000 AXNT20 KNHC 211736 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST FRI DEC 21 2012 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 1645 UTC. ...ITCZ/MONSOON TROUGH... THERE IS CURRENTLY NO PORTION OF THE MONSOON TROUGH OVER THE ATLC WATERS. THE ITCZ BEGINS OVER LAND AND CONTINUES TO THE COAST OF LIBERIA NEAR 7N11W EMERGING OVER WATER ALONG 8N20W 5N30W 2N53W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 30W-42W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER TROUGH CONTINUES TO COVER THE EASTERN CONUS EXTENDING INTO THE GULF OF MEXICO SUPPORTING A STRONG COLD FRONT WHICH HAS MOSTLY MOVED EAST OF THE BASIN. AS OF 1500 UTC...THE FRONT HAS PUSHED SE OF FLORIDA INTO THE NW CARIBBEAN CONTINUING ACROSS THE YUCATAN PENINSULA INTO SOUTHERN MEXICO. A DRY...COOL...AND STABLE AIRMASS IS LEFT IN ITS WAKE PROVIDING CLEAR SKIES ACROSS FLORIDA AND THE NORTHERN GULF. SOME FAIR WEATHER STRATOCUMULUS CLOUDS COVER THE SOUTHERN GULF...ESPECIALLY THE BAY OF CAMPECHE. GALE FORCE WINDS ALSO CONTINUE IN THE SW GULF...BUT ARE EXPECTED TO DIMINISH BELOW GALE FORCE BY 1800 UTC. STRONG NW WINDS SPREAD OVER THE REMAINDER OF THE BASIN REACHING 20-25 KT. SURFACE HIGH PRESSURE IS BEGINNING TO BUILD IN ACROSS THE GULF BEHIND THE FRONT CURRENTLY ANCHORED BY A 1033 MB HIGH OVER SOUTHERN TEXAS. THE RIDGE IS EXPECTED TO SHIFT EAST OVER THE NEXT FEW DAYS BEFORE ANOTHER FRONT ENTERS THE NW GULF IN THE MIDDLE OF NEXT WEEK. CARIBBEAN SEA... MOSTLY DRY AIR ALOFT COVERS THE CARIBBEAN AROUND A SMALL UPPER RIDGE AXIS EXTENDING FROM THE YUCATAN PENINSULA TO CENTRAL CUBA WITH ZONAL WESTERLY FLOW COVERING THE REMAINDER OF THE BASIN. THIS DRY AIR IS PROVIDING MOSTLY FAIR CONDITIONS BASIN-WIDE. HOWEVER...A FEW AREAS OF SHOWER ACTIVITY ARE PRESENT. A LINE OF POSSIBLE SHOWERS IS IN THE NW CARIBBEAN ASSOCIATED WITH THE COLD FRONT THAT HAS PUSHED THROUGH THE GULF OF MEXICO DURING THE PAST DAY AND NOW EXTENDS FROM WESTERN CUBA TO THE YUCATAN PENINSULA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE IN THE SW CARIBBEAN ALONG THE COASTS OF NICARAGUA...COSTA RICA...AND PANAMA DUE TO WIND CONVERGENCE AS 20-25 KT WINDS HIT THE COAST. FINALLY...AN AREA OF SHOWERS/ISOLATED THUNDERSTORMS IS MOVING THROUGH THE SOUTHERN WINDWARD ISLANDS SOUTH OF 14N WESTWARD TO 67W. TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE MAJORITY OF THE AREA REACHING 25 KT NEAR THE COAST OF COLOMBIA. EXPECT THE FRONT IN THE NW CARIBBEAN TO CONTINUE TO PUSH SE WITH STRONG NORTH WINDS UP TO 25 KT BEHIND IT. ATLANTIC OCEAN... A STRONG COLD FRONT IS PUSHING THROUGH THE WEST ATLC SUPPORTED BY A DEEP LAYER TROUGH OVER THE EASTERN CONUS. AS OF 1500 UTC...THE FRONT ENTERS THE DISCUSSION AREA NEAR 32N73W CONTINUING TO THE BAHAMAS AT 27N78W TO CUBA AT 23N82W. A LINE OF SHOWERS/THUNDERSTORMS IS ALONG THE FRONT AXIS WITH ISOLATED SHOWERS WITHIN 60 NM. GALE FORCE WINDS ARE BOTH EAST AND WEST OF THE FRONT NORTH OF 3ON. WEAK SURFACE RIDGING IS TO THE EAST AROUND A 1018 MB HIGH NEAR 28N66W. THE HIGH IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 63W. A SECOND DEEP LAYER TROUGH IS IMPACTING THE CENTRAL ATLC ALONG 45W SUPPORTING A COLD FRONT ENTERING THE AREA NEAR 32N37W AND CONTINUING ALONG 23N47W 19N61W AND DISSIPATING TO 19N68W. ISOLATED SHOWERS ARE ALONG THE AXIS. GALE FORCE WINDS ARE WEST OF THE FRONT N OF 29N. A PRE-FRONTAL SURFACE TROUGH IS EAST OF THE FRONT ALONG 31N37W 23N43W 18N51W. SCATTERED SHOWERS ARE WITHIN 100 NM E OF THE AXIS. THE REMAINDER OF THE EAST ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1028 MB HIGH SW OF PORTUGAL. THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 12W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON