000 AGXX40 KNHC 041915 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 315 PM EDT THU APR 4 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... THE STRONG MCS THAT YESTERDAY PRODUCED NUMEROUS STRONG TSTM ACTIVITY WITH FREQUENT LIGHTNING STRIKES HAS SHIFTED TO THE E AND SE PORTIONS OF THE GULF DURING THE MORNING AND EARLY AFTERNOON. A COLD FRONT THAT EXTENDS FROM A 1013 MB LOW JUST INLAND OF THE COAST OF THE FLORIDA PANHANDLE NEAR APALACHICOLA SW TO 26N91W AND TO THE WESTERN BAY OF CAMPECHE. A WEAK SURFACE TROUGH IS AHEAD OF THE FRONT EXTENDING ROUGHLY FROM NEAR 25N90W S TO THE EASTERN BAY OF CAMPECHE AS WAS REVEALED BY THE 1514 UTC ASCAT PASS FROM THIS MORNING. BOTH LATEST NWS RADAR AND SATELLITE IMAGERY DISPLAYS SHOW THAT TSTM ACTIVITY OUT AHEAD OF THE FRONT ASSOCIATED WITH THE MCS FEATURE REMAINS QUITE ACTIVE...BUT NOT AS POTENT AS YESTERDAY. ACCORDING TO THE LATEST LIGHTNING DETECTION DATA...LIGHTNING STRIKES WITH THIS ACTIVITY HAVE DIMINISHED AS WELL. THE ACTIVITY IS NOTED FROM 25N TO 28N E OF 85W WITH SCATTERED SHOWERS AND ISOLATED TSTMS ELSEWHERE E OF 86W. MODEL WINDS AT 850-700 MB INDICATE THAT THE UPPER LEVEL ENVIRONMENT REMAINS FAVORABLE FOR THIS CONVECTION ACTIVITY TO POSSIBLY INTENSIFY OR DEVELOP INTO MORE STRONG CELLS AS IT SHIFTS ESE THROUGH FRI. MARINERS SHOULD BE ADVISED THAT HAZARDOUS WIND AND SEAS CONDITIONS CAN BE EXPECTED WITH THIS ACTIVITY INTO FRI. BUOYS AND A FEW SHIP REPORTS ARE REPORTING SEAS IN THE GENERAL RANGES OF 6-9 FT BEHIND THE FRONT S OF 26N...AND 3-5 FT ELSEWHERE WITH LOWER SEAS OF 2-3 FT IN THE FAR NORTHERN PORTIONS OF THE GULF. MODELS IN GOOD AGREEMENT THAT THE AFOREMENTIONED LOW PRES WILL CONTINUE TO TRACK NE TO ACROSS THE FLORIDA PENINSULA THIS AFTERNOON WITH THE COLD FRONT REACHING FROM NEAR TAMPA FLORIDA TO THE NORTHERN YUCATAN PENINSULA LATE TONIGHT...FROM SW FLORIDA TO THE YUCATAN CHANNEL EARLY FRI...THEN EXIT THE REGION FRI AFTERNOON. HIGH PRES WILL BUILD ACROSS THE AREA IN THE WAKE OF THE FRONT. HIGH PRES WILL THEN SHIFT EASTWARD SAT AND SUN AS LOW PRES DEEPENS OVER THE CENTRAL UNITED STATES ALLOWING FOR SOUTHERLY RETURN FLOW TO INCREASE OVER THE WESTERN GULF THROUGH TUE. FOR THE GRIDDED FORECAST...I BLENDED THE 12 UTC GFS GUIDANCE WITH THE PREVIOUS OFFICIAL GRIDS. I MADE SOME MINOR TWEAKS TO INCREASE SEAS SLIGHTLY OVER THE EASTERN PORTION OF THE N CENTRAL GULF ZONE (13) FOR TONIGHT AND EARLY FRI. SW N ATLC S OF 31N W OF 55W... THE PRELIMINARY SURFACE ANALYSIS HAS A WEAKENING COLD FRONT EXTENDING FROM NEAR 31N48W SW TO NEAR 26N58W WHERE IT WEAKENS AS A STATIONARY FRONT TO 25N66W. A WARM FRONT IS JUST N OF THE FAR NW PORTION EXTENDING SW TO THE WEAK 1013 MB LOW OVER THE WESTERN FLORIDA PANHANDLE. THE WARM FRONT WILL CONTINUE TO LIFT N AS THE LOW LIFTS NE TO ACROSS SE GEORGIA. THE ASSOCIATED STRONG COLD FRONT WILL MOVE INTO THE NW PORTION EARLY FRI...AND QUICKLY REACH FROM NEAR 31N74W TO STRAITS OF FLORIDA AND WESTERN CUBA FRI EVENING. AS STATED IN PREVIOUS FORECASTS DISCUSSIONS... WINDS MAY APPROACH GALE FORCE N OF 30N THU NIGHT AND FRI...BUT AGAIN NONE OF THE GFS ENSEMBLE PROBABILITY FORECASTS INDICATE GALE FORCE WINDS ARE LIKELY S OF 31N. STILL CANNOT RULE OUT SLY WINDS OF 25-30 KT WINDS LIKELY IN ZONE AMZ111 FRI...WITH BUILDING SEAS TO AROUND 11 OR 12 FT THE MODELS AND EVEN THE ENSEMBLE FORECAST GUIDANCES HAVE COME INTO MORE OF A CONSENSUS THAT LOW PRES WILL FORM ALONG THE FRONT OVER THE NE PORTION OF THE AREA SAT...AND TRACK NEWD AWAY FROM THE REGION. THE 00 UTC ECMWF ENSEMBLE FORECAST SHOWS THE LOW FURTHER S INTO THE FORECAST ZONE OF 115 LATE SAT INTO SUN. WILL LEAN TOWARDS A LOW POSN CLOSER TO 30N SAT INTO SUN...AND HIGHLIGHT THE INCREASING NE FLOW TO ITS NW IN A TIGHTENING PRES GRADIENT...BUT SHOULD BE RATHER SHORT-LIVED WITH THE LOW QUICKLY LIFTING NE SUN AND WEAK HIGH PRES SETTLING SWD BEHIND IT. ONCE THIS TAKES PLACE...MODELS AGREE THAT HIGH PRES THEN BUILDS WESTWARD OVER THE NORTHERN PORTION INTO TUE...AND BECOMES THE MAIN FEATURE INFLUENCING THE WIND REGIME THROUGHOUT. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... THE OVERALL SYNOPTIC PATTERN HAS CHANGED LITTLE SINCE 24-48 HRS AGO. FRESH TO STRONG NE TO E WINDS PREVAIL ACROSS MOST OF THE EAST CARIBBEAN AND TROPICAL N ATLC. HIGH PRES CENTERED NE OF THE AREA WITH A WEAK LOW LEVEL PERTUBATION ALONG 55W IS ENHANCING TRADE WINDS OVER THE NE PORTION OF THE TROPICAL N ATLC WITH SEAS TO 8 FT THERE PRIMARILY IN A NE SWELL. FRESH TO STRONG SE WINDS ARE EXPECTED IN THE GULF OF HONDURAS ARE PRESENTLY SLOWLY DIMINISHING. THE AFOREMENTIONED GULF OF MEXICO COLD FRONT IS PROGGED BY GFS/ECMWF/UKMET MODEL GUIDANCE TO REACH THE YUCATAN CHANNEL EARLY FRI...THEN WEAKEN OVER THE NW CARIBBEAN DURING THE REST OF FRI INTO SAT. MODERATE TO FRESH E TRADE WINDS WILL PREVAIL ACROSS THE REGION SAT THROUGH MON AS HIGH PRES TAKES CONTROL OF THE ATLC REGION AND FAR NORTHERN PORTIONS OF THE CARIBBEAN AND TROPICAL N ATLC ZONES. 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 AGUIRRE