000 AGXX40 KNHC 160746 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 400 AM EDT SAT MAY 16 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. SW N ATLC AND TROPICAL ATLC... A DEEP LAYERED LOW CENTERED NEAR 35N53W IS DISRUPTING THE SUBTROPICAL RIDGE...DIMINISHING TRADE WINDS OVER MUCH OF THE TROPICAL ATLC AND CARIBBEAN. THE MERIDIONAL PRESSURE GRADIENT ON THE NW SIDE OF THE LOW IS GENERATING GALE FORCE WINDS WELL NORTH OF THE FORECAST AREA. CONFIDENCE IS INCREASING THAT WINDS THIS STRONG WILL NOT MOVE INTO THE HIGH SEAS FORECAST AREA AS THE MODELS AGREE ON KEEPING THE TIGHTEST PRES GRADIENT N OF 31N. THE HIGH PRESSURE RIDGE JUST W OF BERMUDA SHOULD REMAIN RELATIVELY STATIONARY BUT WEAKEN THROUGH MON WHEN A COLD FRONT...WHICH THE MODELS AGREE ON CARRYING OFF THE U.S. E COAST SUN...REACHES THE REGION. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE STRENGTH AND TIMING OF THIS FRONT TUE AND WED AS IT INTERACTS WITH THE DEEP LAYER TROUGH CURRENTLY OVER CUBA. CONFIDENCE DECREASES SIGNIFICANTLY IN THE 00Z GFS TUE-WED AS THE GFS IS THE FASTEST MODEL TO DRAW THE DEEP LAYER LOW NORTHWARD TOWARD FL. ITS ALSO APPEARS TO HAVE GRID-SCALE FEEDBACK ISSUES ASSOCIATED WITH A VORTICITY MAX IT MOVES NORTHWARD INTO THE LOW CIRCULATION FROM THE NW CARIBBEAN WED-THU. GULF OF MEXICO... THE MODELS HAVE TRENDED WESTWARD OVER THE LAST SEVERAL RUNS WITH THE DEEP LAYER TROUGH PASSING THROUGH CUBA INTO THE GULF OF MEXICO. MEANWHILE...THE MODELS ARE IN BETTER AGREEMENT ON AMPLIFYING THE TROUGH PASSING THROUGH THE SOUTHEAST AS IT APPROACHES THE CENTRAL GULF OF MEXICO AND ALLOWING A VORTICITY MAXIMUM ASSOCIATED WITH THAT TROUGH TO DROP SOUTH INTO THE GULF. THE 18Z GFS WAS THE MOST AGGRESSIVE MODEL WITH THIS ENERGY DROPPING INTO THE GULF. IN TURN...IT LIFTED THE ENERGY CURRENTLY ASSOCIATED WITH THE DEEP LAYER TROUGH OVER CUBA NORTHWARD AND WAS MUCH DEEPER WITH THE RESULTANT...PINCHED OFF A DEEPER LOW OVER THE SE GULF OF MEXICO ON TUE THAN THE OTHER MODELS. THE 00Z GFS IS NO LONGER AS DEEP...BUT CONTINUES TO BE THE MOST NORTHERLY SOLUTION HERE BY TUE. THE 18Z GFS ALSO HAS GRID-SCALE FEEDBACK ISSUES ON THE EAST COAST OF FL ON TUE THAT CAUSE IT TO DEVELOP A SECOND SURFACE CENTER AWAY FROM THE MAIN SYSTEM IN THE GULF. THE 00Z RUN STILL CARRIES THIS PATTERN...BUT DEVELOPS THE EASTERN FL TROUGHING LATER. THIS FEEDBACK ALSO EXPLAINS THE EASTWARD TREND IN THE GFS LOW TRACK BY WED...COUNTER TO THE LONG TERM TREND. CONFIDENCE BREAKS DOWN IN THE 00Z GFS AS A RESULT. FORECAST FAVORS THE MORE CONSISTENT ECMWF. CARIBBEAN... WITH THE SUBTROPICAL RIDGE WEAKENED BY THE LOW OVER THE CENTRAL N ATLC AND THE TROUGH OVER THE NW CARIBBEAN...THE EXTENT OF THE EASTERLY TRADE WINDS HAVE SHRUNK OVER THE CARIBBEAN. VARIABILITY WITH THE STRENGTH AND POSITION OF THE TROUGH OVER THE NW CARIBBEAN DUE TO THE UNCERTAINTY WITH THE STRENGTH AND TIMING OF THE COLD FRONT IN THE GULF OF MEXICO WILL DICTATE THE PATTERN OVER THE WESTERN CARIBBEAN. THE ECMWF IS FAVORED THERE. ELSEWHERE...LOOK FOR THE TRADE WINDS TO CONTINUE TO DIMINISH THROUGH SUN AS THE HIGH PRES RIDGE TO THE NORTH WEAKENS. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FORECASTER SCHAUER CLARK. TROPICAL PREDICTION CENTER.