000 AXNT20 KNHC 041813 CCA TWDAT TROPICAL WEATHER DISCUSSION...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN SEP 04 2011 ...CORRECTED FOR POSITION OF T.S. LEE... 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 1730 UTC. ...SPECIAL FEATURES... TROPICAL STORM LEE IS CENTERED NEAR 30.4N 91.8W AT 04/1800 UTC OR 35 NM WSW OF BATON ROUGE LOUISIANA AND ABOUT 20 NM NE OF LAFAYETTE LOUISIANA MOVING NNE AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 55 KT. SATELLITE AND LIGHTNING DATA INDICATE SCATTERED MODERATE/ISOLATED STRONG CONVECTION REMAINS OVER WATER IN THE SE QUADRANT OF LEE WITH TWO MAIN CONVECTIVE BANDS. THE INNERMOST BAND EXTENDS FROM NEAR 26N94W TO SRN MISSISSIPPI NEAR 30N90W CONTINUING INLAND AS INDICATED BY DOPPLER RADAR. THE SECOND...AND BROADER BAND EXTENDS FROM NEAR 23N92W TO THE FLORIDA PANHANDLE NEAR 30N86W WITH RAINFALL CONTINUING INTO ALABAMA...GEORGIA...AND MISSISSIPPI. RADAR IMAGERY ALSO INDICATES SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM OF THE STORM CENTER WITH THE STRONGEST ACTIVITY NE OF THE CENTER. SOME ISOLATED SHOWERS ALSO EXTEND TO JUST W OF THE WRN COAST OF THE FLORIDA PENINSULA. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/ WTNT33 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HURRICANE KATIA IS CENTERED NEAR 21.9N 59.2W AT 04/1500 UTC OR ABOUT 315 NM NE OF THE NORTHERN LEEWARD ISLANDS MOVING NW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 966 MB. MAXIMUM SUSTAINED WIND SPEED IS 85 KT WITH GUSTS TO 105 KT. OVER THE PAST SEVERAL HOURS KATIA HAS RAPIDLY INTENSIFIED AND HAS REACHED CATEGORY 2 STATUS. NUMEROUS STRONG CONVECTION IS AROUND THE SW SIDE OF THE CENTER FROM 21N-23N BETWEEN 59W-61W. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS ELSEWHERE FROM 20N-25N BETWEEN 57W-62W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS MOVING WWD AT 10-15 KT ACROSS THE CAPE VERDE ISLANDS FROM 16N24W TO 10N22W. UPPER AIR TIME SECTION ANALYSES FROM DAKAR SENEGAL INDICATES THAT THE WAVE MOVED OFF THE COAST OF AFRICA AROUND 24 HOURS AGO. MOISTURE ASSOCIATED WITH THE WAVE EXTENDS OVER TO ABOUT 18N WITH HIGHEST VALUES LOCATED IN LOW LATITUDES AROUND 8N. SCATTERED MODERATE/STRONG CONVECTION IS MAINLY SW OF THE WAVE FROM 5N-11N BETWEEN 22W-29W. TROPICAL WAVE EXTENDS FROM 19N41W TO A NEARLY DISSIPATED 1013 MB LOW NEAR 14N37W. WHILE THERE IS CLEAR CYCLONIC FLOW AROUND THE WAVE AXIS INDICATED BY AN ASCAT SCATTEROMETER PASS...IT APPEARS THAT IT HAS OPENED UP INTO A TROUGH WITHOUT A CLOSED CIRCULATION AROUND THE LOW. GLOBAL MODEL GUIDANCE INDICATES THAT THE WAVE IS NO LONGER EMBEDDED WITHIN THE MONSOON TROUGH AND MAY DAMPEN OVER THE NEXT 24-48 HOURS...BUT A DISCERNIBLE FEATURE CAN BE TRACKED OVER THE NEXT SEVERAL DAYS AND MAY BEGIN TO GAIN A NORTHERLY COMPONENT IN ITS MOTION. CURRENTLY SCATTERED MODERATE CONVECTION IS E OF THE WAVE FROM 13N-18N BETWEEN 32W-39W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 17N16W TO THE BASE OF A TROPICAL WAVE NEAR 10N22W. DUE TO THE CIRCULATION OF A TROPICAL WAVE FARTHER W IN THE CENTRAL TROPICAL ATLC...THE MONSOON TROUGH HAS BROKEN W OF THE WAVE AXIS NEAR THE CAPE VERDE ISLANDS. AS THE WAVES MOVE WWD...THE MONSOON TROUGH WILL BUILD BACK IN. THE ITCZ PICKS UP S OF THE CENTRAL TROPICAL ATLC WAVE ALONG 8N39W TO 5N58W. ...DISCUSSION... GULF OF MEXICO... TROPICAL STORM LEE...WITH CENTER NOW INLAND OVER LOUISIANA...DOMINATES THE MAJORITY OF THE GULF OF MEXICO TODAY. THE STORM IS FORECAST TO MOVE SLOWLY NE AND WILL LIKELY CONTINUE TO IMPACT THE BASIN...ESPECIALLY THE ERN HALF...FOR THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. MUCH OF THE PRECIPITATION WITH LEE IS ON THE ERN SIDE OF THE STORM WITH RAINBANDS IMPACTING THE FLORIDA PANHANDLE...SW GEORGIA...ALABAMA...MISSISSIPPI...AND LOUISIANA. THE HEAVIEST RAINFALL ALSO LIES UNDERNEATH AN AREA OF DIFFLUENCE ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER LEE...AND AN UPPER LEVEL RIDGE COVERING THE FAR ERN GULF. WITH TOTAL RAINFALL AMOUNTS OF 10-15 INCHES AND MAXIMUM AMOUNTS OF 20 INCHES...FLOODING IS A MAJOR THREAT FOR MUCH OF THE SE UNITED STATES. REFER TO FLOOD PRODUCTS AND HURRICANE LOCAL STATEMENTS ISSUED BY LOCAL NWS FORECAST OFFICES FOR MORE DETAILED INFORMATION ON THESE THREATS. AS LEE DRIFTS NE...A FRONTAL SYSTEM IS EXPECTED TO MERGE WITH IT WHICH WILL SWEEP A COLD FRONT THROUGH THE NW GULF. DRY AIR BEHIND THE FRONT WILL PROVIDE FAIR CONDITIONS IN THE WAKE OF THE FRONT...WHILE THE ERN HALF OF THE BASIN WILL REMAIN UNDER THE HIGH MOISTURE VALUES ASSOCIATED WITH LEE. CARIBBEAN SEA... MAINLY NELY FLOW ALOFT COVERS THE FAR WRN CARIBBEAN AROUND AN UPPER LEVEL RIDGE OVER THE ERN GULF OF MEXICO. THIS IS ALSO DRAWING SOME MOISTURE FROM TROPICAL STORM LEE INTO THIS PORTION OF THE AREA SUPPORTING SOME ISOLATED PATCHES OF SHOWERS/THUNDERSTORMS BETWEEN 74W-83W. ACTIVE STORMS ARE CURRENTLY N AND W OF JAMAICA...ACROSS CENTRAL CUBA...AND NEAR PANAMA AND COSTA RICA. THE ACTIVITY NEAR CENTRAL AMERICA IS ALSO ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS FROM THE E PACIFIC ACROSS NICARAGUA TO NRN COLOMBIA. THE ERN CARIBBEAN IS EXPERIENCING FAIR WEATHER WITH MOSTLY CLEAR SKIES AND NE-E LIGHT TO MODERATE TRADEWIND FLOW. DRY AIR ALOFT ALSO COVERS THIS PORTION OF THE BASIN AROUND A WEAK UPPER LEVEL RIDGE CENTER N OF VENEZUELA NEAR 13N68W. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... THE FAR WRN ATLC IS EXPERIENCING MOSTLY FAIR WEATHER INFLUENCED BY WEAK SURFACE RIDGING OVER NORTH CAROLINA AND MOSTLY DRY AIR ALOFT. SOME UPPER LEVEL CLOUDS EXTEND OVER FLORIDA ASSOCIATED WITH OUTFLOW FROM LEE. A WEAK SURFACE TROUGH ANALYZED AT 1200 UTC NEAR 31N71W TO 28N74W HAS DISSIPATED AS OF 1500 UTC. SCATTERED SHOWERS/THUNDERSTORMS ARE E OF THIS AREA ALONG A SWATH FROM 22N75W TO 31N68W ASSOCIATED WITH UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL TROUGH SITTING OVER THE WRN ATLC ALONG 71W. HURRICANE KATIA IS TO THE E IMPACTING THE CENTRAL ATLC. SEE SPECIAL FEATURES FOR MORE DETAILS. AN UPPER LEVEL RIDGE TO THE E OF KATIA NEAR 21N49W IS SUPPORTING A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH NEAR 32N44W. A PAIR OF TROPICAL WAVES ARE IMPACTING THE CENTRAL AND ERN TROPICAL ATLC. THESE WAVES ARE EXPECTED TO DRIFT WWD BEFORE GAINING A NLY COMPONENT AND WILL MOVE AROUND THE SUBTROPICAL RIDGE. AN UPPER LEVEL TROUGH COVERING THE ERN ATLC FROM 30N26W TO 16N36W IS HELPING ENHANCE CONVECTION NEAR THE WRN MOST TROPICAL WAVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON