000 AXNT20 KNHC 191737 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON DEC 19 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1700 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS INLAND OVER W AFRICA TO THE COAST OF GUINEA NEAR 9N13W CONTINUING SW TO 7N16W. THE ITCZ CONTINUES FROM 7N16W ALONG 4N26W 5N43W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-5N BETWEEN 17W-28W. ...DISCUSSION... GULF OF MEXICO... SURFACE RIDGING DOMINATES THE GULF OF MEXICO TODAY AROUND A 1030 MB HIGH JUST OFF THE COAST OF NORTH CAROLINA NEAR 35N76W. THIS PATTERN IS PROVIDING MAINLY E-SE FLOW OF 15 KTS ACROSS MUCH OF THE BASIN WITH STRONGER WINDS UP TO 20 KTS IN THE NW CORNER ALONG THE TEXAS COAST. ALOFT...AN UPPER LEVEL RIDGE IS ACROSS THE BASIN EXTENDING FROM THE NW CARIBBEAN AND NWD ACROSS THE ERN CONUS SUPPORTING THE SURFACE RIDGE. DRY AIR ACCOMPANYING THE UPPER RIDGE IS KEEPING THE MAJORITY OF THE BASIN UNDER MOSTLY CLEAR SKIES AND FAIR WEATHER. A FEW AREAS OF STRATOCUMULUS CLOUDS DOT THE NE AND WRN PORTIONS WITH RADAR IMAGERY INDICATING ISOLATED SHOWERS ARE ALSO ALONG THE TEXAS COASTLINE. THE SURFACE RIDGE IS EXPECTED TO SHIFT EWD AS A COLD FRONT MOVES OFF THE TEXAS COAST IN ABOUT 24 HOURS. CARIBBEAN SEA... NE-E TRADEWIND FLOW OF 15-20 KTS IS ACROSS MUCH OF THE CARIBBEAN TODAY WITH A FEW OBSERVATIONS S OF HISPANIOLA INDICATING 25 KTS. PATCHES OF ISOLATED SHOWERS ARE EMBEDDED WITHIN THE TRADEWIND FLOW WITH MORE CONCENTRATED ACTIVITY OVER THE NW CARIBBEAN AND ALONG THE COAST OF CENTRAL AMERICA DUE TO DIFFLUENCE ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE E PACIFIC AND AN UPPER LEVEL RIDGE COVERING THE CARIBBEAN EXTENDING FROM VENEZUELA TO WRN CUBA AND NWD ACROSS THE ERN CONUS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN S OF 11N BETWEEN 76W-84W DUE TO SURFACE CONVERGENCE NEAR THE MONSOON TROUGH EXTENDING ACROSS PANAMA TO NRN COLOMBIA. EXPECT A FRONTAL BOUNDARY N OF THE BASIN IN THE W ATLC TO BEGIN BRINGING SHOWERS TO HISPANIOLA AND THE NRN LEEWARD ISLANDS WITHIN THE NEXT 12-24 HOURS. A SURFACE TROUGH AND ASSOCIATED CONVECTION IS ALSO E OF THE WINDWARD ISLANDS AND IS EXPECTED TO ADVECT WWD WHICH WILL IMPACT THE SRN WINDWARD ISLANDS. ATLANTIC OCEAN... A SHORTWAVE UPPER TROUGH OVER THE NW ATLC IS SUPPORTING A COLD FRONT ENTERING THE DISCUSSION AREA ALONG 32N54W 26N58W 22N67W 22N76W AND DISSIPATING TO CENTRAL CUBA. GALE FORCE WINDS ARE NOTED N OF 29N BEHIND THE FRONT. DUE TO DRY AIR ALOFT...ISOLATED SHOWERS ARE ONLY WITHIN 60 NM AHEAD OF THE AXIS WITH WIDESPREAD STRATOCUMULUS CLOUDS BEHIND IT. A PRE-FRONTAL TROUGH IE E OF THE FRONT ALONG 50W N OF 25N. POSSIBLE ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. A SURFACE RIDGE IS BUILDING IN BEHIND THE FRONT CURRENTLY ANCHORED AROUND A 1030 MB HIGH JUST OFFSHORE OF NORTH CAROLINA. FARTHER S IN THE TROPICAL ATLC...A SURFACE TROUGH IS ALONG 14N52W TO 9N56W. SCATTERED SHOWERS ARE WITHIN 200 NM NW OF THE AXIS. THE REMAINDER OF THE ERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING AROUND A 1034 MB HIGH OVER THE AZORES ISLANDS. ALOFT...AN UPPER LEVEL RIDGE IS CENTERED NEAR 34N25W SUPPORTING THE SURFACE RIDGE. A WEAK SHORTWAVE UPPER TROUGH IS ALONG 33N42W TO 21N32W CAUSING LITTLE SIGNIFICANT WEATHER. EXPECT THE FRONTAL SYSTEM IN THE CENTRAL ATLC TO MOVE NE OVER THE NEXT SEVERAL DAYS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON