000 AXNT20 KNHC 041751 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE SEP 04 2012 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 1745 UTC. ...SPECIAL FEATURES... TROPICAL STORM LESLIE WAS CENTERED NEAR 25.0N 62.5W AT 04/1500 UTC. THIS LOCATION WAS ABOUT 525 MI...840 KM SSE OF BERMUDA. LESLIE IS MOVING N AT 3 KT WITH AN ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB...AND MAXIMUM SUSTAINED WIND SPEEDS OF 55 KT GUSTING TO 65 KT. NUMEROUS MODERATE TO STRONG CONVECTION IS FROM 20N-29N BETWEEN 56W-63W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2 /WTNT22 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION THIRTEEN WAS UPGRADED TO TROPICAL STORM MICHAEL AT 04/1500 UTC...LOCATED NEAR 27.0N 43.5W...ABOUT 1220 MI...1965 KM SW OF THE AZORES. MICHAEL IS MOVING NNW AT 4 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB WITH MAXIMUM SUSTAINED WIND SPEEDS OF 35 KT GUSTING TO 45 KT. PUBLIC ADVISORIES ON TROPICAL STORM MICHAEL ARE ISSUED UNDER WMO HEADER WTNT33 KNHC AND UNDER AWIPS HEADER MIATCPAT3. THE FORECAST/ ADVISORIES ARE ISSUED UNDER WMO HEADER WTNT23 KNHC AND UNDER AWIPS HEADER MIATCMAT3. MICHAEL IS GENERATING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION FROM 26N-29N BETWEEN 41W-45W. ...TROPICAL WAVES... THE TROPICAL WAVE MOVING ACROSS THE CENTRAL TROPICAL ATLC CONTINUES TO BE DIFFICULT TO PIN DOWN. AS OF 04/1200 UTC...THE WAVE AXIS IS ANALYZED FROM 20N38W TO 12N39W. HOWEVER...MODEL GUIDANCE AND LIMITED OBSERVATIONS NEAR THIS SYSTEM INDICATED NO CYCLONIC CURVATURE NEAR THE WAVE AXIS...NOR AT 700 MB LEVEL... WHERE CYCLONIC CURVATURE SHOULD BE BEST PRONOUNCED. THERE IS MORE CYCLONIC CURVATURE AROUND THE MONSOON TROUGH IT IS LIKELY THAT THIS WAVE BECAME EMBEDDED IN THE MONSOONAL GYRE SEVERAL DAYS AGO. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST OF SENEGAL NEAR 16N16W CONTINUING WSW ALONG 16N23W 12N33W TO 11N43W...WHERE THE ITCZ AXIS CONTINUES TO NEAR 11N66W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 150-170 NM ON EITHER SIDE OF THE MONSOON TROUGH E OF 45W. ...DISCUSSION... GULF OF MEXICO... DRY AIR ALOFT IS NOTED ACROSS THE UPPER LEVELS OF THE GULF BASIN. THIS UPPER LEVEL ENVIRONMENT IS SUPPORTIVE OF FAIR WEATHER CONDITIONS ACROSS MOST OF THE GULF BASIN AND A SURFACE RIDGE ANCHORED BY A 1017 MB HIGH CENTERED OVER THE NE GULF NEAR 27N87W PROVIDING LIGHT TO GENTLE ANTICYCLONIC FLOW ACROSS THE AREA. DESPITE THE LOCATION OF THE SURFACE HIGH CENTER... SCATTERED SHOWERS AND THUNDERSTORMS ARE DEPICTED ON DOPPLER RADAR IMAGERY...IMPACTING THE COASTAL WATERS NEAR THE FLORIDA PANHANDLE AND ALABAMA N OF 28N E OF 89W. THE ACTIVITY IS ASSOCIATED TO AN UPPER LEVEL SHORTWAVE TRACKING S ACROSS THE SE CONUS. MODEL GUIDANCE SUGGEST THIS UPPER FEATURE WILL GENERATE A SURFACE LOW PRESSURE SYSTEM WITHIN THE CONVECTIVE REGION... KEEPING THE RAIN SHOWERS ACTIVITY OVER THE NE AND N-CENTRAL WATERS OF THE GULF OVER THE NEXT 24 HOURS. OTHERWISE...AN UPPER LOW LOCATED IN THE WRN ATLC SPINNING JUST SEVERAL MILES OFF THE SE FLORIDA PENINSULA WILL DRIFT WEST BRING A SLIGHT CHANCE FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE STRAITS OF FLORIDA AND FAR ERN GULF DURING THE NEXT 24 HOURS. FAIR WEATHER WILL REMAIN ELSEWHERE ACROSS THE REMAINDER OF THE BASIN DURING THE FORECAST PERIOD. CARIBBEAN SEA... WATER VAPOR IMAGERY CONTINUES TO SHOW DRY AIR ALOFT ACROSS MOST OF THE CARIBBEAN BASIN THIS AFTERNOON...ASSOCIATED TO AN UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED OVER HISPANIOLA. MIDDLE TO UPPER LEVEL MOISTURE INCREASES OVER THE FAR SW BASIN...S OF 14N W OF 76W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN THIS REGION...IN CLOSE PROXIMITY WITH THE ERN PACIFIC MONSOON TROUGH ANALYZED ACROSS SRN NICARAGUA TO TO NRN COLOMBIA. THE SURFACE FLOW OVER THE FAR ENE CARIBBEAN CONTINUES UNDER THE INFLUENCE OF THE LARGE CYCLONIC WIND FIELD ASSOCIATED TO TROPICAL STORM LESLIE...LOCATED NNE OF THE NORTHERN LEEWARD ISLANDS. OTHERWISE ...GENTLE TO MODERATE EASTERLY TRADE WIND FLOW IS ELSEWHERE ACROSS THE DISCUSSION AREA...INCREASING TO 25 KT OVER THE COASTAL WATERS OF NRN COLOMBIA. GLOBAL MODELS SUGGEST THE CONVECTION OVER THE SW BASIN CONTINUING DURING THE NEXT 24-36 HOURS...WITH NO OTHER CHANGES ELSEWHERE ACROSS THE DISCUSSION AREA. ATLANTIC OCEAN... WATER VAPOR IMAGERY CONTINUES TO SHOW AN UPPER LOW WOBBLING IN THE WRN ATLC BETWEEN THE NW BAHAMAS AND THE SE FLORIDA PENINSULA AROUND 26N79W. SURFACE CONVERGENCE AND MIDDLE TO UPPER LIFTING GENERATED BY THE UPPER LOW IS PRODUCING AN AREA OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 24N-28N BETWEEN 77W-81W INCLUDING INLAND PORTIONS OF THE NW BAHAMAS AND THE FLORIDA PENINSULA. THIS AREA OF SHOWERS IS EXPECTED TO LINGER DURING THE NEXT 24 HOURS...BEFORE THE UPPER LOW BEGINS TO LIFT N LATER THIS EVENING. FARTHER EAST... THE LOW LEVEL CENTER OF TROPICAL STORM LESLIE BECAME EXPOSED TRACKING NORTHWARD. SEE SPECIAL FEATURES SECTION ABOVE FOR MORE DETAILS. THE NEXT SYSTEM IS NEWLY UPGRADED TROPICAL STORM MICHAEL TO THE WELL TO THE E OF LESLIE ...ALSO DESCRIBED IN THE SAME SECTION ABOVE. THIS LEAVES THE REMAINDER OF THE ATLC BASIN UNDER FAIR WEATHER CONDITIONS... PROVIDED BY A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED NEAR 22N25W..COMBINED WITH DRY SAHARAN DUST ALOFT NOTED ON METEOSAT-9 IMAGERY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA