000 AGXX40 KNHC 031857 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT WED APR 3 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 MAIN FEATURE CONTINUES TO THE STRONG MCS OVER THE N CENTRAL GULF PRODUCING NUMEROUS STRONG TSTM ACTIVITY WITH FREQUENT LIGHTNING STRIKES OVER THE NORTHERN ZONES E OF ABOUT 92W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE OVER THE NORTHERN GULF. TO FURTHER ENHANCE MATTERS WITH RESPECT TO THE ONGOING WEATHER...A LOW PRES CENTER OF 1009 MB IS ANALYZED NEAR 28N93W WITH A COLD FRONT EXTENDING SW TO INLAND MEXICO AT MATAMOROS. A WARM FRONT EXTENDS FROM THE LOW ESE TO NEAR 25N85W. IN ADDITION...A RATHER VIGOROUS MID/UPPER LEVEL CUT-OFF LOW IS NOTED OVER THE CENTRAL PLAINS WITH AMPLE DIFFLUENCE ALOFT TO ITS E FURTHER HELPING TO SUSTAIN THE ONGOING DEEP CONVECTION. BUOYS AND HIGH RAISED OIL PLATFORMS HAVE BEEN REPORTING GUSTY AND SHIFTY WINDS THROUGH THIS MORNING AND EARLY AFTERNOON AS A RESULT OF THE CONVECTION. SEAS HAVE RAISED TO AROUND 7 FT...SOMETIMES BRIEFLY 8 FT...OVER THE EASTERN PART OF THE N CENTRAL GULF ZONE. SEAS ELSEWHERE ARE 4- 5 FT...EXCEPT 2-3 FT IN THE FAR NW PART NEAR THE TEXAS COAST. MODELS IN PRETTY GOOD AGREEMENT THAT THE LOW PRES CURRENTLY NOTED WILL QUICKLY RACE NE TO THE VICINITY OF SE LOUISIANA AND THE MISSISSIPPI DELTA REGION TONIGHT INTO THU. THE LOW WILL THEN MOVE ENE ACROSS THE WESTERN FLORIDA PANHANDLE THU NIGHT AND FRI WHILE SLOWLY DEEPENING...THEN TURN NE AND CONTINUE ACROSS THE SE UNITED STATES THU NIGHT AND FRI. THE LOW WILL PUSH THE COLD FRONT ACROSS THE REMAINDER OF THE WESTERN GULF THROUGH EARLY THU...TO A POSITION FROM NEAR TAMPA FLORIDA TO NE YUCATAN PENINSULA BY LATE THU NIGHT...AND TO JUST SE OF THE GULF BY EARLY FRI AFTERNOON. GENTLE TO MODERATE E-SE WINDS WILL PREVAIL ACROSS THE REGION SAT...THEN BECOMING MODERATE TO FRESH WESTERN AND CENTRAL PORTION SUN AND MON IN RESPONSE TO DEEPENING LOW PRES OVER THE CENTRAL U.S. FOR THE GRIDDED FORECAST...I BLENDED THE 12 UTC GFS WITH THE 00 UTC ECMWF INTO THE PREVIOUS OFFICIAL GRIDS. I MADE SOME TWEAKS ...IN THE UPWARD SCALE...TO WINDS AND SEAS OVER THE N CENTRAL ZONE (13) E PORTION...AND THE MOST OF THE NE ZONE (15) THROUGH THU EVENING. SW N ATLC S OF 31N W OF 55W... THE PRELIMINARY SURFACE ANALYSIS HAS A WEAKENING COLD FRONT EXTENDING FROM NEAR 31N58W SW TO NEAR 25N65W WHERE IT BECOMES VERY ILL DEFINED BASED ON THE THE LATEST 1354 UTC ASCAT PASS. HIGH PRES RIDGING IS PRESENT OVER THE CENTRAL PORTION OF THE AREA...BUT SLIDING EASTWARD WITH TIME IN RESPONSE TO THE GULF OF MEXICO LOW AND FRONTAL SYSTEM PROGRESSING ENE. THIS SYSTEM IS FORECAST BY NWP MODELS TO TRACK NEWD FROM THE GULF OF MEXICO TO ACROSS THE SE UNITED STATES TONIGHT THROUGH THU NIGHT WHILE DEEPENING. THE ASSOCIATED STRONG COLD FRONT WILL MOVE INTO THE NW PORTION EARLY FRI...AND QUICKLY REACH FROM NEAR 31N76W TO STRAITS OF FLORIDA AND WESTERN CUBA FRI EVENING. THE MODELS AND EVEN THE ENSEMBLE FORECAST GUIDANCES HAVE COME INTO MORE OF A CONSENSUS THAT LOW PRES WILL FORM ALONG THE FRONT AND MOVE ESE ACROSS THE FAR NORTHERN WATERS THROUGH EARLY SUN...BEFORE LIFTING NE AWAY FROM THE REGION. THE 00 UTC ECMWF ENSEMBLE FROM LAST NIGHT IS MORE PRONOUNCED WITH THIS SCENARIO THAN THE GFS MEAN ENSEMBLE FROM 12 UTC THIS MORNING. THE GFS MEAN ENSEMBLE DOES NOT REALLY SHOW THIS LOW UNTIL LATE SAT...AND EVEN THEN IT IS JUST NE OF THE FAR NE BOUNDARY OF THE AREA MOVING NE AND AWAY FROM THE FORECAST WATERS. OVERALL...I BELIEVE THE 12 UTC OPERATIONAL GFS...SIMILAR TO THE 00 UTC GFS RUN FROM LAST NIGHT...IS TOO FAST WITH THE COLD FRONT AS IT SWEEPS ACROSS THE AREA. FOR THIS FORECAST WILL BE BLEND THE GFS WITH ECMWF THOUGH FRI NIGHT...THEN USE THE GFS FOR THE REMAINDER OF THE FORECAST PERIOD. WILL FORECAST THE FRONT TO REACH FROM NEAR 31N74W TO EASTERN CUBA SAT AFTERNOON...AND FROM NEAR 31N68W TO 25N68W AND STATIONARY TO EASTERN CUBA BY LATE SUN. THE PRES DIFFERENCE BETWEEN IT AND HIGH PRES OVER THE CENTRAL AND EASTERN PORTIONS WILL INCREASE WINDS AND SEAS ACROSS THE NORTHERN WATERS THU THROUGH FRI BEFORE DIMINISHING FRI NIGHT INTO SAT AS THESE CONDITIONS SPREAD EASTWARD. 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. GENTLE TO MODERATE E-NE WINDS WILL PREVAIL ACROSS THE REGION SUN AND MON AS HIGH PRES TAKES PRECEDENCE ACROSS THE REGION. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... THE OVERALL SYNOPTIC PATTERN HAS CHANGED LITTLE SINCE 24 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 CONTINUES TO S ENHANCING TRADE WINDS OVER A BROAD AREA OF THE TROPICAL N ATLC WITH SEAS OF 8 TO 11 FT BASED ON BUOY OBSERVATIONS AND AN EARLIER ALTIMETER PASS. FRESH TO STRONG SE WINDS ARE EXPECTED IN THE GULF OF HONDURAS THROUGH THU AS LOW PRES OVER N/CENTRAL GULF OF MEXICO TIGHTENS A PRES GRADIENT W OF 85W. THE COLD FRONT ASSOCIATED WITH THIS DEVELOPING LOW PRES SYSTEM IS EXPECTED 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