000 AGXX40 KNHC 010707 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 308 AM EDT THU NOV 01 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... 1019 MB HIGH PRES CENTERED NEAR 25N88W AT 0000 UTC WILL WEAKEN AHEAD OF THE WEAKENING FRONT OVER THE NE GULF FROM TAMPA BAY TO 28N86W. THIS FRONT HAS BEEN FORCED BY SHORTWAVE ENERGY WRAPPING AROUND THE S SIDE OF THE VAST CIRCULATION ASSOCIATED WITH THE REMNANTS OF SANDY. A NEW SHORTWAVE SYSTEM MOVING THROUGH THE SOUTHEAST ATTM IS EXPECTED TO REINFORCE THIS FRONT TODAY. DESPITE THE REINVIGORATION OF THE FRONT...WINDS AND SEAS WILL REMAIN BELOW ADVISORY CRITERIA. HIGH PRES WILL MOVE INTO THE NE GULF BEHIND THIS BOUNDARY FRI THROUGH SUN AND PUSH EASTWARD BY MON AS A WEAK COLD FRONT MOVES INTO THE NE GULF COASTAL PLAIN. THE 00Z GFS AND ECMWF ARE IN GOOD AGREEMENT ON THE FORECAST FOR LIGHT WINDS AND RELATIVELY BENIGN SEAS THROUGH MON AND ARE VERY SIMILAR WITH THE FRONTAL MON. A BLEND OF THE 00Z GFS AND ECMWF WAS USED TO UPDATE THE WINDS AND THE WW3 GUIDANCE WAS USED TO UPDATE THE WAVE FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... LATER TODAY...THE DOMINANT SWELL DIRECTION IN THE ATLC PASSAGES IS EXPECTED SHIFT TO NE AS SWELL FROM A DEEP LAYER LOW NEAR 30N35W MAKES ITS WAY INTO THE REGION. THIS SWELL IS NOT EXPECTED TO BEGIN SUBSIDING UNTIL THE WEEKEND. SEAS OVER 8 FT WILL BE CONFINED TO THE NORTHEASTERN PORTION OF THE TROPICAL N ATLC. A SURFACE TROUGH WAS ANALYZED IN THE CENTRAL CARIBBEAN FROM 15N74W TO 10N76W. CONVECTION HAS WANED NEAR THE TROUGH OVER THE PAST FEW HOURS...WITH SOME LINGERING S OF 12N. CONVECTIVE ACTIVITY NEAR THE TROUGH IS EXPECTED TO INCREASE TODAY AND FRI 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 BY FRI WHEN WEAK LOW PRES MAY DEVELOP ALONG IT NEAR 11N. THE 0232 UTC ASCAT PASS SHOWS FRESH N WINDS ALREADY IN PLACE ALONG THE COAST OF NICARAGUA. BOTH THE 00Z GFS AND ECMWF CARRY THESE FRESH WINDS INITIALLY. THE GFS HAS TRENDED WEAKER WITH THIS LOW BY THE WEEKEND. THE 00Z RUN NOW LIFTS THE UPPER JET NORTHEASTWARD AWAY FROM THE SURFACE TROUGH...DIMINISHING THE ATMOSPHERIC LIFT AND WEAKENING THE LOW. THIS IDEA IS IN LINE WITH THE ECMWF SOLUTION OVER THE PAST FEW DAYS WHICH PREFERRED A LESS DEFINED LOW LEVEL CIRCULATION. MEANWHILE...THE PRES GRADIENT BETWEEN HIGH PRES IN THE GULF OF MEXICO AND THE LINGERING SURFACE BOUNDARY OVER THE WINDWARD PASSAGE IS FORCING FRESH TO STRONG NE WINDS IN THE PASSAGE ACCORDING TO THE SAME ASCAT PASS. THERE IS SIGNIFICANT CONVECTION NEAR THIS TROUGH ATTM. THE GFS DOES A BETTER JOB THAN THE ECMWF HERE. THESE WINDS ARE EXPECTED TO BE SHORT LIVED AS THE TROUGH IS PULLED NORTHEASTWARD AND THE HIGH TO THE W WEAKENS. ASIDE FROM THE WINDWARD PASSAGE...WINDS AND SEAS SHOULD REMAIN BELOW ADVISORY CRITERIA UNTIL THE WEEKEND WHEN HIGH PRES MOVES EASTWARD OVER FL AND INTO THE SW N ATLC...BUILDING THE PRES GRADIENT OVER THE CENTRAL CARIBBEAN. A BLEND OF THE 00Z GFS AND ECMWF WAS USED TO ADJUST THE FORECAST AND THE GFS-BASED WW3 WAS USED TO UPDATE THE SEAS. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE LEAD BOUNDARY OF THE VAST CIRCULATION ASSOCIATED WITH THE REMNANTS OF SANDY STRETCHED FROM 31N63W TO THE WINDWARD PASSAGE AT 0000 UTC. THIS BOUNDARY HAS WEAKENED CONSIDERABLY BUT CONVECTION REMAINS ACTIVE AHEAD OF THE TROUGH PRIMARY S OF 24N. A COLD FRONT EXTENDS FROM NEAR 31N71W TO FOR PIERCE FLORIDA. THE 0236 UTC ASCAT PASS SHOWS A FRESH TO STRONG WESTERLY BREEZE LINGERS BEHIND THE FRONT. THE PREVIOUS FORECAST GRIDDED WINDS AND SEAS WERE BEEFED UP HERE INITIALLY TO REFLECT OBSERVATIONS. MEANWHILE...A STRONG SHORTWAVE PASSING THROUGH THE SE U.S. ON THE S EDGE OF THE EXPANSIVE CIRCULATION ASSOCIATED WITH THE REMNANTS OF SANDY IS EXPECTED TO INVIGORATE THIS FRONT WITH A SURGE OF COOLER AND DRIER AIR...SENDING THE FRONT SOUTHWARD THROUGH THE FL PENINSULA THROUGH FRI. HOWEVER...BOTH THE 00Z GFS AND ECMWF AGREE ON WINDS DIMINISHING BELOW 25 KT ON FRI OVER N WATERS. BY SAT...THE AIRMASS BEHIND THE WEAKENING FRONT WILL MODIFY OVER THE RELATIVELY WARM WATER. THE LONG PERIOD NW SWELL GENERATED EARLIER BY SANDY HAS GENERALLY SUBSIDED AND LOCALLY GENERATED WINDSEA IS TAKING OVER. THE NW SWELL WILL BATTLE IMPINGING NE SWELL FROM A SYSTEM WELL E OF THE AREA NEAR 30N35W BEGINNING LATER TODAY. THE VAST CIRCULATION TO THE N WILL SEND ONE LAST COLD FRONT INTO N WATERS SAT AS THE DEEP LAYER TROUGH MOVES EASTWARD. HIGH PRES MOVES ACROSS THE FL PENINSULA BEHIND THIS FRONT BY SUN AND A NEW FRONT MOVES INTO FAR NW WATERS MON WITH LITTLE FANFARE. CONFIDENCE IS LOW IN ALL OF THE SHORTWAVE DETAILS CRUCIAL TO THE SURFACE FORECAST. A BLEND OF THE 00Z GFS AND ECMWF WAS USED TO UPDATE THE FORECAST TO ACCOUNT FOR UNCERTAINTY. 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