000 AXNT20 KNHC 182349 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED JAN 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 06N11W TO 05N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N20W TO 03N31W TO THE EQUATOR NEAR 50W. ISOLATED MODERATE CONVECTION IS FROM 02N-07N BETWEEN 46W-50W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL WESTERLY FLOW IS DOMINATE OVER THE GULF THIS EVENING BETWEEN AN UPPER LEVEL RIDGE PRIMARILY S OF 25N AND A BROAD UPPER LEVEL TROUGH PROGRESSING OVER THE EASTERN CONUS WITH AXIS EXTENDING FROM THE MID-ATLC STATES SOUTHWESTWARD TO EASTERN TEXAS. THIS UPPER LEVEL FEATURE SUPPORTS A COLD FRONT THAT MEANDERS FROM NORTHERN FLORIDA NEAR 30N83W TO 26N90W TO EAST-CENTRAL MEXICO NEAR 22N98W. MOSAIC DOPPLER RADAR AND SATELLITE IMAGERY INDICATE NUMEROUS SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE FRONT N OF 27N...AND WITHIN 45 NM EITHER SIDE OF THE FRONT ELSEWHERE. THE FRONT IS EXPECTED TO GRADUALLY BECOME MORE DIFFUSE OVER THE GULF WATERS AS MOST OF THE MID-LEVEL ENERGY ASSOCIATED WITH IT MOVES NE OF THE REGION OVERNIGHT. HIGH PRESSURE WILL THEN ONCE AGAIN ESTABLISH ITSELF OVER THE GULF THURSDAY AND PROVIDE SOUTHERLY RETURN FLOW NORTH OF A RIDGE AXIS EXTENDING FROM THE CENTRAL FLORIDA PENINSULA TO SOUTHERN MEXICO NEAR 20N97W. SOUTHERLY WINDS ARE FORECAST TO INCREASE ACROSS THE WESTERN GULF AHEAD OF A DEVELOPING AREA OF LOW PRESSURE ACROSS THE SOUTHERN PLAINS AND THE ASSOCIATED FRONTAL BOUNDARY FORECAST TO ENTER THE NW GULF LATE SATURDAY. CARIBBEAN SEA... CONFLUENT UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER THE CARIBBEAN BASIN THIS EVENING ON THE WESTERN PERIPHERY OF AN UPPER LEVEL TROUGH AXIS THAT EXTENDS FROM THE CENTRAL ATLC NEAR 28N50W TO A BASE NEAR 14N66W. VERY DRY AIR AND STRONG SUBSIDENCE ARE PROVIDING FOR AN OVERALL STABLE ATMOSPHERE ALOFT WHICH IN TURN IS LIMITING ANY SIGNIFICANT AREAS OF DEEP CONVECTION. WHILE THE PRESSURE GRADIENT...WHICH HAS BEEN STRONG THE PAST FEW DAYS...RELAXES SOMEWHAT WITH A FRONTAL TROUGH MOVING ACROSS THE SW NORTH ATLC REGION...TRADES REMAIN E-NE IN THE RANGE OF 15 TO 25 KT EVERYWHERE EXCEPT OVER THE NW CARIBBEAN. THESE WINDS ARE FORECAST TO PERSIST THROUGH THE UPCOMING WEEKEND. OTHERWISE THIS EVENING...AREAS OF LOW-LEVEL CLOUDS AND POSSIBLE EMBEDDED ISOLATED SHOWERS ARE OVER MUCH OF THE AREA WITHIN THE TRADEWIND FLOW. ATLANTIC OCEAN... AN APPROACHING UPPER LEVEL TROUGH IS ACROSS THE SE CONUS WITH AXIS EXTENDING FROM THE MID-ATLC STATES SW TO EASTERN TEXAS. THIS TROUGH SUPPORTS A COLD FRONT ANALYZED FROM 32N79W TO THE GEORGIA COAST NEAR 31N81W THEN SW INTO THE GULF OF MEXICO. NUMEROUS SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 180 NM SE OF THE FRONT AS IT CONTINUES TO MOVE OFF TO THE E-NE OVER THE NEXT 24 HOURS. EAST OF THE INFLUENCE OF THE COLD FRONT...AN UPPER LEVEL RIDGE WITH AXIS FROM 32N67W TO 23N76W IS SUPPORTIVE OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED NEAR 34N50W. MOSTLY FAIR CONDITIONS ARE ASSOCIATED WITH THE HIGH PRESSURE AREA. FARTHER EAST...AN UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM 36N40W TO 20N60W THEN SW INTO THE EASTERN CARIBBEAN SEA. THE TROUGH SUPPORTS A COLD FRONT ANALYZED FROM 32N35W TO 28N38W WHERE IT BECOMES STATIONARY TO 22N52W. SCATTERED SHOWERS ARE OCCURRING WITHIN 180 NM EITHER SIDE OF THE FRONT. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1037 MB HIGH CENTERED WEST OF THE IBERIAN PENINSULA NEAR 42N14W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN