000 AGXX40 KNHC 171903 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EST THU NOV 17 2011 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... EARLY MORNING CONVECTION HAS DIMINISHED TO ONLY A FEW ISOLATED SHOWERS ALONG THE COLD FRONT CURRENTLY PROGRESSING ACROSS THE SOUTHEASTERN HALF OF THE BASIN. THIS ACTIVITY RESIDES MAINLY FROM SOUTH OF TAMPA BAY SW TO NEAR 25N86W. THE MODELS HAVE TRENDED A BIT FASTER COMPARED TO THIS TIME YESTERDAY WITH THE FRONTAL TIMING...CARRYING THE WEAKENING FRONT INTO S FLORIDA FRI MORNING. THE GFS CONTINUES TO SHOW WINDS ABOUT 5 KT STRONGER BEHIND THE FRONT THAN THE ECMWF IN THE MIDDLE AND EASTERN GULF TODAY AND TONIGHT. CURRENTLY...THE STRONGER GFS IS VERIFYING BETTER THAN THE ECMWF WITH THE WINDS BEHIND THE FRONT OBSERVED FROM SHIP...BUOY...AND OFFSHORE OIL RIGS INDICATING 25 KT NE WINDS THROUGH THE MORNING HOURS. A 17/1542 UTC ASCAT PASS ALSO INDICATED 25 KT WINDS OVER THE NW GULF ZONE. WITH THE GFS AND ECMWF BOTH TRENDING FASTER AND IN FAIRLY GOOD AGREEMENT IN THE NEAR-TERM...FORECAST LEANS HEAVILY ON THE GFS FOR THE FORECAST WITH THE FRONT AND THE RE-ESTABLISHMENT OF SE RETURN FLOW ON THE BACKSIDE OF HIGH PRES TRAILING THE FRONT BY SAT. CARIBBEAN SEA AND TROPICAL N ATLC... HIGH PRES N OF THE AREA CONTINUES TO CREATE A STRONG ENOUGH PRES GRADIENT ACROSS THE CARIBBEAN TO SUPPORT FRESH NE TRADE WINDS PRIMARILY OVER THE CENTRAL CARIBBEAN ACCORDING TO THE ASCAT PASS FROM 17/1404 UTC. THESE FRESH TRADES WILL DIMINISH LATER TODAY AS A COLD FRONT MOVES THROUGH EASTERN PORTIONS OF THE GULF OF MEXICO INTO THE SW NORTH ATLC...ERODING THE RIDGE AXIS CURRENTLY IN PLACE FROM BERMUDA TO THE STRAITS OF FLORIDA NEAR 24N80W. FRESH NE WINDS ALSO LIE OVER THE TROPICAL NORTH ATLC N OF 19N WHERE THE PRES GRADIENT IS TIGHT BETWEEN THE AFOREMENTIONED RIDGE AND LOW LEVEL TROUGHING ALONG 47W-52W. THERE IS CONSIDERABLE DISAGREEMENT WITH THE EVOLUTION OF THIS TROUGHING...WITH THE GFS DEVELOPING A STRONG LOW PRES SYSTEM BY SUN NE OF THE AREA IN THE VICINITY OF 25N54W. HOWEVER...THE GEFS MEAN CARRIES A DISTINCT LOW FROM 15N TO 25N BETWEEN 50W AND 60W SAT THROUGH MON...SO THERE IS SOME AGREEMENT AMONG THE GFS ENSEMBLE MEMBERS ON THIS SCENARIO. FOR NOW CONFIDENCE REMAINS LOW AND THE FORECAST WILL BLEND THE GFS AND ECMWF SOLUTIONS WHICH KEEPS THE STRONGEST WINDS AND HIGHEST SEAS PRIMARILY IN THE NW CORNER OF THE TROPICAL N ATLC ZONE WHERE THE PRES GRADIENT WILL REMAIN GREATEST BETWEEN THE TROUGHING AND RIDGING OVER THE SW NORTH ATLC. SW N ATLC S OF 31N W OF 55W... THE 1400 UTC ASCAT PASS AND SHIP/BUOY OBSERVATIONS SHOW FRESH TRADE WINDS ARE CONFINED PRIMARY S OF 24N E OF THE BAHAMAS IN THE AREA S OF THE RIDGE AXIS WHICH EXTENDS FROM NEAR BERMUDA TO THE STRAITS OF FLORIDA NEAR 24N80W. A PRE-FRONTAL SURFACE TROUGH HAS MOVED OFF THE NORTHERN FL COAST WITH ONLY LINGERING ISOLATED SHOWERS REMAINING N OF 28N W OF 76W. FRESH S TO SW WINDS LIE AHEAD OF THE TROUGH WITH AN EARLIER MORNING ASCAT PASS INDICATING SW WINDS TO 20 KT ENTERING THE FAR NW PORTION OF THE AREA. THE TROUGH WILL BE OVERTAKEN BY A COLD FRONT THIS AFTERNOON INTO THE EVENING AS THE RIDGE CURRENTLY IN PLACE WILL RETREAT NORTHEASTWARD AHEAD OF IT. AS EXPLAINED IN THE GULF OF MEXICO SECTION...THE MODELS HAVE TRENDED FASTER CARRYING THE FRONT THROUGH FLORIDA TODAY THROUGH FRI. RIDGING WILL AGAIN BUILD OVER THE AREA BEHIND THE COLD FRONT FRI. WINDS WILL REMAIN FRESH TO STRONG OVER MUCH OF THE SW NORTH ATLC OFFSHORE ZONE... SAVE NW WATERS...OVER THE WEEKEND AS HIGH PRES BEHIND THE FRONT PRESSES AGAINST THE PERSISTENT TROUGHING JUST E OF THE AREA AND N OF THE TROPICAL N ATLC ZONE. THERE IS CONSIDERABLE DISAGREEMENT IN THE DETAILS WITH THIS TROUGHING...WITH THE GFS DEVELOPING A STRONG LOW PRES SYSTEM BY SUN. HOWEVER...THE GEFS MEAN CARRIES A DISTINCT LOW FROM 15N TO 25N BETWEEN 50W AND 60W SAT THROUGH MON...SO THERE IS SOME AGREEMENT AMONG THE GFS ENSEMBLE MEMBERS ON THIS SCENARIO. FOR NOW CONFIDENCE REMAINS LOW AND THE FORECAST WILL BLEND THE GFS AND ECMWF SOLUTIONS. WARNINGS... GULF OF MEXICO... .NONE. .CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. .SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER HUFFMAN