000 AGXX40 KNHC 040713 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 215 AM EST FRI JAN 04 2013 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 03/1638 UTC ASCAT PASS WAS THE LAST SCATTEROMETER PASS TO CLIP A PORTION OF THE SW GULF WHERE GALE WINDS ARE BELIEVED TO BE OCCURRING. THE MORE RECENT 0350 UTC ASCAT PASS WAS E OF 95W IN THIS AREA AND SHOWED WINDS TO 25 KT...CONSISTENT WITH BOTH THE 0000 UTC GFS AND ECMWF. WINDS AND SEAS SHOULD DIMINISH BY MORNING AS THE FRONT STRETCHED FROM FORT MYERS FLORIDA THROUGH 21N94W TO THE BAY OF CAMPECHE WEAKENS AND LIFTS NORTHWARD IN RESPONSE TO MID AND UPPER LEVEL RIDGING BUILDING AHEAD OF A TROUGH MOVING THROUGH THE SW UNITED STATES. THIS TROUGH WILL PROVIDE A SECONDARY SURGE OF NORTHERLY FLOW TO THE WESTERN GULF BY SUN...BUT IT IS NOT EXPECTED TO PARTICULARLY COLD. NEITHER THE 0000 UTC GFS NOR THE ECMWF SHOW GALE FORCE WINDS AND THE 0000 UTC GEFS SHOWS NO CHANCE OF A GALE. HOWEVER...THE 1500 UTC SREF SHOWS AS HIGH AS A 40 PERCENT CHANCE OF GALES AND THE FNMOC ENSEMBLES SHOW A 5 PERCENT CHANCE OF GALES SUN EVENING. IT GENERALLY DOES NOT TAKE MUCH TO PRODUCE GALES IN THIS AREA...BUT WOULD LIKE TO SEE MORE DECISIVE MODEL AGREEMENT BEFORE PULLING THE TRIGGER ON A GALE WARNING HERE...ESPECIALLY WITH A RELATIVELY WEAK AND PROGRESSIVE DEEP-LAYER TROUGH LIKE THE ONE PREDICTED. LATER IN THE PERIOD...CONFIDENCE DROPS FURTHER AS THE GFS AND ECMWF DIVERGE WITH THEIR HANDLING OF THE NEXT TROUGH TO IMPACT THE REGION. THE ECMWF SOLUTION...WHICH CARRIES A CUT OFF LOW ALONG THE U.S./MEXICO BORDER MON/TUE IS AN OUTLIER COMPARED TO THE GLOBAL MODELS AND IS CONSIDERABLY SLOWER AND DEEPER THAN BOTH THE 0000 UTC GEFS MEAN AND THE 03/1200 UTC ECMWF ENSEMBLE MEAN. USED THE 0000 UTC GFS TO ADJUST THE GRIDDED FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... AN E-W RIDGE OVER THE SW N ATLC ALONG 26N DOMINATES THE WIND REGIME IN THE CARIBBEAN AND TROPICAL N ATLC. THE 0206 UTC ASCAT PASS SHOWS THE STRONGEST WINDS LIES OVER THE CENTRAL CARIBBEAN. THE STRONGER 0000 UTC GFS MATCHES UP BETTER WITH THE 30 KT WINDS SHOWN BY THE ASCAT PASS THAN THE 0000 UTC ECMWF...UKMET...OR FNMOC. THE GFS SHOWS WINDS TO GALE FORCE ALONG THE COAST OF COLOMBIA IN THE EARLY MORNING HOURS OVER THE WEEKEND...WITH A BRIEF REPRIEVE MON AS A COLD FRONT DISRUPTS THE SUBTROPICAL HIGH BEFORE INCREASING TO GALE FORCE AGAIN TUE. THE GEFS ENSEMBLES SHOW AS HIGH AS A 20-30 PERCENT CHANCE OF GALES HERE ON THE WEEKEND MORNINGS...WITH THE OTHER GLOBAL MODELS SHOWING A SOLID AREA OF 30 KT WINDS DURING THOSE TIMES. CONFIDENCE IS SLIGHTLY HIGHER IN THE MORE ACCURATELY INITIALIZED GFS SOLUTION. IT WILL BE USED TO ADJUST THE FORECAST AND A GALE WILL BE ISSUED FOR THE COAST OF COLOMBIA OVER THE WEEKEND. SW N ATLC S OF 31N W OF 55W... THE NORTHERN PORTION OF THE COLD FRONT FROM 31N71W TO FORT PIERCE FLORIDA WILL RACE EASTWARD THROUGH THE WEEKEND WHILE THE PORTION OVER FLORIDA AND JUST N OF THE BAHAMAS REMAINS RELATIVELY STATIONARY. THE NEXT DEEP-LAYER TROUGH WILL MOVE OFF THE MID-ATLC U.S. COAST ON SUNDAY AND FINALLY SEND THE WEAK FRONT E OF FLORIDA. FRESH WINDS ARE CURRENTLY CONFINED TO NEAR THE LEADING EDGE OF THE FRONT AND IN THE REGION FROM THE ANEGADA PASSAGE TO THE WINDWARD PASSAGE S OF 22N. AS THE FRONT MOVES E...SO WILL THE FRESH BREEZE OVER N WATERS. THE SECOND FRONT WILL SLOWLY MOVE OFFSHORE SUN AND WINDS WILL INCREASE BOTH AHEAD AND BEHIND THE FRONT BY MON...WITH A FRESH TO STRONG BREEZE EXPECTED OVER MUCH OF THE AREA BY TUE. AS MENTIONED IN THE GULF OF MEXICO SECTION...THE GFS IS ALIGNED WITH THE MODEL CONSENSUS AND ENSEMBLES IN THE LATER PORTION OF THE FORECAST PERIOD. THE 0000 UTC GFS WAS USED TO UPDATE THE FORECAST HERE. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .GALE WARNING...GMZ023. CARIBBEAN SEA AND TROPICAL N ATLC... .GALE WARNING...AMZ031. SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER