000 AXNT20 KNHC 041748 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT DEC 04 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 09N13W 06N20W 06N40W 05N48W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ AND ANALYZED FROM 02N-10N ALONG 50W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 02N-10N BETWEEN 41W-48W EAST OF THE SURFACE TROUGH WHILE LOW-LEVEL CONVERGENCE WEST OF THE SURFACE TROUGH IS GENERATING ISOLATED MODERATE CONVECTION FROM 03N-09N BETWEEN 48W-55W. ...DISCUSSION... GULF OF MEXICO... CONFLUENT FLOW ALOFT OVER THE GULF IS LEADING TO WIDESPREAD SUBSIDENCE IN SUPPORT OF A BROAD 1022 MB HIGH CENTERED NEAR 26N90W. THIS SURFACE HIGH IS PROVIDING THE ENTIRE GULF WITH FAIR CONDITIONS AND MOSTLY CLEAR SKIES THIS AFTERNOON. THROUGH THE WEEKEND...AS THE HIGH SHIFTS SOUTHWARD AND WEAKENS SLIGHTLY...A COLD FRONT CURRENTLY INLAND OVER CENTRAL TEXAS WILL BEGIN TO IMPACT THE GULF COAST AND NORTHERN GULF WATERS EARLY SUNDAY. BY LATE SUNDAY...N TO NE WINDS BEHIND THE FRONT WILL SPREAD SOUTHWARD AS THE FRONT SHIFTS EASTWARD INTO THE W ATLC AND NW CARIBBEAN SEA. CARIBBEAN SEA... AN UPPER LEVEL TROUGH CONTINUES TO SWEEP ACROSS THE W ATLC AND INTRODUCE VERY DRY AIR ALOFT OVER THE WESTERN CARIBBEAN W OF 75W. FURTHERMORE...CONFLUENCE ALOFT ALONG 20N SUPPORTS SUBSIDENCE AND THE EXTENSION OF SURFACE RIDGING FROM THE GULF OF MEXICO TO NW OF A LINE FROM THE WINDWARD PASSAGE TO EASTERN HONDURAS PROVIDING GENERALLY FAIR CONDITIONS. HOWEVER...A FEW ISOLATED SHOWERS ARE OCCURRING FROM 16N-19N BETWEEN 84W-87W. FARTHER EAST...THE UPPER LEVEL TROUGH ALSO SUPPORTS A COLD FRONT ANALYZED FROM HISPANIOLA NEAR 20N70W TO 18N75W THEN CONTINUES AS A SHEAR LINE ALONG 17N80W TO 14N83W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONTAL BOUNDARY WHILE CONVERGENT NE AND E TRADES ARE FOCUSING MOISTURE AND ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF THE SHEAR LINE. THE REMAINDER OF THE CARIBBEAN E OF 75W IS UNDER THE INFLUENCE OF UPPER LEVEL RIDGING CENTERED IN THE TROPICAL ATLC NEAR 10N50W. THE ASSOCIATED UPPER LEVEL DIFFLUENT ENVIRONMENT IS ENHANCING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SE CARIBBEAN S OF 15N E OF 72W...INCLUDING THE ABC ISLANDS...NW VENEZUELA...AND THE WINDWARD ISLANDS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS LOCATED OVER THE W ATLC WITH AXIS EXTENDING FROM 32N65W TO 23N76W. THIS UPPER LEVEL FEATURE SUPPORTS A PRIMARY COLD FRONT ANALYZED FROM 32N57W SW ALONG 26N60W TO NORTH OF HISPANIOLA NEAR 20N70W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. TO THE NW...A SECONDARY COLD FRONT EXTENDS FROM A 1001 MB LOW CENTERED NEAR 36N63W TO 30N68W. WHILE OVERALL STABLE CONDITIONS CONVECTIVELY EXIST W OF THE PRIMARY FRONT TO 81W...EARLY MORNING SCATTEROMETER PASSES DEPICTED A STRONG NORTHWESTERLY WIND FIELD REACHING UP TO 25 KT N OF 26N. BY EARLY SUNDAY...GALE FORCE CONDITIONS ARE EXPECTED N OF 30N BETWEEN 68W AND 78W. OVER THE EASTERN ATLC...UPPER LEVEL TROUGHING IS ALONG 26W DIPPING SOUTHWARD TO 20N. THIS TROUGHING SUPPORTS A 983 MB LOW CENTERED NORTH OF THE AREA NEAR 37N28W AND A PAIR OF COLD FRONTS. THE MAIN COLD FRONT IS ANALYZED ALONG 32N27W 28N30W TO 23N40W... WHILE A DISSIPATING COLD FRONT IS ALONG 32N21W TO 22N29W. LITTLE SIGNIFICANT DEEP CONVECTION IS NOTED WITH EITHER FRONT... HOWEVER...NW TO W WINDS REMAIN IN THE 20-30 KT RANGE N OF 24N BETWEEN 20W-35W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN/MONTALVO