000 AGXX40 KNHC 191805 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 115 PM EST MON NOV 19 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... A RIDGE EXTENDS NNE-SSW FROM THE FL PANHANDLE TO THE SW BAY OF CAMPECHE. A COLD FRONT EXTENDS W ACROSS THE FL STRAITS TO NEAR 25N85W. NE LOW LEVEL WINDS CONTINUE AT 15-20 KT WITH SEAS 4-6 FT ACROSS THE GULF WATERS E OF 87W...WHILE NE-E WINDS AT 10-15 KT ARE OBSERVED ELSEWHERE ACROSS THE GULF. EXPECTING THE WEAK TROUGH...THAT CURRENTLY THAT EXTENDED FROM 20N86W TO 25N89W THIS MORNING...TO SHIFT W AND BECOME ORIENTATED SW-NW FROM THE SE BAY OF CAMPECHE TO NEAR 25N94W ACCOMPANIED BY A 15-20 KT NW-N-NE WIND SHIFT ALONG THE TROUGH AXIS. THIS TROUGH WILL DRIFT SLOWLY W-SW AND GRADUALLY DISSIPATE WED NIGHT AS HIGH PRESSURE STRENGTHENS INCREASING THE NLY WINDS TO 20 KT AGAIN OVER THE GULF WATERS E OF 84W. LIGHT LOW LEVEL RETURN FLOW BEGINS TO SET UP OVER THE NW WATERS THU AS HIGH PRESSURE THEN CENTERED OVER AL SHIFTS W TO OVER SW LA ON FRI...EFFECTIVELY SHIFTING THE RIDGE ORIENTATION FROM NE-SW TO NW-SE LATE FRI INTO SAT. BLENDED LATEST GFS...UKMET AND ECMWF WITH PREVIOUS OFFICIAL FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE PRES GRADIENT CONTINUES TO MAINTAIN NW-N WINDS OF 20-25 KT ACROSS THE W-CENTRAL WATERS FROM 11-18N W OF 81W WITH SEAS 5-8 FT. NE-E TRADES AT 10-15 KT WITH SEAS 2-4 FT CONTINUE ACROSS THE REMAINDER OF THE CARIBBEAN WITH MOSTLY ENE 15 KT WINDS AND SEAS 6-7 FT OBSERVED ACROSS THE TROPICAL ATLC WATERS. THE GRADIENT WILL TIGHTEN SOME TONIGHT INCREASING THE N-NE FLOW TO 15-20 KT ACROSS THE CARIBBEAN W OF 78W...DIMINISHING BELOW 20 KT OVER THE AREA N OF 16N ON FRI. AN ENE-WSW RIDGE WILL SHIFT S OVER THE NORTHERN PORTION OF THE TROPICAL ATLC ON TUE. THE 10-15 KT TRADES CURRENTLY OVER THE NORTHERN PART OF THE TROPICAL N ATLC ARE EXPECTED TO DIMINISH TO 5-10 KT TONIGHT...BECOMING ANTICYCLONIC AROUND THE RIDGE EVERYWHERE N OF 15N FROM TUE-SAT. THE RIDGE WILL SHIFT FURTHER SE ALLOWING A WEAKENING COLD FRONT TO MOVE INTO THE ATLC WATERS N OF THE VIRGIN ISLANDS ON FRI...THEN STALLING FROM 22N58W TO THE LEEWARDS ON SAT. BLENDED LATEST GFS...UKMET AND ECMWF WITH PREVIOUS OFFICIAL FORECAST. SW N ATLC W OF 55W... SURFACE LOW PRES AT 30N78W TRAILS A COLD FRONT SW TO THE FL STRAITS WITH NLY FLOW AT 20-25 KT...SEAS 7-11 FT...OBSERVED W OF THE LOW AND FRONT. A BROAD TROUGH EXTENDS NE FROM HISPANIOLA TO NEAR 26N68W. THE FRONT WILL CONTINUE E MERGING WITH THE TROUGH ON TUE NIGHT WITH A COMPLEX LOW PATTERN JUST N OF THE AREA. GUIDANCE NOW SUGGESTS ONE SURFACE LOW WILL RACE OFF TO THE NE...WHILE THE WESTERN LOW SHIFTS SE BACK INTO THE AREA NEAR 31N69W ON TUE NIGHT...WITH A STRONG COLD FRONT ROTATING AROUND THE LOW INTO AREA LATE WED...WITH A STRONGER REINFORCING SECONDARY SURGE ARRIVING AT 31N ON THU MORNING. GUIDANCE BEGINNING TO AGREE ON GALE CONDITIONS N OF 30N BETWEEN 68-73W LATE THU...AND N OF 28N BETWEEN 60-70W EARLY FRI...WITH GALE CONDITIONS LIFTING NE OF AREA LATE FRI. THE ASSOCIATED NLY LONG PERIOD SWELL WILL PROPAGATE S ACROSS THE ENTIRE AREA...WITH SEAS SUBSIDING TO 8 FT AS THEY REACH THE SE BAHAMAS AND ATLC APPROACHES TO CARIBBEAN LATE SAT. USED A BLEND OF GFS...UKMET AND ECMWF WITH PREVIOUS OFFICIAL GRIDS FOR PACKAGE. 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. GALE CONDS EXPECTED N OF 30N BETWEEN 68-73W LATE THU AND N OF 28N BETWEEN 60-70W EARLY FRI. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER NELSON