000 AGXX40 KNHC 250701 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT TUE SEP 25 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 UPPER JET CONTINUES TO LIFT THE MOIST AIR IN PLACE OVER THE SOUTHERN GULF OF MEXICO...WITH HIGH CLOUDS FOUND OVER MUCH OF THE EASTERN GULF AND SHOWERS AND THUNDERSTORMS OVER MUCH OF THE SOUTHERN GULF. A WEAK FRONT HAS STALLED FROM NEAR THE FLORIDA KEYS TO 23N88W. THUNDERSTORMS ARE PRIMARILY FOUND NEAR THIS BOUNDARY AND THE 0342 UTC ASCAT PASS SHOWS A FRESH BREEZE PRIMARILY FOUND JUST TO THE N OF THE BOUNDARY OVER THE CENTRAL GULF. THE 00Z GFS AND ECMWF ARE WELL INITIALIZED HERE AND SHOW WINDS DIMINISHING AFTER SUNRISE. CONDITIONS REMAIN RELATIVELY QUIET WITH WINDS 20 KT OR LESS AND SEAS LESS THAN 8 FT FOR THE REMAINDER OF THE FORECAST PERIOD...WITH GRADUALLY WEAKENING HIGH PRES TO THE NE OF THE GULF DRIVING THE LOW LEVEL FLOW. THE 00Z GFS SEEMED LIKE A REASONABLE CHOICE FOR UPDATING THE FORECAST. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE 0202 UTC ASCAT PASS SHOWED A SOLID AREA OF FRESH TO STRONG E-NE WINDS IN NW WATERS. THE 00Z GFS AND ECMWF ARE ON THE WEAK SIDE WITH THE WIND SPEEDS HERE COMPARED TO THE ASCAT PASS...SO ADJUSTMENTS WILL BE MADE TO THE FIRST FEW PERIOD OF THE FORECAST. BOTH MODELS DIMINISH WINDS BELOW 20 KT THIS AFTERNOON. THE ECMWF WAVE MODEL CARRIES SEAS TO 9 FT WHILE THE GFS-BASED WW3 ONLY GETS WAVE HTS UP TO 7 FT. BUOY OBSERVATIONS IN THE OFFSHORE AREA ARE ALL 7 FT HERE...WITH THE AREA OF MAX SEAS LIKELY NOT SAMPLED. WILL ADJUST THE SEAS A BIT HIGHER THAN THE CURRENT FORECAST BASED ON THIS GUIDANCE FOR THE FIRST FEW PERIODS. THE FRONTAL BOUNDARY THAT MADE ITS WAY THROUGH NW WATERS YESTERDAY IS STALLED FROM 31N70W TO NEAR MIAMI...FLORIDA. THE FRONT IS WEAKENING AND IS FORECAST TO DISSIPATE BY WED. WINDS AND SEAS REMAIN BELOW ADVISORY CRITERIA ELSEWHERE THROUGH THE REMAINDER OF THE PERIOD. AGAIN...THE 00Z GFS SEEMED LIKE A REASONABLE CHOICE FOR UPDATING THE GRIDS BEYOND THE FIRST FEW PERIOD. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE TROPICAL WAVE OVER THE LEEWARD ISLANDS REMAINS DIFFICULT TO FIND AS IT INTERACTS WITH THE UPPER TROUGH STRETCHED FROM THE NE CARIBBEAN INTO THE COAST OF COLOMBIA. THIS INTERACTION HAS CAUSED CONVECTION TO FLARE AHEAD OF THE WAVE WHERE UPPER DIFFLUENCE IS ENHANCING VERTICAL LIFT. THIS WAVE SHOULD REMAIN A FOCUS FOR CONVECTION AS IT MAKES ITS WAY INTO EASTERN CARIBBEAN TODAY. ONCE THE WAVE MOVES W OF THE UPPER TROUGH AXIS...PASSING THROUGH THE CENTRAL CARIBBEAN WED AND INTO THE WESTERN CARIBBEAN BY FRI...CONVECTION SHOULD WANE AS MOVES INTO A REGION OF MORE CONFLUENT FLOW ALOFT. THE 0158 UTC ASCAT PASS SHOWS AN AREA OF STRONG TRADES WINDS ALONG THE COAST OF COLOMBIA AS FAR N AS 16N...WITH BUOY 42058 REPORTING 21 KT AND 8 FT SEAS AT 0600 UTC. SHIPS C6KD7 REPORTING 26 KT NEAR 14N72W WITH 10 FT SEAS AT 0300 UTC...DIHE REPORTING 25 KT NEAR 15N76.5W WITH 10 FT SEAS AT 0000 UTC AND VRGT8 REPORTING 22 KT NEAR 15N80W WITH 10 FT SEAS AT 0000 UTC. THE 00Z GFS APPEARS BETTER INITIALIZED COMPARED TO THE OBSERVATIONS THAN THE WEAKER ECMWF. IT WILL BE USED TO ADJUST THE GRIDS HERE...WITH WINDS AND SEAS EXPECTED TO DIMINISH BELOW ADVISORY CRITERIA BY WED AFTERNOON. TRADES REMAIN WEAK THU THRU SAT AS THE DRIVING HIGH PRES TO THE N WEAKENS. 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