000 AGXX40 KNHC 060701 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT SUN MAY 06 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE QUIET PERIOD CONTINUES IN THE GULF OF MEXICO WITH WINDS EXPECTED TO REMAIN AT 15 KT OR LOWER AND SEAS NO HIGHER THAN 5 FT THROUGH THU. THE NEXT THREAT OF ORGANIZED PRECIPITATION COMES MON OVER THE NE GULF AHEAD OF A BACKDOOR COLD FRONT DROPPING INTO NE FL THAT WILL NOT MAKE IT INTO THE GULF. ANOTHER COLD FRONT WILL REACH THE NORTHERN GULF COAST ON WED AND LIE BETWEEN 27N-28N THU. THE UKMET AND GFS BUILD 20 KT WINDS BEHIND THE FRONT WHILE THE ECMWF DOES NOT. MEANWHILE...THE GFS IS FASTER CARRYING THE LEADING EDGE OF THE FRONT EASTWARD THROUGH FL THAN THE ECMWF...WITH THE TWO MODELS ON THE EXTREMES OF THE MODEL SUITE. A BLEND OF THE GFS AND ECMWF WAS USED TO ADJUST THE TIMING OF THE FRONT...BUT LEANED TOWARD THE STRONGER GFS WINDS BEHIND THE FRONT. CARIBBEAN SEA... TROUGHING OVER THE CENTRAL ATLC HAS WEAKENED THE SUBTROPICAL RIDGING OVER THE CARIBBEAN AND LESSENED THE PRES GRADIENT YIELDING A GENTLE TO MODERATE BREEZE AND SEAS 5 FT OR LESS. THESE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE END OF THE PERIOD ON THU. THERE IS SOME DISAGREEMENT BETWEEN THE MODELS ON THE STRENGTH OF THE TROUGHING OVER THE EASTERN CARIBBEAN TODAY THROUGH WED...WITH THE 00Z GFS DISTINCT LOW PRES SYSTEM WITH WINDS TO 20 KT. GRID-SCALE FEEDBACK CONTINUES TO BE A PROBLEM FOR THE GFS LATE SUN INTO EARLY MON. THE 00Z UKMET IS WEAKER WITH THE TROUGHING HERE AND THE WINDS THAN THE GFS WHILE THE 00Z ECMWF LOOKS MORE LIKE A COMPROMISE BETWEEN THE TWO...WITH THE ECMWF SHOWING A FEW BARBS TO 20 KT ON MON NEAR ITS MORE POORLY DEFINED AREA OF LOWEST PRES. BOTH THE GFS AND ECMWF AGREE TO MOVE THE BULK OF THE ENERGY ASSOCIATED WITH THE SYSTEM INTO THE TROPICAL N ATLC ON WED. THE COMPROMISE ECMWF SOLUTION WILL BE USED TO ADJUST THE GRIDDED FORECAST HERE. ATLANTIC... FOR THE TROPICAL N ATLC...PLEASE SEE THE DISCUSSION OF THE TROUGHING IN THE EASTERN CARIBBEAN THAT IS EXPECTED TO SHIFT NORTHEASTWARD INTO THE TROPICAL N ATLC WED. THE 00Z GFS IS THE STRONGEST OF THE MODELS WITH MID LEVEL ENERGY AS IT MOVES INTO THE TROPICAL N ATLC AND APPEARS TO BE AN OUTLIER. ADJUSTMENTS WERE MADE TOWARD THE WEAKER ECMWF. FARTHER N...THE MOST SIGNIFICANT MODEL DIFFERENCES LIE WITH A FRONTAL WAVE THAT STALLS N OF THE BAHAMAS ON MON. THE 00Z GFS...UKMET...AND CMC CARRY A STRONGER LOW HERE THAN THE ECMWF BY MON AFTERNOON AND LIFT THE LOW NORTHWARD AHEAD OF A SLOW MOVING COLD FRONT ON TUE MORE RAPIDLY. THE GFS HAS TRENDED TOWARD A WEAKER AND SLOWER LOW BY TUE COMPARED TO THE 18Z RUN. THIS IS A TREND TOWARD THE ECMWF SOLUTION. THE SLOW MOVING COLD FRONT WILL MOVE INTO NW WATERS THU. THE MODELS GENERALLY AGREE ON THE AREA OF 20 KT SW WINDS OVER NW WATERS AHEAD OF THE FRONT STARTING WED EVENING...WITH THE GFS THE FASTEST MODEL WITH THE FRONT AND THE ECMWF THE SLOWEST. OVERALL...A BLEND OF THE 00Z GFS AND ECMWF SEEMS LIKE A WAY TO ADJUST THE GRIDDED FORECAST. 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... .NONE. ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER