000 AGXX40 KNHC 311826 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 230 PM EDT MON AUG 31 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... COLD FRONT EXTENDS FROM MEXICO BEACH...FLORIDA WESTWARD ALONG 28N/29N TO SEADRIFT...TEXAS. A SERIES OF SHORTWAVE SYSTEMS PASSING E THROUGH THE S EDGE OF THE DEEP LAYER TROUGH OVER THE EASTERN CONUS WILL INDUCE WEAK LOW PRES AREAS THAT WILL MAKE THE BOUNDARY WAVY AS IT SLOWLY MOVES SE THROUGH THE WESTERN HALF OF THE GULF. AS IS NORMALLY THE CASE WITH SUCH FINE SCALE FEATURES...THE MODELS SHOW SOME DISAGREEMENT WITH THE POSITIONING OF THE BOUNDARY. THE LAST TWO RUNS OF THE GFS HAVE GRID-SCALE FEEDBACK PROBLEMS OVER THE GULF OF MEXICO EARLY TUE MORNING WHEN IT APPEARS TO OVER-ENHANCE A VORT AND INDUCES A STRONGER SURFACE LOW FARTHER W IN THE NORTHERN GULF THAN THE OTHER MODELS. THEREFORE...STRAYED FROM THE GFS HERE AND LEANED MORE HEAVILY ON THE UKMET AND ECMWF SOLUTIONS. OVERALL...WINDS WILL BE LESS THAN 20 KT IN THE GULF THIS PERIOD DESPITE THE LINGERING FRONT...BUT THE WEATHER PATTERN WILL SUPPORT ACTIVE CONVECTION NEAR THIS BOUNDARY AND SHIFTING INTO THE EASTERN GULF WED/THU. CARIBBEAN AND TROPICAL N ATLC W OF 55W... FRESH TO STRONG TRADE WINDS CONTINUE TO BLOW ACROSS CENTRAL CARIBBEAN PARTICULARLY S OF 15N WITH A STRONG BREEZE ALONG COAST OF COLOMBIA. A TROPICAL WAVE ALONG 77W WILL ENHANCE THESE WINDS WITH WINDS AND SEAS DIMINISHING BY WED AS THE PRES GRADIENT EASES DUE TO THE NW PROGRESSION OF THE LOW PRES SYSTEM NEAR 15N52W 1008 MB AT 1200 UTC. FURTHER DEVELOPMENT OF THIS SYSTEM IS EXPECTED OVER THE NEXT 48 HOURS. DURING THIS TIME...THE SYSTEM MAY BECOME A TROPICAL CYCLONE. THE CURRENT FORECASTS CARRIES THE LOW THROUGH THE N PORTION OF THE TROPICAL N ATLC ZONE TUE MORNING THROUGH FRI MORNING. BOTH THE QUIKSCAT PASS FROM 1000 UTC AND THE ASCAT PASS FROM 1240 UTC CONFIRM WINDS TO 30 KT WITHIN 330 NM N QUADRANT OF THE LOW...BETWEEN THE LOW CENTER AND THE 1028 MB HIGH PRES TO ITS N NEAR 39N41W. INTERESTS ACROSS THE ANTILLES SHOULD MONITOR PROGRESS OF SYSTEM. SW N ATLC S OF 31N AND W OF 65W... AT 1200 UTC...AN ATLC SURFACE TROUGH WAS OVER THE TURKS AND CAICOS FROM 27N71W TO 20N73W. THIS TROUGH IS ASSOCIATED WITH AN UPPER LOW NEAR 22N68W. QUIKSCAT FROM 1000 UTC AND SEVERAL SURFACE OBSERVATION SHOW WINDS TO 20 KT WITHIN 420 NM E OF THE TROUGH S OF 25N. WINDS NEAR THE SURFACE TROUGH ARE EXPECTED TO DIMINISH BELOW 20 KT AS THE SYSTEM MOVES INTO THE LEADING EDGE OF THE BROAD DEEP LAYER TROUGH CURRENTLY OVER THE EASTERN CONUS AND AS THE TROPICAL LOW NEAR 15N52W PROGRESSES NW...YIELDING MEAN TROUGHING OVER THE SW N ATLC AND SHIFTING THE RIDGE TO THE E OF THE FORECAST AREA RESULTING IN A WEAKER PRES GRADIENT NEAR THIS SURFACE TROUGH. A COLD FRONT CURRENTLY LIES JUST NW OF FORECAST WATERS AND IS EXPECTED TO MEANDER OVER NW WATERS UNTIL THU WHEN THE MODELS AGREE ON DEVELOPING A SURFACE LOW PRES SYSTEM ALONG THE FRONT AS IT MEETS UP WITH THE AFOREMENTIONED SURFACE TROUGH. THIS PATTERN WILL HELP DRIVE THE COLD FRONT FARTHER E INTO N CENTRAL WATERS BY LATE FRI. MEANWHILE...THE TROPICAL LOW WELL SE OF THE AREA IS EXPECTED TO MAKE ITS WAY INTO SW N ATLC WATERS BY FRI...PROCEEDING TO NEAR 22N68W BY SAT MORNING. CONFIDENCE IS LOW IN THE INTENSITY FORECAST FOR THIS SYSTEM...BUT THE 1200 UTC GFS...UKMET...AND 00Z ECMWF ARE IN GENERALLY GOOD AGREEMENT ON THE MOTION. AS STATED EARLIER...THIS SYSTEM IS FORECAST TO DEVELOP FURTHER OVER THE NEXT 48 HOURS AND MAY BECOME A TROPICAL CYCLONE DURING THAT PERIOD. WARNINGS ATLC... .NONE CARIBBEAN... .NONE. GULF OF MEXICO... .NONE $$ FORECASTER SCHAUER CLARK