000 AGXX40 KNHC 150538 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 140 AM EDT THU MAY 15 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO...BUOY...CMAN...AND SHIP REPORTS REVEAL A STEADY AND SOMETIMES BRISK RETURN FLOW ACROSS MOST OF THE GULF EARLY THIS MORNING...ESPECIALLY OVER THE FAR NW. ALL CONFIRM WHAT MODEL DATA HAVE PREDICTED...A CONSTANT E TO SE WIND OF 15 TO OCCASIONALLY 20 KT. SEAS GENERALLY RANGE FROM 3 TO 7 FT...WITH THE HIGHEST VALUES IN THE NW AND N CENTRAL...WHERE THE SE FLOW IS PILING UP THE WATER IN SE WIND WAVES/SWELL. DOMINANT WAVE PERIODS ARE 7 TO 8 SEC IMMEDIATELY OFFSHORE THE TX COAST TO 5-6 SEC OVER THE SOUTHERN HALF OF THE GULF. SATELLITE AND RADAR IMAGERY ALSO INDICATE CONVECTIVE BLOW-UPS EXTENDING FROM THE SIERRA MADRE ORIENTAL INTO S CENTRAL TX ATTEMPTING TO SPREAD TOWARD THE GULF COAST...THOUGH MUCH OF IT HAS TRANSITIONED TO STRATIFORM PRECIPITATION AS THE CONVECTION HAS WEAKENED EARLY TONIGHT. THUS LITTLE...IF ANY...PRECIPITATION IS PRESENTLY OCCURRING OVER THE GULF. WATER VAPOR IMAGERY INDICATES A ONCE VIGOROUS SHORTWAVE TROUGH OVER THE SW CONUS BEING EJECTED INTO THE SOUTHERN PLAINS THIS MORNING AS STRONG UPSTREAM ANTICYCLONIC FLOW SENDS NEW SHORTWAVE ENERGY INTO THE SW. AS THIS IMPULSE SHEARS EASTWARD TODAY...IT SHOULD DRIVE AN ACTIVE COLD FRONT OVER TX TO THE CENTRAL AND UPPER TX COAST BY 00Z TONIGHT. HOWEVER...IT WILL NOT BE UNTIL A MORE POTENT NORTHERN STREAM SHORTWAVE ROTATES THOUGH THE MIDWEST ON ITS WAY INTO THE EASTERN STATES THU THROUGH FRI THAT THE FRONT MOVES AT A QUICKER PACE INTO THE NORTHERN GULF. BEFORE THE FRONT ARRIVES...EXPECT THE CURRENT...STEADY RETURN FLOW TO GRADUALLY WEAKEN FROM W TO E TODAY...WITH THE HIGHEST SEAS AND STRONGEST LOW-LEVEL FLOW OVER THE CENTRAL AND EASTERN GULF BY THIS AFTERNOON. SEAS SHOULD CONTINUE TO RANGE FROM 3 TO 7 FT...WITH HIGHEST SEAS SHIFTING TO N OF 25N BETWEEN 85W AND 92W BY THIS EVENING. AS THE FRONT MOVES OFF THE TX COAST FROM THU EVENING THROUGH FRI MORNING...THE LOW-LEVEL FLOW AHEAD OF IT SHOULD VEER MORE S TO SW AND WEAKEN...CAUSING SEAS TO SUBSIDE SLIGHTLY. SCATTERED CONVECTION SHOULD AGAIN ERUPT...ESP THIS EVENING THROUGH TONIGHT NEAR AND E OF THE BOUNDARY GENERALLY N OF 25N. BEHIND THE FRONT ...A BRIEF BUT STRONG SURGE OF N TO NE FLOW IS FORECAST FRI ...THOUGH THE FLOW SHOULD DIMINISH CONSIDERABLY FRI NIGHT INTO SAT MORNING. MAX SEAS W OF THE FRONT WILL RANGE FROM 5 TO 8 FT IN OLD SE SWELL AND N WIND WAVES. MODELS SUGGEST THE FRONT SHOULD EXTEND FROM THE FL PANHANDLE TO THE BAY OF CAMPECHE FRI EVENING AND WILL CONTINUE TO MAKE SEWD PROGRESS E OF 90W BUT WILL STALL IN THE WESTERN GULF SAT. COMPARED TO THU AND FRI THOUGH...MUCH LIGHTER WINDS BOTH AHEAD OF AND BEHIND THE FRONT SHOULD LEAD TO CALMER SEAS SAT...WITH SEAS SUBSIDING TO 2 TO 5 FT BY SAT EVENING W OF THE FRONT AND 1 TO 3 FT SE OF THE FRONT. FROM SUN THROUGH MON...MODELS SHOW A DEEP TROUGH SETTING UP SHOP NEAR THE U.S. COAST WITH AN EMBEDDED CLOSED CYCLONE RESTING OVER THE NERN STATES. WITH MOST OF THE UPPER-LEVEL SUPPORT WELL AWAY FROM THE GULF COAST BY THIS TIME...MODELS AGREE WELL ON THE GULF FRONT STALLING OUT FROM CENTRAL FL TO ABOUT 25N88W TO THE BAY OF CAMPECHE WHILE GRADUALLY UNDERGOING FRONTOLYSIS. THANKS TO THE TROUGH IN THE EAST...A DEEP- LAYERED CYCLONIC FLOW SHOULD PREVAIL ACROSS THE NORTHERN GULF...WHICH FAVORS W TO NW FLOW OF 5 TO 10 KT ...WHILE N TO NE WINDS PREVAIL W OF THE FRONT S OF 25N. SEAS SHOULD SUBSIDE FURTHER TO 1 TO 3 FT N OF 25N WHILE STILL 2 TO 4 FT SEAS W OF THE FRONT S OF 25N ALSO SUBSIDE TO 1 TO 3 FT BY MON. E OF THE FRONT...1 TO 3 FT SEAS WILL BE THE RULE...ALSO IN A LIGHT REGIME. SW ATLC...THE DEEP STORM SYSTEM OVER THE WESTERN ATLANTIC EARLY THIS WEEK HAS WEAKENED CONSIDERABLY AND HAS SHIFTED NE TO SOUTH OF THE CANADIAN MARITIME PROVINCES. ITS ASSOCIATED COLD FRONT LIES FROM 31N55 TO EASTERN HISPANIOLA EARLY THIS MORNING AND IS ONLY SLOWLY PRESSING FARTHER SE. EVENING QUIKSCAT DATA AND OTHER OBSERVATIONS INDICATE THE AREAL EXTENT OF NW TO N 20 KT WINDS OVER THE SW ATLC HAS CONTINUED TO DIMINISH DURING THE DAY...AND WHAT REMAINS IS NOW OVER THE FAR NE. WEAK HIGH PRES OFF THE SE CONUS COAST IS GRADUALLY BUILDING SE BEHIND THE FRONT AND SHOULD SHIFT RAPIDLY E FRI...AS THE NEXT FRONT APPROACHES THE REGION. THANKS TO THE LONG DURATION AND WIDE FETCH OF GALE TO STORM CONDITIONS OVER THE WESTERN ATLC EARLIER THIS WEEK...MUCH OF THE SW ATLC CONTINUES TO EXPERIENCE SIGNIFICANT LONG PERIOD N TO NE SWELL. BUOY 41047 NEAR 27.5N71.5W REPORTS SEAS OF 10 FT NOW WITH A DOMINANT WAVE PERIOD OF NEARLY 12 SEC AND BUOY 41046 NEAR 24.3N70.5W ALSO HAS 10 FT SEAS WITH A DOMINANT WAVE PERIOD OF 13 SEC. A CLOSER INSPECTION OF TIME SERIES DATA AT EACH OF THESE BUOYS REVEALS THE FOLLOWING: WHILE SEAS AT BUOY 41047 APPEAR TO HAVE PEAKED...SEAS AT BUOY 41046 ARE STEADY IF NOT RISING SLIGHTLY. CURRENTLY...9 TO 14 FT SEAS IN N TO NE SWELL DOMINANT ALL AREAS N AND E OF THE BAHAMAS...WITH HIGHEST SEAS WELL TO THE NE. THE NE SWELL HAS ALSO PENETRATED THE BAHAMAS...WITH SEAS HAVING RISEN TO 4 TO 6 FT W OF THE BAHAMAS AND 6 TO 9 FT W OF THE NW BAHAMAS AND DIRECTLY OFFSHORE THE CENTRAL AND NE FL COASTS. FROM THU INTO FRI...EXPECT LONG PERIOD N TO NE SWELL TO GRADUALLY UNWIND...WITH SEAS OF 9 TO 11 FT ALL AREAS NE OF THE BAHAMAS BY THIS EVENING AND 7 TO 9 FT BY FRI MORNING. THEREAFTER...A NORTHERN STREAM SHORTWAVE TROUGH MOVING OUT OF THE MIDWEST SHOULD USHER IN THE NEXT COLD FRONT...WITH MODELS SHOWING A STEADY SW FLOW N OF 28N W OF 75W INTENSIFYING FRI WHILE SPREAD FROM W TO E OVER THE NORTHERN WATERS THROUGH SAT. WITH SEAS NOT HAVING FULLY RECOVERED...EXPECT SEAS TO RAPIDLY REBUILD TO 7 TO 11 FT AHEAD OF THE FRONT IN A MIXTURE OF OLD NE SWELL AND NEWLY-FORMED SW WIND WAVES. MEANWHILE...FARTHER S...SEAS SHOULD CONTINUE TO SUBSIDE...RANGING FROM 4 TO 6 FT E OF THE BAHAMAS S OF 27N SAT AFTERNOON AND 1 TO 3 FT W OF THE BAHAMAS. ALTHOUGH THIS NEXT FRONT SHOULD COME IN WITH SOME GUSTO...IT SHOULD LEAVE BEHIND ITS UPPER SUPPORT AND ONLY SLOWLY PUSH FARTHER S AND E FROM SAT INTO SUN...LYING FROM 31N75W TO 29N81W SAT MORNING AND 29N65W TO 28N80W SUN MORNING. AN INITIAL BURST OF W TO NW WINDS W OF THE FRONT EARLY SAT SHOULD QUICKLY WIND DOWN...WITH SEAS ONLY BUILDING TO 4 TO 7 FT. FROM SUN INTO MON...EXPECT A LIGHT WIND REGIME OVER THE SOUTHERN HALF OF THE AREA...WITH SEAS RECOVERING TO 2 TO 5 FT E OF THE BAHAMAS AND 1 TO 2 FT W OF THE BAHAMAS. FARTHER N...THE FRONT SHOULD BECOME ESSENTIALLY STATIONARY AND WEAKEN...WHILE A STRONGER SECONDARY FRONT DESCENDS SE OVER THE SERN STATES MON. A W TO SW FLOW OF 10 TO 15 KT SHOULD PREVAIL OVER THE NORTHERN WATERS N OF 28N...WITH NEAR 20 KT WINDS POSSIBLY NEAR 31N. SEAS SHOULD RANGE FROM 3 TO 6 FT W OF THE BOUNDARY....AND 5 TO 8 FT DIRECTLY AHEAD OF THE BOUNDARY N OF 27N IN W WIND WAVES. CARIBBEAN AND N TROPICAL ATLC...MODERATE TRADES COVER THE CARIBBEAN BASIN EARLY THIS MORNING...WEAKER THAN THEY WERE THE LAST DAY OR TWO. THE ONE EXCEPTION TO THIS CONTINUES TO BE OVER THE GULF OF HONDURAS...WHERE WINDS HAVE INTENSIFIED IN RESPONSE TO AN INTENSIFYING RETURN FLOW OVER THE GULF OF MEXICO. ALTHOUGH THERE HAS BEEN NO RECENT SCATTEROMETER DATA...E TO SE WINDS OF 20 TO 25 KT ARE ESTIMATED OVER THIS AREA...WITH SEAS POSSIBLY TO 8 FT. OTHERWISE...AS MENTIONED...THE AREAL EXTENT OF 20 KT WINDS OVER THE SOUTHERN CARIBBEAN IS AT ITS LOWEST IN AT LEAST THE LAST WEEK OR TWO. ASCAT AND QUIKSCAT DATA SHOW A LIMITED AREA OF 20 KT WINDS CLOSE TO THE COAST OF COLOMBIA ...WITH 10 TO 15 KT WINDS ELSEWHERE N OF 15N. WITH SUBTROPICAL RIDGING NOW WELL E OF THE AREA AND LOW PRES DOMINATING MUCH OF THE CENTRAL SUBTROPICAL ATLC...THE CURRENT LIGHT WIND REGIME ACROSS THE CARIBBEAN SHOULD COME AS NO SURPRISE. HOWEVER...HIGH PRES NOW BUILDING SE OVER THE SW ATLC BEHIND A COLD FRONT IS LIKELY LEADING TO NE WINDS OF 15 TO 20 KT OVER THE WINDWARD PASSAGE. THESE WINDS SHOULD FURTHER INCREASE THIS MORNING AND REACH 20 TO PERHAPS 25 KT BEFORE DIMINISHING LATE TODAY AND FRI. IN ADDITION...LONG PERIOD N TO NE SWELL PROPAGATING AWAY FROM THE W ATLC IS NOW ARRIVING OVER THE NORTHERN CARIBBEAN AND BLEEDING THROUGH THE ATLC PASSAGES. FOR EXAMPLE...SEAS OF 6 TO 8 FT ARE NOTED IN THE MONA PASSAGE AND SIMILAR SEAS ARE LIKELY SURROUNDING PUERTO RICO AND THE U.S./BRITISH VIRGIN ISLANDS. BUOY 41043 N OF PUERTO RICO IS CURRENTLY REPORTING 8 FT SEAS WITH A DOMINANT WAVE PERIOD OF 12 SEC. SWELL SHOULD PEAK TODAY AND SLOWLY SUBSIDE GOING INTO THE WEEKEND. FROM SAT THROUGH MON...SUBTROPICAL RIDGING SHOULD GRADUALLY REASSERT ITSELF OVER THE EASTERN AND CENTRAL CARIBBEAN...WHICH SHOULD LEAD TO 20 TO 25 KT WINDS REAPPEARING S OF 15N BETWEEN 70W AND 78W BY LATE SUN OR MON. INDICATIONS ARE THAT...WITH ENHANCED SUBTROPICAL RIDGING BY LATE MON THAT TRADES WILL LIKELY BE CHARACTERIZED AS ABOVE CLIMATOLOGICAL NORMS E OF 75W BY MON/TUE. EXPECT CURRENT SEAS OF 3 TO 5 FT EXCEPT 4 TO 7 FT NEAR THE COAST OF COLOMBIA TO BUILD TO 4 TO 7 FT EXCEPT 6 TO 9 FT OF THE COAST OF COLOMBIA BY LATE MON. WARNINGS... ATLC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. .FORECASTER KIMBERLAIN. TROPICAL PREDICTION CENTER.