000 AGXX40 KNHC 291900 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 PM EST THU NOV 29 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 HIGH PRES RIDGE OVER THE SE U.S. AND EASTWARD INTO W ATLC ALONG 34/35W EXTENDS ACROSS THE NORTHERN GULF TODAY...WITH FRESHENING ENE FLOW BEHIND ATLC FRONTAL SYSTEM SPREADING ACROSS S FLORIDA AND ACROSS SE GULF AND THE STRAITS...PER RECENT PARTIAL SCAT PASSES. ALTHOUGH THE HIGH WILL SHIFT ENE NEXT 48 HOURS...THIS PATTERN WILL PERSIST THROUGH THE WEEKEND AND SUPPORT GENTLE TO MODERATE ANTICYCLONIC WIND FLOW ACROSS THE REGION THROUGH TUE...EXCEPT FOR MODERATE TO FRESH E-NE WINDS IN THE EXTREME SE PORTION AND STRAITS OF FLORIDA. WW3 TYPICALLY DOES NOT CAPTURE PEAK AREA OF SEAS THROUGH THE STRAITS AND ACROSS YUCATAN CHANNEL AND HAVE GONE ABOVE GUIDANCE IN CURRENT FORECASTS...WITH SEAS LIKELY TO BUILD TO 7-8 FT BY SAT EVENING...AND HIGHER AGAINST CURRENT. CARIBBEAN SEA AND TROPICAL N ATLC S OF 19N W OF 55W... ALTHOUGH RIDGE IS N OF AREA AND WILL SHIFT ENE NEXT 48 HOURS...FRONTAL BOUNDARY THROUGH THE CENTRAL BAHAMAS AND SERIES OF LLVL TROUGHS ALONG ABOUT 21N BETWEEN CENTRAL ATLC AND HISPANIOLA FORCING GRADIENT WINDS TO REMAIN N OF THE BASIN...AND WILL ONLY ALLOW FOR FRESH WINDS TO PENETRATE NW PORTIONS AND THE WINDWARD PASSAGE. OTHERWISE...MODERATE NE TO E-NE TRADES WILL PREVAIL ACROSS THE REGION THROUGH TUE. WINDS ACROSS NW PORTIONS WILL DIMINISH TO AROUND 15 KT BY SAT AS HIGH SHIFT OFF E COAST OF U.S. AND WEAKENS...ONLY TO INCREASE TO 20 KT WITH AREAS TO 25 KT LATE SAT NIGHT AND SUN AS REINFORCING HIGH MOVES INTO NW ATLC. LLVL PERTURBATION ALONG ITCZ APPROACHING 60W ATTM ACCOMPANIED BY SCT MOD CNVTN WILL SHIFT W AND THROUGH SRN WINDWARDS NEXT 24 HOURS AND THEN ALONG COAST OF VENEZUELA. OTHERWISE EXPECT 6-7 FT SEAS TO PREVAIL ACROSS THE TROPICAL N ATLC THROUGH TUE IN MIX OF ELY TRADE WIND SWELL AND LONG PERIOD NE. SW N ATLC N OF 19N W OF 55W... COLD FRONT EXTENDING FROM 31N59W THROUGH CENTRAL BAHAMAS THEN DIFFUSE ACROSS CENTRAL CUBA WILL STALL NEXT 6-8 HOURS ACROSS REGIONAL WATERS...THEN TRANSITION TO A SHEAR LINE THROUGH SAT. HIGH PRES SHIFTING SLOWLY ENE FROM THE CAROLINAS THROUGH SAT WILL INCREASE THE GRADIENT N OF THE SHEAR LINE BOUNDARY...WITH NELY 20-25 KT WINDS EXPECTED WITHIN 150-200 NM N OF BOUNDARY IN A CLASSIC SHEAR LINE PATTERN. REINFORCING HIGH ACROSS NW ATLC THIS WEEKEND LIKELY TO EXPAND AREA OF 20-25 KT WINDS TO MUCH OF THE AREA NW OF THE SHEAR LINE...WITH SEAS BUILDING 8-10 FT E OF BAHAMAS. FURTHER EAST...MID ATLC TROUGH HAS ALREADY BEGUN TO CARVE INTO LOW LEVELS WITH 1011 MB LOW BEING ANALYZED NEAR 22N48W. LOW TO LIFT OUT TO NE NEXT FEW DAYS...WITH GLOBAL MODELS THEN DEVELOPING A SECOND LOW N OF PUERTO RICO MON-TUE THAT BECOMES INVOLVED WITH PERSISTING SHEAR LINE...AND ALSO SHEARS OUT TO THE NE THROUGHOUT THE WEEK. GFS STILL MOST AGGRESSIVE WITH THIS FEATURE...AND IS REFLECTED BY DIFFERENCE BETWEEN GFS AND ECMWF ENSEMBLE MEANS. AT PRESENT I HAVE BLENDED GRIDS AND FORECAST CLOSER TO ECMWF IN BOTH WINDS AND SEAS...BOTH WITH FRONTAL POSITIONS DAY 2-3 AND THEN WITH ELONGATED LOW DEVELOPING N OF THE CARIBBEAN ALONG THE SHEAR LINE. MODELS SUGGEST MODERATE POTENTIAL FOR GALES N THROUGH NW OF THE OLD BOUNDARY MON-TUE AND POSSIBLY INTO WED. 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