000 AGXX40 KNHC 180712 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 312 AM EDT SAT APR 18 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE TAIL END OF FRONT IS DRIFTING W ACROSS THE SE/S CENTRAL WATERS WITH ISOLATED SHOWERS LIKELY BEHIND THE BOUNDARY. THIS FRONT IS BEING DRIVEN BY NE TO E FLOW BETWEEN LOW PRES OVER THE W ATLC AND A HIGH OVER THE CAROLINAS. THE QUIKSCAT PASS AROUND 18/0000 UTC INDICATES E TO SE WINDS OF 20 TO 25 KT ACROSS A LARGE PART OF THE GULF. HIGHER GUSTS ARE LIKELY IN TSTM ACTIVITY NEAR THE LOUISIANA AND TEXAS COASTS. BUOYS/SHIPS ARE REPORTING UP TO 9 FT SEAS OVER THE W GULF...DUE TO THE LONG FETCH...WHICH ARE ABOUT ONE FT ABOVE WAVEWATCH GUIDANCE. THE MAIN FORECAST QUESTION IS THE TIMING AND EVOLUTION OF THE BREAK DOWN OF THE SE CONUS RIDGE DUE TO A MID/UPPER-LEVEL LOW OVER THE SOUTHERN ROCKIES BEING EJECTED EASTWARD. THE SPREAD AMONG MODEL GUIDANCE CONTINUES TO NARROW...WITH GENERAL AGREEMENT ON THE MID/UPPER-LEVEL TROUGH BEING POSITIONED OVER THE OHIO VALLEY BY SUNDAY...WITH A RELATIVELY WEAK FRONT ENTERING THE NW GULF EARLY TO MIDDAY SUN. THE FRONT WILL BE INITIALLY FOLLOWED BY NLY 15-20 KT WINDS. HOWEVER...ONCE A VIGOROUS SHORTWAVE TROUGH...CURRENTLY OVER THE NORTHWEST U.S... BECOMING IN PHASE WITH THE AFOREMENTIONED TROUGH NORTHERLY WINDS WILL INCREASE BEGINNING SUN NIGHT OR MON...CLEARING THE REGION BY LATE TUE. NW 20-25 KT WILL AFFECT MUCH OF THE N AND W POTIONS IN THE WAKE OF A SECONDARY SURGE LATE MON AND TUE...THOUGH THERE REMAINS CONCERN FOR STRONGER WINDS IN THE SW GULF...WHERE THE NEARBY TOPOGRAPHY ACTS TO FUNNEL THE COLDER AIR SOUTHWARD. PREVIOUS FORECAST ACCOUNTS FOR THAT SHOWING 30 KT IN THAT REGION AND PLAN ON KEEPING THAT WORDING IN NEXT PACKAGE. SW N ATLC... A COLD FRONT EXTENDS FROM 31N53W TO HISPANIOLA...WITH A REINFORCING BOUNDARY EXTENDING FROM 30N58W TO 28N67W. RECENT SCATTEROMETER DATA INDICATE N-NE 20-25 KT W OF THE BOUNDARIES N OF ABOUT 25N. WAVE HEIGHTS OF 8-13 FT IN NE SWELL IS AFFECTING MUCH OF THE AREA NE OF THE BAHAMAS. SFC HIGH PRES OVER THE CAROLINAS WILL BUILD SE OVER THE REGION TODAY AND SUN ALLOWING WINDS TO RELAX. SLY WINDS INCREASE TO 20-25 KT SUN NIGHT AND THEN EXPAND E MON IN RESPONSE TO AN APPROACHING COLD FRONT IN THE GULF OF MEXICO. THE FRONT IS FORECAST TO MOVE INTO THE NW WATERS TUE. CARIBBEAN AND TROPICAL N ATLC... FRESH TRADE WINDS ARE FORECAST TO CONTINUE ACROSS THE REGION THROUGH EARLY NEXT WEEK...AS A RESULT OF BROAD SURFACE RIDGING N OF THE DISCUSSION AREA. PERIODIC WEAKNESSES IN THIS RIDGING... DUE TO FRONTAL PASSAGES...WILL KEEP THESE TRADES NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES. THE LATEST SCATTEROMETER AND SFC OBSERVATIONS INDICATE NE TO E 20-25 KT NEAR THE COAST OF COLOMBIA AND THE GULF OF HONDURAS AND GENERALLY 15 KT OR LESS ELSEWHERE. A HI-RES QUIKSCAT PASS AROUND 18/0200 UTC REVEALED N-NE 20-25 KT WINDS IN THE WINDWARD PASSAGE. THIS FLOW IS EXPECTED TO CONTINUE FOR ANOTHER DAY BEFORE THE HIGH SHIFTS E CAUSING WINDS TO SHIFT E IN THAT REGION. ALSO...LONG PERIOD NLY SWELL IS FORECAST TO SPREAD THROUGH THE E CARIBBEAN PASSAGES LATER TODAY THROUGH MON. TRADES WILL INCREASE OVER THE E CARIBBEAN AND TROPICAL N ATLC EARLY NEXT WEEK AS HIGH PRESSURE BUILDS OVER THE CENTRAL ATLC...THOUGH THEY WILL DECREASE OVER THE W CARIBBEAN WITH THE APPROACH OF THE GULF OF MEXICO COLD FRONT. ATLC... .NONE.. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FORECASTER CANGIALOSI. TROPICAL PREDICTION CENTER.