000 AGXX40 KNHC 290600 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 200 AM EDT TUE JUL 29 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. ...SW N ATLC... TODAY THROUGH WED NIGHT...MID/UPPER LVL TROF ALONG THE U.S. EAST COAST CONTINUES TO PRODUCE A WEAKNESS IN THE SUBTRPCL RIDGE OVER THE W ATLC. RESULTING SFC RIDGE IS FAIRLY BROAD WITH THE AXIS SUPPRESSED S FROM 28N65W TO STRAITS OF FLORIDA. S/SW WINDS 10-15 KT ARE OCCURRING OVER THE NW WATERS DUE TO FRONTAL BNDRY OFF NORTH CAROLINA. MID/UPPER TROF MOVES E AND FLATTENS OUT THROUGH WED AND ALLOWS THE SFC RIDGE TO SHARPEN WITH MORE PRONOUNCED WLYS N OF THE AXIS AND ELYS ACROSS THE SRN BAHAMAS. WINDS REMAIN LIGHT EXCEPT 10-15 KT OVER NW WATERS AND NEAR GREATER ANTILLES. THU THROUGH SAT...SFC RIDGE REMAINS SUPPRESSED S FROM 26N65W TO THE STRAITS OF FLORIDA THU AS A COLD FRONT MOVES ACROSS THE SE UNITED STATES. PRES GRADIENT INCREASES OVER THE NW WATERS AS THE FRONT APPROACHES AND THEREFORE EXPECT SW WINDS TO INCREASE TO 15-20 KT ON THU. WIND FIELD WILL SPREAD E THROUGH FRI AND THERE ARE HINTS...ACCORDING TO THE GEFS ENSEMBLE MEAN...THAT WINDS COULD INCREASE TO 25 KT NEAR 31N BY FRI. WILL HOLD OFF FOR NOW SINCE NOT EVEN THE OPERATIONAL 00Z GFS SHOWS THIS AT THE MOMENT. SW 15-20 KT SPREADS OVER THE NE WATERS ON SAT THEN DIMINISHES LATER THAT EVENING. ELSEWHERE...A TRPCL WAVE MOVES INTO THE SE WATERS ON THU AND IS EXPECTED TO INCREASE WINDS TO 15-20 KT BEHIND THE AXIS ALTHOUGH LATEST TRENDS HAVE BEEN SHOWING WINDS NOT AS STRONG. ...CARIBBEAN... TODAY THROUGH WED NIGHT...SOUFRIERE HILLS ON MONTSERRAT ERUPTED TONIGHT AROUND 0340Z AND HAS EMITTED AN ASH PLUME THAT IS EXPANDING TO THE NW NEAR ST. KITTS AND NEVIS...AND SE TOWARDS GUADELOUPE. WILL ISSUE ASHFALL ADVISORY BASED ON 0432Z ADVISORY AND FORECAST FROM SAB IN WASHINGTON DC AND WILL MONITOR TRENDS DURING THE MORNING HRS. VISIBILITIES MAY BE LOWERED LESS THAN 1 NM IN AREAS OF HEAVIEST ASHFALL AND/OR EMISSIONS. ELSEWHERE...EVENING QSCAT PASS CONFIRMED E WINDS 20-25 KT OVER THE S/CNTRL CARIBBEAN. LITTLE CHANGE IN THIS AREA IS EXPECTED THROUGH WED NIGHT AS THE ATLC RIDGE HOLDS FIRM. TRPCL WAVE NEAR 44W WILL APPROACH THE TRPCL N ATLC WATERS TODAY WITH NE WINDS INCREASING TO 15-20 KT NE OF THE ISLANDS BY THIS EVENING. SWATH OF NE/E 15-20 KT WINDS SPREADS W TOWARDS PUERTO RICO THROUGH WED NIGHT WITH HIGHEST WINDS STAYING N OF 16N. THU THROUGH SAT...TRPCL WAVE MOVES INTO THE E CARIBBEAN EARLY THU AND WINDS OVER THE S/CNTRL CARIBBEAN BEGIN TO DIMINISH AS THE GRADIENT RELAXES. WINDS WILL BARELY REACH 20 KT NEAREST THE COASTS OF COLOMBIA AND VENEZUELA FRI AND SAT...ESPECIALLY ONCE THE WAVE PASSES. ...GULF OF MEXICO... TODAY THROUGH WED NIGHT...SFC RIDGE EXTENDS FROM THE STRAITS OF FLORIDA TO THE NW GULF IS KEEPING LIGHT WINDS ACROSS THE AREA. WEAK SFC LOW NEAR THE LOUISIANA COAST EARLIER HAS OPENED UP INTO A TROF FROM SE LOUISIANA TO 27N89W AND WILL CONTINUE TO WEAKEN THROUGH THE DAY. DIURNAL EFFECTS WILL PLAY KEY ROLE IN STRENGTH OF WINDS WITH MODEL GUIDANCE NOTING AN INCREASE DURING THE OVERNIGHT PERIODS. GFS SHOWS E/SE WINDS INCREASING TO 15-20 KT TONIGHT...DIMINISHING ON WED...THEN INCREASING AGAIN WED NIGHT OVER THE SW GULF AND OFF THE COAST OF TEXAS. THU THROUGH SAT...SFC RIDGE REMAINS FROM THE STRAITS OF FLORIDA TO THE NW GULF IN THE EXTENDED EXCEPT THAT AN AREA OF HIGH PRES DEVELOPS ALONG THE AXIS OVER THE SE GULF AND MIGRATES TOWARDS THE CNTRL GULF BY SAT. CAN PROBABLY STILL EXPECT NOCTURNAL WINDS TO INCREASE TO 20 KT MAINLY OVER THE SW GULF EACH NIGHT. WARNINGS... ATLANTIC... NONE. CARIBBEAN... ASHFALL ADVISORY FROM 16N TO 18N BETWEEN 61W AND 64W...AMZ086 AND AMZ087. GULF OF MEXICO... NONE. .FORECASTER BERG. TROPICAL PREDICTION CENTER.