000 AGXX40 KNHC 291943 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 245 PM EST SUN NOV 29 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W GULF OF MEXICO... A HIGH PRES RIDGE CENTERED OVER THE NE GULF WILL MOVE OUT OF THE AREA OVERNIGHT AS A COLD FRONT APPROACHES THE TEXAS COAST. SOUTHERLY FLOW TO 20 KT CAN ALREADY BE FOUND IN THE NW GULF AHEAD OF THE COLD FRONT. AS THE COLD FRONT MOVES INTO INTO THE NW GULF MON...A SURFACE WAVE WILL DEVELOP ALONG THE BOUNDARY. THE MODELS STILL DIFFER WITH THE TRACK AND INTENSITY OF THE LOW...BUT ARE COMING INTO BETTER AGREEMENT ON A TRACK THAT MOVES THE SURFACE LOW NE INTO THE MISSISSIPPI AND TENNESSEE VALLEYS WED. THE GFS IS AMONG THE FASTER SOLUTIONS TO CARRY THE LOW AND COLD FRONT EASTWARD INTO THE CENTRAL GULF. THIS APPEARS TO BE DUE TO CONVECTIVE FEEDBACK ASSOCIATED WITH A PIECE OF SHORTWAVE ENERGY MOVING AHEAD OF THE UPPER LOW TUE NIGHT. THE GFS BEGINS TO BE FASTER THAN THE OTHER MODELS AT THIS TIME AND STAMPS OUT NEARLY 5 INCHES OF PRECIPITATION IN 6 HOURS OVER MOBILE BAY. ADJUSTMENTS WERE MADE TOWARD A SLOWER SOLUTION WITH THE COLD FRONT THAN THE GFS AND A WEAKER SURFACE LOW...CLOSER TO THE MODEL CONSENSUS. BOTH THE GFS AND ECMWF SHOW A CENTRAL AND EASTERN GULF GALE EVENT WED WITH 30 TO 40 KT WINDS IN THE SOUTHERLY FLOW AHEAD OF THE FRONT. THE 12O0 UTC GEFS OR THE 0900 UTC SREF ARE BEGINNING TO SHOW MORE SUPPORT FOR THE EVENT WITH A 30 PERCENT CHANCE AND A 15 PERCENT CHANCE OF GALES IN THE GEFS AND SREF...RESPECTIVELY. FOR NOW...CALLING FOR A GALE EVENT TUE AND WED...BUT CONSIDERING THE GFS IS THOUGHT TO BE TOO DEEP WITH THE LOW AND THE ENSEMBLES ARE NOT RESOUNDINGLY SUPPORTING GALES...KEEPING WINDS TO 35 KT. CARIBBEAN AND TROPICAL N ATLC... WINDS ASSOCIATED WITH THE STALLED AND DISSIPATING FRONTAL BOUNDARY CURRENTLY OVER THE NW CARIBBEAN HAVE DROPPED BELOW 20 KT ACCORDING TO THE 1500 UTC ASCAT PASS AND SURFACE OBSERVATIONS. THE FRONT WILL CONTINUE TO BE A FOCUS FOR SHOWERS THE NEXT DAY OR TWO AS IT DISSIPATES. LOOK FOR WINDS TO SHIFT MORE SOUTHERLY IN THE NW CARIBBEAN STARTING MON IN ADVANCE OF THE STRONG COLD FRONT IN THE GULF OF MEXICO. THIS FRONT IS EXPECTED TO PUSH THROUGH THE YUCATAN CHANNEL ON THU AND BRING 20 TO 25 KT NE FLOW BEHIND THROUGH FRI. FARTHER SOUTH...THE PRES GRADIENT N OF THE COLOMBIAN LOW IS RELATIVELY WEAK DUE TO THE WEAK FRONTAL BOUNDARY STRETCHED OVER THE SOUTHERN SW N ATLC ZONE. THE ASCAT PASS FROM 1500 UTC SHOWS WINDS IN THE 20 TO 25 KT RANGE PRIMARILY ALONG THE COAST OF COLOMBIA. EXPECT THE PATTERN TO REMAIN RELATIVELY STAGNANT HERE OVER THE NEXT FEW DAYS. BY MID WEEK...A MORE AMPLIFIED NORTHERN STREAM PATTERN WITH BUILDING HIGH PRES OVER THE CENTRAL N ATLC SHOULD STRENGTHEN THE PRES GRADIENT OVER THE EASTERN CARIBBEAN AND TROPICAL N ATLC...WITH TRADES BUMPING UP IN THESE REGIONS ABOVE 20 KT. MEANWHILE...THE TROPICAL N ATLC IS STARTING TO SEE WAVE HEIGHTS INCREASE ABOVE 8 FT IN THE NW SWELL ASSOCIATED WITH THE COLD FRONT CURRENTLY PASSING N OF THE ZONE. THIS WEAK FRONTAL BOUNDARY WILL APPROACH THE NE CARIBBEAN ISLANDS TOMORROW AND MAY ENHANCE THE CHANCE OF CONVECTION AS IT POOLS LOW LEVEL MOISTURE ALONG THE DISSIPATING BOUNDARY THE NEXT FEW DAYS. SW N ATLC... THE 1458 UTC ASCAT PASS SHOWS LIGHT AND VARIABLE WINDS OVER MUCH OF THE REGION N OF 24N WITH NE FLOW TO 20 KT NEAR THE WINDWARD PASSAGE ASSOCIATED WITH THE LINGERING STATIONARY BOUNFARY. THESE WINDS SHOULD DIMINISH OVERNIGHT AS WELL AS THE NW SWELL IN THE 8 TO 12 FT RANGE OVER THE EASTERN WATERS. THE NEXT COLD FRONT MOVES OFF THE GA COAST OVERNIGHT MON NIGHT. THE GFS IS FASTER AND MORE SOUTHERLY THAN THE OTHER MODELS AS IT MOVES EASTWARD...SO ADJUSTMENTS WERE MADE TO KEEP THE FRONT AND 20 KT WINDS ASSOCIATED WITH THE FRONT N OF 28N. THIS BOUNDARY RETREATS NORTH AS A WARM FRONT OVERNIGHT TUE NIGHT AND SOUTHERLY FLOW INCREASES AHEAD OF THE STRONG COLD FRONT IN THE GULF OF MEXICO. SEE THE GULF OF MEXICO SECTION FOR FORECAST THINKING WHICH FAVORS A WEAKER AND SLOWER SOLUTION THAN THE GFS. THE 1200 UTC GEFS SUPPORTS UP TO A 90 PERCENT CHANCE OF GALES IN THE SW N ATLC ZONE IN THE SOUTHERLY FLOW AHEAD OF THE FRONT AND THE 1200 UTC GFS SHOWS WINDS TO 40 KT WHILE THE WEAKER ECMWF SHOWS MINIMAL GALES. FOR NOW...THE MINIMAL GALE IS FORECAST N OF 26N. WARNINGS... ATLC... AMZ088...GALE CONDITIONS EXPECTED WED AND THU E OF 70W. CARIBBEAN... .NONE. GULF OF MEXICO... GMZ084 AND GMZ086...GALE CONDITIONS EXPECTED N OF 26N LATE TUE INTO WED. $$ FORECASTER SCHAUER