000 AXNT20 KNHC 161136 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST WED DEC 16 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 7N10W 5N24W 6N39W EQ52W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM N AND 60 NM S OF THE AXIS BETWEEN 22W-30W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 32W-37W. ...DISCUSSION... GULF OF MEXICO... AS OF 0900 UTC...AN UPPER LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY TO THE SOUTHERN PLAINS INTO NW MEXICO SUPPORTING A 1018 MB LOW OFF THE NE MEXICO COASTLINE NEAR 24N95W. A COLD FRONT EXTENDS S FROM THE LOW TO VERACRUZ MEXICO CONTINUING INLAND. A PRE-FRONTAL TROUGH IS AHEAD OF THE FRONT ALONG 21N94W 18N95W. A STATIONARY FRONT EXTENDS N OF THE LOW CENTER PARALLELING THE GULF COASTLINE ALONG 27N92W TO 29N87W WHERE IS BECOMES COLD TO THEN OF TAMPA ACROSS NRN FLORIDA TO SAINT AUGUSTINE. SURFACE CONVERGENCE NEAR THE LOW CENTER AND FRONTAL BOUNDARIES ALONG WITH DIFFLUENT FLOW ALOFT TO THE E SIDE OF THE UPPER TROUGH ARE SUPPORTING NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE NW GULF FROM 20N-29N W OF 90W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 100 NM OF THE BOUNDARY ELSEWHERE. A SURFACE TROUGH IS ANALYZED ACROSS S FLORIDA FROM MIAMI TO S OF KEY WEST TO W CUBA. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. N-NE GALE FORCE WINDS UP TO 35 KT ARE CURRENTLY BEHIND THE FRONT IN THE NW GULF S OF 28N W OF 90W. EXPECT THE COLD FRONT ACROSS THE NE GULF AND NRN FLORIDA TO DIP SWD AS THE LOW IN THE NW GULF REMAINS RELATIVELY STATIONARY UNTIL THURSDAY WHEN IT IS FORECAST TO DEEPEN AND MOVE NE-E ACROSS THE GULF. CARIBBEAN SEA... STRONG ELY TRADEWINDS CONTINUE ACROSS THE CARIBBEAN AS A RESULT OF A STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE W ATLC AND LOW PRESSURE OVER NRN COLOMBIA. THE STRONGEST WINDS...UP TO 30 KT...ARE OFF THE COAST OF COLOMBIA. STRONG SUBSIDENCE AND DRY AIR AROUND AN UPPER LEVEL RIDGE WITH AXIS ALONG 70W DOMINATE THE BASIN SUPPORTING GENERALLY FAIR WEATHER ACROSS THE AREA. HOWEVER...A LINE OF ISOLATED LOW-LEVEL SHOWERS EMBEDDED IN THE ELY SURFACE FLOW ARE MOVING QUICKLY FROM THE LEEWARD ISLANDS TO JAMAICA AND S OF W CUBA. A FEW ISOLATED SHOWERS ARE ALSO NOTED OFF THE YUCATAN PENINSULA IN THE FAR NW CARIBBEAN. EXPECT TRADE WINDS TO DIMINISH SLIGHTLY DUE TO LOW PRESSURE IN THE GULF OF MEXICO MOVING EWD WEAKENING THE PRESSURE GRADIENT ACROSS THE CARIBBEAN. ATLANTIC OCEAN... AS OF 0900 UTC...A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N74W TO NEAR SAINT AUGUSTINE FLORIDA CONTINUING INTO THE NE GULF OF MEXICO. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING OVER THE NE CONUS. A SURFACE TROUGH IS ANALYZED S OF THE FRONT FROM N OF FREEPORT BAHAMAS NEAR 28N77W TO MIAMI FLORIDA. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS INDICATED BY RADAR IMAGERY. AN UPPER LEVEL RIDGE EXTENDING FROM THE CARIBBEAN SUPPORTS A SURFACE RIDGE COVERING THE W ATLC ANCHORED BY A 1020 MB HIGH NEAR 25N66W. A SHORTWAVE UPPER LEVEL TROUGH OVER THE CENTRAL ATLC SUPPORTS A 1009 MB LOW NEAR 28N44W. A COLD FRONT EXTENDS FROM THE LOW CENTER ALONG 25N50W 29N61W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. SCATTERED SHOWERS ARE ALSO E OF THE LOW CENTER N OF 25N BETWEEN 33W-40W. FARTHER E...A DEEP LAYER TROUGH SUPPORTS A DYING STATIONARY FRONT EXTENDING FROM THE CANARY ISLANDS TO NW OF THE CAPE VERDE ISLANDS NEAR 21N32W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. THE UPPER LEVEL TROUGH IS ALSO ENHANCING CONVECTION ALONG THE CENTRAL PORTION OF THE ATLC ITCZ. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE. $$ WALTON