000 AGXX40 KNHC 260736 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 305 AM EDT SUN AUG 26 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 PRELIMINARY 06 UTC SURFACE ANALYSIS HAS A RIDGE EXTENDING FROM THE SE U.S. SW TO THE FAR SW PORTION OF THE GULF. AN UPPER LEVEL TROUGH STRETCHES FROM THE ERN U.S. SSW TO A DEVELOPING ELONGATED UPPER LEVEL CENTERED NEAR 22N88W. BUOYS AND OIL RIG PLATFORMS ARE REPORTING E-SE WINDS OF 10-15 KT THROUGHOUT W OF ABOUT 87W...EXCEPT NE-E WINDS OF 10-15 KT S OF 24N AND W OF 90W. ELSEWHERE BUOYS ARE SHOWING NE-E WINDS OF 20 KT...EXCEPT S OF 26N E OF 87W WHERE AN ASCAT PASS FROM 0220 UTC LAST NIGHT ALONG WITH A COUPLE OF SHIPS IN THE AREA ARE REPORTED MUCH HIGHER WINDS...NE 20-25 KT. REPORTED SEA HEIGHT VALUES ARE IN THE 2-4 FT RANGE...EXCEPT 3-5 FT FROM 24N TO 27N BETWEEN 90W AND 95W...AND MUCH HIGHER VALUES IN THE 8-12 FT RANGE IN A NE SWELL S OF 24N E OF 89W. THESE VALUES ARE PRETTY REASONABLE COMPARED TO THE NOAA WAVEWATCH III GUIDANCE VALUES. 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 NW JUST N OF CUBA COAST NEAR 22.1N 77.2W AS OF 11 PM EDT MOVING NW OR 305 DEG AT 15 KT. ISAAC IS FORECAST TO MOVE ALONG THE N CENTRAL COAST OF CUBA AND ACROSS THE STRAITS OF FLORIDA TODAY WHILE INTENSIFYING...REACHING TO NEAR 23.4N 79.4W BY DAYBREAK THIS MORNING. THE HIGHER WINDS FOUND IN THE SE GULF ARE DUE TO THE PRES GRADIENT TIGHTENING THERE AHEAD OF ISAAC. AS OF THE 11 PM (0300 NHC UTC ADVISORY) ISAAC IS FORECAST TO STRENGTHEN INTO A MINIMAL HURRICANE VERY CLOSE TO THE FLORIDA KEYS NEAR 24.6N 81.8W BY EARLY THIS EVENING WITH MAXIMUM WINDS OF 65 KT GUSTS TO 80 KT...AND CONTINUE ON STRENGTHENING TREND AS IT APPROACHES NEAR 25.8N 83.7W MON MORNING WITH WINDS OF 75 KT GUSTS TO 90 KT...AND CONTINUE TO TRACK NW NEAR 27.2N 85.2W BY EARLY MON EVENING WITH MAXIMUM WINDS OF 85 KT GUSTS TO 105 KT...AND APPROACH THE FAR WRN FLORIDA PANHANDLE AT 29.5N 86.5W BY EARLY TUE EVENING BEFORE MOVING INLAND LATER TUE NIGHT INTO WED. ISAAC WILL HAVE A SIGNIFICANT IMPACT ON WINDS AND SEAS OVER MUCH OF THE ERN AND MIDDLE GULF WATERS THROUGH THE FORECAST PERIOD. ASSOCIATED SEAS WILL VARY GREATLY IN ITS PERIPHERY AS WELL WITH SWELLS OF ABOUT THE 6-9 FT RANGE RADIATING OUTWARD INTO MOST OF THE MIDDLE PORTION OF THE GULF. FOR THIS FORECAST PACKAGE WILL LEAN HEAVILY ON PREVIOUS FORECAST WAVE HEIGHT GRIDS. WILL MOST LIKELY ADD AN ADDITIONAL 2-3 FT ONTO THE PREVIOUS OFFICIAL GRID VALUES THAT WERE BASED ON THE ECMWF WAVE GUIDANCE AS THE 00 GFS RUN IS OFF TO THE W OF THE OFFICIAL NHC TRACK AS ISAAC TRACKS NW WHILE INTENSIFYING ACROSS THE ERN GULF MON AND UNTIL IT APPROACHES THE COAST TUE NIGHT. SOUTHWEST NORTH ATLC S OF 31N W OF 65W... THE PRELIMINARY 06 UTC SURFACE ANALYSIS HAS A RIDGE EXTENDING SW OVER THE FAR NW WATERS. BUOYS ARE CURRENTLY REPORTING NE-E WINDS OF 15-20 KT N OF 27N W OF 76W WITH SEAS 4-6 FT...AND E-SE WINDS OF 10-15 KT E OF 76W WITH SEAS OF 4-6 FT IN A SE SWELL. S OF 26N WINDS AND SEAS ARE SIGNIFICANTLY HIGHER DUE TO THE VERY TIGHT PRES GRADIENT RELATED WITH TROPICAL STORM ISAAC NEAR 22.9N 78.0W AT 2 AM EDT OR ABOUT 365 MILES ESE OF KEY WEST FLORIDA MOVING NW OR 305 DEG AT 15 KT WITH A MINIMUM CENTRAL PRES OF 997 MB. THE 0220 UTC ASCAT PASS FROM LAST NIGHT ALONG WITH A FEW SHIP REPORTS REVEALED SUSTAINED NE-E WINDS OF 30-35 KT ON THE PERIPHERY OF ISAAC S OF 26N W OF 76W...AND E-SE WINDS OF 25-30 KT BETWEEN 71W AND 76W EXCEPT TROPICAL STORM FORCE DIRECTLY ASSOCIATED WITH ISAAC AND VERY NEAR AND ACROSS THE CENTRAL AND SE BAHAMAS. SEAS ARE 12 FT AND GREATER S OF 25N BETWEEN 76W AND 80W...AND 5-6 FT IN A N SWELL COMPONENT E OF 76W. THE MAIN FEATURE HIGHLIGHT IMPACTING THE AREA WILL BE ISAAC THROUGH MON NIGHT BEFORE IT MOVES NW INTO THE ERN GULF WITH ITS ASSOCIATED WINDS AND SEA CONDITIONS IN THE SW PORTION OF THE AREA. THESE WINDS AND SEAS WILL GRADUALLY SUBSIDE INTO TUE MORNING. ELSEWHERE A RIDGE WILL EXIST ROUGHLY ALONG 28N INTO DAY 5 (THU) THU MAINTAINING GENERALLY LIGHT SE-S WINDS EXCEPT E IN DIRECTION S OF 23N E OF THE BAHAMAS. SOME OF THE GLOBAL MODELS SUGGEST THAT A WEAK COLD FRONT MOVES ACROSS THE FAR NRN WATERS LATE WED AND THU...WITH PERHAPS SW WINDS OF 15-20 KT AHEAD OF IT N OF ABOUT 28N AND SEAS AROUND 4-6 FT. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... TROPICAL STORM ISAAC WAS LOCATED JUST NE OF THE COAST OF CUBA NEAR 22.9N 78.0W AT 2 AM EDT MOVING NW AT 15 KT WITH MAXIMUM SUSTAINED WINDS OF 50 KT GUSTS TO 60 KT. THE MINIMUM CENTRAL PRESSURE WAS 997 MB. A TROUGH EXTENDS SW FROM ISAAC TO A 1006 MB LOW AT 19N80W AND WNW TO NEAR 19N85W. THE 0218 UTC ASCAT PASS REVEALED NE 20-25 KT WINDS N OF THE TROUGH AND LOW AS WELL AS A FEW SHIPS IN THAT PART OF THE NW CARIBBEAN SEA. SHIP "A8JR6" IN THE WINDWARD PASSAGE REPORTED S WINDS OF 25 KT AT 06 UTC WITH COMBINED SEAS OF 8 FT. BASED ON THE LATEST NHC ADVISORY ISSUED AT 0300 UTC AUG 26... ISAAC IS FORECAST GAIN STRENGTH AS IT TRACKS NW NEAR THE COAST OF CUBA AND ACROSS THE STRAITS OF FLORIDA TOWARDS THE KEYS THROUGH MON EVENING WHILE REACHING MINIMAL HURRICANE FORCE. RESIDUAL SWELLS PRODUCING SEAS OF UP TO 8 FT SE OF CUBA TO BETWEEN HAITI AND JAMAICA INCLUDING THE WINDWARD PASSAGE WILL SUBSIDE TO AROUND 4-6 FT BY EARLY THIS EVENING. THE NW PORTION OF THE CARIBBEAN WILL BE UNDER THE INFLUENCE OF THE LARGE CIRCULATION ASSOCIATED WITH ISAAC THROUGH LATE MON NIGHT AT WHICH TIME WINDS ARE EXPECTED TO BECOME SE-S 15-20 KT THERE. SEAS WILL SUBSIDE TO AROUND 3-5 FT OVER MUCH OF THE NW CARIBBEAN MON NIGHT THROUGH THU. BOTH THE GFS AND ECMWF BNDY LYR WIND FIELDS INDICATE THAT THE PRES GRADIENT INCREASE ACROSS MUCH OF THE CENTRAL CARIBBEAN SEA BEGINNING TONIGHT AND THROUGH THU AS CENTRAL ATLC HIGH ESTABLISHES ITSELF AND COMBINES WITH BROAD LOW PRES LEFT IN THE WAKE OF ISAAC. SEAS THERE BUILD TO 8-10 FT DURING THIS PERIOD. NE-E WINDS OF 10 KT WILL CONTINUE ACROSS THE TROPICAL N ATLC ZONES N OF ABOUT 12N...WHILE E-SE WINDS OF 10 KT WILL REMAIN S OF 12N. SEAS OF 3-5 FT IN A NE TO E SWELL THROUGH TUE NIGHT BEFORE BECOMING MORE LIKE 2-4 FT BY WED. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .HURRICANE WARNING...GMZ015 AND GMZ021. CARIBBEAN SEA... .NONE.. SW N ATLANTIC... .TROPICAL STORM WARNING...AMZ117 AND AMZ123. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE