000 AGXX40 KNHC 160658 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT TUE AUG 16 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 STATIONARY BOUNDARY IS HUNG UP OVER THE NE GULF AND IS EXPECTED TO SLOWLY DISSIPATE AS IT LIFTS NORTHWARD THROUGH WED. THE MAIN IMPACT IS A WIND SHIFT FROM SW TO W TO THE S OF THE BOUNDARY TO W TO NW TO THE N OF THE BOUNDARY. THIS WIND SHIFT IS EVIDENT IN THE CURRENT SURFACE OBSERVATIONS. ASIDE FROM DIURNALLY DRIVEN MODERATE TO FRESH NE BREEZE OFF THE W COAST OF THE YUCATAN...WINDS WILL REMAIN AT OR BELOW A MODERATE BREEZE ACROSS THE ENTIRE GULF THROUGH FRI WITH A WEAK NW TO SE ORIENTED RIDGE PREVAILING ACROSS THE GULF OF MEXICO THROUGH TUE WITH HIGH PRES LINGERING IN THE NW GULF INTO FRI. MORE UNCERTAINTY COMES INTO PLAY BY THE WEEKEND WITH THE TRACK AND STRENGTH OF THE TROPICAL WAVE THAT WAS OVER THE LESSER ANTILLES AT 00Z. THE CURRENT FORECAST THINKING LEANS TOWARD THE 00Z GFS WHICH CARRIES AN OPEN WAVE THROUGH THE YUCATAN PENINSULA ON SAT. SEE THE CARIBBEAN SEA SECTION BELOW FOR MORE DETAILS. CARIBBEAN SEA... WINDS HAVE INCREASED TO FRESH AT BUOY 42060 SINCE 00Z AHEAD OF THE TROPICAL WAVE PASSING THROUGH THE LESSER ANTILLES. THE PRES GRADIENT IS BEGINNING TO STRENGTHEN N OF THE WAVE AS THE RIDGE BUILDS OVER THE SW N ATLC IN THE WAKE OF T.S. GERT. THE 0156 UTC ASCAT PASS SHOWS THE DIMINISHED TRADES AREA ALSO STARTING TO EXPAND OVER THE CENTRAL CARIBBEAN AS THE RIDGE BUILDS TO THEN. THE 00Z GFS HAS TRENDED TOWARD A LARGER AREA OF STRONG WINDS WITH THE SYSTEM OVER THE NORTHERN CARIBBEAN. THE 00Z ECMWF AND UKMET AGREE WITH THE GFS ON THE STRENGTH OF THE WINDS...BUT THEY NOW CARRY A DISTINCT LOW PRES SYSTEM INTO THE WESTERN CARIBBEAN BY LATE THU/FRI. CONFIDENCE IS LOW IN THE FORECAST. WILL NOT MAKE ANY SIGNIFICANT CHANGES AT NIGHT. THEREFORE...THE FORECAST WILL FOLLOW THE 00Z GFS WHICH MAINTAINS AN OPEN WAVE MOVING THROUGH THE YUCATAN PENINSULA SAT. TROPICAL N ATLC W OF 55W... FRESH E WINDS BEHIND THE TROPICAL WAVE CURRENTLY PASSING THROUGH THE LESSER ANTILLES SHOULD LINGER OVER THE N HALF OF THE ZONE THROUGH WED AS THE PRES GRADIENT REMAINS STRONG BETWEEN THE WAVE AND THE SUBTROPICAL RIDGE BUILDING WESTWARD TO THE S OF T.S. GERT. THE NEXT TROPICAL WAVE TO MOVE INTO THE AREA WAS ALONG 22W AT 00Z. THE 00Z GFS DEVELOPS THIS SYSTEM INTO A 1002 MB LOW TROPICAL STORM PASSING INTO THE ZONE ALONG 14N LATE SAT. IT IS BY FAR THE STRONGEST OF THE MODELS. THE UKMET CARRIES AN OPEN WAVE TO 60W AT THAT TIME WITH A LARGE AREA OF STRONG WINDS N OF THE LOW. THE 00Z ECMWF IS SIMILAR THE UKMET...BUT A FULL DAY SLOWER BY SAT. WITH CONFIDENCE LOW...WILL NOT MAKE MAJOR CHANGES TO THE PREVIOUS FORECAST EXCEPT TO BUMP THE STRONGEST WINDS FROM FRESH TO STRONG AS THE CURRENT MODEL CONSENSUS SUGGESTS. SOUTHWEST N ATLC... HIGH PRES IS BUILDING WESTWARD ALONG 27N TO THE S OF T.S. GERT AND INCREASING THE PRES GRADIENT BETWEEN THE COLD FRONT OFF THE NE FLORIDA COAST AND THIS RIDGE. FRESH SW WINDS OVER N CENTRAL WATERS ARE EXPECTED TO DIMINISH LATER TODAY AS THE WEAKENING FRONT IS SHOVED NORTHWARD BY THE EXPANDING RIDGE. AN INVERTED TROUGH FROM THE SE BAHAMAS INTO WESTERN CUBA AT 00Z WILL CONTINUE W-NW THROUGH S WATERS TODAY THROUGH WED WITH MODERATE TO FRESH E TO SE WINDS EXPECTED TO EXPAND ACROSS THE AREA E OF THE TROUGH AS THE PRES GRADIENT INCREASES BETWEEN HIGH PRES BUILDING TO THE NE AND LOWER PRES ASSOCIATED WITH THE TROUGH AND A TROPICAL WAVE TO THE SE OF THIS TROUGH. MEANWHILE...THE LONG-WAVE TROUGH ASSOCIATED WITH THE FRONT CURRENTLY OFF THE NE FL COAST WILL RECEIVE A REINFORCING SHOT OF SHORTWAVE ENERGY THU THAT WILL AMPLIFY THE MID TO UPPER-LEVEL TROUGHING. THE MID LEVEL ENERGY ASSOCIATED WITH THE INVERTED TROUGH WILL MOVE NORTHWARD INTO THE LEADING EDGE OF THE LONG-WAVE TROUGH OVER THE SE U.S. COAST THU. WHILE THE LOW LEVEL BOUNDARY ASSOCIATED WITH THE AMPLIFIED LONG-WAVE TROUGH WILL REMAIN N OF THE AREA THU THROUGH SAT...THE IMPACT OVER THE SW N ATLC WILL BE A WEAKENED RIDGE AND GRADUALLY DIMINISHING TRADE WINDS OVER S WATERS LATE THU THROUGH AND SAT. 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