000 AGXX40 KNHC 180755 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 355 AM EDT THU APR 18 2013 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 COLD FRONT IS MOVING SE THROUGH TEXAS ASSOCIATED WITH A STRONG UPPER TROUGH DIGGING THROUGH THE ROCKIES INTO THE CENTRAL PLAINS AND MISSISSIPPI VALLEY. THE FRONT WILL MOVE OFF THE TEXAS COAST INTO THE FAR NW GULF OF MEXICO BY LATE AFTERNOON. GRADIENT FLOW BEHIND THE FRONT WILL APPROACH GALE FORCE THROUGH THE LATE AFTERNOON AND EARLY EVENING. AS UNSEASONABLY COOL AIR ASSOCIATED WITH THIS FRONT REACHES THE SOMEWHAT WARMER WATERS OFFSHORE IN GMZ011...THE RESULTANT BOUNDARY LAYER INSTABILITY WILL ALLOW GALE FORCE FLOW ABOVE THE SURFACE TO MIX DOWN TO THE WATER IN THE FORM OF FREQUENT GUSTS. A GALE WARNING IS IN EFFECT FOR EARLY FRI OVER GMZ011 ACCORDINGLY. SUSTAINED GALES CAN BE EXPECTED IN THE WEDGE OF COOLER AIR THAT WILL PUSH DOWN THE MEXICAN COAST TO THE SW GULF THROUGH FRI AND FRI NIGHT. GFS ENSEMBLE AND SREF OUTPUT CONTINUE TO SHOW DECENT PROBABILITIES FOR GALES IN THE FAR WESTERN GULF DURING THIS TIME PERIOD. FAVORED THE STRONGER GFS AND ECMWF OVER THE UKMET FOR THE WESTERN GULF. MEANWHILE THE FRONT WILL CONTINUE TO PUSH SE AS THE SUPPORTING UPPER TROUGH DIGS E ACROSS THE MISSISSIPPI VALLEY INTO THE EASTERN UNITED STATES. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONT MAINLY OVER THE NORTHERN GULF WATERS. MUCH OF THE UPPER DYNAMICS WILL LIFT NE TOWARD NEW ENGLAND THROUGH SAT...ALLOWING THE FRONT TO STALL FROM SW FLORIDA TO THE EASTERN BAY OF CAMPECHE BY LATE SAT. WINDS AND SEAS WILL DIMINISH THROUGH SAT OVER THE ENTIRE GULF AS THE GRADIENT WEAKENS...LEAVING GENERALLY LIGHT TO MODERATE EASTERLY FLOW ACROSS THE GULF SUN AS HIGH PRES BUILDS N OF THE AREA...SHIFTING E TO SE AS THE HIGH PRES SHIFTS E. NO SIGNIFICANT DIFFERENCES IN MODEL OUTPUT FOR THIS FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... WEAKER HIGH PRES ACROSS CENTRAL ATLC IS MAINTAINING FRESH TRADES OVER THE S CENTRAL CARIBBEAN AND IN THE GULF OF HONDURAS WITH MAINLY MODERATE EASTERLY WINDS PREVAILING ACROSS THE REMAINDER OF THE CARIBBEAN. STRENGTHENING HIGH PRES ACROSS THE NW ATLC WILL BUILD S INTO THE REGION LATE THU THROUGH THE WEEKEND TO STRENGTHEN FLOW AREA WIDE. WINDS AND SEAS SLOWLY SUBSIDE MON. NO SIGNIFICANT DIFFERENCES IN MODEL SOLUTIONS ARE NOTED. SW N ATLC S OF 31N W OF 55W... WEAK TROUGHING N OF 25N IS KEEPING TRADE WIND FLOW LIGHT FOR THE MOMENT OVER MUCH OF THE AREA...WITH SCATTEROMETER...ALTIMETER AND BUOY DATA REPORTING GENERALLY 10 TO 15 KT FLOW ACROSS THE REGION. SEAS ARE RUNNING 5 TO 6 FT OUTSIDE THE BAHAMAS. TRADE WINDS WILL START TO INCREASE TODAY S OF 25N AS HIGH PRES BUILDS OVER THE NW AND N CENTRAL ATLC. SE RETURN FLOW WILL START TO INCREASE TONIGHT AND EARLY FRI N OF 27N W OF 73W...OVER AMZ111 AND 113...AHEAD OF AN APPROACHING COLD FRONT. GLOBAL MODELS REMAIN IN GOOD AGREEMENT TIMING THE ARRIVAL OF THE FRONT ALONG THE NE FLORIDA COAST BY FRI NIGHT. THE FRONT WILL SHIFT E BEFORE STALLING FROM REACH FROM 31N76W TO E CENTRAL FLORIDA BY LATE SAT...THEN MEANDERING NORTHWARD THROUGH SUN AND MON. SEAS WILL BUILD AS HIGH AS 9 FT OUTSIDE THE BAHAMAS AND TCI S OF 22N FRI AND SAT IN NE TO E SWELL AND ENHANCED TRADES...BEFORE SUBSIDING BELOW 8 FT SUN INTO MON AS TRADES DIMINISH. WARNINGS... GULF OF MEXICO... .GALE CONDITIONS EXPECTED GMZ011...GMZ017...GMZ023 FRI. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLC... .NONE. EFFECTIVE 9 APRIL 2013...TAFB GRIDDED MARINE FORECASTS FOR 10-M WINDS...10-M WIND GUSTS...SIGNIFICANT WAVE HEIGHTS AND HAZARDS FOR THE OFFSHORE AND HIGH SEAS DOMAIN ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) ON AN EXPERIMENTAL BASIS AT: HTTP://PREVIEW.WEATHER.GOV/GRAPHICAL ADDITIONAL INFORMATION IS AVAILABLE AT: WWW.NWS.NOAA.GOV/OM/NOTIFICATION/PNS13OFFSHORE_HIGHSEAS.HTM NOTE...GRIDDED MARINE FORECASTS AT: WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE ARE NO LONGER AVAILABLE. $$ FORECASTER CHRISTENSEN