000 AGXX40 KNHC 240724 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 325 AM EDT SUN SEP 24 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... THE SOUTHERN STREAM OF THE SPLIT UPPER JET FEEDING INTO THE DEEP LAYER TROUGH OVER THE EASTERN U.S. IS DIRECTING TROPICAL MOISTURE FROM THE PACIFIC NEWD INTO THE GULF OF MEXICO WHERE SHOWERS AND THUNDERSTORMS CAN BE FOUND OVER MUCH OF THE GULF S OF 27N. A WEAK COLD FRONT HAS MADE ITS WAY THROUGH THE NE GULF WITH ITS W PORTION DISSIPATING S OF LOUISIANA. THE REMAINDER WILL CONTINUE S INTO SOUTHERN FL AND THE KEYS WHERE IT SHOULD STALL ON TUE. EASTERLY WINDS HAVE INCREASED TO A FRESH TO STRONG BREEZE AND SEAS TO 6 FT PRIMARILY OVER THE WEST CENTRAL GULF ACCORDING TO THE 0402 UTC ASCAT PASS AND BUOY 42055...WITH THIS BUOY REPORTING 25 KT E-NE WINDS AT 0600 UTC. THESE CONDITIONS ARE EXPECTED TO DIMINISH TONIGHT. WINDS AHEAD OF THE FRONT HAVE TRENDED STRONGER IN THE 00Z GFS AND ECMWF COMPARED TO THIS TIME YESTERDAY AND THE OBSERVATIONS CONFIRM THESE CONDITIONS. THE NEW GUIDANCE WILL BE USED TO ADJUST THE GRIDS TOWARD THESE STRONGER INITIAL WINDS IN THE SW AND W CENTRAL GULF. OTHERWISE...FRESH TO MODERATE FLOW DRIVEN BY HIGH PRES TO THE NE OF THE GULF WILL DRIVE THE WINDS AND SEAS. THE MODELS ARE IN GOOD AGREEMENT. USED THE GFS TO ADJUST THE FORECAST. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE COLD FRONT HAS MOVED THROUGH NW WATERS AND SKIES HAVE CLEARED BEHIND IT. THE UPPER TROUGH IS SLOWLY CATCHING UP TO THE LOW LEVEL BOUNDARY. AS A RESULT...THICKNESSES ARE EXPECTED TO CONTINUE DROPPING BEHIND THE FRONT AND WINDS WILL PICK UP TO A FRESH BREEZE BY AFTERNOON ACCORDING TO THE 00Z GFS. THE 00Z ECMWF ALSO INCREASES THE WIND HERE THIS AFTERNOON...BUT DIMINISHES THE WIND BY TUE MORNING. THE GFS ALLOWS THE FRESH BREEZE TO CONTINUE THROUGH TUE EVENING. THIS COOLER AIR OVER THE WARM WATERS OF THE GULF STREAM WILL PERHAPS ALLOW FOR MORE VERTICAL MIXING OF THE HIGHER WINDS ALOFT. ALSO...THE OVERALL TREND IN THE GFS AND ECMWF IS TOWARD A STRONGER COLD FRONT. THEREFORE...WILL ADJUST THE GRIDS TOWARD THE STRONGER 00Z GFS SOLUTION OVER NW WATERS AND BRING SEAS TO 8 FT LIKE THE WW3 SUGGESTS. ELSEWHERE...THE MODELS ARE IN REASONABLE AGREEMENT WITH THE EVOLUTION OF THE COLD FRONT WHICH IS EXPECTED TO STALL FROM SOUTH FL TO BERMUDA BY TUE BEFORE BEGINNING TO DISSIPATE. HIGH PRES BEHIND THE FRONT WILL BREAKDOWN BY WED. SINCE THE GFS IS ALREADY FAVORED OVER NW WATERS...WILL USE IT TO ADJUST THE FORECAST FOR THE REMAINDER OF THIS AREA. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE ALONG 57W/58W WAS DIFFICULT TO FIND YESTERDAY AS IT BEGAN TO INTERACT WITH THE UPPER TROUGH STRETCHED FROM THE NE CARIBBEAN INTO THE S CENTRAL CARIBBEAN. THIS INTERACTION CAUSED CONVECTION TO FLARE AHEAD OF THE WAVE. SURFACE PRESSURES REVEAL THE WAVE AXIS IS LIKELY FARTHER E THAN THE 0000 UTC ANALYSIS. THIS MAKES THE LONG-TERM FORWARD MOTION A MORE REALISTIC 15 KT. THIS WAVE SHOULD REMAIN A FOCUS FOR CONVECTION AS IT MAKES ITS WAY THROUGH THE LESSER ANTILLES TODAY AND THE EASTERN CARIBBEAN TUE. ONCE THE WAVE MOVES W OF THE UPPER TROUGH AXIS...PASSING THROUGH THE CENTRAL CARIBBEAN WED AND INTO THE WESTERN CARIBBEAN THU...CONVECTION SHOULD WANE AS IT ENTERS A REGION OF MORE CONFLUENT FLOW ALOFT. WHILE BUOY 41101 SHOWS SEAS REMAIN OVER 8 FT IN THE TROPICAL N ATLC NEAR THE WAVE....THE 0036 UTC ASCAT PASS AND SURFACE OBSERVATIONS DO NOT SHOW WINDS HIGHER THAN 20 KT. THE MODELS AGREE ON WINDS BELOW ADVISORY CONDITIONS AS WELL. THE 0218 UTC ASCAT PASS CENTERED NEAR 68W PICKED UP A BROAD AREA OF FRESH TO STRONG WINDS IN THE AREA OF A TIGHT PRES GRADIENT BETWEEN THE SURFACE RIDGE INTRUDING INTO THE NE CARIBBEAN FROM THE N AND THE TROPICAL WAVE TO THE E. THE MODELS ARE ALL RUNNING AROUND 5 KT TOO LIGHT WITH THE WINDS HERE...WITH THE 00Z GFS CLOSEST TO THE AREAL EXTENT OF THE WIND FIELD. WILL ADJUST THE FORECAST TOWARD THE 00Z GFS AND THE OBSERVATIONS...WITH WINDS AND/OR SEAS EXPECTED TO REMAIN ABOVE ADVISORY CRITERIA INTO WED. 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