000 AXNT20 KNHC 291751 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT DEC 29 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. ...THE ITCZ/THE MONSOON TROUGH... ITCZ AXIS EXTENDS FROM WEST AFRICA AT THE COAST OF SIERRA LEONE TO 02N25W TO 04N38W TO 02N50W IN NE BRAZIL. SCATTERED MODERATE CONVECTION FROM 02N-06N BETWEEN 20W-40W. ISOLATED MODERATE ELSEWHERE WITHIN 120 NM NORTH AND 90 NM SOUTH OF AXIS. ...DISCUSSION... GULF OF MEXICO... COLD FRONT EXTENDS FROM N FLORIDA BIG BEND TO 23N90W TO 19N92W IN THE BAY OF CAMPECHE. SCATTERED STRONG CONVECTION NOTED ON SATELLITE IMAGERY N OF 25N E OF FRONT. ISOLATED SHOWERS ALONG TEXAS COAST AND N OF 28N W OF 90W. STRONG SOUTHWESTERLY WINDS AHEAD OF FRONT SHIFT NORTHWEST TO NORTH BEHIND BOUNDARY. STRONG UPPER LEVEL SUPPORT IN THE WAY OF 170 KT JETSTREAM SHIFT MORE TO THE NORTH WEAKENING FRONT ONCE IT MOVES EAST OF FLORIDA PENINSULA. BROAD UPPER LEVEL RIDGE COVER ENTIRE GULF BEHIND FRONT WITH COLD...DRY AND STABLE AIR MASS BRINGING A TOUCH OF WINTER WEATHER TO THE LOWER LATITUDES. RIDGE SHIFT EAST AND ALLOWS NEXT FRONTAL SYSTEM TO MOVE INTO NORTHWEST GULF EARLY TUE. THE CARIBBEAN SEA... FAIR...DRY AND STABLE CONDITIONS RULE ACROSS THE BASIN WITH FRESH EAST TO NORTHEAST TRADES OBSERVED E OF 80W AS BROAD SURFACE RIDGE SPREADS THROUGH ENTIRE SOUTHWEST NORTH ATLC. GENTLE TO MODERATE BREEZE NOTED W OF 80W IN ADVANCE OF COLD FRONT APPROACHING YUCATAN PASSAGE. NOT MUCH CONVECTION EXPECTED INTO NORTHWEST CARIBBEAN FROM FRONTAL BOUNDARY SUN AS MOST SUPPORTING ENERGY EXPECTED TO SHIFT NORTH AWAY FROM SOUTHERN PART OF FRONT. SCATTERED CONVECTION COULD DEVELOP OVER PANAMA AND COSTA RICA DUE TO LOW PRESSURE CENTER FORMING IN EASTERN PACIFIC JUST S OF PANAMA. THE ATLANTIC OCEAN... VERY BROAD MID TO UPPER LEVEL RIDGE COVERS SOUTHWEST NORTH ATLC SUPPORTING WEAK SURFACE HIGH PRESSURE CENTER 1024 MB AT 30N52W. WEAK LOW PRESSURE CENTER 1017 MB JUST SE OF ANTICYCLONE AT 24N42W HAS ATTENDANT TROUGH MEANDERS FROM 18N42W TO 18N47W BRINGING SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM ON ITS EAST SEMICIRCLE...LITTLE CONVECTION ELSEWHERE IN CENTRAL ATLC. LOW EXPECTED TO DISSIPATE EARLY SUN WHILE TROUGH WEAKENS AND MOVES NORTHEAST. APPROACHING COLD FRONT FROM GULF OF MEXICO PROMPTS SCATTERED MODERATE TO STRONG CONVECTION OFF FLORIDA EAST COAST WITH MAIN CLUSTER MOSTLY NORTH OF 27N EAST OF 72W. FRONT HAS ALSO BROUGHT STRONG SOUTHWESTERLIES WITHIN 180 NM EAST OF BOUNDARY WHICH WILL SHIFT NORTHWEST ONCE FRONT MOVES EAST OF FLORIDA COAST. FARTHER EAST...UPPER LEVEL CYCLONE AT 24N39W SUPPORTS ABOVE MENTIONED SURFACE LOW PRESSURE AT 24N42W WITH ITS ATTENDANT SURFACE TROUGH. CYCLONE EXPECTED TO WEAKEN AND BE FORCED EAST BY WESTERN ATLC RIDGE MOVING EAST DISSIPATING SURFACE LOW PRESSURE. REMAINDER OF EASTERN ATLC UNDER BROAD RIDGE AROUND HEALTHY 1032 MB HIGH PRESSURE CENTER OVER AZORES ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALLY BARNES