000 AGXX40 KNHC 060805 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT APR 6 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... COLD FRONT HAS MOVED THROUGH STRAITS AND NW CARIB WITH WINDS GRADUALLY ABATING ACROSS THE SE HALF OF THE BASIN BEHIND FRONT. SHARP CYCLONIC TURNING WITHIN FRONTAL ZONE YIELDING NNW WINDS ACROSS EXTREME SE PORTIONS LIKELY IN THE 15- 20 KT RANGE...WITH SEAS 7-8 FT EXTENDING INTO YUCATAN CHANNEL. RECENT BUOY OBS SUGGEST WW3 VERIFYING WELL ACROSS THE BASIN...JUST A FOOT OR TWO LOW WITH THE MAX SEAS ACROSS AND INTO YUCATAN CHANNEL. 1021 MB SURFACE HIGH LOOKS TO HAVE DROPPED INTO THE SW LOUISIANA COASTAL WATERS WITH RETURN FLOW ALREADY DEVELOPING ACROSS FAR WRN WATERS. UPPER TROUGH TO CONTINUE TO SHIFT E ACROSS FLORIDA PENINSULA TODAY...DRAGGING FRONTAL ZONE JUST AHEAD OF IT AND ALLOWING SURFACE HIGH TO SHIFT ENE TO BIG BEND REGION BY 00Z THIS EVENING THEN BECOME ABSORBED INTO E COAST RIDGE SUN WITH SE TO S RETURN FLOW DEVELOPING ACROSS ENTIRE BASIN SUN. LOW PRES IS FORECAST TO DEEPEN IN THE LEE OF THE ROCKIES AND ACROSS THE TEXAS PANHANDLE MON THROUGH WED ALLOWING FOR SOUTHERLY RETURN FLOW TO INCREASE 20-25 KT OVER W HALF OF GULF MON AND ACROSS MOST OF THE GULF TUE THROUGH WED...WITH POTENTIAL FOR ISOLATED AREAS TO 30 KT. WAVEWATCH SHOWS SEAS BUILDING TO 10 FT OVER THE WESTERN GULF BY WED. THIS SEEMS REASONABLE GIVEN THE EXPECTED DURATION OF THE RETURN FLOW AND LARGE FETCH AREA. WILL BLEND IN NEAR 50-50 BLEND OF ECMWF-GFS THROUGH WED FOR NEXT PACKAGE AND ADJUST WW3 TO SHOW BROADER AREA OF 6-8 FT SEAS. SW N ATLC S OF 31N W OF 55W... COLD FRONT HAS MOVED THROUGH S FLORIDA THIS AFTERNOON AND EVENING AND NOW EXTENDS FROM NEAR 31N72W TO DEVELOPING LOW PRES NEAR 28.5N76W...THEN THROUGH NW BAHAMAS TO E CENTRAL CUBA ALONG 80W. GLOBAL MODELS HAVE BEEN FORECASTING A LOW TO DEVELOP ALONG FRONT BUT HAS BEEN DIFFICULT TO DETERMINE WHICH MODEL WAS MOST LIKELY. GFS ENSEMBLE MEAN SEEMS AN APPROPRIATE COMPROMISE BETWEEN DETERMINISTIC GFS AND ECMWF MODELS...AND HAVE USED THIS THROUGH 72 HRS. NLY FLOW BEHIND LOW AND FRONT DEPICTED AT 20-25 KT PER A 0206 ASCAT PASS AND WILL GENERATE SEAS THAT WILL PROPAGATE AND GET IN W OF BAHAMAS INTO SE FLORIDA COASTAL WATERS NEXT 24-36 HOURS. LOW WILL SHIFT NE ALONG FRONT NEXT 24-48 HOURS AND DEEPEN TO GALE ONCE OUT OF LOCAL WATERS THIS EVENING...WITH N TO NE GALES IN NW QUAD DIRECTLY WAVE ENERGY S AND SW INTO NW PORTIONS...WHERE WW3 HAS GONE AS HIGH AS 15 FT BY SUN EVENING JUST N OF LOCAL WATERS ALONG 63W. S TO SW FLOW AHEAD OF FRONT EXPECTED AROUND 20 KT WITHIN ABOUT 150 N E OF FRONT TODAY THEN INCREASING 20-30 KT ACROSS SE QUAD OF DEVELOPING LOW LATE THIS AFTERNOON AND EVENING ACROSS FAR NE WATERS. IT WAS FELT THAT CONVECTIVELY INDUCED WINDS COULD RAISE WINDS TO 25 KT THRESHOLD FOR HSF AT 00Z ALONG AND E OF FRONTAL BOUNDARY...BUT WILL INSERT WINDS AND SEAS THERE BY 00Z THIS EVENING. FRONT TO WASH OUT AND LIFT NW LATE SUN INTO MON WITH HIGH SHIFTING E INTO W ATLC...INDUCING FRESH TRADES THROUGH THE SRN CORRIDOR BETWEEN GREATER ANTILLES AND BAHAMAS MON THROUGH WED...AND BEYOND. PEAK SEAS TO 9 FT IN NNE WIND SWELL EXPECTED THIS EVENING AND TONIGHT ACROSS W PORTIONS BEHIND FRONT...SHIFTING NE THROUGH TUE. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... COLD FRONT ACROSS NW CARIB FROM NEAR E CENTRAL CUBA ALONG 80W TO NE HONDURAS WILL CONTINUE TO SHIFT SE NEXT 12-18 HOURS BEFORE STALLING NEAR HONDURAS-NICARAGUA BORDER TO ERN CUBA...THEN BEGINNING TO WEAKEN AND DRIFT SLOWLY NW AS INCREASING TRADES DEVELOP SUN-MON AS HIGH PRES MOVES INTO W ATLC AND TIGHTENS GRADIENT. MODELS SHOWING STRONG TRADES TO 25 KT S OF 13N FROM SE CARIB TO OFFSHORE OF COLOMBIA SUN...WITH SEAS BUILDING TO 8 FT BY SUN EVENING...THEN EXPENDING NWD MON ACROSS CENTRAL CARIB AND RETURNING LLVL JET TO MORE TYPICAL POSITION OFF OF VENEZUELA AND COLOMBIA. NOCTURNAL MAX TO 30 KT LIKELY MON AND TUE NIGHTS OFF OF COLOMBIA AND HIGH PRES RESIDES OVER W ATLC...WITH SEAS BUILDING TO 10 FT THERE EACH NIGHT. PRESENTLY NNW WINDS 20-25 KT SPILLING THROUGH YUCATAN CHANNEL AND DOWN E COAST OF YUCATAN AND INTO GULF OF HONDURAS...WITH SEAS BUILDING 6-9 FT. WINDS AND SEAS EXPECTED TO GRADUALLY DIMINISH THERE BY LATE MORNING-AFTERNOON AS WINDS BEGIN TO VEER N TO NNE. E OF THE ISLANDS...HIHG PRES WILL OPEN UP INTO THE DEVELOPING LOW ALONG THE FRONT TODAY BEFORE THE LOW MOVES NE INTO CENTRAL ATLC...AND E CENTRAL HIGH RETREATS E BY MON...WEAKENING PRES GRADIENT AND ASSOCIATED WINDS. SEAS ACROSS THE TROPICAL ATLC WATERS CURRENTLY 6-8 FT IN ENE WIND SWELL AT AROUND 9 SECS PER RECENT OBS FROM 41040. TRADES AND ASSOCIATED SEAS TO DIMINISH MON THROUGH MID WEEK AS E ATLC HIGH MOVES E AND WEAKENS. WARNINGS... GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLC... .NONE. EFFECTIVE 20 MARCH 2013...TAFB GRIDDED MARINE FORECASTS FOR 10-M WINDS...10-M WIND GUSTS...SIGNIFICANT WAVE HEIGHTS AND HAZARDS 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 WILL BE DISCONTINUED ONCE THE "OCEANIC" VIEW IS ADDED TO THE EXPERIMENTAL NDFD GRAPHICAL INTERFACE. $$ FORECASTER STRIPLING