000 AXNT20 KNHC 092353 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST FRI DEC 09 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 2345 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH REMAINS INLAND ACROSS AFRICA EXTENDING ACROSS THE COUNTRIES OF GHANA...COTE D' IVOIRE...LIBERIA...AND SIERRA LEONE. THE ITCZ ENTERS THE ATLC WATERS ACROSS THE COAST OF GUINEA NEAR 10N15W...CONTINUING WESTWARD ALONG 10N20W 7N30W 9N40W TO 7N47W. SCATTERED MODERATE CONVECTION IS FROM 3N-11N BETWEEN 25W-41W. ...DISCUSSION... GULF OF MEXICO... FAIR WEATHER CONDITIONS ARE PRESENT ACROSS THE GULF THIS EVENING...INFLUENCED BY A LARGE 1034 MB RIDGE OF HIGH PRESSURE MOVING ACROSS THE CENTRAL CONUS. DESPITE THE BENIGN WEATHER...A GREAT PORTION OF THE BASIN IS COVERED BY OVERCAST LOW LEVEL STRATOCUMULUS CLOUDS WITH A FEW POSSIBLE ISOLATES SHOWERS OBSERVED ON NIGHT-VISIBLE IMAGERY...ESPECIALLY ACROSS THE COASTAL WATERS OF MEXICO W OF 95W. WATER VAPOR IMAGERY SHOWS SOME MID-UPPER LEVEL MOISTURE MOVING ACROSS THE NW BASIN... EMBEDDED IN THE SOUTHWESTERLY WIND FLOW THAT COVERS THE DISCUSSION AREA. AS THE SURFACE RIDGE SETTLES OVER THE SE CONUS...SHORT RANGE COMPUTER MODELS ARE IN GOOD AGREEMENT WITH A TIGHT PRESSURE GRADIENT DEVELOPING OVER MOST OF THE GULF WATERS N OF 22N...GENERATING GUSTY NE WINDS UP TO 25 KT. ALSO LOOK FOR INCREASING PRECIPITATION OVER THE FAR ERN AND WRN PORTIONS OF THE GULF DURING THE FORECAST PERIOD. CARIBBEAN SEA... A REMNANT CLOUD/SHEAR LINE IS ANALYZED OVER THE NW CARIBBEAN FROM 21N82W TO ERN HONDURAS NEAR 15N84W. A RECENT SATELLITE SCATTEROMETER PASS OVER THIS AREA REVEALED E-NE CONVERGING LOW LEVEL WINDS INCREASING FROM 10 KT T0 20 KT FROM E TO W ALONG THE AXIS...GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 100 NM W OF THE AXIS. THIS FEATURE IS EXPECTED TO LINGER OVER THE NEXT 24 HOURS. AN E-W ELONGATED NARROW UPPER LEVEL LOW/TROUGH IS LOCATED N OF PUERTO RICO. THIS UPPER LEVEL FEATURE IS GENERATING SHOWERS AND THUNDERSTORMS AFFECTING THE US/UK VIRGIN ISLANDS AND PUERTO RICO WATERS N OF 16N E OF 68W. THE CONVECTION IN THIS REGION IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS. EASTERLY TRADE WIND FLOW IS OBSERVED ACROSS THE CARIBBEAN E OF 77W WITH A FEW ISOLATED LOW TOP SHOWERS EMBEDDED IN THE FLOW. THIS FLOW TURNS CYCLONICALLY W OF 77W AND ESPECIALLY OVER THE FAR SW BASIN...IN RESPONSE OF THE LOWER PRESSURE REGION ASSOCIATED TO THE MONSOON TROUGH ANALYZED ACROSS COSTA RICA INTO NRN COLOMBIA. SCATTERED SHOWERS AND THUNDERSTORMS ARE S OF 12N BETWEEN 75W-82W. ATLANTIC OCEAN... THE PREVIOUSLY W ATLC WEAK STATIONARY FRONT ANALYZED DURING THE PAST SEVERAL DAYS HAS LOST THE UPPER LEVEL SUPPORT AS THE FLOW ALOFT BECOMES MORE DRY AND FROM THE SSW. HENCE...THE SURFACE FEATURE HAS BEEN CHANGED TO A SURFACE TROUGH ANALYZED FROM 31N74W TO 22N78W. THIS FEATURE WAS SLOWLY TRACKING WESTWARD OVER THE LAST 6-8 HOURS...GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 40 NM EITHER SIDE OF ITS AXIS. WELL TO THE EAST OF THIS FEATURE...AN UPPER LEVEL LOW SPINS NEAR 23N49W. THIS UPPER LEVEL FEATURE REFLECTS A SURFACE TROUGH EXTENDING FROM 27N47W ALONG 22N47W TO 15N61W. MID-UPPER LEVEL DIFFLUENCE IN THE VICINITY OF THE SURFACE TROUGH IS GENERATING A BROAD AREA OF SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 200-250 NM E OF THE SURFACE TROUGH. WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL MOISTURE ASSOCIATED TO THIS SYSTEM MOVING EASTWARD ACROSS THE ERN ATLC BASIN WITHOUT ANY INFLUENCE AT SURFACE...DUE TO A STRONG SURFACE RIDGE ANCHORED BY A 1030 MB HIGH W OF THE AZORES NEAR 37N35W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA