000 AGXX40 KNHC 300715 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 315 AM EST FRI NOV 30 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... STRONG HIGH PRES OVER THE CAROLINAS WILL DRIVE THE WINDS OVER THE GULF THROUGH TUE. A COLD FRONT WILL WEAKEN THIS HIGH PRES AND PUSH IT EASTWARD TUE INTO WED...WITH THE WEAKENED FRONT EXPECTED TO MOVE INTO THE NW GULF BY EARLY WED. MODERATE ANTICYCLONIC FLOW WILL DOMINATE MUCH OF THE REGION WITH THE EXCEPTION OF THE SE GULF. WITH SEVERAL SHIP OBSERVATIONS REPORTING FRESH TO STRONG E-NE WINDS IN THE SE GULF AND STRAITS OF FLORIDA THIS MORNING...WILL NEED TO BUMP UP THE GRIDS ABOUT 5 KT IN THIS AREA INITIALLY. THIS INCREASE SHOULD EXTEND INTO THE FORECAST PERIOD AS THE SYNOPTIC PATTERN SHOULD REMAIN RELATIVELY UNCHANGED OVER THE NEXT FEW DAYS. AS MENTIONED IN EARLIER DISCUSSION...WW3 TYPICALLY DOES NOT CAPTURE PEAK AREA OF SEAS THROUGH THE STRAITS AND ACROSS YUCATAN CHANNEL. GRIDS WILL GO ABOVE GUIDANCE IN THE UPDATED FORECAST...WITH SEAS LIKELY TO LINGER AROUND 6-8 FT THROUGH TUE...AND LIKELY EVEN HIGHER AGAINST CURRENT. CARIBBEAN SEA AND TROPICAL N ATLC S OF 19N W OF 55W... STRONG HIGH PRES OVER THE CAROLINAS IS DRIVING THE EASTERLY FLOW THROUGH THIS REGION. A SHEAR LINE N OF THE AREA AND A SERIES OF LOW LEVEL TROUGHS MOVING W THROUGH THE NE CARIBBEAN TOWARD THE WINDWARD PASSAGE ARE FORCING GRADIENT WINDS TO REMAIN N OF THE BASIN...AND WILL ONLY ALLOW FOR FRESH WINDS TO PENETRATE NW PORTIONS AND THE WINDWARD PASSAGE. OTHERWISE...MODERATE NE TO E-NE TRADES WILL PREVAIL ACROSS THE REGION THROUGH TUE. BUMPED UP WINDS INITIALLY AROUND 5 KT IN THE WINDWARD PASSAGE COMPARED TO THE 00Z GFS AND ECMWF BASED ON SEVERAL RECENT SHIP REPORTS OF STRONG NE WINDS AND SEAS TO 10 FT. THE ECMWF AND GFS AGREE ON DIMINISHING THE WINDS HERE THOUGH THIS AFTERNOON AND RETURN THE FRESH TO STRONG NE FLOW ON SUN AS THE SHEAR LINE TO THE N UNDULATES. THE GLOBAL MODELS SEEM TO HAVE A HARD TIME RESOLVING THE FUNNELING THROUGH THE WINDWARD PASSAGE. THEY ARE FREQUENTLY TOO LOW WITH THE WIND SPEED HERE UNDER A BROADLY FRESH TO STRONG NE FLOW REGIME. THEREFORE...BUMPED THE WINDS UP 5 KT COMPARED TO THE MODELS SUN THROUGH TUE AND ADJUSTED SEAS ACCORDINGLY. ELSEWHERE...AN AREA OF SCATTERED MODERATE CONVECTION IS SLOWLY MOVING W THROUGH THE TROPICAL N ATLC ZONE S OF 12N. THIS CONVECTION IS BEING FORCED BY A SYSTEM THAT IS STRONG IN THE MID-LEVELS BUT DIFFICULT TO IDENTIFY AT THE SURFACE. THE HEAVIEST PRECIPITATION SHOULD MOVE INLAND WITH THE SYSTEM AS IT CONTINUES W OVER THE NEXT DAY OR TWO. SW N ATLC N OF 19N W OF 55W... MOST OF THE COLD FRONT THAT HAD STRETCHED THROUGH THE CENTRAL BAHAMAS YESTERDAY HAS TRANSITIONED TO A SHEAR LINE. THE COLD FRONT LIES FROM 31N55W TO 27N60W AND IS THEN A SHEAR LINE THROUGH 25N67W TO 21N72W WITH FRESH TO STRONG E-NE WINDS TO THE N AND MODERATE E-NE WINDS TO THE S OF THE SHEAR LINE. SEAS HAVE BUILT TO 8-10 FT E OF BAHAMAS ACCORDING TO BUOYS 41046 AND 41047 AS WELL AS SHIPS C6XP7 AND 9HA3047. WHILE THE POSITION OF THE SHEAR LINE IS EXPECTED TO UNDULATE OVER THE NEXT FEW DAYS...THE CONDITIONS N OF THE BOUNDARY SHOULD CHANGE LITTLE. E OF THE FORECAST AREA...A MID LEVEL LOW IS EXPECTED TO DEEPEN OVER THE NEXT FEW DAYS AS IT IS DRAWN NORTHWARD TOWARD THE LEADING EDGE OF THE AFOREMENTIONED COLD FRONT. THE GFS HAD BEEN ONE OF THE DEEPEST AND FASTEST SOLUTIONS WITH THIS SYSTEM...BUT THE UKMET HAS CAUGHT UP TO THE GFS AND THE ECMWF IS TRENDING STRONGER. THE 00Z GEFS MEMBERS SHOW NO CHANCE OF GALE CONDITIONS DEVELOPING IN THE HSFAT2 WATERS...WAITING UNTIL THE SYSTEM IS N OF 31N TO DEEPEN ENOUGH FOR GALES. LATER IN THE FORECAST PERIOD...THE MODELS HAVE BACKED OFF ON THE DEVELOPMENT OF A LOW N OF PUERTO RICO ON MON-TUE THAT BECOMES INVOLVED WITH THE PERSISTING SHEAR LINE. THE 00Z ECMWF AND GFS AGREE ON THE DEVELOPMENT OF A POSITIVELY-TILTED DEEP-LAYERED TROUGH SETTING UP FROM 31N50W TO HISPANIOLA DURING THIS TIME AND CARRY ANY SURFACE WAVES QUICKLY NORTHEASTWARD ALONG THE BOUNDARY AND E OF THE FORECAST AREA. THE GEFS 34-KT WIND SPEED PROBABILITIES SHOW ONLY BRIEFLY SHOW A 20 PERCENT CHANCE OF GALES N OF 26N BETWEEN 50W AND 65W. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER