000 AGXX40 KNHC 301959 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 PM EST FRI NOV 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... BROAD RIDGE CENTERED ON STRONG HIGH PRES OVER THE CAROLINAS WILL DRIVE THE WINDS OVER THE GULF THROUGH TUE. INVERTED LLVL TROUGH ACROSS CENTRAL GULF ALONG 88W IS PRODUCING CONVERGENCE BEHIND IN STRETCHING THROUGH THE STRAITS...PRODUCING BROKEN CLOUDINESS AND MODERATE SHOWERS...WHILE SHORTWAVE MOVING E ACROSS THE GULF IS ACTING TO ENHANCE THIS CONVECTION WITH SCT TOPS 25-32K FT. WW3 WAY UNDERDONE AT 12Z THIS MORNING ACROSS THIS AREA...UP TO 3 FT AND STILL APPEARS AT LEAST 2 FT LOW. SEAS LIKELY 8 FT POSSIBLY 9 FT AGAINST CURRENT IN THE STRAITS ATTM. GRADIENT WINDS WILL CONTINUE 20 TO LOCALLY 25 KT ACROSS THE SE PORTION AND STRAITS THROUGH TUE BEFORE HIGH BEGINS TO SHIFT NE AND GRADIENT RELAXES. DOWNSTREAM SEAS WILL ALSO NEED TO BE ADJUSTED UPWARDS N OF THE YUCATAN. CARIBBEAN SEA AND TROPICAL N ATLC S OF 19N W OF 55W... STRONG HIGH PRES ALONG N CAROLINA COAST IS DRIVING THE EASTERLY FLOW THROUGH THIS REGION...NORTH OF A STALLED SHEAR LINE STRETCHING FROM THE CENTRAL ATLC NEAR 26N60W THROUGH THE CENTRAL BAHAMAS TO E CENTRAL CUBA. LLVL TROUGHS ACROSS N PORTIONS OF THE CARIB ACROSS THE WINDWARD PASSAGE AND ALONG 66W ARE COMBINING WITH SHEAR LINE TO FORCE GRADIENT WINDS N OF THE BASIN. HOWEVER FRESH NELY FLOW IS PENETRATING THE NW THIRD...TO THE NW OF THE TAIL END OF THE SHEAR LINE. STRONG WINDS THROUGH THE WINDWARD PASSAGE OVERNIGHT HAVE DIMINISHED CONSIDERABLY AS LLVL TROUGH HAS SHIFTED W INTO E CUBA. THIS GENERAL PATTERN WILL PREVAIL THROUGH THE WEEKEND AS THE SHEAR LINE IS NUDGED SLIGHTLY S...AND THROUGH THE SE BAHAMAS AND E CUBA BY SUN. GLOBAL MODELS HAVE SHIFTED TO FORMATION OF LOW PRES S OF THE SHEAR LINE TO N OF THE LEEWARD ISLANDS LATE SUN-MON...WITH HIGH PRES AND FRESH TO STRONG WINDS BUILDING SW ACROSS THE GREATER ANTILLES AND WATERS W OF 70W AND N OF 16N MON...YIELDING A RAPID AND SIGNIFICANT BUILDING OF SEAS. WINDS COULD REACH NEAR 30 KT THROUGH WINDWARD PASSAGE AND IN LEE OF CUBA. ELSEWHERE...AN AREA OF SCATTERED CONVECTION HAS INCREASED CONSIDERABLY PAST 6 HOURS INVOF LLVL VORT ALONG 60W NEARING COAST OF VENEZUELA. GFS HANGS ON TO LLVL TROUGH IN THIS AREA FOR NEXT FEW DAYS...AND THUS CONVECTION SHOULD CONTINUE TO FLARE THERE. OTHERWISE...LIGHT TO MODERATE NE TRADES SHOULD CONTINUE UNTIL SUN...WHEN WINDS VEER SE AS LOW BEGINS TO DEVELOP N OF LEEWARDS. SW N ATLC N OF 19N W OF 55W... SHEAR LINE CONTINUES FROM THE CENTRAL ATLC NEAR 26N60W THROUGH THE CENTRAL BAHAMAS TO E CENTRAL CUBA AND WILL SINK VERY SLOWLY SSE NEXT 48 HOURS AS BROAD W ATLC RIDGE SHIFTS SLIGHTLY E. FRESH NE FLOW 20-25 KT WILL CONTINUE N OF BOUNDARY ALLOWING SEAS TO BUILD UP TO 11 FT JUST E OF BAHAMAS ALONG ABOUT 24N. LLVL TROUGH MOVING SLOWLY W ALONG N CARIBBEAN MENTIONED ABOVE ARE INTERACTING WITH FAVORABLE WLY SHEAR TO BRIEFLY ENHANCE SCT CONVECTION...ESPECIALLY WITH WRN TROUGH ALONG 74W.WW3 DOING REASONABLE JOB WITH SEAS WITHIN FRESH ZONE OF NE WINDS N OF SHEARLINE...ALTHOUGH RECENT BUOYS ALONG SRN EDGE UP TO 10 FT...WHICH IS MORE IN LINE WITH ECWAVE MODEL. PATTERN TO PERSIST THROUGH SUNDAY AS MENTIONED ABOVE WHEN LOW BEGIN TO EVOLVE N OF MONA PASSAGE SUN SHIFTING ENE THROUGH MON...THEN DEVELOPING N OF LEEWARDS MON. ALTHOUGH MODELS HAVE SHIFTED CYCLOGENESIS ZONE TO N OF LEEWARDS IN PAST FEW RUNS...AND ARE IN REASONABLE AGREEMENT...THERE REMAINS DIFFERENCES IN ALIGNMENT BETWEEN ECMWF AND GFS THAT WILL AFFECT GRADIENT ALONG OLD BOUNDARY. ECMWF SUGGESTING CHANCE FOR GALES ALONG 23N BY 00Z MON...WHILE GFS IS ALIGNED MORE E TO W INITIALLY...AND ONLY SHOWING WINDS TO 25 KT IN THAT ZONE. THUS CONFIDENCE NOT EXTREMELY HIGH AND TAKING AN AVERAGE. BLENDED GRIDS ALMOST 50-50 WITH TWO MODELS FOR 12Z GRAPHICS WITH NEXT FEW RUNS TO BE REVEALING. 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 STRIPLING