000 AXNT20 KNHC 222351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU DEC 22 2011 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 INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N10W TO 05N17W TO 05N31W TO 01N50W. ISOLATED MODERATE CONVECTION IS FROM 03N-08N BETWEEN 25W-32W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING NORTHEASTWARD OVER THE LOWER MISSISSIPPI RIVER VALLEY THIS EVENING AND SUPPORTS A COLD FRONT ANALYZED FROM NEW ORLEANS LOUISIANA SOUTHWESTWARD INTO THE WESTERN GULF ALONG 26N94W TO 21N97W AND INLAND OVER INTERIOR EAST-CENTRAL MEXICO. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT N OF 27N WITH ISOLATED SHOWERS OCCURRING WITHIN 60 NM EITHER SIDE OF THE FRONT S OF 27N. EAST OF THE FRONT...A SURFACE RIDGE ANCHORED IN THE SW NORTH ATLC CONTINUES TO SLIDE EASTWARD AND WEAKEN ACROSS THE EASTERN GULF AND FLORIDA PENINSULA. BY LATE FRIDAY THE RIDGE IS EXPECTED TO BE EAST OF THE BASIN AS THE COLD FRONT CONTINUES TO MOVE EASTWARD ACROSS THE NE GULF WHILE STALLING ACROSS THE CENTRAL AND SW GULF AS THE UPPER LEVEL SUPPORT MOVES WELL NE OF THE AREA. N TO NE WINDS IN THE RANGE OF 15 TO 20 KT ARE EXPECTED WEST OF THE FRONT THROUGH SATURDAY UNTIL REINFORCING MIDDLE TO UPPER LEVEL ENERGY ARRIVES LATE SATURDAY INTO SUNDAY WITH N-NE WINDS INCREASING AND SEAS BUILDING W OF 90W THROUGH THE REMAINDER OF THE WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS FROM THE SE CARIBBEAN NEAR 12N62W NW OVER HISPANIOLA NEAR 19N72W AND INTO THE SW NORTH ATLC TO AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 27N80W. WATER VAPOR IMAGERY INDICATES MOSTLY DRY AIR AND SUBSIDENCE IS PRESENT OVER MUCH OF THE BASIN THIS EVENING IN THE MIDDLE AND UPPER LEVELS. HOWEVER...AT THE SURFACE A STRONGER THAN NORMAL PRESSURE GRADIENT IS SET UP ACROSS THE ENTIRE BASIN WITH A STRONG 1028 MB HIGH CENTERED IN THE SW NORTH ATLC NEAR 31N61W AND LOW PRESSURE CENTERED OVER CENTRAL COLOMBIA AS 1005 MB NEAR 06N73W. EAST-NORTHEAST TRADES REMAIN STRONG IN THE RANGE OF 20 TO 30 KT...WITH GALE FORCE CONDITIONS LOCATED FROM 11N-16N BETWEEN 73W-78W. OTHERWISE...A FEW AREAS OF ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY FROM 11N-15N BETWEEN 65W-71W...FROM 17N-21N BETWEEN 84W-88W... AND FROM 09N-15N BETWEEN 81W-86W. THE SURFACE HIGH OVER THE SW NORTH ATLC IS EXPECTED TO REMAIN STATIONARY AND THUS THE STRONG TRADES ARE EXPECTED TO PERSIST THROUGH THE REMAINDER OF THE WEEKEND. ATLANTIC OCEAN... SURFACE RIDGING AROUND A 1028 MB HIGH CENTERED NEAR 31N61W IS PROVIDING MOSTLY FAIR WEATHER ACROSS THE SW NORTH ATLC THIS EVENING. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 27N80W. FARTHER EAST...AN UPPER LEVEL TROUGH WITH AXIS ALONG 40W CONTINUES TO SUPPORT A STATIONARY FRONT IN THE CENTRAL ATLC ANALYZED INTO THE DISCUSSION AREA NEAR 32N34W THEN SW ALONG 30N38W TO 24N41W. ISOLATED SHOWERS ARE OCCURRING OVER THE AREA N OF 20N BETWEEN 33W-42W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1033 MB HIGH CENTERED W-SW OF THE IBERIAN PENINSULA NEAR 38N17W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN