000 AGXX40 KNHC 170814 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 415 AM EDT FRI JUL 17 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... BROAD UPPER LEVEL TROUGHING DOMINATES THE ERN TWO-THIRDS OF THE U.S. THIS MORNING...WITH UPPER LEVEL RIDGING ALONG ABOUT 30N LEAVING SUBSIDENCE AND SINKING AIR...AND STABLE MID LEVEL CONDITIONS ACROSS MUCH OF THE SW N ATLC AND MOST OF THE GULF S OF 27N. AT THE SURFACE...THE ATLANTIC RIDGE EXTENDS WWD ACROSS FLORIDA AND WEAKLY WWD THROUGH THE GULF...MAINTAINING LIGHT TO MODERATE FLOW...WITH STRONGEST WINDS OF 10-15 KT ACROSS THE EXTREME SRN AND NW GULF...WHERE SEAS ARE 2-3 FT. LITTLE CHANGE IN THIS PATTERN IS EXPECTED THROUGH SAT...UNTIL A WEAK FRONTAL ZONE DROPS INTO THE N GULF SUN. AMPLE LOW LEVEL MOISTURE LINGERING ACROSS THE NW AND N GULF AHEAD OF THIS BOUNDARY EXPECTED FOR SUN WILL CONTINUE TO PROVIDE SCATTERED SHOWERS AND ISOLATED TO SCATTERED TSTMS AND MAY BECOME MORE ORGANIZED ALONG THE FRONT AS IT SINKS INTO THE AREA SUN. OTHERWISE...WINDS AND SEAS WILL REMAIN MODEST. CARIBBEAN... FRESH TO STRONG TRADE WINDS AFFECTING MOST OF THE CARIBBEAN DURING THE PAST 36-48 HOURS WILL GRADUALLY BEGIN TO ABATE THIS AFTERNOON INTO THE WEEKEND AS THE LOW LEVEL WIND SURGE ACCOMPANYING THE TROPICAL WAVE CURRENTLY ACROSS THE YUCATAN SHIFTS W AND NW AND EXITS THE REGION. RECENT SCATTEROMETER PASSES SUGGEST THAT 20 KT WINDS COVER ALL BUT THE NW AND THE EXTREME SE CARIB...WITH GALES OR NEAR GALES STILL OCCURRING ACROSS THE SW CARIB...WHERE SEAS ARE EXPECTED TO PEAK AGAIN AROUND 15 FT THIS MORNING. 9 FT SEAS CURRENTLY EXTEND AS FAR N AS 15N OR SO...AS BUOY 42058 CONTINUES TO FLUCTUATE JUST UNDER 9 FT THIS MORNING. GALES ARE EXPECTED TO END BY THIS AFTERNOON... AND ALTHOUGH THE TREND WILL BE FOR DECREASING WINDS AND SEAS DURING THE NEXT 48 HOURS...SEAS WILL REMAIN HIGH ACROSS THE SW AND FAR WRN CARIB DUE TO THE LONG FETCH OF E TO NE WINDS . A BROAD ZONE OF SAHARAN AIR AND VERY DRY AND STABLE CONDITIONS DOMINATES MOST OF THE CARIB W OF 70W THIS MORNING...WITH ISOLATED CNVTN FIRING ACROSS THE WATERS OF THE WRN CARIB BEHIND THE TROPICAL WAVE. 20 KT NELY FLOW HAS BEGUN TO SPREAD ACROSS THE FAR ERN CARIB OVERNIGHT AHEAD OF THE NEXT TROPICAL WAVE MOVING INTO THE MID 50'S. SCATTERED PASSING TRADE WIND SHOWERS AND A FEW TSTMS WILL AFFECT THE LESSER ANTILLES AND PUERTO RICO DURING THE NEXT 12 HOURS...WITH DIURNAL FORCING YIELDING MORE SIGNIFICANT RAINS THIS AFTERNOON OVER LARGER ISLANDS. AS WINDS BEGIN TO SUBSIDE ACROSS THE W HALF OF THE BASIN TONIGHT INTO SAT...THIS NEXT WAVE WILL MOVE ACROSS THE LESSER ANTILLES AND ADVECT MOISTURE AND WEATHER NW ACROSS THE ERN CARIB. LOOK FOR SOME SQUALLS AND GUSTY WINDS THIS MORNING AS SHOWERS MOVE INTO THE E AND NE CARIB AND MIX WITH A NARROW ZONE OF SAHARAN AIR AHEAD OF THIS APPROACHING WAVE. ATLC... A SURFACE RIDGE CONTINUES FROM THE NE ATLANTIC SW TO THE NW BAHAMAS AND SRN FLORIDA...AND IS MAINTAINING A BROAD ZONE OF 20 KT WINDS...WITH POCKETS OF 20-25 KT...ACROSS MUCH OF THE TROPICAL ATLANTIC BETWEEN 14N-22N AND INTO THE CARIB...MONA AND WINDWARD PASSAGES. THE SW N ATLC IS ON THE PERIPHERY OF THIS RIDGE AND REMAINS IN MODEST WINDS AND SEAS AT 15 KT AND 5 FT OR LESS. MEANWHILE...8-9 FT SEAS ARE THE GENERAL RULE ACROSS MUCH OF THE TROPICAL ATLANTIC IN THIS LONG FETCH OF ELY TRADES. THE RIDGE IS FORECAST TO SHIFT W-SW DURING THE NEXT SEVERAL DAYS...AND INCREASE THE PRESSURE GRADIENT ACROSS THE NRN PORTIONS OF THE NEXT FEW TROPICAL WAVES MOVING W ACROSS THE ATLANTIC. TROPICAL WAVE CURRENTLY MOVING ACROSS THE BASIN HAVE BROAD CIRCULATIONS AND ARE BRINGING SUFFICIENT MOISTURE TO PRODUCE ZONES OF ACTIVE WEATHER...ESPECIALLY BEHIND THE WAVES IN THE SELY FLOW. THE MID LEVEL STEERING FLOW IS FORECAST TO SHIFT MORE SELY BETWEEN 40W AND 60W DURING THE NEXT FEW DAYS...AND WILL TRANSPORT THE BULK OF WINDS...MAX SEAS...AND ACTIVE WEATHER ACROSS THE EXTREME NE CARIB AND ADJACENT OPEN ATLC...AND NOT DUE WWD INTO THE CARIB AS HAS BEEN THE CASE OF RECENT. WARNINGS ATLC... .NONE. CARIBBEAN... .GALE WARNING IN EFFECT FOR PORTIONS OF AMZ084 AND AMZ086 THROUGH FRI AFTERNOON. GULF OF MEXICO... .NONE. FORECASTER STRIPLING. TROPICAL PREDICTION CENTER.