000 AXNT20 KNHC 222351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU SEP 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM OPHELIA AT 22/2100 UTC IS NEAR 13.8N 48.9W...OR ABOUT 770 NM ESE OF THE LEEWARD ISLANDS. OPHELIA IS MOVING WEST NEAR 11 KT. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. PUBLIC ADVISORIES ABOUT OPHELIA ARE ISSUED UNDER WMO HEADER WTNT31 KNHC AND UNDER AWIPS HEADER MIATCPAT1. FORECAST/ ADVISORIES ABOUT OPHELIA ARE ISSUED UNDER WMO HEADER WTNT21 KNHC AND UNDER AWIPS HEADER MIATCMAT1. THE STORM CONTINUES TO BE SHEARED BY AN UPPER LEVEL TROUGH TO THE W WHICH IS DISPLACING THE CONVECTION TO THE ERN HALF OF THE STORM. A CLUSTER OF STRONG CONVECTION IS FROM 14N-17N BETWEEN 46W-48W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 10N-13N BETWEEN 44W-47W. NUMEROUS MODERATE CONVECTION IS ELSEWHERE FROM 14N-19N BETWEEN 42W-49W. ...TROPICAL WAVES... TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS ALONG 20N29W TO 11N32W MOVING W NEAR 15 KT. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE BROAD CYCLONIC FLOW IN THE LOW-MID LEVELS AROUND THE WAVE AXIS. A RECENT WINDSAT SCATTEROMETER PASS ALSO INDICATES SURFACE CYCLONIC FLOW AROUND THE AXIS. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT ENHANCED DEEP LAYER MOISTURE ACCOMPANIES THE WAVE ALSO EXTENDING WELL N OF THE WAVE AXIS. ISOLATED MODERATE/STRONG CONVECTION IS W OF THE WAVE AXIS FROM 10N-12N BETWEEN 33W-38W. ...THE ITCZ/THE MONSOON TROUGH... A SMALL PORTION OF THE MONSOON TROUGH EXTENDS FROM NEAR THE COAST OF AFRICA AT 8N17W WHERE SOME EVIDENT MID-LEVEL CYCLONIC TURNING IS OCCURRING CONTINUING TO E OF THE TROPICAL WAVE AXIS NEAR 10N30W. A CLUSTER OF NUMEROUS STRONG CONVECTION IS MOVING OFF THE AFRICAN COAST FROM 10N-13N BETWEEN 14W-18W. SCATTERED MODERATE/STRONG CONVECTION IS S OF THE AXIS FROM 4N-7N BETWEEN 18W-24W. ...DISCUSSION... THE GULF OF MEXICO... A LONGWAVE UPPER LEVEL TROUGH MOVING ACROSS THE CENTRAL UNITED STATES IS IMPACTING THE WEATHER IN THE ERN GULF OF MEXICO. DIFFLUENCE AROUND THE ERN SIDE OF THE UPPER TROUGH IS SUPPORTING A LARGE AREA OF STRONG SHOWERS/THUNDERSTORMS ACROSS CENTRAL FLORIDA AND THE IMMEDIATE OFFSHORE WATERS FROM 26N-30N E OF 85W. THE UPPER TROUGH IS ALSO SUPPORTING A SURFACE TROUGH EXTENDING FROM SE LOUISIANA INTO THE BAY OF CAMPECHE ALONG 29N91W TO 21N92W. ISOLATED SHOWERS/THUNDERSTORMS ARE E OF THE SURFACE TROUGH N OF 23N E OF 90W. THE REMAINDER OF THE WRN GULF IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT. EXPECT THE SURFACE TROUGH IS REMAIN SOMEWHAT STATIONARY BEFORE BEING ABSORBED BY A COLD FRONT THAT WILL MOVE ACROSS THE AREA ON SATURDAY. MOIST CONDITIONS WILL REMAIN OVER THE ERN GULF OF MEXICO. THE CARIBBEAN SEA... STRONG SHOWERS/THUNDERSTORMS ARE ACROSS THE YUCATAN PENINSULA...CUBA...JAMAICA...AND HISPANIOLA THIS EVENING MOST LIKELY THE RESULT OF WIDESPREAD DEEP MOISTURE AND DAYTIME HEATING. SOME OF THE ACTIVITY OVER HISPANIOLA IS ALSO INFLUENCED BY A WEAK 1012 MB DISSIPATING LOW CURRENTLY JUST S OF THE DOMINICAN REPUBLIC NEAR 18N70W. A LARGE CLUSTER OF SHOWERS/ISOLATED THUNDERSTORMS IS ALSO E OF NICARAGUA AND COSTA RICA FROM 10N-13N BETWEEN 79W-83W WITH SCATTERED ACTIVITY ACROSS MUCH OF CENTRAL AMERICA. THE LARGE CLUSTER IS INFLUENCE BY UPPER LEVEL DIFFLUENCE AROUND AN UPPER LEVEL TROUGH WITH AXIS DOWN CENTRAL AMERICA. SOME OF THE ACTIVITY IS ALSO INFLUENCED BY THE MONSOON TROUGH EXTENDING ACROSS THE COSTA RICA/PANAMA BORDER TO NRN COLOMBIA. ISOLATED SHOWERS ARE ALSO EMBEDDED WITHIN THE 15 KT TRADEWIND FLOW OVER THE ERN CARIBBEAN. MUCH OF THE CARIBBEAN WILL REMAIN UNDER MOIST CONDITIONS OVER THE NEXT COUPLE OF DAYS WITH SOME DRY AIR AHEAD OF OPHELIA MOVING INTO THE ERN CARIBBEAN. THE ATLANTIC OCEAN... THE AREA OF SHOWERS/THUNDERSTORMS ACROSS THE ERN GULF OF MEXICO AND FLORIDA EXTEND INTO THE ATLC WATERS NW OF A LINE FROM 27N80W TO 32N77W ASSOCIATED WITH A LONGWAVE UPPER LEVEL TROUGH MOVING ACROSS THE CENTRAL UNITED STATES. A BROAD SURFACE RIDGE COVERS THE REMAINDER OF THE W/CENTRAL ATLC SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 31N71W. HOWEVER...AN INVERTED UPPER TROUGH TO THE S ACROSS ERN CUBA AND THE NW BAHAMAS IS PROVIDING DIFFLUENCE ALOFT TO SUPPORT SCATTERED SHOWERS/THUNDERSTORMS N OF THE ERN BAHAMAS FROM 22N-27N BETWEEN 68W-75W. ANOTHER UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC ALONG 53W. A SHORTWAVE TROUGH EXTENDS OFF THE MAIN TROUGH SUPPORTING ANOTHER AREA OF SCATTERED SHOWERS/THUNDERSTORMS FROM 23N-28N BETWEEN 60W-64W FARTHER E...TROPICAL STORM OPHELIA IS IMPACTING THE CENTRAL TROPICAL ATLC. THE AFOREMENTIONED UPPER TROUGH ALONG 53W CONTINUES TO SHEAR OPHELIA. A SURFACE TROUGH HAS FORMED TO THE S OF THE STORM ALONG 10N49W TO 8N55W SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF THE AXIS. WEAK SURFACE RIDGING COVERS THE ERN ATLC AROUND A 1023 MB HIGH BETWEEN THE AZORES ISLANDS AND MADEIRA ISLANDS. ALOFT...AN UPPER LEVEL RIDGE IS CENTERED TO THE E OF OPHELIA NEAR 17N38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON