000 AGXX40 KNHC 211858 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 255 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 STATIONARY FRONT EXTENDING FROM S FLORIDA SW TO INLAND THE N CNTRL YUCATAN PENINSULA. HIGH PRES IS ANALYZED ACROSS THE NRN HALF OF THE GULF...WHILE A RATHER ACTIVE SURFACE TROUGH EXTENDS FROM 27N90W TO THE ERN BAY OF CAMPECHE. THE LATEST AND CURRENT BUOY AND OIL PLATFORM STATIONS SHOW NE-E WINDS OF 10-15 KT OVER THE MAJORITY OF THE GULF...WITH THE EXCEPTIONS OF THE FAR WRN GULF WHERE THE WINDS ARE E-SE IN DIRECTION...AND IN THE SW GULF WHERE LIGHT NLY WINDS ARE NOTED. THE BUOYS CURRENTLY SHOW SEAS IN THE RANGE OF 3-5 FT S OF 27N E OF 95W WITH A FEW REPORTS OF SEAS TO 6 FT IN THE CENTRAL GULF ZONE 019. SEAS ELSEWHERE ARE IN THE RANGE OF 2-4 FT...WITH THE LOWEST OF THESE CONFINED TO THE FAR NW PART OF THE GULF. THESE VALUES ARE VERY CLOSE TO THE GRIDDED WAVEWATCH GUIDANCE. WILL FOLLOW THIS GUIDANCE CLOSELY FOR THIS FORECAST. LATEST SATELLITE IMAGERY SHOWS A SIGNIFICANT INCREASE IN TSTM ACTIVITY ASSOCIATED WITH THE SURFACE TROUGH...AND FURTHER AIDED BY RIPPLES UPPER LEVEL ENERGY IN FAST UPPER FLOW THROUGH THE BASE OF A BROAD UPPER TROUGH THAT COVERS THE SE U.S. AND MOST OF THE NRN AND CENTRAL GULF PORTIONS. THE TSTM ACTIVITY IS CONFINED TO S OF 28N BETWEEN 84W AND 89W...WITH RESULTANT UPPER DEBRIS CLOUDINESS SPREADING EWD. 700-850 MB MODEL MOISTURE FIELDS AND SURFACE MOISTURE CONVERGENCE GUIDANCE SUGGEST THAT THE SURFACE TROUGH MAY DRIFT A LITTLE TO THE W OVER THE NEXT 24 HRS BEFORE IT DRIFTS E AND WEAKENS...WITH THE ASSOCIATED MOISTURE AND WEATHER CONTINUING THROUGH MON NIGHT. BY THEN THE MOISTURE SHOULD BE LESS IN COVERAGE WITH MAINLY SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SE PART OF THE GULF INTO THE MIDDLE OF THE UPCOMING WEEK. AS FOR THE SHORT AND LONG TERM FORECAST WILL FOLLOW PERSISTENCE OF MODEL GUIDANCE AND PREVIOUS FORECAST THINKING IN FORECASTING THE STATIONARY FRONT TO DISSIPATE BY LATE MON NIGHT. HIGH PRES OVER THE SE U.S. WILL SLIDE EASTWARD THROUGH TUE IN RESPONSE TO THE NEXT COLD FRONT FORECAST TO APPROACH THE GULF. HIGH CONFIDENCE IN MODELS WITH TIMING AND PERSISTENCE OF THE NEXT COLD FRONT TO APPROACH THE LEADS TO KEEPING A FORECAST OF THE FRONT MOVING INTO THE NW GULF EARLY ON WED. AFTER THEN WILL FOLLOW MAINLY THE ECMWF GUIDANCE...WHICH IS SIMILAR TO HPC'S THINKING ON THE DAYS 3-5 PROGS FOR FRONTAL POSN ACROSS THE GULF. SO WILL FORECAST THE FRONT TO A POSN FROM THE WRN FLORIDA PANHANDLE TO THE SW GULF LATE WED NIGHT AS IT BEGINS TO WEAKEN...FROM CENTRAL FLORIDA TO BAY OF CAMPECHE THU...THEN DISSIPATE AS A STATIONARY FRONT OVER THE SE AND S CNTRL WATERS LATE THU AND FRI. MODELS SUGGEST THAT N-NE WINDS WILL BRIEFLY REACH 15-20 KT OVER A SMALL PORTION OF THE WRN GULF BEHIND THE FRONT...AND BE LIGHTER N-NE AT 10-15 KT ELSEWHERE NW OF THE FRONT. SEAS ARE NOT EXPECTED TO BUILD UP TOO MUCH BEHIND THE FRONT...AT MOST 5 OR 6 FT. WEAK HIGH PRES THEN SETTLES IN OVER THE NRN GULF LATE WED THROUGH FRI. 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 REVEALED NE WINDS OF 15-20 KT OVER THE NE PORTION OF THE SEA...AND NE-E 10-15 KT ELSEWHERE. BUOYS AND A FEW SHIP OBSERVATIONS ARE REPORTING NE 15-20 KT WINDS OVER THE NRN AND CENTRAL TROPICAL N ATLC ZONES. THE OBSERVATIONS SHOW SEAS IN THE 6-7 FT RANGE IN THE SW AND NE PORTIONS OF THE CARIBBEAN...AND MUCH LOWER IN THE 3-5 FT RANGE ELSEWHERE EXCEPT FOR 2-3 FT W OF 79W. SEAS IN THE TROPICAL N ATLC ZONE ARE 6-8 FT IN NE SWELLS OVER THE NRN AND CENTRAL PORTION. THE RIDGE IS FORECAST TO CONTINUE TO WEAKEN THROUGH TUE AS IS SLIDES EASTWARD ALLOWING FOR A WEAK PRES GRADIENT THROUGHOUT. THE NE SWELLS ACROSS THE TROPICAL N ATLC WILL SLOWLY SUBSIDE THROUGH EARLY MON...ALLOWING FOR THE CURRENT SEAS OF 6-8 FT TO LOWER TO 6 OR 7 FT THROUGH MOST OF WED...THEN LOWER TO 5-6 FT INTO THU AND FRI. 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 CENTRAL BAHAMAS. A WEAKENING STATIONARY FRONT EXTENDS FROM 31N76W TO SE FLORIDA. THE ASCAT PASS FROM 1422 UTC THIS MORNING REVEALED NE WINDS OF 20 KT OVER THE SE PORTION...AND LIGHTER E-SE WINDS OF 10-15 KT OVER MOST OF THE WRN PORTION. OBSERVED EAS ARE GENERALLY 6-8 FT OVER THE FAR SRN WATERS E OF THE BAHAMAS AND ENE PORTIONS. SEAS ELSEWHERE ARE 4-7 FT...EXCEPT 3-5 FT W OF THE BAHAMAS. WILL CONTINUE WITH CONTINUITY WITH PREVIOUS FORECAST AND MODEL PERSISTENCE IN FORECASTING THE FRONT TO GRADUALLY WEAKEN TO A TROUGH MON AS IT BEGINS TO DRIFT W. HIGH PRES WILL BUILD S ALONG THE SE U.S. COAST AND NE FLORIDA COAST TONIGHT THROUGH TUE AS THE TROUGH THEN STARTS TO MOVES E. BEFORE THE TROUGH LIFTS NE AWAY FROM THE AREA...THE PRES GRADIENT BETWEEN THE HIGH AND THE TROUGH WILL RESULT IN NE WINDS OF 20-25 KT OVER THE FAR NW WATERS THROUGH MON NIGHT...WITH SEAS BUILDING UP TO 9 OR 10 FT. THE GRADIENT WEAKENS TUE ALLOWING FOR THESE CONDITIONS TO SUBSTANTIALLY SUBSIDE THROUGH DAY 5. .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