000 AGXX40 KNHC 310716 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 317 AM EDT WED OCT 31 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... OBSERVATIONS SHOW WINDS AND SEAS HAVE SETTLED DOWN BELOW ADVISORY CRITERIA IN THE NE GULF AS OF 0600 UTC. HIGH PRES CENTERED NEAR 26N90W WILL LINGER OVER THE CENTRAL GULF THROUGH THU BEFORE WEAKENING AHEAD OF A SPOKE IN THE VAST CIRCULATION ASSOCIATED WITH POST-TROPICAL CYCLONE SANDY EXPECTED TO CLIP THE NE GULF. HIGH PRES WILL MOVE INTO THE NE GULF BEHIND THIS BOUNDARY FRI THROUGH SUN. WINDS AND SEAS WILL REMAIN BELOW ADVISORY CRITERIA AS THE W EDGE OF THIS BOUNDARY PASSES S ALONG THE W COAST OF FL THU. WINDS MAY BRIEFLY REACH 20 KT NEAR THE NW COAST OF THE YUCATAN PENINSULA EACH EVENING WED THROUGH SAT. THE 00Z GFS AND ECMWF ARE IN AGREEMENT ON THE FORECAST FOR LIGHT WINDS AND RELATIVELY BENIGN SEAS. THE 00Z GFS AND WW3 GUIDANCE WAS BLENDED WITH CONTINUITY TO UPDATE THE FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... NW SWELL PROPAGATING INTO THE ATLC/CARIBBEAN PASSAGES AND THROUGH THE TROPICAL N ATLC WATERS WILL GRADUALLY SUBSIDE TODAY INTO THU. BY THU NIGHT...THE DOMINANT SWELL DIRECTION WILL SHIFT TO NE AS SWELL FROM A DEEP LAYER LOW NEAR 30N30W MAKES ITS WAY INTO THE REGION. A SURFACE TROUGH IS IN THE CENTRAL CARIBBEAN REACHING FROM THE SW DOMINICAN REPUBLIC TO THE NORTHERN COAST OF COLOMBIA. CONVECTION IS NOTED WITHIN 170 NM EITHER SIDE OF THE TROUGH S OF 15N. CONVECTIVE ACTIVITY NEAR THE TROUGH IS EXPECTED TO INCREASE OVER THE NEXT FEW DAYS AS IT MOVES UNDER THE REAR RIGHT QUADRANT OF A SOUTHERLY UPPER JET...PROVIDING DIFFLUENT CONDITIONS ALOFT AND ENHANCING CONVECTION. THE TROUGH IS FORECAST TO DRIFT WESTWARD DURING THE NEXT FEW DAYS...REACHING 80W THU WHEN WEAK LOW PRES MAY DEVELOP ALONG IT NEAR 11N. THE TROUGH IS FORECAST TO STALL OVER THE SW CARIBBEAN THROUGH SUN. THE 00Z ECMWF APPEARS TO BE TRENDING TOWARD THE STRONGER GFS SOLUTION WITH THE AREA OF FRESH EASTERLY WINDS EXCEPTED NEAR THE TROUGH. MEANWHILE...THE UKMET HAS TRENDED TOWARD MORE DEVELOPMENT OF THE SURFACE LOW AND TAKES A 1006 MB LOW INTO EASTERN NICARAGUA BY EARLY SUN MORNING. THE OTHER MODELS DO NOT HANG ONTO SUCH A WELL-DEFINED CIRCULATION BY LATE IN THE FORECAST PERIOD. THEREFORE...WILL CONTINUE TO USE THE GFS AND ITS WW3 TO ADJUST THE FORECAST. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... A COLD FRONT EXTENDS FROM NEAR 31N65W TO THE WINDWARD PASSAGE. THE 0114 UTC AND 0256 UTC ASCAT PASSES SHOW FRESH TO NEAR GALE FORCE WINDS BEHIND THE FRONT...GENERALLY IN THE AREA N OF 26N. THIS FRONT IS THE LEAD BOUNDARY OF THE EXPANSIVE CIRCULATION ASSOCIATED WITH ASSOCIATED WITH INLAND POST-TROPICAL CYCLONE SANDY. THE DEEP-LAYER CIRCULATION WILL CONTINUE TO SEE A FEW SURGES OF COLD...DRY AIR WITH NW WINDS MIXING TO THE SURFACE IN THE SW N ATLC...MAINLY N OF 27N...AS SHORTWAVE ENERGY WRAPS S OF THE MID TO UPPER LEVEL LOW TO THE THE N. ONE OF THESE SPOKES IN THE VAST CIRCULATION WILL SEND A SURGE OF COOLER...DRIER AIR SOUTHEASTWARD THROUGH THE REGION THU THAT WILL QUICKLY MODIFY OVER THE RELATIVELY WARM WATER. WINDS ARE EXPECTED TO REMAIN BELOW GALE FORCE WITH THE 00Z GEFS SHOWING A ZERO PERCENT CHANCE OF GALE FORCE WINDS ANYWHERE S OF 31N. LONG PERIOD NW SWELL GENERATED EARLIER BY SANDY...WITH SEAS AS HIGH AS 14 FT ACCORDING TO THE 0510 UTC JASON1 AND JASON2 PASSES...CONTINUE TO LINGER OVER NEARLY THE ENTIRE REGION E OF THE BAHAMAS. THIS SWELL WILL GRADUALLY DIMINISH AS IT BATTLES IMPINGING NE SWELL FROM A SYSTEM WELL E OF THE AREA NEAR 30N30W BEGINNING THU. ACTIVE CONVECTION CAN BE FOUND AHEAD OF THE LEAD COLD FRONT N OF THE DOMINICAN REPUBLIC AND PUERTO RICO THIS MORNING. THIS AREA IS EXPECTED TO BE FAVORED FOR CONVECTION THROUGH FRI WHEN THE SECONDARY BOUNDARY SHOULD STRETCH THE MID-LEVEL ENERGY IN THE REGION NORTHEASTWARD...THINNING THE CONVECTION. THE 00Z MODELS AGREE ON MARINE CONDITIONS IMPROVING SIGNIFICANTLY BY FRI AS THE DEEP LAYER TROUGH PASSES TO THE E AND HIGH PRES MOVES INTO WESTERN WATERS BEHIND IT. CONFIDENCE IS LOW WITH THE DETAILS FOR THE ENERGY ROTATING AROUND THE BROAD UPPER LOW AND THEIR THE SURFACE IMPLICATIONS. WILL BLEND THE 00Z GFS AND ECMWF IN THE SW N ATLC AND BUMP UP THE WAVE HEIGHTS SLIGHTLY EARLY IN THE PERIOD COMPARED TO THE 00Z WW3 BASED ON THE JASON PASSES. 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