000 AGXX40 KNHC 120659 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT FRI AUG 12 2011 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... A WEAK NW TO SE ORIENTED RIDGE OF HIGH PRESSURE WILL PREVAIL ACROSS THE GULF OF MEXICO THROUGH THE FORECAST PERIOD. LATEST OBSERVATIONS INDICATE A LIGHT TO GENTLE BREEZE ACROSS MUCH OF THE GULF WITH SEAS GENERALLY 1 TO 3 FT. THE EXCEPTIONS LIE IN THE NW GULF WHERE A MODERATE SE BREEZE AND SEAS TO 4 FT ARE CURRENTLY IN PLACE AND EXPECTED TO PERSIST THROUGH SAT NIGHT BEFORE DIMINISHING SUN AS WELL AS ALONG THE NORTHERN AND WESTERN YUCATAN PENINSULA EACH EVENING/NIGHT WHERE DIURNALLY DRIVEN LOCAL EFFECTS WILL BRIEFLY INCREASE WINDS TO A FRESH BREEZE. A WEAK TROPICAL WAVE WILL PASS THROUGH THE SW GULF LATE SUN THROUGH MON AND INCREASE THE CHANCE OF PRECIPITATION OVER THE AREA BUT HAVE LITTLE IMPACT ON THE WINDS OR SEAS. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE APPROACHING 80W WILL SHIFT W OF THE AREA SUN. PRECIPITATION IS SKEWED TO THE NORTHERN PORTION OF THE WAVE OVER THE WINDWARD PASSAGE AND EASTERN CUBA AT THE MOMENT. THIS WAVE WILL NOT HAVE A SIGNIFICANT AFFECT ON THE WINDS ACROSS THE WESTERN CARIBBEAN BUT SHOULD CONTINUE TO CARRY PRECIPITATION WESTWARD WITH IT. WINDS IN THE CARIBBEAN ARE MAINLY DRIVEN BY THE PRESSURE GRADIENT BETWEEN THE RIDGE OVER THE SW N ATLC ALONG 26N AND LOWER PRESSURE OVER SOUTH AMERICA. THIS GRADIENT WILL MAINTAIN FRESH TO STRONG TRADES MAINLY OVER THE CENTRAL CARIBBEAN THROUGH THE FIRST HALF OF THE WEEKEND. THE TRADES ARE EXPECTED TO DIMINISH AS THE RIDGE OVER THE SW N ATLC WEAKENS AND A SURFACE LOW...POSSIBLY A TROPICAL CYCLONE...MOVES INTO THE TROPICAL N ATLC EARLY NEXT WEEK. THIS WILL WEAKEN THE PRESSURE GRADIENT OVER THE CARIBBEAN WITH MODERATE TO FRESH TRADES PREVAILING. LOW PRESSURE CURRENTLY EMBEDDED IN THE MONSOON TROUGH WILL MOVE INTO THE NE PORTION OF THE TROPICAL N ATLC WATERS SUN/MON. THIS LOW MAY DEVELOP INTO A TROPICAL CYCLONE. THERE CONTINUES TO BE DISAGREEMENT BETWEEN THE GFS AND ECMWF WITH REGARD TO THE LOW WITH THE 00Z GFS MORE AGGRESSIVE WITH ITS FURTHER DEVELOPMENT. THE 00Z ECMWF HAS BACKED OFF COMPARED TO ITS 11/12Z FORECAST AND NOW LOSES THE CLOSED LOW LEVEL CIRCULATION AND WINDS OVER 20 KT ON DAY 1 OF THE FORECAST PERIOD. THIS SEEMS WEAK COMPARED TO THE 2030 UTC WINDSAT PASS. THE GFS CONTINUES TO BE FASTER THAN THE ECMWF...MOVING THE SYSTEM W-NW AT OVER 20 KT IN THE SHORT RANGE. THIS IS MUCH FASTER THAN EXPECTED...ESPECIALLY CONSIDERING SOME DEVELOPMENT IS EXPECTED. WINDS ASSOCIATED TO THIS FEATURE ARE FORECAST TO BE 20-25 KT OVER THE NE PORTION OF THE TROPICAL N ATLC ZONE AS THE SYSTEM MOVES THROUGH SUN/MON. THE LOW IS CURRENTLY FORECAST TO EXIT THE AREA LATE MON AND LIFT N AS IT IS STEERED BY THE LEADING EDGE OF DEEP LAYER TROUGHING OVER THE SW N ATLC. A SECOND AREA OF LOW PRESSURE WILL APPROACH THE CENTRAL PORTION OF THE TROPICAL N ATLC BY MID WEEK. THIS LOW ALSO HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE. INTERESTS IN THE E CARIBBEAN SHOULD CONTINUE TO MONITOR THE PROGRESS OF BOTH OF THESE DISTURBANCES DURING THE NEXT WEEK. SOUTHWEST N ATLC... A 1018 MB HIGH PRES IS POSITIONED NEAR 26N65W WITH A RIDGE EXTENDING TO THE NORTHERN BAHAMAS. A DEEP LAYER TROUGH LIES JUST OFF THE SE U.S. COAST AND THE TAIL OF THE STATIONARY BOUNDARY AT THE SURFACE ASSOCIATED WITH THIS DEEP LAYER TROUGHING WAS FROM 31N72W TO 28N76W AT 00Z. THIS TROUGHING IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS. THIS TROUGHING WILL LINGER OVER THE SAME GENERAL AREA THROUGH SAT AND BRING ADDITIONAL RAINFALL TO FLORIDA...CUBA AND THE WESTERN BAHAMAS. THE HIGH WILL HOLD NEARLY STATIONARY THROUGH EARLY SAT BEFORE WEAKENING AND SENDING THE LINGERING RIDGE TO THE NW-N EARLY NEXT WEEK. WITH THIS SCENARIO...EXPECT LIGHT TO MODERATE WINDS AND FAIRLY TRANQUIL SEAS THROUGH THE WEEKEND. AN AREA OF LOW PRES...A POSSIBLE TROPICAL CYCLONE...MAY ENTER THE EASTERN PORTION BY TUE...BUT CONFIDENCE IS VERY LOW ON THE STRENGTH OR TRACK OF THE SYSTEM BY THAT TIME. IT IS EXPECTED TO BE STEERED NORTHWARD BY THE COLD FRONT MOVING OFF THE NE FL COAST ON TUE. WARNINGS... GULF OF MEXICO... .NONE. CARIBBEAN AND TROPICAL N ATLC... .NONE. SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER