000 AGXX40 KNHC 200856 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE MIAMI FL 456 AM EDT MON JUL 20 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE BROAD UPPER LEVEL TROUGH ACROSS THE CENTRAL AND ERN U.S. HAS SHARPENED DURING THE PAST 24 HOURS...WITH WIDESPREAD CONVECTION ALONG AND AHEAD OF A COLD FRONT ALONG THE GULF COAST DIMINISHING ALMOST ENTIRELY FROM THE LATE AFTERNOON AND EVENING HOURS. S/W ENERGY THAT IGNITED THIS CNVTN YESTERDAY IS LIFTING OUT TO THE NE ON E SIDE OF TROUGH...AND HAS SWEPT AWAY WITH IT A GOOD PORTION OF THE DEEP MOISTURE INTO THE NE GULF AND ACROSS FLORIDA...GEORGIA AND OFF THE ERN SEABOARD. THIS HAS ALSO NUDGED THIS WEAK FRONTAL BOUNDARY SE INTO THE NE AND N CENTRAL GULF...EXTENDING ACROSS THE FLORIDA PANHANDLE AND INTO SE GEORGIA. HOWEVER...SUFFICIENT MOISTURE REMAINS ACROSS THE NRN GULF AHEAD OF THIS DYING BOUNDARY...AND ANOTHER S/W IS FORECAST TO DIVE INTO THE BACKSIDE OF THE TROUGH TODAY...AND SHOULD YIELD ANOTHER ACTIVE AFTERNOON FROM THE UPPER TEXAS COAST...ALONG THE BOUNDARY E AND SEWD TO THE W COAST OF FLORIDA. ADDITIONAL WEAK DISTURBANCES ARE FORECAST TO MOVE THROUGH THE W SIDE OF THIS UPPER TROUGH FOR THE NEXT FEW DAYS...AND KEEP THUNDERSTORMS ACTIVE OVER THE NORTHERN GULF. THE FRONT IS EXPECTED TO STALL ACROSS THE NE GULF AND DISSIPATE THIS EVENING INTO TUE. A 1018 MB SURFACE HIGH PRES AREA WAS CENTERED JUST SOUTH OF THE FRONTAL BOUNDARY NEAR 26N87W. THIS WEAK HIGH IS MAINTAINING GENERALLY LIGHT TO MODERATE WINDS ACROSS THE GULF...AND LITTLE CHANGE IS EXPECTED THROUGH THE UPCOMING WEEK. THE EXCEPTION TO ALL THIS WILL REMAIN ACROSS THE SE BAY OF CAMPECHE AND WRN YUCATAN COAST...WHERE LATE AFTERNOON AND EVENING NLY WINDS WILL INCREASE EACH DAY TO 15-20 KT...AND ALSO ALONG THE TEXAS AND UPPER MEXICAN COAST...WHERE 15 KT SELY FLOW WILL PREVAIL. CARIBBEAN... WINDS AND SEAS HAVE CONTINUED TO SUBSIDE IN THE WRN CARIBBEAN... WHERE EVENING SCATTEROMETER PASSES SHOWED WINDS OFF THE COLOMBIA COAST DOWN TO AROUND 20 KT...POSSIBLY GUSTING TO 25 KT...AND SEAS TO 8 FT. A LONG NELY FETCH ACROSS THE W HALF OF THE BASIN CONTINUES TO GENERATE MAXIMUM SEAS FARTHER W...AND INTO THE FAR SW CARIB...WHERE THEY ARE ESTIMATED AT 9-10 FT. THE E HALF OF THE BASIN HAS BECOME THE MOST ACTIVE PORTION WIND AND WEATHER WISE IN THE PAST 24-36 HOURS AS A TROPICAL WAVE HAS MARCHED ACROSS THE ERN CARIB AND ADJACENT ATLC...AND WAS ALONG 75W...AND HAD WEAKENED CONSIDERABLY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH THIS WAVE WERE AFFECTING CUBA AND THE SURROUNDING WATERS. A LOW LEVEL WIND SURGE ASSOCIATED WITH A TROPICAL WAVE APPROACHING THE LESSER ANTILLES HAS RACED OUT AHEAD OF THAT WAVE...AND MOVED ACROSS THE NE CARIBBEAN THIS EVENING AND EARLY TONIGHT TO PRODUCE SQUALLS AND THUNDERSTORMS PRODUCING WIDESPREAD WIND GUSTS IN EXCESS OF 30 KT...WITH A GUST OVER 40 KT OBSERVED IN ST THOMAS. THIS WIND SURGE INCREASED WINDS AND SEAS ACROSS THE EXTREME NE CARIB TO 20-25 KT AND SEAS TO 6 TO 7 FT...AND WAS MOVING INTO THE CENTRAL CARIB S OF HISPANIOLA...WHILE THE SURGE CONTINUES TO RACE NW TOWARD THE SE BAHAMAS AND ATLC TO THE E. WINDS AND SEAS HAVE SINCE RELAXED A BIT ACROSS THE E CARIB TO NEAR 20 KT. THE PRESSURE GRADIENT BETWEEN THE ATLC RIDGE AND BROAD LOW PRES ACROSS S AMERICA WILL MAINTAIN FRESH WINDS ACROSS THE E AND CENTRAL CARIB FOR THE NEXT FEW DAYS...WITH THE NEXT PASSING TROPICAL WAVE TO ENHANCING THIS FLOW. HIGHEST WINDS AND SEAS DURING THE NEXT SEVERAL DAYS WILL OCCUR IN THE ATLC JUST OUTSIDE OF THE NE CARIB...BUT WITH WINDS IN THE PASSAGES THERE TO SEE SIMILAR CONDITIONS AS THE OPEN SW N ATLC. THE NEXT TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE LESSER ANTILLES THIS MORNING...REACH 65W THIS EVENING...AND 72/73W BY TUESDAY EVENING. E TO E-SE WINDS ACROSS THE N PORTION OF THIS WAVE WILL INCREASE AGAIN TODAY ACROSS THE NE CARIB TO 20-25 KT...WITH SEAS BUILDING 6 TO 8 FT BY LATE AFTERNOON...AND WILL SPREAD INTO THE S OR CARIBBEAN COASTS OF THE LOCAL ISLANDS LATE THIS AFTERNOON AND TONIGHT. SCATTERED SQUALLS AND TSTMS WILL BE CAPABLE OF PRODUCING WIND GUSTS TO 40 KT AND HIGHER. ATLANTIC S OF 31N W OF 55W... A SURFACE RIDGE EXTENDING FROM THE CENTRAL ATLC TO THE NORTHERN BAHAMAS. AN UPPER LOW LOCATED JUST NE OF THE NW BAHAMAS WITH TROUGH EXTENDING SW TO WRN CUBA IS PRODUCING AN UNSTABLE ATMOSPHERE. A MODEST INCREASE IN WINDS AND MOISTURE ASSOCIATED WITH THE WEAKENED TROPICAL WAVE ACROSS THE CENTRAL CARIBBEAN IS INTERACTING WITH THIS UPPER LOW TO PRODUCE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS FROM CENTRAL CUBA N AND NE INTO THE SW N ATLC...AND WILL BE REINFORCED BY THE WIND SURGE RACING NW ACROSS HISPANIOLA AND TOWARDS THE BAHAMAS. THIS WILL NOT ONLY BRING ABOUT INCREASING WINDS AND SEAS TO THIS AREA...BUT ALSO MAINTAIN VERY ACTIVE AND WIDESPREAD WEATHER...WITH THE POTENTIAL FOR VERY STRONG TSTMS WITH STRONG GUSTY WINDS AND FREQUENT LIGHTNING. SELY WINDS OF 20-25 KT ARE EXPECTED TO SHIFT FROM N OF HISPANIOLA...NW INTO THE SE BAHAMAS AND ATLC WATERS S OF 25N DURING THE DAY...AND INTO THE CENTRAL BAHAMAS ON TUESDAY. THIS WILL SET UP A LONG AND NEARLY STATIONARY FETCH OF E TO SE WINDS DURING THE NEXT FEW DAYS TO GENERATE HIGH SEAS ACROSS THIS AREA THAT WILL PROPAGATE S OF AND THROUGH THE BAHAMAS. 8 FT SEAS HAVE ALREADY SPREAD INTO THE TURKS AND CAICOS AND SE BAHAMAS. CURRENT WWIII GUIDANCE IS FORECASTING SEAS ACROSS THAT AREA TO REACH 9-10 FT BY TUESDAY EVENING...WITH 6 FT SEAS THEN REACHING ALL THE WAY TO GREAT ABACO ISLAND. LOOK FOR ACTIVE WEATHER TO DOMINATE THE BAHAMAS REGION AND GRADUALLY SPREAD N AND NW TO 30N AND BEYOND THROUGHOUT THE WEEK...GENERALLY REMAINING A DEGREE OR TWO JUST OFF THE FLORIDA COAST. WARNINGS ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. $$ FORECASTER STRIPLING