000 AGXX40 KNHC 120714 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 330 AM EDT SUN OCT 12 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS... DEEP LAYER CUT-OFF CYCLONE HAS NOW MOVED OVER STRAITS OF FLORIDA HELPING DIG SURFACE TROUGH ACROSS FLORIDA PENINSULA INTO NW CUBA. LARGE MID-UPPER LEVEL ANTICYCLONE OVER ERN MEXICO EXTENDS RIDGE OVER ENTIRE GULF OF MEXICO BRINGING IN DRY STABLE AIR MASS UNDER ITS SUBSIDENCE UMBRELLA. NARROW RIDGE COVERS ERN HALF OF SW N ATLC ANCHORED IN ANTICYCLONE JUST N OF HISPANIOLA. FINALLY ...UPPER LEVEL TROUGH EXTENDS N FROM CYCLONE JUST OVER MONA PASSAGE NE TO 22N65W AND BEYOND. CONFLUENT FLOW TRAPPED BETWEEN NARROW RIDGE AND THE LATTER TROUGH MAINTAIN DRY AIR MASS IN EXTREME SE CORNER OF BASIN. SURFACE... SURFACE TROUGH OVER FLORIDA PENINSULA SEPARATES TROPICAL MOIST AIR MASS ON EAST SIDE AND DRY STABLE AIR ON W SIDE. WEATHER ASSOCIATED WITH TROUGH REMAINS OVER SE FLORIDA AND ERN CUBA AND PARTLY OVER NW CARIBBEAN BUT CONVECTION IS DIMINISHING IN COVERAGE AND INTENSITY. TROUGH EXPECTED TO DISSIPATE AS BROAD HIGH PRES CENTER OVER NE CONUS DRIFTS S WITHIN NEXT 24-26 HRS. AS RIDGE STRENGTHENS AND EXTENDS INTO SW N ATLC...STRONG E-NE WINDS SPREAD THROUGHOUT MOST OF BASIN WITH SEAS BUILDING TO 8-9 FT. NWW3 SOLUTION OF 10-11 FT MIGHT BE OVERDOING IN COVERAGE OF 20-25 KT WINDS AS WELL AS HEIGHT...SINCE IT HAS MUCH LARGER FETCH DISTANCE. WEAKER THAN CLIMATOLOGICAL MEAN CARIBBEAN E WINDS APPEAR SUSPICIOUS AS LARGE AREA OF LOWER THAN NORMAL COVER ERN HALF OF BASIN. GFS SOLUTION SHOW DEVELOPMENT OF LOW PRES SYSTEM WHICH ...IF ACCURATE MOVE NW TOWARDS HISPANIOLA THEN SHIFT NE FORCED BY DEEP TROUGH NEAR MONA PASSAGE. WIND AND SEA HEIGHTS FORECAST IS VERY UNCERTAIN AS INTENSITY OF LOW PRES SYSTEM...IF IT EVER FORMS...REMAINS QUESTIONABLE. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER WALLY BARNES. TROPICAL PREDICTION CENTER.