000 AGXX40 KNHC 240643 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 240 AM EDT FRI AUG 24 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 06 UTC SURFACE ANALYSIS HAS A 1019 MB HIGH CENTERED IN THE NE GULF AT 29N86W WITH A RIDGE TO THE SW GULF. SCATTERED TSTMS EARLIER NOTED IN THE SW GULF FROM 23N TO 26N BETWEEN 91W AND 96W UNDER DIFFLUENT FLOW BETWEEN AN UPPER TROUGH OVER THE ERN PART OF THE GULF AND BROAD ANTICYCLONIC FLOW ACROSS THE WRN GULF ARE RAPIDLY WEAKENING. BUOYS AND OIL RIG PLATFORMS ARE REPORTING E-SE WINDS OF 10-15 KT S OF THE RIDGE EXCEPT NE-E WINDS 10-15 KT IN THE SW GULF...AND S-SW WINDS OF 15-20 KT N OF THE RIDGE IN THE NW GULF. SEAS ARE IN THE 2-4 FT RANGE W OF 89W...AND 1-2 FT E OF 89W. THESE VALUES ARE CLOSE TO THE NOAA WAVEWATCH III GUIDANCE HEIGHTS. WILL USE GUIDANCE FOR MOST OF THE FORECAST PERIOD. UPCOMING SIGNIFICANT CHANGES TO WINDS AND SEAS WILL BE ATTRIBUTED TO TROPICAL STORM ISAAC CURRENTLY TRACKING WNW ACROSS THE ERN CARIBBEAN SEA IS FORECAST TO INTO THE FAR SE GULF NEAR 24.8N 82.0W BY EARLY SUN EVENING. BEFORE THEN...THE PRES GRADIENT WILL BEGIN TO INCREASE ON SAT...WITH SEAS ALSO BEGINNING TO BUILD 10 OR 11 FT SUN AFTERNOON. THE LATEST NHC ADVISORY VALID 03 UTC AUG 24 FORECASTS ISAAC TO STRENGTHEN TO A MINIMAL HURRICANE AS IT TRACKS NW ACROSS THE ERN GULF THROUGH AFTER IT ENTERS THE SE GULF LATE SUN. WINDS AND SEAS WILL SIGNIFICANTLY BUILD OVER MUCH OF THE ERN EARLY INTO MIDDLE PORTION OF NEXT WITH ISAAC. ASSOCIATED SEAS WILL VARY GREATLY IN IN ITS PERIPHERY AS WELL WITH SWELLS RADIATING OUTWARD INTO THE MIDDLE PORTIONS OF THE GULF. MOST LIKELY WILL HAVE TO RELY ON VARIOUS WAVEWATCH MODELS GUIDANCES AND ASSOCIATED ENSEMBLES FOR THE FORECAST DURING THAT PORTION OF THE FORECAST PERIOD. SOUTHWEST NORTH ATLC S OF 31N W OF 65W... THE 06 UTC SURFACE ANALYSIS HAS A RIDGE EXTENDING FROM 31N68W SW TO CENTRAL FLORIDA. BUOYS SHOW E-SE WINDS OF 10-15 KT N OF THE RIDGE...EXCEPT S-SW 10 KT WINDS N OF 28N. SEAS ARE 2-4 FT E OF 77W...AND 1-2 FT N OF THE RIDGE. S OF THE RIDGE...WINDS ARE INCREASING DUE TO THE TIGHTENING PRES GRADIENT THERE WITH ISAAC TO THE S IN THE ERN CARIBBEAN. AN ASCAT PASS FROM 0122 UTC LAST NIGHT SHOWED NE-E WINDS OF 20-30 KT S OF 25N AND E OF THE BAHAMAS. THIS IS ALSO WHERE VERY LARGE SEAS HAVE BUILD IN THE LARGE E-SE FETCH N OF ISAAC. MAX SEAS THERE ARE 15-17 FT NEAR 2N167W. S OF THE RIDGE AND W OF THE BAHAMAS NE-E WINDS OF 20 KT ARE BEING REPORTED BY A FEW SHIPS THERE...AND BY BUOYS NEAR THE FLORIDA KEYS. A PARTIAL ASCAT PASS FROM 0302 UTC LAST NIGHT SHOWED THESE WINDS AS WELL. SEAS THERE ARE 8-10 FT. THE RIDGE WILL LIFT NWD THROUGH THE NEXT 72 HRS AS TROPICAL STORM ISAAC CONTINUES ITS TRACK ACROSS THE CARIBBEAN SEA AND INTO THE ERN GULF. A TIGHT PRES GRADIENT WILL REMAIN ACROSS THE SRN PORTION OF THE AREA...S OF ABOUT 26N WITH THE STRONGEST IMPACT S OF 24N...THROUGH EARLY NEXT WEEK. WIND AND SEA CONDITIONS OVER THE SRN WATERS WILL GRADUALLY SHIFT WESTWARD DURING THIS TIME WITH THE WNW PROGRESS OF ISAAC INTO THE GULF OF MEXICO...HOWEVER LINGERING SWELLS PRODUCING SEAS UP TO 10 FT SHOULD LINGER OVER THE FAR WRN PORTION W OF THE BAHAMAS BY MON NIGHT BEFORE SUBSIDING TO 5-7 FT TUE. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... TROPICAL STORM ISAAC WAS CENTERED NEAR 16.9N 69.4W AT 2 AM EDT WITH MAXIMUM SUSTAINED WINDS 35 KT GUSTS TO 45 KT. THE MINIMUM CENTRAL PRESSURE WAS 1001 MB...WITH A FORWARD MOTION OF WNW OF 290 DEG AT 16 KT. ISSAC HAS A LARGE CIRCULATION COMPOSED OF RAINBANDS FROM 11N TO 18N AND BETWEEN 63W AND 75W. THE ASCAT PASS FROM 0122 UTC LAST NIGHT NICELY CAPTURED THE CIRCULATION OVER THE ERN SEMICIRCLE. THE BUOYS NEAR ISAAC ARE ALSO REVEALING THAT THE LARGE CIRCULATION AFFECTED JUST ABOUT THE ENTIRE ERN AND CENTRAL CARIBBEAN SEA INCLUDING THE ISLANDS THERE. BASED ON THE LATEST NHC ADVISORY...ISAAC IS FORECAST TO ONLY STRENGTHEN SLIGHTLY THIS MORNING AS IT REACHES NEAR 17.5N 70.7W. IT IS FORECAST TO WEAKEN SLIGHTLY AS IT REACHES NEAR 18.8N 73.1W EARLY TONIGHT...THEN TURN NW TO OVER ERN CUBA NEAR 20.2N 75.4W SAT MORNING AND CONTINUE NW TO NEAR 21.8N 77.7W BY SAT EVENING. ISAAC IS THEN FORECAST TO EXIT THE CARIBBEAN...AND ENTER THE SE GULF OF MEXICO SUN. THE HIGHEST SEAS WILL REMAIN IN THE N SEMICIRCLE OUTSIDE OF THE IMMEDIATE CARIBBEAN...WITH LARGE SWELLS IMPACTING THE NE-E FACING SIDES OF THE ISLANDS. SOME OF THIS SWELL WILL MANAGE TO BLEED THROUGH THE ATLC PASSAGES. WILL REFLECT THIS ON THE NEXT SET OF PUBLISHED GRID DATA. TROPICAL DEPRESSION IN THE CENTRAL TROPICAL ATLC IS FORECAST TO PASS VERY NEAR THE FAR NE TROPICAL N ATLC ZONE ON SAT NIGHT. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA... .HURRICANE WARNING...AMZ023. .TROPICAL STORM WARNING...AMZ15...AMZ021 AND AMZ025. SW N ATLANTIC... .TROPICAL STORM WARNING...AMZ117...AMZ123 AND 125. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE