000 AGXX40 KNHC 101859 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 PM EST MON DEC 10 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... A STRONG COLD FRONT PUSHED OFF THE TEXAS COAST THIS MORNING AND REACHED FROM 30N91W TO 25N98W AT 1500 UTC. BUOY 42020 IN THE COASTAL WATERS REACHED 31 KT AT 1500 UTC BEHIND THE FRONT AND IS REPORTING 11 FT SEAS AS OF 1700 UTC. THIS BUOY HAS AN ELEVATION OF 5 METERS...SO THE WIND SPEED AT 10 METERS IS LIKELY HIGHER. THE 1634 UTC ASCAT PASS SHOWS WINDS TO NEAR GALE FORCE...AND IT USUALLY RUNS AROUND 5 KT TOO LOW AT THESE WIND SPEEDS. THE 1200 UTC GFS RUN SHOWS GALES AT THE BUOY LOCATION AT 1500 UTC. SURROUNDING BUOYS AND PLATFORMS SEEMS TO CORROBORATE THE GFS SHORT-TERM FORECAST WHILE THE 1200 UTC ECMWF IS ABOUT 10 KT TOO LOW WITH THE STRONGEST WINDS. THE HSFAT2 WAS UPDATED TO REFLECT CURRENT GALE CONDITIONS N OF THE FRONT. THE 1200 UTC GFS CONTINUES THE GALE THROUGH 0600 UTC AS THE STRONGEST WINDS MOVE SOUTHWARD ALONG THE MEXICAN COAST. STRANGELY...THE 1200 UTC GEFS ENSEMBLES HAVE BACKED OFF CONSIDERABLY ON THE PROBABILITY OF GALE FORCE WINDS COMPARED TO THE 0600 UTC RUN...WITH THE LATEST RUN ONLY SHOWING A 40-50 PERCENT CHANCE OF A GALE AT 0000 UTC TONIGHT. DESPITE THIS AND THE WEAKER ECMWF...FOLLOWED THE GFS SHORT-TERM FORECAST WHICH IS IN BEST AGREEMENT WITH THE OBSERVATIONS. THE WW3 IS ABOUT 3 FT TOO LOW AT BUOY 42020 AND IN THE SURROUNDING AREA COMPARED TO THE AVAILABLE OBSERVATIONS. THE FORECAST WAS BUMPED UP TO MATCH THE CURRENT OBSERVATIONS AS WELL AS IN THE FORECAST PERIOD...ESPECIALLY IN THE REGION OF 25-35 KT WINDS. THE MODELS AGREE ON CARRYING A MORE AMPLIFIED MID-LEVEL TROUGH THROUGH THE NORTHERN GULF WED THAT WILL REINFORCE THE COLD FRONT AND ENHANCE WINDS BEHIND THE FRONT TUE NIGHT AND WED. THE 1200 UTC GFS SOLUTION IS THE STRONGEST AND SLOWEST GLOBAL MODEL WITH THIS TROUGHING. HOWEVER...SINCE ITS STRONGER SOLUTION APPEARS TO BE DOING BETTER INITIALLY...WILL BLEND IT WITH THE ECMWF SOLUTION IN THE LONGER RANGES. CARIBBEAN SEA AND TROPICAL N ATLC S OF 19N W OF 55W... THE 1200 UTC GFS APPEARS WELL INITIALIZED IN THE CENTRAL CARIBBEAN AND TROPICAL N ATLC. THE WW3 ALSO IS REASONABLY WELL INITIALIZED WITH THE EXCEPTION OF THE CARIBBEAN ZONE FROM 15N TO 18N BETWEEN 80W AND 85W WHERE THE WW3 IS RUNNING 2-3 FT HIGHER THAN BUOY 42057 IN THE E-SE SWELL SW OF JAMAICA. ADJUSTMENTS WILL BE MADE TO CORRECT FOR THIS DISCREPANCY. THE SUBTROPICAL HIGH DRIVING THE WINDS IN THE REGION WILL SHIFT EASTWARD BEGINNING TONIGHT AS THE COLD FRONT EXPECTED TO PASS THROUGH THE GULF OF MEXICO ADVANCES EASTWARD. THE STRONGEST WINDS WILL GRADUALLY SHIFT EASTWARD WITH THE STRONGEST PRESSURE GRADIENT. THE COLD FRONT IS EXPECTED TO CLIP THE YUCATAN CHANNEL LATE THU NIGHT. THE 0000 UTC GFS SEEMS REASONABLE HERE. SW N ATLC FROM 19N TO 31N W OF 55W... WINDS ARE LIGHT TO MODERATE TODAY THROUGH THE REGION WITH THE EXCEPTION OF FRESH TO STRONG NE TRADES IN THE FAR SE CORNER. THE GLOBAL MODELS DO A GOOD JOB CAPTURING THE WIND FIELD AND THE WAVE MODELS APPEAR REASONABLY WELL INITIALIZED. THE MODELS DIVERGE WITH THE STRENGTH AND TIMING OF THE COLD FRONT EXPECTED TO PASS THROUGH THE GULF AND APPROACH NW WATERS BEGINNING TUE. AS EXPLAINED IN THE GULF OF MEXICO SECTION...THE 1200 UTC GFS IS STRONGER AND SLOWER THAN THE OTHER GLOBAL MODELS WITH THE SECONDARY TROUGH PASSING THROUGH THE NORTHERN GULF WED...BUT ITS STRONGER INITIALIZATION WITH THE LEAD TROUGH SUPPORTING THE COLD FRONT COMPARES BEST TO THE OBSERVATIONS. A BLEND OF THE GFS AND ECMWF WAS RECOMMENDED THERE BEYOND TUE. IN THE ATLC...THE GFS SOLUTION DEVELOPS A STRONGER SURFACE WAVE ASSOCIATED WITH THE SECONDARY TROUGH CLOSER TO SHORE THAN THE OTHER MODELS. THE 1200 UTC ECMWF HAS TRENDED CLOSER TO THE GFS AND IS THE MODEL CLOSEST TO THE GFS SOLUTION CARRYING THE WAVE AND FRONT EASTWARD WITH THE ECMWF FASTER CARRYING THE COLD FRONT SOUTHEASTWARD. THE GFS DEVELOPS A GALE JUST N OF THE AREA BY 0600 UTC THU WHILE THE ECMWF WAITS UNTIL 1800 UTC THU TO BUMP WINDS N OF THE AREA NEAR THE WAVE TO 30 KT. WITH THE ECMWF TRENDING TOWARD THE GFS...A BLEND OF THEIR SOLUTIONS SEEMS LIKE A GOOD BET HERE. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .GALE WARNING FROM 21N TO 28N W OF 96W THROUGH TONIGHT... GMZ011....GMZ017...AND GMZ023. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER