000 AXNT20 KNHC 272342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE DEC 27 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 MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N11W TO 05N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N19W TO 04N35W TO 02N50W. SCATTERED MODERATE CONVECTION IS FROM 02N-06N BETWEEN 20W-41W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH IS LOCATED OVER THE GREAT LAKES REGION WITH AXIS EXTENDING SOUTHWARD TO THE SOUTHERN MISSISSIPPI RIVER VALLEY AND INTO THE GULF TO A BASE NEAR 26N92W. THIS TROUGH SUPPORTS A COLD FRONT ANALYZED FROM NE FLORIDA NEAR JACKSONVILLE TO TAMPA BAY AND INTO THE SE GULF ALONG 28N83W TO 23N88W TO 20N93W. ISOLATED SHOWERS ARE OCCURRING WITHIN 75 NM EITHER SIDE OF THE FRONT AND POSSIBLE ISOLATED SHOWERS OCCURRING OVER THE SW GULF S OF 23N W OF 92W. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF MOSTLY WESTERLY ZONAL FLOW ALOFT AND A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED OVER THE RIO GRANDE RIVER VALLEY NEAR 29N101W. WITH THE COLD FRONT EXPECTED TO PUSH EAST OF THE BASIN BY EARLY WEDNESDAY AND HIGH PRESSURE TO SLIDE EASTWARD FROM TEXAS TO THE SE CONUS...NORTHERLY WINDS WILL PERSIST AND CONDITIONS ARE EXPECTED TO REMAIN FAIR THROUGH LATE WEDNESDAY INTO EARLY THURSDAY. CARIBBEAN SEA... AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS FROM NORTHERN VENEZUELA NEAR 10N67W NW TO NEAR 18N83W. WATER VAPOR IMAGERY INDICATES VERY DRY AIR AND SUBSIDENCE OVER MUCH OF THE BASIN THIS EVENING WHICH IS RESULTING IN RATHER TRANQUIL CONDITIONS AT THE SURFACE. HOWEVER...FRESH TO STRONG E-NE TRADES CONTINUE GENERALLY BETWEEN 70W-80W AND THIS OVERALL PATTERN IS FORECAST TO PERSIST THROUGH EARLY FRIDAY AS A RIDGE WILL POSITION ITSELF IN THE SW NORTH ATLC AND INCREASE THE TRADES DUE TO AN INCREASED PRESSURE GRADIENT. THE TRADES WILL REMAIN STRONG BASIN-WIDE THROUGH THE UPCOMING WEEKEND. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY THIS EVENING ACROSS THE GREAT LAKES REGION AND THIS TROUGH SUPPORTS A COLD FRONT ANALYZED AT 27/2100 UTC FROM 34N79W TO THE FLORIDA COAST NEAR 29N81W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 150 NM EAST OF THE FRONT. THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A 1023 MB SURFACE HIGH CENTERED JUST EAST OF BERMUDA NEAR 33N66W. FARTHER EAST...AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NORTH OF THE DISCUSSION AREA NEAR 37N51W AND AN ASSOCIATED TROUGH AXIS ALONG 52W. THE COLD FRONT IS ANALYZED FROM 32N48W TO 28N50W TO 24N60W TO 24N65W THEN AS A DISSIPATING COLD FRONT ON THE SOUTHERN PERIPHERY OF THE AFOREMENTIONED SURFACE RIDGE TO 26N72W. WITH MOISTURE REMAINING LIMITED WITH THIS FRONT...ONLY POSSIBLE ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE BOUNDARY. THE MAIN IMPACT WITH THIS FRONT IS GALE FORCE NW WINDS TO 35 KT NORTH OF 29N W OF THE COLD FRONT TO 55W. THESE CONDITIONS S OF 31N OVER THE FORECAST WATERS ARE ANTICIPATED TO DIMINISH BELOW WARNING CRITERIA THROUGH THE OVERNIGHT HOURS. THE REMAINDER OF THE EASTERN ATLC ALOFT IS DOMINATED BY AN UPPER LEVEL LOW CENTERED NEAR 21N29W. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO BE DRAWN N-NE ON THE SOUTHEASTERN PERIPHERY OF THE UPPER LEVEL LOW WITH ISOLATED SHOWERS OCCURRING FROM NORTH OF THE ITCZ AXIS ALONG 05N TO 24N E OF 28W. WIDELY SCATTERED SHOWERS ARE OCCURRING CLOSER TO THE UPPER LEVEL LOW CENTER FROM 19N-26N BETWEEN 26W-33W. AT THE SURFACE N OF 20N...A SURFACE RIDGE AXIS EXTENDS FROM 36N20W TO 23N42W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN