000 AGXX40 KNHC 260723 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 325 AM EDT WED SEP 26 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... FAIRLY TRANQUIL CONDITIONS WITH WINDS AND SEAS BELOW ADVISORY THRESHOLDS WILL PREVAIL THROUGH FRI. MORE UNCERTAINTY COMES INTO THE FORECAST FOR THE WEEKEND WHEN SOME OF THE FORECAST MODELS SHOW ENERGY FROM EASTERN PACIFIC HURRICANE MIRIAM PASSING OVER THE RIDGE ALOFT OVER NE MEXICO AND MOVING INTO THE BACKSIDE OF THE AMPLIFYING EASTERN U.S. TROUGH...FORCING A COLD FRONT OFF THE TEXAS COAST. THE 00Z GFS HAS TRENDED SLOWER CARRYING THE ENERGY THROUGH TEXAS AND THE ASSOCIATED COLD FRONT INTO THE GULF COMPARED TO ITS 18Z AND 12Z RUNS. ALSO...THE GFS NOW CARRIES A SURFACE LOW TO THE TEXAS COAST AROUND 06Z SUN. THE 00Z ECMWF ALSO CARRIES A SURFACE LOW TO THE TEXAS COAST AT THIS TIME. THIS IS A FASTER TREND IN THE ECMWF COMPARED TO ITS 12Z RUN. THESE MODELS SEEM TO BE CONVERGING ON A SOLUTION. THE ECMWF HAS TRENDED CONSIDERABLY STRONGER WITH THE WINDS BEHIND THE FRONT ON SUN...AS HAS THE GFS. THE PRIMARY DIFFERENCE BETWEEN THE MODELS IS THE TRACK OF THE SURFACE WAVE ALONG THE FRONT...WITH THE ECMWF STRONGER AND MORE NORTHEASTERLY THAN THE GFS ON MON. CONFIDENCE IS LOW IN THE DETAILS HERE THIS FAR OUT. THE FORECAST WILL BE ADJUSTED TOWARD A BLEND OF THE 00Z GFS AND ECMWF FROM FRI ONWARD. IT IS HEARTENING TO SEE THE MODELS BEGINNING TO CONVERGE ON A SOLUTION. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE 0140 UTC ASCAT PASS SHOWS FRESH WINDS WERE STILL FOUND OVER FAR NW WATERS...BUT WINDS SHOULD GRADUALLY DIMINISH HERE TODAY. THE FRONTAL BOUNDARY THAT MADE ITS WAY THROUGH NW WATERS SUN IS STALLED FROM 31N66W TO NEAR MIAMI...FLORIDA. THE FRONT IS WEAKENING AND IS FORECAST TO DISSIPATE TODAY. WINDS AND SEAS REMAIN BELOW ADVISORY CRITERIA UNTIL SUN. THE 00Z GFS BUILDS SOUTHERLY WINDS TO 25 KT ALONG 70W AS IT CARRIES A MID TO UPPER LEVEL TROUGH EASTWARD FROM FL INTO THE CENTRAL ATLC AND MIXES THE SOUTHERLY JET AHEAD OF THE TROUGH TO THE SURFACE. THE 00Z ECMWF...NOGAPS...AND UKMET ARE NOT AS STRONG WITH THE SOUTHERLY FLOW HERE DESPITE CARRYING A SIMILAR SURFACE PRES GRADIENT...KEEPING WINDS TO A FRESH BREEZE AT MOST. THE GRIDS WILL BE ADJUSTED CLOSER TO THE ECMWF FORECAST E OF THE BAHAMAS LATE IN THE PERIOD. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE TROPICAL WAVE OVER THE CENTRAL CARIBBEAN REMAINS DIFFICULT TO FIND AS IT INTERACTS WITH THE UPPER TROUGH STRETCHED FROM THE NE CARIBBEAN TO THE COAST OF COLOMBIA. THIS INTERACTION HAD CAUSED CONVECTION TO FLARE NEAR THE WAVE YESTERDAY WHERE UPPER DIFFLUENCE IS ENHANCING VERTICAL LIFT. NOW THAT THE WAVE IS MOVING W OF THE UPPER TROUGH AXIS...THE CONVECTION IS WANING AS IT MOVES INTO A REGION OF MORE CONFLUENT FLOW ALOFT. THE 0136 UTC ASCAT PASS SHOWS A SMALL AREA OF STRONG TRADES WINDS ALONG THE COAST OF COLOMBIA WHILE SHIP A8SG2 REPORTED 9 FT SEAS NEAR 12N75.5W AT 0600 UTC. THE 00Z GFS AND ITS WW3 APPEARS BETTER INITIALIZED COMPARED TO THE OBSERVATIONS THAN THE WEAKER ECMWF. THEY WILL BE USED TO ADJUST THE GRIDS HERE EARLY IN THE FORECAST...WITH WINDS AND SEAS EXPECTED TO DIMINISH BELOW ADVISORY CRITERIA THIS AFTERNOON. TRADES REMAIN WEAK THU AND FRI AS THE DRIVING HIGH PRES TO THE N WEAKENS. OVER THE WEEKEND...HIGH PRES IS EXPECTED TO BUILD IN THE CENTRAL ATLC AND FORCE A TIGHTER PRES GRADIENT OVER THE CARIBBEAN E OF 75W. WITH THE GFS A STRONG OUTLIER OVER THE SW N ATLC WITHIN THE BELT OF THESE STRONGER WINDS...WILL HEDGE TOWARD THE ECMWF WHEN ADJUSTING THE LONG-TERM FORECAST 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