000 AXNT20 KNHC 100533 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT DEC 10 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0500 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH REMAINS INLAND ACROSS AFRICA EXTENDING TO THE COAST OF NRN GUINEA NEAR 11N15W. THE ITCZ CONTINUES FROM 11N15W ALONG 7N26W 8N41W 7N49W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-8N BETWEEN 23W-40W. ...DISCUSSION... GULF OF MEXICO... SURFACE RIDGING CONTINUES TO COVER THE GULF OF MEXICO TONIGHT AROUND A 1035 MB HIGH OVER ERN NEBRASKA. DESPITE THE HIGH PRESSURE...LOW-LEVEL CLOUDS AND POSSIBLE ISOLATED SHOWERS ARE EMBEDDED WITHIN THE ANTI-CYCLONIC FLOW ESPECIALLY OVER THE ERN GULF AND FAR WRN GULF NEAR THE COAST OF MEXICO. FROM SATELLITE IMAGERY...IT APPEARS THAT A SURFACE TROUGH MAY HAVE FORMED IN THE SE GULF WHICH COULD BE CONTRIBUTING TO THE SHOWER ACTIVITY. ALOFT...A BROAD UPPER LEVEL TROUGH IS MOVING ACROSS THE BASIN WITH AXIS FROM LOUISIANA TO THE YUCATAN PENINSULA. WATER VAPOR IMAGERY INDICATES DRY AIR SE OF A LINE FROM NE FLORIDA NEAR 30N81W TO THE BAY OF CAMPECHE NEAR 21N97W. TO THE NW OF THIS LINE...UPPER LEVEL MOISTURE IS PRESENT SUPPORTING SOME UPPER LEVEL CLOUDS ACROSS THE NRN GULF. AS THE HIGH PRESSURE SYSTEM OVER THE CENTRAL CONUS SHIFTS EWD AND STRENGTHENS SLIGHTLY THE PRESSURE GRADIENT OVER THE GULF WITH ALSO STRENGTHEN. THIS WILL CAUSE AN INCREASE IN NE-E WINDS OF 20-25 KTS BASIN-WIDE OVER THE NEXT 24 HOURS. ISOLATED SHOWERS WILL ALSO LIKELY REMAIN OVER THE FAR WRN AND ERN PORTIONS OF THE GULF. CARIBBEAN SEA... DRY AIR ALOFT OVER THE NW CARIBBEAN IS MAINTAINING MOSTLY FAIR WEATHER EXCEPT FOR AN AREA OF SCATTERED SHOWERS NEAR A SHEAR AXIS EXTENDING FROM 21N82W TO 15N84W. THE AXIS DEPICTS THE DELINEATION BETWEEN 20 KT NLY WINDS TO THE W AND 10 KT NELY WINDS TO THE E. THIS IS CREATING CONVERGENCE ALONG THE AXIS AND SUPPORTING SCATTERED SHOWERS WITHIN 100 NM W OF THE AXIS. AN AREA OF SCATTERED SHOWERS IS ALSO FROM 10N-12N BETWEEN 77W-79W WITH ISOLATED SHOWERS S OF 16N BETWEEN 75W-83W DUE TO BROAD CYCLONIC FLOW AROUND THE MONSOON TROUGH AXIS EXTENDING ACROSS CENTRAL COSTA RICA TO NRN COLOMBIA. SHOWERS/THUNDERSTORMS ARE ALSO IMPACTING PUERTO RICO AND THE NRN-MOST LEEWARD ISLANDS DUE TO AN ELONGATED UPPER LEVEL TROUGH TO THE NW OF THE ISLANDS. MOST CONDITIONS ARE EXPECTED TO REMAIN OVER THIS PORTION OF THE BASIN FOR AT LEAST THE NEXT 24 HOURS. THE REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR CONDITIONS WITH 15-20 KT NE-E TRADEWIND FLOW. ATLANTIC OCEAN... A SURFACE TROUGH CONTINUES TO IMPACT THE WRN ATLC ALONG 31N73W 27N77W 23N77W. SCATTERED SHOWERS ARE WITHIN 75 NM NW OF THE AXIS. ALOFT...AN UPPER LEVEL RIDGE DOMINATES THE WRN ATLC CENTERED NEAR 30N62W PROVIDING MOSTLY FAIR WEATHER BESIDES THAT NEAR THE SURFACE TROUGH...AND SCATTERED SHOWERS NEAR THE NRN LEEWARD ISLANDS DUE TO A WEAK ELONGATED UPPER TROUGH ALONG 23N69W TO 17N62W. FARTHER E...AN UPPER LEVEL LOW IS IMPACTING THE CENTRAL ATLC CENTERED NEAR 23N48W. IT IS SUPPORTING A SURFACE TROUGH ALONG 28N49W 22N27W 17N51W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY E OF THE AXIS WITHIN 300 NM...WITH SIMILAR ACTIVITY WITHIN 150 NM TO THE W FROM 22N-26N. MOISTURE NEAR THE UPPER LOW IS ALSO BEING DRAWN ACROSS THE ERN ATLC TO NRN AFRICA IN WLY FLOW ALONG AROUND A NARROW UPPER LEVEL TROUGH EXTENDING FROM THE UPPER LOW TO THE MADEIRA ISLANDS AN ACROSS WRN SPAIN. TO THE S...AN UPPER LEVEL RIDGE DOMINATES THE TROPICAL ATLC SUPPORTING A 1033 MB HIGH WHICH IS COVERING THE REMAINDER OF THE ERN ATLC. EXPECT THE TROUGH IN THE CENTRAL ATLC TO DRIFT WWD OVER THE NEXT COUPLE OF DAYS WHILE THE TROUGH IN THE WRN ATLC GRADUALLY DISSIPATES. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON