AND THE SE CONUS EXTENDS OVER THE W ATLC WITH A SHORTWAVE UPPER TROUGH EXTENDING FROM THE N BAHAMA ISLANDS TO 31N76W AND A NARROW UPPER RIDGE TO THE E EXTENDING FROM THE N COAST OF CUBA NEAR 21N76W TO BEYOND 32N71W PROVIDING A DIFFLUENT ENVIRONMENT ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM THE COAST OF CUBA NEAR 22N77W ACROSS THE BAHAMAS ALONG 26N75W TO BEYOND 32N74W. AN ELONGATED UPPER TROUGH EXTENDS FROM 30N68W THROUGH AN UPPER LOW NEAR 26N67W TO THE VIRGIN ISLANDS. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 90 NM OF LINE FROM 24N65W TO 28N69W. THE UPPER RIDGE ASSOCIATED WITH OPHELIA COVERS THE AREA FROM 10N-27N BETWEEN 53W-64W. A WEAK SURFACE RIDGE DOMINATES THE W AND CENTRAL ATLC N OF 25N BETWEEN 55W-80W ANCHORED BY 1019 MB HIGH JUST W OF BERMUDA. AN UPPER TROUGH EXTENDS S OVER THE E ATLC TO 21N BETWEEN 18W-35W WITH TRAILING A SURFACE TROUGH THAT EXTENDS FROM 32N39W TO 27N45W AND CLUSTERS OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE TROUGH AXIS. A WEAK SURFACE RIDGE COVERS THE REMAINDER OF THE E ATLC ANCHORED BY A 1020 MB HIGH S OF THE MADEIRA ISLANDS NEAR 21N18W. HIGH PRESSURE OVER THE W/CENTRAL ATLC WILL REMAIN STATIONARY BUT GRADUALLY WEAKEN THROUGH THU THEN SHIFT NE OF THE AREA FRI AND SAT. A WEAK FRONT WILL MOVE INTO THE FAR W ATLC THU TO FRI AND WILL REACH THE CENTRAL BAHAMAS SAT. A STRONGER FRONT WILL MOVE INTO THE FAR W ATLC SAT AND RAPIDLY MOVE E MERGING WITH THE WEAK FRONT ON SUN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW