000 AXNT20 KNHC 120537 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SUN DEC 12 2010 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0500 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED FROM LIBERIA 6N11W ALONG 7N20W 9N27W 5N39W 3N52W. A SURFACE TROUGH EXTENDS FROM S OF THE CAPE VERDE ISLANDS NEAR 13N23W TO 6N28W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-8N BETWEEN 27W-35W...AND FROM 3N-7N BETWEEN 38W-43W. ...DISCUSSION... GULF OF MEXICO... AS OF 0300 UTC...A COLD FRONT HAS PUSHED OFF THE COAST OF TEXAS EXTENDING FROM NEAR ATCHAFALAYA BAY AT 29N92W TO BROWNSVILLE TEXAS AT 26N98W. THE FRONT IS SUPPORTED BY A LONGWAVE UPPER LEVEL TROUGH EXTENDING FROM THE UPPER MIDWEST TO SRN TEXAS AND ACROSS NRN MEXICO. A LINE OF SHOWERS...SOME STRONG...EXTEND UP TO 60 NM AHEAD OF THE FRONT. 20 KT NLY WINDS ARE NOTED BEHIND THE FRONT. AS THE FRONT PUSHES FARTHER SE...GALE FORCE WINDS ARE EXPECTED BEHIND IT WITHIN 24 HRS. THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1017 MB HIGH OFF THE SW COAST OF FLORIDA NEAR 25N84W. DRY AIR ALOFT IN MAINLY ZONAL WLY FLOW COVERS THIS AREA MAINTAINING FAIR CONDITIONS WITH PATCHES OF STRATOCUMULUS CLOUDS. EXPECT THE SURFACE RIDGE TO WEAKEN AS THE COLD FRONT RACES ACROSS THE BASIN AND REACHES S FLORIDA BY 24 HRS. CARIBBEAN SEA... DRY AIR AND SUBSIDENCE AROUND AN UPPER LEVEL RIDGE CENTERED OVER NW COLOMBIA IS KEEPING MUCH OF THE CARIBBEAN UNDER FAIR CONDITIONS TONIGHT. A LINE OF SHOWERS/POSSIBLE THUNDERSTORMS EXTENDS FROM HISPANIOLA TO PANAMA ALONG 19N72W 16N80W 9N80W SUPPORTED BY SURFACE CONVERGENCE BETWEEN N-NE WINDS ACROSS THE NW CARIBBEAN AND NE-E TRADE WINDS ACROSS THE REMAINDER OF THE BASIN. SOME SHOWERS ACROSS THE MONA PASSAGE ARE ATTRIBUTED TO A SURFACE TROUGH IN THE W ATLC THAT REACHES TO THE NW TIP OF PUERTO RICO. EXPECT A LINE OF SHOWERS TO CONTINUE IN THE CENTRAL CARIBBEAN AS NLY WINDS INCREASE IN THE NW PORTION OF THE AREA AHEAD OF THE COLD FRONT THAT IS MOVING ACROSS THE GULF OF MEXICO. THE FRONT SHOULD REACH THE NW CARIBBEAN EARLY MONDAY. ATLANTIC OCEAN... MAINLY ZONAL FLOW ALOFT COVERS THE W AND CENTRAL ATLC NO LONGER PROVIDING EXTRA SUPPORT TO THE SURFACE FEATURES. HOWEVER...A WEAKENING SURFACE TROUGH STILL REMAINS OFF THE ERN FLORIDA COAST. THE TROUGH EXTENDS FROM A 1012 MB LOW NEAR 27N60W ALONG 25N69W 26N76W 30N77W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE AXIS. A RECENT ASCAT SCATTEROMETER PASS INDICATES WINDS UP TO 20 KTS N OF THE BOUNDARY WITH WEAKER WINDS TO THE S. A SECOND SURFACE TROUGH EXTENDS SW FROM THE SAME LOW PRESSURE CENTER TO WRN PUERTO RICO. POSSIBLE ISOLATED SHOWERS ARE WITHIN 30 NM EITHER OF THIS BOUNDARY. A DISSIPATING STATIONARY FRONT DRAPES ACROSS THE N CENTRAL ATLC ALONG 30N46W TO 29N57W SUPPORTING SCATTERED SHOWERS N OF 27N BETWEEN 44W-60W. TO THE S OF THIS BOUNDARY...STRONGER SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM 23N-27N BETWEEN 48W-57W ASSOCIATED WITH AN UPPER LEVEL JET IN THE ZONAL WLY FLOW ALOFT. THE REMAINDER OF THE E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH NEAR 26N39W. THE RIDGE IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE WITH AXIS FROM NRN S AMERICA TO THE AZORES ISLANDS. AN UPPER LEVEL TROUGH IS TO THE E OF THIS RIDGE EXTENDING FROM THE CANARY ISLANDS TO THE CAPE VERDE ISLANDS SUPPORTING A LOW PRESSURE SYSTEM TO THE N OF THE DISCUSSION AREA WITH A SURFACE TROUGH EXTENDING INTO THE AREA TO THE E OF THE CANARY ISLANDS. THIS UPPER LEVEL TROUGH IS ALSO ENHANCING CONVECTION ALONG THE ITCZ AND THE SURFACE TROUGH EMBEDDED WITHIN THE AXIS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON