000 AXNT20 KNHC 112348 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 11 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... TROPICAL STORM MARIA IS CENTERED NEAR 19.8N 65.2W AS OF 2100 UTC...OR ABOUT 100 NM NNE OF SAN JUAN PUERTO RICO. MARIA IS CURRENTLY MOVING WNW AT 8 KT. MINIMUM CENTRAL PRESSURE IS 1005 MB WITH MAXIMUM SUSTAINED WIND SPEEDS OF 50 KT WITH GUSTS TO 60 KT. PLEASE READ THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE SYSTEM CONTINUES TO BE SHEARED WITH MOST OF THE CONVECTION TO THE E AND N OF THE CENTER. CURRENTLY NUMEROUS STRONG CONVECTION IS FROM 16N-19N BETWEEN 60W-63W...AND FROM 18N-22N BETWEEN 62W-65W. NUMEROUS MODERATE CONVECTION IS ELSEWHERE FROM 15N-23N BETWEEN 59W-66W. SOME OF THIS HEAVY RAINFALL IS CURRENTLY OVER THE NRN LEEWARD ISLANDS AND THE VIRGIN ISLANDS. TROPICAL DEPRESSION NATE...DOWNGRADED AT 2100 UTC...IS CURRENTLY INLAND NEAR 20.6N 97.6W...OR ABOUT 25 NM SSW OF TUXPAN MEXICO. NATE IS MOVING WNW NEAR 7 KTS. MINIMUM CENTRAL PRESSURE IS 1010 MB WITH MAXIMUM SUSTAINED WIND SPEED OF 30 KT WITH GUSTS TO 40 KT. THIS SYSTEM IS EXPECTED TO CONTINUE TO WEAKEN AND DISSIPATE IN 24 HOURS. PLEASE READ THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 250 NM OF THE CENTER. ...TROPICAL WAVES... TROPICAL WAVE IN THE ATLC ALONG 19N47W TO 8N53W IS MOVING WWD AT 15-20 KT. THE WAVE LIES AHEAD OF A LARGE SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS ALSO INDICATE BROAD CYCLONIC FLOW AROUND THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE IS IMPACTING THE WRN CARIBBEAN ALONG 20N84W TO 11N83W MOVING W NEAR 10 KT. SIGNIFICANT DEEP LAYER MOISTURE COVERS THE WRN CARIBBEAN EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THE SRN EXTENT OF THE WAVE LIES JUST N OF THE MONSOON TROUGH. SCATTERED MODERATE/STRONG CONVECTION IS FROM 12N-16N BETWEEN 75W-82W...AND FROM 11N-19N BETWEEN 82W-87W. A CLUSTER OF STRONG CONVECTION IS FROM 11N-15N BETWEEN 86W-89W ACROSS WRN NICARAGUA...HONDURAS...AND EL SALVADOR. STRONG ACTIVITY IS ALSO ACROSS THE YUCATAN PENINSULA AND PORTIONS OF CUBA. DUE TO THE LARGE AREA OF MOISTURE PRESENT...IT IS HARD TO DETERMINE WHAT IS SOLELY ASSOCIATED WITH THE WAVE. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 20N16W ALONG 15N22W 10N28W 8N38W. THE ITCZ CONTINUES FROM 8N38N TO 9N48W WHERE SOME WEAK SE-NE WIND CONVERGENCE HAS REFORMED BEHIND THE WAVE STILL E OF THE LESSER ANTILLES. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-12N BETWEEN 17W-23W. ISOLATED MODERATE/STRONG CONVECTION IS FROM 3N-8N BETWEEN 23W-34W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO FROM 6N-9N BETWEEN 41W-44W. ...DISCUSSION... THE GULF OF MEXICO... T.D. NATE IS NOW INLAND OVER MEXICO...BUT IS STILL PRODUCING ISOLATED SHOWERS/THUNDERSTORMS OVER THE BAY OF CAMPECHE S OF 24N. STRONG SHOWERS/THUNDERSTORMS ARE ALSO MOVING OVER THE WRN HALF OF THE YUCATAN PENINSULA AND OVER THE ERN BAY OF CAMPECHE. THIS MAY BE INFLUENCED BY MOISTURE ASSOCIATED WITH A TROPICAL WAVE IN THE WRN CARIBBEAN...AS WELL AS DIFFLUENCE ALOFT BETWEEN AN UPPER LEVEL RIDGE OVER THE WRN CARIBBEAN AND A WEAK INVERTED UPPER TROUGH OVER THE SRN BAY OF CAMPECHE. MAINLY SWLY FLOW COVERS MUCH OF THE BASIN BETWEEN THE UPPER RIDGE IN THE WRN CARIBBEAN AND WRN ATLC...AND AN UPPER LEVEL TROUGH OVER THE ERN CONUS. WATER VAPOR IMAGERY INDICATES THAT DRY AIR ALOFT IS PUSHING INTO THE NW GULF MAINTAINING FAIR CONDITIONS. A FEW ISOLATED SHOWERS ARE S OF THIS DRY AIR BOUNDARY ALONG A LINE FROM 28N88W TO 25N96W. A FEW STRONG STORMS ARE ALSO OVER SW FLORIDA AND NEAR CAPE CANAVERAL FLORIDA. EXPECT WEAK SURFACE RIDGING TO FORM OVER THE NRN GULF WHICH WILL REMAIN STATIONARY TROUGH MUCH OF THE WEEK. THE CARIBBEAN SEA... A TROPICAL WAVE IN THE WRN CARIBBEAN IS PRODUCING A LARGE AREA OF SHOWERS/THUNDERSTORMS ACROSS THE WRN HALF OF THE BASIN. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 12N-16N BETWEEN 75W-82W...AND FROM 11N-19N BETWEEN 82W-87W. A CLUSTER OF STRONG CONVECTION IS FROM 11N-15N BETWEEN 86W-89W ACROSS WRN NICARAGUA...HONDURAS...AND EL SALVADOR. STRONG ACTIVITY IS ALSO ACROSS THE YUCATAN PENINSULA AND PORTIONS OF CUBA. SIMILARLY STRONG ACTIVITY IS ACROSS NRN COLOMBIA AND NW VENEZUELA MOST LIKELY ASSOCIATED WITH THE MONSOON TROUGH EXTENDING FROM COSTA RICA TO NRN COLOMBIA. SOME OF THE SHOWERS OVER CUBA MAY BE ASSOCIATED WITH A WEAK SURFACE TROUGH EXTENDING FROM SE FLORIDA TO CENTRAL CUBA. THE ERN CARIBBEAN IS FEELING THE IMPACTS OF T.S. MARIA. STRONG SHOWERS/THUNDERSTORMS ARE CURRENTLY HITTING THE NRN LEEWARD ISLANDS AND THE VIRGIN ISLANDS. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. ALOFT...AN UPPER LEVEL RIDGE COVERS THE WRN CARIBBEAN CENTERED NEAR 20N79W. DRY AIR IS WRAPPING AROUND THE ERN SIDE WHICH IS HELPING MAINTAIN FAIR CONDITIONS ACROSS HISPANIOLA. UPPER LEVEL RIDGING IS ALSO OVER THE ERN CARIBBEAN DUE TO THE OUTFLOW OF MARIA. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE WRN CARIBBEAN AS THE TROPICAL WAVE SLOWLY MOVES WWD. INTERESTS IN THE NE CARIBBEAN SHOULD CONTINUE TO MONITOR THE PROGRESS OF T.S. MARIA. THE ATLANTIC OCEAN... SCATTERED SHOWERS/THUNDERSTORMS ARE BETWEEN CUBA AND THE NW BAHAMAS/SE FLORIDA ASSOCIATED WITH A WEAK SURFACE TROUGH EXTENDING FROM 25N80W TO S OF CENTRAL CUBA. T.S. MARIA IS JUST N OF THE VIRGIN ISLANDS PRODUCING A LARGE AREA OF SHOWERS/THUNDERSTORMS ACROSS THE CENTRAL ATLC. SEE SPECIAL FEATURES FOR MORE DETAILS. AN UPPER LEVEL TROUGH ALONG 63W...SANDWICHED BETWEEN AN UPPER LEVEL RIDGE OVER THE WRN ATLC AND THE OUTFLOW OF MARIA...IS PRODUCING SHEAR ACROSS MARIA WHICH CONTRIBUTES TO THE ELONGATED PATTERN IN THE SHOWER ACTIVITY. FARTHER E...A SERIES OF HIGH PRESSURE CENTERS DOT THE ERN ATLC PRODUCING A BROAD SURFACE RIDGE WHICH IS MAINTAINING MOSTLY FAIR WEATHER BESIDES THAT ASSOCIATED WITH A TROPICAL WAVE IN THE TROPICAL ATLC. ALOFT...AN UPPER LEVEL TROUGH IS ALONG 39W WITH A WEAK UPPER LEVEL RIDGE ALONG 30W. EXPECT T.S. MARIA TO BE THE MAIN FOCUS IN THE ATLC BASIN FOR THE NEXT SEVERAL DAYS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON