000 AGXX40 KNHC 030727 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 230 AM EST MON DEC 03 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 JUST OFFSHORE OF THE CAROLINAS WILL CONTINUE TO DRIVE THE WINDS OVER THE GULF THROUGH TUE. WITH THE 0312 UTC ASCAT PASS SHOWING FRESH TO STRONG E WINDS IN THE GULF S OF 25N E OF 85W INCLUDING THE STRAITS OF FLORIDA...WILL HEDGE TOWARD THE STRONGER 00Z GFS INITIALLY AND THROUGH TUE AS COMPARED TO THE WEAKER 00Z ECMWF. THE WW3 TYPICALLY DOES NOT CAPTURE PEAK AREA OF SEAS THROUGH THE STRAITS AND ACROSS YUCATAN CHANNEL WHEN WINDS ARE AGAINST THE CURRENT. FORECAST GRIDS WILL GO ABOVE GUIDANCE IN THE UPDATED FORECAST...WITH SEAS LIKELY TO LINGER AROUND 6-8 FT TILL TUE. SHIP HPYE REPORTED 10 FT SEAS NEAR THE COAST OF CUBA AT 22.5N84.8W AT 0000 UTC. THIS IS 5 FT HIGHER THAN THE 00Z WW3 AND THE 00Z EC WAVE. AT THE SAME TIME...SHIP 5BDK2 REPORTED 8 FT SEAS NEAR 23N88W WHICH WAS 3 FT HIGHER THAN EITHER WAVE MODEL. THE GFS AND WW3 WILL BE USED FOR THE FORECAST THROUGH TUE...WITH ADJUSTMENTS MADE IN THE SE GULF. A COLD FRONT WILL WEAKEN THE DRIVING HIGH PRES AND PUSH IT EASTWARD STARTING TUE NIGHT...WITH THE WEAKENED FRONT EXPECTED TO MOVE INTO THE NW GULF BY EARLY WED WITH LITTLE FANFARE ASIDE FROM SHOWERS AND THUNDERSTORMS. THE 00Z GFS AND ECMWF HAVE TRENDED TOWARD CARRYING THE FRONT FARTHER S INTO THE CENTRAL GULF THAN THEIR 00Z RUNS YESTERDAY...BUT WINDS AND SEAS WILL STILL REMAIN WELL BELOW ADVISORY CRITERIA. AS THE DEEP LAYER TROUGH ASSOCIATED WITH THE FRONT REACHES THE CENTRAL GULF...THE 00Z GFS BECOMES MORE PROGRESSIVE AND WEAK OUTLIER COMPARED TO THE REST OF THE GUIDANCE. THIS APPEARS TO HAVE NO INFLUENCE ON THE SURFACE PATTERN OVER THE GULF. THE FRONT IS EXPECTED TO DISSIPATED OVER THE CENTRAL GULF THU. BY FRI...DEEP-LAYER TROUGHING BUILDING IN THE U.S. PLAINS STATES WILL ENHANCE RETURN FLOW OVER THE WESTERN GULF WITH SOUTHERLY WINDS BECOMING FRESH. BEYOND TUE...A BLEND OF THE GFS AND ECMWF SOLUTIONS WILL BE USED TO UPDATE THE GRIDS. CARIBBEAN SEA AND TROPICAL N ATLC S OF 19N W OF 55W... STRONG HIGH PRES JUST OFF THE CAROLINA COAST CONTINUES TO DRIVE THE NE FLOW THROUGH THE CARIBBEAN. THE REMAINS OF A SHEAR LINE HAS DIPPED SOUTHWARD FROM THE ATLC...ALLOWING FRESH TO STRONG WINDS TO PENETRATE THE NW CARIBBEAN AS WELL AS THE WINDWARD PASSAGE ACCORDING TO THE 0310 UTC ASCAT AND 2234 UTC WINDSAT PASSES. BOTH THE 00Z GFS AND ECMWF ARE TOO SMALL WITH THE AREAL EXTENT OF THE FRESH TO STRONG WINDS IN THE NW CARIBBEAN...WITH A SLIGHT EDGE GOING TO THE GFS WHICH WILL BE USED FOR THE FORECAST HERE THROUGH TUE. 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. ONCE AGAIN...BUMPED THE WINDS UP A BIT COMPARED TO THE MODELS THROUGH TUE AND ADJUSTED SEAS ACCORDINGLY. OTHERWISE...MODERATE TO LIGHT NE TRADES WILL PREVAIL ACROSS THE REGION THROUGH FRI DESPITE LOW CONFIDENCE IN THE EVOLUTION OF THE PATTERN NE OF THIS AREA. SEE THE SECTION BELOW FOR DETAILS. SW N ATLC N OF 19N W OF 55W... FRESH TO STRONG NE WINDS DOMINATE THE FORECAST AREA AS A TIGHT PRES GRADIENT IS IN PLACE BETWEEN TROUGHING OVER THE EASTERN CARIBBEAN AND SOUTHEASTWARD MIGRATING HIGH PRES OFF THE CAROLINA COAST. THE 00Z GFS AND ECMWF APPEAR TO BE DOING REASONABLY WELL WITH THE WIND FIELD...BUT THEIR CORRESPONDING WAVE MODELS CONTINUE TO RUN ABOUT A FOOT TOO LOW COMPARED TO OBSERVATIONS OVER MUCH OF THE AREA. CONFIDENCE IS SOMEWHAT LOW IN THE FORECAST FOR THE REGION E OF 70W AS THE LINGERING MID LEVEL ENERGY ASSOCIATED WITH THE DISSOLVED SHEAR LINE INTERACTS WITH AN AMPLIFYING...POSITIVELY TILTED MID-LEVEL TROUGH AND ITS ASSOCIATED ENERGY. THE 00Z GFS DEVELOPS A WEAK LOW PRES SYSTEM NEAR 21N60W TODAY AND QUICKLY SENDS IT E OF THE AREA WHILE THE ECMWF DEVELOPS A MORE AMPLIFIED LOW THAT LINGERS OVER THE REGION LONGER. THE UKMET LOOKS LIKE A BLEND OF THESE SOLUTIONS. A BLEND WAS USED FOR THE FORECAST. THIS WEAK LOW SHOULD DRAG THE SURFACE TROUGH ANALYZED FROM 25N60W TO 20N68W AT 0000 UTC EASTWARD...ALLOWING FRESH TO STRONG NE WINDS TO BUILD BEHIND IT. THE MODELS AGREE ON WINDS AND SEAS DIMINISHING HERE WED AND THU. A NEW COLD FRONT WILL MOVE INTO NW WATERS BY THU. THE 00Z GFS IS CONSIDERABLY STRONGER WITH THIS FRONT THAN THE 00Z ECMWF AND UKMET WHICH BUILD AN INVERTED TROUGH THROUGH THE BAHAMAS AND KEEP THE FRONT FARTHER N. THE 00Z GFS IS A MORE PROGRESSIVE AND WEAK OUTLIER COMPARED TO THE REST OF THE GUIDANCE AS THE DEEP LAYER TROUGH PASSING THROUGH THE GULF OF MEXICO WED REACHES THE SW N ATLC. THE 00Z ECMWF IS PREFERRED HERE. 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