000 AXNT20 KNHC 122318 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT NOV 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 2300 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC ALONG 12N16W 8N19W 6N26W. THE ITCZ CONTINUES FROM 6N26W ALONG 7N38W 7N50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-10N BETWEEN 32W-41W. ...DISCUSSION... GULF OF MEXICO... A SURFACE RIDGE CONTINUES TO DOMINATE THE GULF OF MEXICO THIS EVENING ANCHORED BY A 1027 MB HIGH OVER SW GEORGIA WITH AXIS EXTENDING FROM THE NE GULF TO THE SW GULF. ANTI-CYCLONIC SURFACE FLOW OF 10-15 KTS IS AROUND THE RIDGE REACHING 20 KTS ALONG THE TEXAS COAST. CLUSTERS OF STRATOCUMULUS CLOUDS COVER MUCH OF THE BASIN WITH THE CLEAREST SKIES OVER THE FAR ERN GULF. ALOFT...AN UPPER LEVEL RIDGE EXTENDS ACROSS MUCH OF MEXICO AND INTO THE ERN CONUS SUPPORTING THE SURFACE RIDGE. WATER VAPOR IMAGERY INDICATES VERY DRY AIR ALOFT OVER THE MAJORITY OF THE BASIN EXCEPT FOR A LITTLE MOISTURE PRESENT OVER THE FAR NW CORNER. EXPECT SURFACE RIDGING TO REMAIN ACROSS THE BASIN FOR THE NEXT COUPLE OF DAYS. CARIBBEAN SEA... DRY AIR ALOFT OVER THE GULF OF MEXICO EXTENDS OVER THE NW CARIBBEAN MAINTAINING FAIR CONDITIONS WITH A FEW LOW-LEVEL STRATOCUMULUS CLOUDS. ISOLATED SHOWERS ARE NOTED ACROSS BELIZE AND NRN HONDURAS ASSOCIATED WITH A SMALL AREA OF MOISTURE LEFT BEHIND BY A FRONTAL BOUNDARY THAT DISSIPATED LAST NIGHT. ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM THE W ATLC ACROSS WRN CUBA TO HONDURAS WITH UPPER LEVEL RIDGING COVERING THE REMAINDER OF THE BASIN CENTERED NEAR 17N69W. THIS PATTERN IS CREATING AN AREA OF DIFFLUENCE ALOFT WITH MOIST SWLY FLOW FROM THE SW CARIBBEAN TO THE WINDWARD PASSAGE. THIS COMBINED WITH THE MONSOON TROUGH WHICH EXTENDS FROM THE COSTA RICA/PANAMA BORDER TO NRN COLOMBIA...AND A LOW-MID LEVEL TROUGH S OF JAMAICA IS CAUSING SCATTERED SHOWERS/THUNDERSTORMS S OF 16N BETWEEN 72W-83W. SHOWER/THUNDERSTORM ACTIVITY WILL LIKELY REMAIN IN THIS AREA OVER THE NEXT DAY OR SO AND BEGIN TO ADVECT WWD IN THE E PACIFIC. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO OVER THE DOMINICAN REPUBLIC INFLUENCED BY THE UPPER LEVEL TROUGH. THE ERN CARIBBEAN IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT. A WEAK SURFACE TROUGH IS JUST W OF THE WINDWARD ISLANDS ASSOCIATED WITH AN AREA OF LOW LEVEL MOISTURE SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 61N E OF 64W. ATLANTIC OCEAN... SURFACE RIDGING AND DRY AIR ALOFT ARE KEEPING THE FAR WRN ATLC UNDER FAIR CONDITIONS. AN UPPER LEVEL TROUGH ALONG 35N72W TO WRN CUBA IS SUPPORTING A COLD FRONT ALONG 32N52W 27N61W 24N70W BECOMING STATIONARY TO ERN CUBA NEAR 21N77W. ISOLATED SHOWERS ARE WITHIN 30 NM OF THE AXIS. AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS IS ALSO S OF THE FRONT ALONG A LINE FROM 20N70W TO 23N65W. ACROSS THE ERN ATLC...AN UPPER LEVEL RIDGE EXTENDS FROM THE ERN CARIBBEAN TO NEAR 41N42W SUPPORTING A 1024 MB SURFACE HIGH NEAR 35N40W. A SHORTWAVE UPPER LEVEL TROUGH IS JUST E OF THE RIDGE FROM 24N51W TO 13N59W SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS E OF THE WINDWARD ISLANDS FROM 8N14N BETWEEN 53W-63W. A SECOND UPPER TROUGH IS FARTHER E EXTENDING BETWEEN THE AZORES ISLANDS AND CANARY ISLANDS TO W OF THE CAPE VERDE ISLANDS SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N12W TO 26N15W. A WEAK 1011 MB SURFACE LOW IS ALSO EMBEDDED WITHIN THE SURFACE RIDGE NEAR 20N35W. EXPECT THE SOUTHERN PORTION OF THE FRONTAL BOUNDARY IN THE CENTRAL/WRN ATLC TO BEGIN TO DISSIPATE WHILE THE NRN PORTION CONTINUES TO PUSH EWD. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON