000 AGXX40 KNHC 301816 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 215 PM EDT TUE OCT 30 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 SURFACE THROUGH REACHES FROM FLORIDA BAY TO N OF THE YUCATAN PENINSULA NEAR 23N90W. THIS TROUGH WILL PUSH SE OF THE AREA LATER TODAY INTO TONIGHT. OTHERWISE HIGH PRES CENTERED OVER LOUISIANA WILL SHIFT SE BECOMING CENTERED OVER THE CENTRAL GULF BY WED MORNING. FRESH TO STRONG NORTHERLY WINDS REMAIN IN THE NE GULF BETWEEN THE BUILDING HIGH AND THE EXTENSIVE OUTER CIRCULATION OF POST-TROPICAL CYCLONE SANDY NOW WELL INLAND OVER THE NE U.S. THESE WINDS WILL GRADUALLY DIMINISH TO 20 KT OR LESS WED MORNING WITH PRIMARILY TRANQUIL WINDS AND SEAS ACROSS THE BASIN WED THROUGH SAT. WINDS MAY BRIEFLY REACH 20 KT NEAR THE NW COAST OF THE YUCATAN PENINSULA EACH EVENING WED THROUGH SAT. THE 12Z GFS AND ECMWF ARE IN AGREEMENT ON THIS FORECAST. THE 12Z GFS AND WW3 GUIDANCE WAS BLENDED WITH CONTINUITY TO UPDATE THE FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... LARGE AND LONG PERIOD NW SWELL GENERATED BY SANDY CONTINUES TO PROPAGATE TO THE ATLC/CARIBBEAN PASSAGES AND THROUGH THE TROPICAL N ATLC WATERS. THIS SWELL WILL GRADUALLY SUBSIDE THROUGH THE END OF THE WEEK. THE REMNANTS OF A COLD FRONT IN THE FORM OF A SURFACE TROUGH REACH FROM EASTERN CUBA TO W OF JAMAICA. SCATTERED SHOWERS CONTINUE TO DEVELOP AND SPREAD TO THE SE ACROSS THE NW CARIBBEAN IN AN UNSTABLE AIRMASS DUE TO COLD AIR THAT SPILLED IN BEHIND THE FRONT OVER THE WARM CARIBBEAN WATERS. A SURFACE TROUGH IS IN THE CENTRAL CARIBBEAN REACHING FROM THE MONA PASSAGE TO THE GUAJIRA PENINSULA. VERY ACTIVE CONVECTION IS PRESENT FROM THE TROUGH AXIS SW TO EASTERN PANAMA WHERE THE MONSOON TROUGH IS AMPLIFIED TO THE NE...AND UNDER UPPER DIFFLUENCE ALOFT. THE TROUGH IS FORECAST TO DRIFT WESTWARD DURING THE NEXT FEW DAYS...REACHING 80W BY FRI MORNING WHEN WEAK LOW PRES MAY DEVELOP ALONG IT NEAR 11N PRIOR TO THE TROUGH REACHING CENTRAL AMERICA. THE 12Z GFS AND UKMET AGREE ON STRONGER WINDS ASSOCIATED WITH THE DEVELOPING LOW WHILE THE ECMWF IS WEAKER. WITH SUCH AN AMPLIFIED UPPER PATTERN ALOFT ALREADY IN PLACE...WILL CONTINUE TO SIDE WITH THE STRONGER GFS AND UKMET FOR NOW. IN THE MEANTIME...LIGHT TO MODERATE WINDS WILL PREVAIL ACROSS THE CARIBBEAN OUTSIDE OF ANY AREAS OF CONVECTION WITH PRIMARILY 2-4 FT SEAS THROUGH WED...BUILDING TO 3 TO 5 FT WED NIGHT AND THU. THE 12Z GFS AND WW3 WERE BLENDED WITH CONTINUITY IN THE CARIBBEAN AND TROPICAL N ATLC TO UPDATE THE FORECAST. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE EXPANSIVE...DEEP-LAYER CIRCULATION ASSOCIATED WITH INLAND POST-TROPICAL CYCLONE SANDY 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. WINDS ARE EXPECTED TO REMAIN BELOW GALE FORCE WITH THE 12Z GEFS SHOWING A ZERO PERCENT CHANCE OF GALE FORCE WINDS ANYWHERE S OF 31N THROUGH SAT. SEAS AS HIGH AS 14 FT CONTINUE TO LINGER IN THE REGION IN THE LONG PERIOD NW SWELL GENERATED EARLIER BY SANDY...IMPACTING NEARLY THE ENTIRE REGION...INCLUDING THE N SHORES OF THE NE CARIBBEAN ISLANDS... ARE EXPECTED TO SUBSIDE TUE THROUGH WED. THE 12Z MODELS AGREE ON MARINE CONDITIONS IMPROVING SIGNIFICANTLY BY THU AND FRI. THE 12Z GFS AND WW3 WERE BLENDED WITH CONTINUITY FOR THE FORECAST. 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 LEWITSKY