000 AGXX40 KNHC 251808 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 210 PM EDT THU SEP 25 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... SHORT-TERM /THIS AFTERNOON THROUGH FRI NIGHT/...A STEEP PRESSURE GRADIENT BETWEEN SURFACE RIDGING OVER THE SOUTHERN STATES AND LOW PRESSURE OVER CENTRAL AMERICA AND THE CARIBBEAN IS CURRENTLY CAUSING MODERATE TO STRONG NE WINDS ACROSS MUCH OF THE GULF OF MEXICO. SHIP AND BUOY DATA INDICATE THAT THE STRONGEST WINDS OF 20 TO 25 KT ARE GENERALLY CONFINED TO THE CENTRAL AND SW GULF WATERS ALONG WITH WAVE HEIGHTS OF 6 TO 10 FT IN NE SWELL. THERE WERE EVEN A FEW ISOLATED 30 KT WINDS NEAR AND JUST N OF THE LEADING EDGE OF THE HIGHER PRESSURE BUILDING SOUTHWARD...ROUGHLY N OF 23N AS REVEALED BY A 1214 UTC QUIKSCAT PASS. IN FACT...THE WESTERN GULF DATA BUOY 42002 NEAR 25.8N93.7W SAW SEAS CREST AT 10 FT EARLIER THIS MORNING. FARTHER N...WINDS HAVE ALREADY BEGUN TO ABATE N OF ABOUT 27-28N...WITH MOST SHIPS AND BUOYS NOW REPORTING 15 TO 20 KT WINDS WITH SEAS OF 4 TO 6 FT EXCEPT 3 TO 4 FT NEAR SHORE. OVER THE NEXT 24 TO 36 HOURS...GUIDANCE SHOWS THE PRESSURE GRADIENT RELAXING OVER MOST OF THE GULF EXCEPT IN THE SW WHERE 20 TO OCCASIONALLY 25 KT N TO NE WINDS SHOULD CONTINUE S OF 24N W OF 92W THROUGH FRI MORNING AND THEN BE CONFINED TO THE BAY OF CAMPECHE FRI AFTERNOON AND EVENING. WHILE WAVE HEIGHTS OF 6 TO 10 FT IN NE SWELL WILL CONTINUE TO BE THE RULE OVER THE SW WATERS...DECREASING WINDS TO THE N WILL HERALD SUBSIDING SEAS OF 3 TO 5 FT EXCEPT 1 TO 3 FT NEAR THE NORTHERN GULF COAST BY FRI EVENING. LONG-TERM /SAT THROUGH TUE/... THE ONLY AREA OF ENHANCED WINDS OVER GULF WATERS THIS WEEKEND SHOULD BE OVER THE SW AND BAY OF CAMPECHE...AS MODELS STILL SHOW A TIGHT GRADIENT BETWEEN RELATIVE LOW PRESSURE OVER THE CARIBBEAN BASIN AND THE GULF. AT MOST...NORTHERLY WINDS OF 20 KT COULD OCCASIONALLY PREVAIL S OF 22N SAT THROUGH TUE...WITH SEAS OF 4 TO 7 FT SUBSIDING TO 3 TO 5 FT. OTHERWISE...NE TO E WINDS SHOULD PREVAIL OVER THE REMAINDER OF THE GULF EXCEPT OVER THE FAR NE AND N CENTRAL WATERS WERE WINDS SHOULD BLOW W TO NW 10 KT OR LESS THROUGH THE PERIOD. EXPECT WAVE HEIGHTS TO RANGE FROM 2 FT OR LESS OVER THE FAR N TO 2 TO 4 FT OVER ALL OTHER AREAS. CARIBBEAN/TROPICAL N ATLC... SHORT-TERM /THIS AFTERNOON THROUGH FRI NIGHT/ LOWER-THAN-AVERAGE PRESSURE AND A WEAK PRESSURE GRADIENT OVER THE CARIBBEAN BASIN HAS LEFT TRADES NEARLY NON-EXISTENT THE PAST FEW DAYS...AND THIS PATTERN SHOULD CONTINUE AT LEAST THROUGH EARLY FRI. IN FACT...QUIKSCAT AND BUOY DATA SUGGEST THAT WINDS ARE LESS THAN 10 KT EXCEPT IN A NARROW BAND N OF 14N BETWEEN 65W AND 70W WHERE S TO SW 10 TO 15 KT PREVAIL. SEAS ARE 1 TO 2 FT ARE COINCIDENT WITH THE LIGHT WINDS EXCEPT AGAIN IN THE SAME NARROW BAND...WHERE 3 TO POSSIBLY 5 FT SEAS ARE PRESENT. MODEL GUIDANCE IS IN GOOD AGREEMENT...HOWEVER...THAT LOW-LEVEL RIDGING WILL NOSE INTO THE EASTERN WATERS BEGINNING FRI AFTERNOON. STILL THOUGH...THE PRESSURE PATTERN SHOULD NOT BE ENOUGH TO INTRODUCE ANYTHING BUT NEAR OR JUST BELOW TRADES. EXPECT EASTERLY WINDS OF 10 TO 15 KT TO PREVAIL MOST AREAS... EXCEPT IN THE AREA S OF 15N BETWEEN 69W AND 76W WHERE NE TO E WINDS OF UP TO 20 KT ARE POSSIBLE. SEAS SHOULD BUILD OVER THE LATTER AREA TO 4 TO 7 FT BY SAT EXCEPT 5 TO 8 FT CLOSER TO THE COAST OF COLOMBIA. LONGER-TERM /SAT THROUGH TUE/...LITTLE CHANGE IS EXPECTED TO THE ABOVE PATTERN FROM THE WEEKEND INTO EARLY NEXT WEEK EXCEPT POSSIBLY A MINOR INCREASE IN WINDS OVER THE CENTRAL CARIBBEAN SAT AND SUN. OF MORE IMPORTANCE THOUGH WILL BE THE ARRIVAL OF SIGNIFICANT LONG PERIOD NE SWELL OVER THE NORTHERN TROPICAL N ATLC WATERS AND NE ATLC PASSAGES STARTING LATE SAT AND CONTINUING THROUGH TUE. SEAS ARE FORECAST TO BUILD UP TO 6 TO 9 FT OVER THE TROPICAL N ATLC WATERS N OF 17N SUN AND SUBSIDE SOME BEFORE PEAKING AGAIN TUE WITH 6 TO 10 FT. SIMILAR BUT SLIGHTLY LOWER SEAS OF 5 TO 8 FT IN NE SWELL SHOULD BLEED THROUGH THE NE ATLC PASSAGES...FROM THE MONA TO THE ANEGADA PASSAGE. SW ATLC... SHORT-TERM /THIS AFTERNOON THROUGH FRI NIGHT/ TWO HIGH IMPACT FEATURES ARE CURRENTLY IMPACTING MARINE CONDITIONS IN THE SW N ATLC. ONE IS A LARGE STORM CENTER LOCATED OFF THE CAROLINAS WHICH IS SLOWLY APPROACHING THE NC/SC BORDER. THE EXPANSIVE WINDFIELD SURROUNDING STORM EXTENDS INTO THE NW WATERS...WITH A SOLID AREA OF NW TO N 20 TO 25 KT WINDS N OF 27N W OF THE FRONT TO ABOUT 74W. HOWEVER...SINCE THEN...NUMEROUS BUOY OFFSHORE THE FL NE COAST HAVE SHOWN A SHARP REDUCTION OF WINDS WITH MOST INDICATING 15 TO 20 KT NOW. THAT BEING SAID ...SIGNIFICANT LONG PERIOD NE SWELL CONTINUES TO ARRIVE OVER THE ALL AREAS E OF THE BAHAMAS...WITH THE HIGHEST SEAS OF 11 TO 16 FT OBSERVED OVER THE FAR NW. IN FACT...BUOY 41010 NEAR 29N78.5W IS CURRENTLY REPORTING 14-15 FT SEAS. WINDS SHOULD CONTINUE TO GRADUALLY ABATE OVER THE NW TONIGHT INTO FRI...BUT THE NE SWELL WILL CONTINUE TO BE SIGNIFICANT. HOWEVER...THE SWELL SHOULD SLOWLY SUBSIDE TO 7 TO 10 FT BY FRI MORNING AND TO 6 TO 9 FT BY FRI NIGHT. THE SECOND AREA OF CONCERN IS A GALE CENTER NEAR 23N69W MOVING N AT ABOUT 7 KT...WHICH COULD BECOME A TROPICAL CYCLONE AT ANY TIME. REGARDLESS OF WHETHER THIS OCCURS OR NOT...GALE FORCE WINDS AND SEAS OF 12 TO 16 FT WITHIN ABOUT 90 NM OF THE E SEMICIRCLE SHOULD SPREAD NORTHWARD N OF 21N-22N TODAY AND E OF 69W. NUMEROUS TSTMS AND SQUALLS E OF THE CENTER COULD ALSO CAUSE LOCALLY HIGHER WINDS AND SEAS. ELSEWHERE WITHIN 300 NM E SEMICIRCLE OF LOW EXPECTS WINDS OF 20 TO 30 KT AND SEAS OF 9 TO 14 FT. THE LOW IS CENTERED E OF A DEEP-LAYERED TROUGH OVER THE SE U.S. AND SHOULD ACCELERATE NORTHWARD TONIGHT AND FRI...LYING CLOSE TO 28N69W FRI MORNING AND NORTH OF THE AREA ALONG 68-69W BY FRI EVENING. OTHERWISE...ADDITIONAL NE SWELL FROM THE STRONG WINDS WHICH HAVE LASTED FOR SEVERAL DAYS OFF THE U.S. EAST COAST HAS ENGULFED THE REMAINDER OF THE SW N ATLC WATERS AND HAVE EVEN SPREAD SOUTHWARD ALONG THE FLORIDA E COAST. ONLY OVER THE WATERS W OF THE BAHAMAS HAVE BEEN PROTECTED...WITH MOST REPORTS INDICATING NO MORE THAN 1 TO 3 FT SEAS. LONGER-TERM /SAT THROUGH TUE/ AFTER BOTH CYCLONES EXIT THE AREA SAT...A WEAK SURFACE RIDGE SHOULD BEGIN INFLUENCING THE AREA...WITH A MEAN AXIS FROM 27N65W TO WEST PALM BEACH SATURDAY MORNING...FROM 29N65W TO CAPE CANAVERAL SUN MORNING...AND THEN ALONG 28-30N MON AND TUE. S OF THE RIDGE AXIS E TO SE WINDS OF 10 TO 15 KT SHOULD PREVAIL EXCEPT S OF 23N E OF 72W WHERE 15 TO 20 KT ARE INDICATED IN THE MODEL GUIDANCE. SEAS OF 4 TO 7 FT SHOULD BE THE RULE E OF THE BAHAMAS WITH 1 TO 2 FT W OF THE BAHAMAS EXCEPT 2 TO 4 FT W OF THE SE BAHAMAS. N OF THE RIDGE AXIS A SW TO W WIND FLOW OF 10 TO 15 KT SHOULD DECREASE TO 10 KT OR LESS SUN THROUGH TUE. THE REST OF THE NE SWELL SHOULD BE PURGED FROM THE AREA SAT AND SUN ...WITH SEAS RELAXING TO 3 TO 5 FT E OF THE BAHAMAS AND 1 TO 2 FT W OF THE BAHAMAS. WARNINGS... ATLANTIC... .GALE WARNING...AMZ80...FROM 21-29N E OF 69W. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER KIMBERLAIN. TROPICAL PREDICTION CENTER.