000 AGXX40 KNHC 201856 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 250 PM EDT SAT APR 20 2013 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS. GULF OF MEXICO... LATEST SURFACE ANALYSIS HAS THE COLD FRONT EXTENDING FROM FORT MYERS FLORIDA SW TO 24N86W TO INLAND THE NW YUCATAN PENINSULA. HIGH PRES IS PRESENT ELSEWHERE ACROSS THE GULF BEHIND THE FRONT. THE FRONT IS WEAKENING...AND SO THE RECENT TIGHT PRES GRADIENT THAT PRODUCED THE STRONG TO GALE FORCE NLY WINDS BEHIND THE FRONT OVER PORTION OF THE WESTERN GULF YESTERDAY HAS SLACKEN. THE LATEST BUOY AND OIL PLATFORM STATIONS ARE CURRENTLY REPORTING NE WINDS OF 15-20 KT BETWEEN THE FRONT AND 91W...AND S OF 24N W OF 91W. WINDS ELSEWHERE ARE LIGHTER...NE-E AT 10-15 KT. WINDS SE OF THE FRONT ARE S-SW 5 KT. THE BUOYS CURRENTLY SHOW MAX COMBINED SEAS DOWN TO 10 FT IN THE FAR SRN PART OF THE BAY OF CAMPECHE AS BUOY 42055 AT 22N94W IS CURRENTLY REPORTING. SEAS ELSEWHERE ARE 6-9 FT PRIMARILY IN A NE SWELL...EXCEPT 3-5 FT IN THE NW PORTION WITH LOWER SEAS OF 2-3 FT IN THE EXTREME NW PORTION. THE 12 UTC GRIDDED WAVEWATCH GUIDANCE IS VERY CLOSE TO THESE VALUES...SO WILL FOLLOW GUIDANCE CLOSELY FOR THIS FORECAST. THE UPPER TROUGH SUPPORTING THE COLD FRONT HAS BECOME RATHER BROAD OVER THE CENTRAL CONUS AS IT LIFTS ENE WITH THE UPPER FLOW BEING SWLY ACROSS THE FRONT AS SEEN IN THE LATEST SATELLITE WATER VAPOR IMAGERY. THUS THE FORWARD PROGRESS OF THE FRONT IS SLOWING DOWN WITH TIME. MODELS ALSO SUGGEST THIS TREND. WILL CONTINUE WITH MODEL PERSISTENCE OF CURRENT OBSERVED TREND WITH THE FRONT...AND FORECAST THE FRONT TO REACH A POSITION FROM NEAR NAPLES TO THE NW YUCATAN PENINSULA EARLY THIS EVENING AND BECOME STATIONARY. WITH JUST ABOUT NO FAVORABLE UPPER SUPPORT REMAINING...THE FRONT WILL GRADUALLY DISSIPATE THROUGH EARLY MON. MOISTURE CONVERGENCE PROGS INDICATE THAT A LINGERING TROUGH FROM THE TAIL-END OF THE TROUGH WILL BE IN THE VICINITY OF THE SW GULF AND BAY OF CAMPECHE THROUGH AT LEAST MON WITH SCATTERED SHOWERS AND ISOLATED TSTMS NEAR AND ALONG IT. SEAS WILL CONTINUE TO SUBSIDE ACROSS THE GULF THROUGH EARLY NEXT WEEK AS SUGGEST BY WAVEWATCH GUIDANCES. HIGH PRES OVER THE SE U.S. WILL SLIDE EASTWARD THROUGH TUE IN RESPONSE TO THE NEXT COLD FRONT FORECAST TO APPROACH THE GULF. THIS NEXT COLD FRONT IS STILL FORECAST...BY A GENERAL MODEL AGREEMENT TO ENTER THE FAR NW GULF LATE TUE NIGHT INTO EARLY WED MORNING. THE LATEST GFS MEAN ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT WITH THE DETERMINISTIC GFS WITH TIMING OF THE FRONT INTO THE NW GULF. THIS FRONT...SIMILAR TO THE PRESENT ONE...WILL MOVE TO NEAR A SE LOUISIANA TO SW GULF LINE BY LATE WED. MODELS SUGGEST THAT NLY FLOW BEHIND THE FRONT WILL NOW BE LIGHTER THAN PREVIOUSLY ANTICIPATED WITH WINDS BECOMING N-NE AT 15-20 KT BEHIND THE FRONT WED...AND SEAS BUILDING TO 8 FT. BY LATE WED...THE FRONT WILL ALREADY HAVE BEEN UNDERGOING WEAKENING AS IT REACHES THE FAR NE GULF...WITH WINDS BECOMING VARIABLE AT 5-10 KT OVER MUCH OF THE N CENTRAL AND NE GULF WATERS. THE FRONT THEN SHIFTS E OF THE AREA THU. HIGH PRES BUILDS S AND SW ACROSS THE NRN AND CENTRAL PORTIONS THU WITH LIGHT TO MODERATE E-SE WINDS THROUGHOUT AND RATHER LOW SEA STATE. IN REGARDS TO THE GRIDS...FOR WED I FAVORED A BLEND OF THE ECMWF WITH THE GFS WEIGHING MORE TOWARDS THE ECMWF WHEN THE FRONT FIRST EMERGES OFF THE TEXAS COAST. FOR OTHER TIME PERIODS...I BLENDED THE 12 UTC GFS WITH THE 00 UTC ECMWF FROM LAST NIGHT INTO THE PREVIOUS OFFICIAL GRIDS. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... HIGH PRES CENTERED OVER THE CENTRAL ATLC CONTINUES TO WEAKEN. AN ASCAT PASS FROM THIS MORNING CONFIRMED THAT MODERATE TO FRESH NE-E TRADES CONTINUE ACROSS MOST OF THE CENTRAL CARIBBEAN...WHILE LIGHT TO MODERATE E-SE WINDS ARE ELSEWHERE ACROSS THE CARIBBEAN. ASCAT DATA ALSO SHOWED NE 20 KT WINDS OVER MOST OF THE NRN AND CENTRAL TROPICAL N ATLC ZONES. SEAS ARE IN THE 6-8 FT RANGE IN THE SW CARIBBEAN...AND MUCH LOWER ELSEWHERE ACROSS THE CARIBBEAN. SEAS IN THE TROPICAL N ATLC ZONE ARE 6-9 FT IN NE SWELLS OVER THE NRN AND CENTRAL PORTION. THE RIDGE IS FORECAST TO CONTINUE TO WEAKEN THROUGH MON AS IS SLIDES SOME TO THE E ALLOWING FOR WINDS TO DIMINISH TO OVER THE CENTRAL CARIBBEAN AND NRN AND CENTRAL PORTIONS OF THE TROPICAL N ATLC. THE NE SWELLS ACROSS THE TROPICAL N ATLC WILL SLOWLY SUBSIDE THROUGH SUN ALLOWING FOR THE CURRENT SEAS OF 8-9 FT TO LOWER TO 6 OR 7 FT THROUGH MOST OF WED...THEN LOWER TO 5-6 FT INTO THU. SW N ATLC S OF 31N W OF 55W... THE 18 UTC PRELIMINARY SURFACE ANALYSIS HAS A RIDGE OF HIGH PRES EXTENDING FROM 30N65W SW TO THE NRN BAHAMAS. A COLD FRONT HAS ENTERED THE AREA...AND ANALYZED FROM 31N76W TO INLAND NRN WEST PALM BEACH. THE PRESENT PRES GRADIENT IS MAINTAINING FRESH TO STRONG WINDS OVER THE SRN PART OF THE AREA AND GENTLE TO MODERATE WINDS OVER THE NRN PART OF THE AREA AS DEPICTED BY THE ASCAT PASS FROM THIS MORNING AS WELL AS IN THE SHIP AND BUOY OBSERVATIONS. SEAS ARE GENERALLY 7-9 FT OVER THE FAR SRN WATERS E OF THE BAHAMAS...AND 5-8 FT ELSEWHERE E OF THE BAHAMAS. SEAS W OF THE BAHAMAS ARE LOWER...IN THE 3-5 FT RANGE. NO MAJOR DEVIATIONS ARE EXPECTED WITH THE FORECAST OF THE FRONT AS ADVERTISED IN PREVIOUS FORECASTS. MODELS ARE IN PRETTY GOOD AGREEMENT WITH FRONTAL POSITIONS AND TIMING AS IT GRADUALLY PROGRESSED EASTWARD ACROSS THE WESTERN PART OF THE AREA OVER THE NEXT FEW DAYS. WILL FORECAST THE FRONT TO WEAKEN TO A TROUGH TONIGHT INTO SUN MORNING...THEN DRIFT NW TO THE FAR NW WATERS DURING THE REST OF SUN AND INTO MON. HIGH PRES WILL BUILD S ALONG THE SE U.S. COAST AND NE FLORIDA COAST MON AND TUE AS THE TROUGH MOVES NE AWAY FROM THE AREA. BEFORE THE TROUGH LIFTS NE AWAY FROM THE AREA...THE PRES GRADEINT BETWEEN THE HIGH AND THE TROUGH WILL RESULT IN NE WINDS OF 20-25 KT WITH POSSIBLE BRIEF GUSTS TO 30 KT OVER THE FAR NW WATERS LATE TONIGHT AND THROUGH SUN NIGHT...WITH SEAS BUILDING UP TO 10 FT. THE GRADEINT WEAKENS MON ALLOWING FOR THESE CONDITIONS TO SUBSIDE INTO THE MIDDLE OF NEXT WEEK. .WARNINGS...ANY CHANGES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... GMZ011...NONE. GMZ013...NONE. GMZ015...NONE. GMZ017...NONE. GMZ019...NONE. GMZ021...NONE. GMZ023...GALE WARNING TONIGHT. GMZ025...NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... AMZ011...NONE. AMZ013...NONE. AMZ015...NONE. AMZ017...NONE. AMZ019...NONE. AMZ021...NONE. AMZ023...NONE. AMZ025...NONE. AMZ027...NONE. AMZ029...NONE. AMZ031...NONE. AMZ033...NONE. AMZ035...NONE. AMZ037...NONE. AMZ039...NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... AMZ111...NONE. AMZ113...NONE. AMZ115...NONE. AMZ117...NONE. AMZ119...NONE. AMZ121...NONE. AMZ123...NONE. AMZ125...NONE. AMZ127...NONE. *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://PREVIEW.WEATHER.GOV/GRAPHICAL FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE