000 AGXX40 KNHC 181806 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 206 PM EDT WED APR 18 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A WEAK SHORT WAVE TROUGH IS MIGRATING THROUGH THE TENNESSEE VALLEY THIS AFTERNOON. THIS IS PROVIDING SUPPORT TO A COLD FRONT THAT EXTENDS FROM A 1013 MB LOW PRES CENTER NEAR 30N87W TO 25N90W. A WEAKENING STATIONARY FRONT CONTINUES TO 18N93W. THE LOW PRES WILL MIGRATE TO THE ENE TOWARD THE GEORGIA COAST BY LATE THU BEFORE DISSIPATING. HIGH PRES IS BUILDING BEHIND THE FRONTAL BOUNDARY FROM THE MID MISSISSIPPI VALLEY TO SOUTH TEXAS...ALLOWING WINDS TO DIMINISH ACROSS THE WESTERN GULF. SHIP AND BUOY OBSERVATIONS SHOW NE WINDS OVER THE WESTERN GULF HAVE ALREADY DIMINISHED TO BELOW 20 KT...MORE QUICKLY THAN MODEL GUIDANCE IS SUGGESTING. MODERATE E TO SE WINDS WILL PREVAIL ACROSS THE GULF THROUGH FRI AS THE HIGH PRES WILL DRIFT E AND WEAKEN AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHERN ROCKIES. GLOBAL MODEL GUIDANCE IS SHOWING THE FRONT TO BE FAIRLY STRONG FOR THIS LATE IN THE SEASON...ENTERING THE GULF FRI NIGHT. THE 00 UTC ECMWF WAS SLIGHTLY STRONGER THAN THE LATEST GFS RUNS. BOTH INDICATE LOW PRES MOVING THROUGH THE MISSISSIPPI RIVER DELTA BY MIDDAY SAT. CONFIDENCE ON FRONT PERFORMANCE IS FAIRLY HIGH GIVEN THAT DYNAMICAL GUIDANCE IS IN GOOD AGREEMENT WITH BOTH TIMING AND STRENGTH OF FEATURES...WIND SPEEDS AND SEA HEIGHTS...WITH LITTLE OR NO CHANGES FROM RUN TO RUN. THE ECMWF SHOWED WINDS TO 30 KT OVER THE NW GULF BY SUN...WITH THE LATEST GFS AND SREF HINTING A SMALL AREA OF GALE CONDITIONS ALONG THE COAST OF VERACRUZ. GIVEN THE PROGRESSIVE CHARACTER OF THIS SYSTEM...AS WELL AS MINIMAL COLD AIR ADVECTION...WILL HOLD OFF ON GALE FOR THAT AREA. THE LOW PRES LIFTS OUT LATE SUN INTO MON FOLLOWED BY HIGH PRES BUILDING INTO THE MID MISSISSIPPI VALLEY ALLOWING WINDS AND SEAS TO DIMINISH FROM WEST TO EAST ACROSS THE GULF THROUGH MON. CARIBBEAN SEA... HIGH PRES CENTERED NE OF THE BAHAMAS IS MAINTAINING MODERATE TO FRESH TRADE WINDS OVER THE EASTERN AND CENTRAL CARIBBEAN. BUOY AND SCATTEROMETER DATA SHOW 15 TO 20 KT FROM SOUTH OF PUERTO RICO AND HISPANIOLA TO THE COLOMBIAN COAST...AS WELL AS THROUGH THE WINDWARD PASSAGE TO BETWEEN CUBA AND JAMAICA. THESE WINDS WILL DIMINISH TODAY AND TONIGHT AS THE HIGH PRES N OF THE AREA WEAKENS. SE WINDS WILL INCREASE OVER THE NW CARIBBEAN LATE FRI INTO SAT AHEAD OF A COLD FRONT MOVING THROUGH THE GULF OF MEXICO. THE SOUTHERN PORTION OF THE FRONT WILL CLIP THE NW CARIBBEAN WATERS SAT INTO SUN FOLLOWED BY FRESH NW FLOW. THE WEAKENING FRONT WILL STALL AND DISSIPATE FROM CENTRAL CUBA TO EASTERN HONDURAS BY LATE SUN. HIGH PRES BUILDING N OF THE AREA BEHIND THE FRONT WILL MAINTAIN MODERATE TO FRESH NW TO N WINDS THROUGH THE YUCATAN CHANNEL TO THE GULF OF HONDURAS THROUGH LATE MON. TROPICAL N ATLC S OF 19N W OF 55W... THE REMNANTS OF SHEAR LINE HAVE BECOME ILL-DEFINED THROUGH THE LEEWARD ISLANDS. LIGHT TO MODERATE TRADE WINDS WILL PERSIST THROUGH FRI. THE TRADES WILL INCREASE TO 15 TO 20 KT S OF 15N E OF 58W THIS WEEKEND INTO EARLY NEXT WEEK AS HIGH PRES BUILDS N OF THE AREA. NO SIGNIFICANT SWELL IS EXPECTED. SW NORTH ATLC S OF 31N W OF 55W... A 1022 MB HIGH PRES AREA IS CENTERED NEAR 29N75W. THIS WILL SHIFT NE THROUGH LATE FRI AHEAD OF A DEEP LOW PRES SYSTEM AND TRAILING COLD FRONT MOVING OFF THE GULF. SOUTHERLY FLOW WILL INCREASE OVER THE WATERS N OF THE BAHAMAS AND E OF 70W SAT THROUGH MON AS THE LOW PRES LIFTS NE FROM THE MISSISSIPPI DELTA TO THE CAROLINAS SAT THROUGH MON. THE LATEST GFS RUN FROM 12 UTC AND THE ECMWF RUN FROM 00 UTC SHOW SOUTHERLY FLOW TO NEAR GALE FORCE BY SUN NIGHT OVER THE WATERS N OF 28N BETWEEN 73W AND 77W. WAVEWATCH SHOWS SEAS IN THAT AREA BUILDING TO 12 FT. THE FRONT WILL MOVE THROUGH FLORIDA AND INTO THE ATLC WATERS LATE SUN INTO EARLY MON. THE FRONT WILL REACH FROM 31N70W TO THE STRAITS OF FLORIDA BY LATE MON...AND FROM BERMUDA TO CENTRAL CUBA BY LATE TUE. NW TO N WINDS BEHIND THE FRONT WILL GRADUALLY DIMINISH. NOTE... EFFECTIVE APR 3, 2012 AT 1800 UTC THE OFFSHORE WATERS FORECAST ZONES CHANGED FOR THE CARIBBEAN AND SW N ATLANTIC AND THE GULF OF MEXICO. ISSUANCE TIME FOR THE GULF OF MEXICO OFFSHORE WATERS FORECASTS IS REFERENCED TO THE EASTERN TIME ZONE. FOR DETAILS SEE WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE (LOWER CASE). GULF OF MEXICO... .NONE. .CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. .SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER CHRISTENSEN