000 AXNT20 KNHC 122340 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED OCT 12 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. ...TROPICAL WAVES... TROPICAL WAVE IS IN THE ERN TRPCL ATLC ALONG 14N20W TO 8N24W MOVING W NEAR 10 KT. THE WAVE REMAINS LOW AMPLITUDE...BUT DOES COINCIDE WITH A SLIGHT SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-10N BETWEEN 20W-27W. ...THE ITCZ/THE MONSOON TROUGH... ONLY A SMALL PORTION OF THE MONSOON TROUGH EXISTS W OF THE TROPICAL WAVE AXIS ALONG 7N25W 8N32W. THE ITCZ CONTINUES FROM 8N32W ALONG 8N40W 5N52W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM S...AND 280 NM N OF THE AXIS BETWEEN 27W-48W. SIMILAR ACTIVITY IS ALSO FROM 2N-10N BETWEEN 51W-59W. ...DISCUSSION... THE GULF OF MEXICO... MAINLY WLY FLOW ALOFT COVERS THE GULF OF MEXICO BETWEEN AN UPPER LEVEL RIDGE TO THE S CENTERED OVER THE YUCATAN PENINSULA AND AN UPPER LEVEL TROUGH TO THE N OVER THE ERN CONUS. MOSTLY DRY AIR ALOFT COVERS THE NW AND SE PORTIONS MAINTAINING FAIR CONDITIONS WITH A SWATCH OF MOISTURE EXTENDING FROM THE SW TO NE BEING DRAWN FROM THE MOISTURE ASSOCIATED WITH WHAT IS NOW T.D. JOVA WHICH IS INLAND OVER SW MEXICO. THIS UPPER LEVEL MOISTURE IS SUPPORTING HIGH CLOUDS. A SURFACE TROUGH ALSO EXTENDS SW TO NE ACROSS THE BASIN FROM A WEAK 1009 MB SURFACE LOW NEAR 24N93W TO THE BIG BEND OF FLORIDA TO NEAR 31N83W. POSSIBLE ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. A FEW STRONGER STORMS ARE ALSO NOTED NEAR LAKE OKEECHOBEE FLORIDA. THE SURFACE LOW IS EXPECTED TO CONTINUE TO WEAKEN AS A WEAK FRONT ENTERS THE NW GULF THURSDAY. THE CARIBBEAN SEA... DRY AIR ALOFT IS BEING WRAPPED AROUND THE ERN SIDE OF AN UPPER LEVEL RIDGE OVER THE YUCATAN PENINSULA WHICH IS HELPING MAINTAIN FAIR CONDITIONS ACROSS THE FAR NW CARIBBEAN. HOWEVER...A NARROW UPPER LEVEL TROUGH OVER THE BAHAMAS...ERN CUBA...AND JAMAICA IS PLACING DIFFLUENT FLOW OVER THE CENTRAL CARIBBEAN. THIS IS PRODUCING ISOLATED SHOWERS/THUNDERSTORMS N OF 14N BETWEEN 69W-75W WITH SIMILAR ACTIVITY ALSO OVER JAMAICA AND PUERTO RICO. THE MONSOON TROUGH REMAINS N OF ITS USUAL LOCATION AND CURRENTLY EXTENDS JUST E OF T.D. TWELVE-E ACROSS SE MEXICO...GUATEMALA...NRN HONDURAS ALONG 16N AND CONTINUES SE TO NRN COLOMBIA ALONG 15N83W TO 11N75W. STRONG SHOWERS/THUNDERSTORMS ARE S OF THE AXIS CONCENTRATED OVER HONDURAS...NRN NICARAGUA...COSTA RICA...PANAMA...AND OVER THE SW CARIBBEAN FROM 9N-13N BETWEEN 78W-83W. ACROSS THE ERN CARIBBEAN...A NARROW UPPER LEVEL RIDGE IS ALONG 67W WHICH IS DRAWING DRY AIR ALOFT OVER THIS PORTION OF THE BASIN MAINTAINING MOSTLY FAIR WEATHER BESIDES SOME ISOLATED SHOWERS ACROSS THE WINDWARD ISLANDS ASSOCIATED WITH AN AREA OF LOW-LEVEL MOISTURE. THE ATLANTIC OCEAN... A NARROW UPPER LEVEL TROUGH EXTENDS FROM THE CENTRAL BAHAMAS SWD ALONG 76W PLACING DIFFLUENT FLOW ALOFT ACROSS HISPANIOLA AND THE SE BAHAMAS. THE UPPER TROUGH ALSO SUPPORTS A WEAK 1009 MB LOW NEAR 23N75W WITH A SURFACE TROUGH EXTENDING THROUGH IT ALONG 26N76W TO 22N73W. THE COMBINATION OF SURFACE CONVERGENCE AND DIFFLUENCE ALOFT IS SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-25N BETWEEN 70W-74W. AN UPPER LEVEL RIDGE IS TO THE E ALONG 67W SUPPORTING SURFACE RIDGING EXTENDING FROM A 1028 MB HIGH CENTERED S OF NEWFOUNDLAND. A LONGWAVE UPPER TROUGH EXTENDS ALONG 39N40W TO E OF THE LESSER ANTILLES NEAR 11N59W. A SHEARLINE...REMNANTS OF AN OLD FRONTAL BOUNDARY EXTENDS ALONG 30N34W 22N48W 25N63W. ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS. AN UPPER LEVEL RIDGE COVERS THE FAR ERN ATLC ALONG 13N33W TO 36N24W SUPPORTING SURFACE RIDGING AROUND A 1026 MB HIGH NEAR 47N9W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON