000 AGXX40 KNHC 280759 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 355 AM EDT TUE AUG 28 2012 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 IS TROPICAL STORM ISAAC LOCATED NEAR 27.4N 87.7W OR ABOUT 145 MILES SE OF THE MOUTH OF THE MISSISSIPPI RIVER...OR ABOUT 220 MILES SSE OF BILOXI MISSISSIPPI MOVING NW AT 10 KT WITH MAXIMUM WINDS OF 60 KT GUSTS TO 75 KT AND PRES OF 978 MB. LATEST BUOY OBSERVATIONS SHOW COMBINED SEAS OF UP TO 14 FT IN THE MIDDLE PART OF THE GULF ABOUT 190 NM SW OF THE CENTER OF ISAAC. THE LATEST NHC ADVISORY VALID 0300 UTC AUG 28 HAS ISAAC FORECAST TO STRENGTHEN INTO A HURRICANE WITH MAXIMUM WINDS OF 70 KT GUSTS TO 85 KT NEAR 28.0N 88.0W BY DAYBREAK THIS MORNING...THEN REACH THE TIP OF SE LOUISIANA NEAR 29.1N 89.2W BY EARLY TONIGHT WITH MAXIMUM WINDS OF 80 KT GUSTS TO 110 KT...AND FURTHER INLAND TO NEAR 29.9N 90.1W DAYBREAK ON WED AS IT BEGINS TO WEAKEN REACHING 30.7N 90.7W AS A TROPICAL STORM ON WED EVENING. ISAAC WILL HAVE A SIGNIFICANT IMPACT ON WINDS AND SEAS OVER MUCH OF THE ERN AND MIDDLE GULF WATERS MAINLY N OF 25N E OF 94W THROUGH WED NIGHT...N OF 26N BETWEEN 84W-92W THU WITH SEAS SUBSIDING TO 6-8 FT LATE THU. DURING FRI...SEAS ARE FORECAST TO SUBSIDE TO 4-6 FT IN THE FAR N CENTRAL PART OF THE GULF...AND TO 2-4 FT FRI NIGHT AND SAT. OUTSIDE OF ISAAC'S WARNING IMPACT REGION AND AWAY FROM THE ELSEWHERE 20-33 KT WINDS...WINDS WILL BE ON THE LIGHT SIDE. THEY WILL BECOME SE-S IN DIRECTION WITH THE EXCEPTION OF THE SW GULF WHERE THEY WILL BE E-SE 15-20 KT LATE THU THROUGH SAT. SEAS WILL SUBSIDE TO 3-5 FT ELSEWHERE OVER THE IMPACT AREAS OF ISAAC THU THROUGH SAT...WITH LOWER SEAS OF 1-2 FT IN THE ERN PART OF THE GULF AND 2-3 FT IN THE BAY OF CAMPECHE. WILL FOLLOW NOAA WAVEWATCH III GUIDANCE FOR THIS PACKAGE. SOUTHWEST NORTH ATLC S OF 31N W OF 65W... THE PRELIMINARY 06 UTC SURFACE ANALYSIS HAS A RIDGE EXTENDING ALONG 30N E OF ABOUT 78W. A TIGHT PRES GRADIENT REMAINS OVER THE FAR WRN PORTION BETWEEN THE RIDGE AND THE LARGE CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL STORM ISAAC MOVES NW ACROSS THE ERN GULF OF MEXICO. BUOYS ARE REPORTING SE-S WINDS OF 20-25 KT W OF 76W WITH SEAS OF 6-9 FT. WINDS ARE LIGHTER ELSEWHERE...E-SE 10-15 KT EXCEPT SW 5-10 KT N OF THE RIDGE AND E-SE 15-20 KT S OF 23N BETWEEN 76W-71W. SEAS ELSEWHERE ARE 3-5 FT IN A SWELLS...EXCEPT 5-7 FT WITHIN THE AREA OF 15-20 KT S OF 23N BETWEEN 76W-71W. THE TIGHT PRES GRADIENT OVER THE WRN PORTION WILL SLACKEN THROUGH THIS MORNING ALLOWING FOR THE SE-S 20-25 KT WINDS TO DIMINISH TO 10-15 KT DURING TODAY. THE RIDGE ALONG 30N WILL SHIFT S TO NEAR 28N TONIGHT THROUGH WED NIGHT...THEN TO 27N THU AND TO E OF THE AREA FRI AND SAT IN RESPONSE TO A WEAK COLD FRONT THAT BRUSHES ACROSS THE FAR NRN WATERS. BOTH GFS AND ECMWF BOUNDARY LAYER WIND GUIDANCE SUGGEST THAT FRONT MAY BE PRECEDED BY SW-W WINDS OF 10-15 KT. WAVEWATCH GUIDANCE INDICATES THAT SEAS SHOULD BE 4-6 FT AHEAD OF THE FRONT. THE RIDGE WILL BECOME THE DOMINATE WEATHER FEATURE FOR THIS FORECAST PERIOD...AND MAINTAIN LIGHT E-SE WINDS THROUGHOUT WITH THE EXCEPTIONS OF WINDS BECOMING N-NE 10 KT BEHIND THE FRONT...AND E WINDS OF 15 KT S OF 25N E OF THE BAHAMAS. SEAS ELSEWHERE SHOULD BE IN THE 3-5 FT RANGE...LOWERING TO 2-3 FT IN THE NW PORTION WED NIGHT THROUGH SAT. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... WITH TROPICAL STORM ISAAC NOW FURTHER NW OVER THE NW PART OF THE ERN GULF OF MEXICO...WINDS IN THE NW CARIBBEAN ARE RESPONDING BY DIMINISHING AND BECOMING SE-S 10-15 KT WITH SEAS OF 2-3 FT EXCEPT 5-7 FT IN A NLY SWELL. BUOY 42056 AT 20N85W HAS SEAS IN THE 2-3 FT RANGE. E-SE TRADES ARE IN THE RATHER LIGHT RANGE ELSEWHERE...E-SE IN DIRECTION WITH SEAS OF 3-5 FT WITH THE EXCEPTION OF THE CENTRAL PORTION OF THE CARIBBEAN WHERE E-SE WINDS OF 20-25 KT CONTINUE N OF 12N BETWEEN 69W AND 70W AS A TIGHT PRES GRADIENT BETWEEN THE ATLC RIDGE AND BROAD LOW PRES IN THE WRN CARIBBEAN PERSISTS. SEAS IN THE CENTRAL PORTION OF THE CARIBBEAN SEA ARE IN THE 8-10 FT. BUOY 42058 AT 15N75W IS CURRENTLY REPORTING E-SE WINDS OF 20 KT WITH SEAS OF 8-10 FT. BOTH THE GFS AND ECMWF BOUNDARY LAYER WIND FIELDS INDICATE THAT THE TIGHT PRES GRADIENT BRINGING THE SE 20-25 WINDS ACROSS THE CENTRAL CARIBBEAN WILL CONTINUE THROUGH THE PERIOD...BUT DIMINISH SOME IN AREAL COVERAGE ON SAT WITH SEAS LOWERING TO 6-8 FT. NE-E WINDS OF 10 KT WILL CONTINUE ACROSS THE TROPICAL N ATLC ZONES N OF ABOUT 12N AND ELSEWHERE ACROSS THE CARIBBEAN...WHILE E-SE WINDS OF 10 KT WILL REMAIN S OF 12N. SEAS OF 3-5 FT IN A NE TO E SWELL LAST THROUGH TUE NIGHT BEFORE BECOMING MORE LIKE 2-4 FT BY WED. GENERAL CONSENSUS OF THE GLOBAL MODELS IS INDICATING THAT NEXT TROPICAL FEATURE TO MOVE IN THE TROPICAL N ATLC FORECAST ZONE WILL BE ON SAT...PROBABLY LATE ON THAT DAY. THE GFS MODEL RUNS HAVE TOO FAST IN TRACKING THIS FEATURE ACROSS THE TROPICAL ATLC AS WELL AS TOO INTENSE WITH ITS WINDS. THIS FEATURE IS CURRENTLY ANALYZED AS A LOW WITH AN ATTENDANT TROPICAL WAVE...BUT COULD VERY WELL BE A STRENGTHENING LOW PRES SYSTEM BY THAT TIME. WILL HAVE TO WAIT FOR FUTURE MODELS TO SEE HOW THEY RESOLVE THIS MATTER BEFORE BE MORE DEFINITIVE ON A FORECAST FOR THIS FEATURE. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .HURRICANE WARNING...GMZ013 AND GMZ015. .TROPICAL STORM WARNING...GMZ019 N OF 25N E OF 89W. CARIBBEAN SEA... .NONE.. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE