000 AGXX40 KNHC 120547 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 150 AM EDT MON MAY 12 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO...A VIGOROUS CLOSED LOW PUSHING THROUGH THE MID-ATLANTIC HAS DRIVEN A COLD FRONT INTO THE NORTHERN HALF OF THE GULF EARLY THIS MORNING. LATEST SFC ANALYSIS SHOWS THE FRONT EXTENDING FROM 29N83W TO 26N88W TO AROUND 25N97W. WITH 00Z UPPER-AIR DATA ALREADY SHOWING MODEST HEIGHT RISES OVER THE SOUTH CENTRAL STATES...IT APPEARS THAT THE WESTERN END OF THE FRONT HAS SLOWED AND SHOULD COME TO A HALT THIS MORNING...BEFORE ATTEMPTING TO LIFT NORTHWARD AS A WARM FRONT LATE TODAY. A LATE EVENING QUIKSCAT PASS CONFIRMS WHAT BUOYS...CMANS...AND COASTAL OBSERVATIONS ARE INDICATING...AN AREA OF 20 KT W TO NW FLOW IMMEDIATELY BEHIND THE FRONT OVER THE NE GULF WATERS N OF 28N AND E OF THE MOUTH OF THE MS RIVER AND SEAS OF 3 FT OVER THE CENTRAL GULF TO NEAR 7 FT OVER THE EXTREME NE GULF. ELSEWHERE N OF THE FRONT...WINDS HAVE ALREADY VEERED N TO NE OVER THE NW AT 10 TO 15 KT AND SEAS OF 3 TO 5 FT. OTHERWISE...SEVERAL DATA PLATFORMS SUGGEST THAT LIGHT WINDS COVER THE REMAINDER OF THE GULF S OF THE FRONT...EXCEPT FOR A SMALL AREA IMMEDIATELY AHEAD OF THE FRONT OVER THE EASTERN GULF...WHERE SW WINDS OF 20 KT ARE NOTED. OVER THE NEXT FEW DAYS...THE CLOSED CYCLONE IN THE E SHOULD DEEPEN OVER THE WESTERN ATLANTIC...WHILE HEIGHTS FURTHER RISE OVER THE GULF IN RESPONSE TO SHORTWAVE RIDGING REBUILDING IN THE WAKE OF THE W ATLC TROUGH. WITH THE MAIN DYNAMICS MOVING AWAY FROM THE AREA...W TO NW WINDS OF 20 KT OVER THE NE GULF NOW SHOULD DIMINISH THIS AFTERNOON...AS THE FRONT ESSENTIALLY STALLED NEAR A FT MYERS-BROWNSVILLE LINE. THE SHORT DURATION OF 20 KT WINDS SHOULD ALLOW SEAS TO BEGIN SUBSIDING...WITH SEAS OF 1 TO 3 FT EXPECTED E OF 90W BY TUE. LATER THIS WEEK...ANOTHER VIGOROUS SHORTWAVE NOW DIGGING INTO THE FAR NW CONUS SHOULD SPLIT...WITH THE SOUTHERN STREAM PORTION DIGGING DEEP INTO THE SW TUE-WED. EVEN THOUGH THE 00Z GFS APPEARS WEAKER AND IS QUICKER TO BRING THIS SYSTEM ONTO THE SOUTHERN PLAINS BY MID-WEEK COMPARED TO THE 18Z NCEP ENS MEAN AND 12Z ECMWF...THE EFFECT OVER GULF WATERS IS EXPECTED TO BE MINIMAL. ALL MODELS SHOW LOW PRESSURE REFORMING OVER THE SOUTHERN PLAINS...WHICH SHOULD REACTIVATE A RETURN FLOW W OF 90W STARTING LATE TUE AND THEN OVER ALL WATERS BY WED AFTERNOON. SINCE THE GFS MAY BE TO QUICK TO BRING LOW PRESSURE E...THERE IS A CHANCE THAT SOME OF THE RETURN FLOW COULD BE TOO STRONG. NONETHELESS...A STEADY 20 TO OCCASIONALLY 25 KT SE TO S FLOW SHOULD CAUSE SEAS TO BUILD TO 5 TO 8 FT BY THU OVER THE CENTRAL AND WESTERN GULF IN SE WIND WAVES...WHILE 3 TO 5 FT SEAS DOMINATE THE EASTERN WATERS. MODEL GUIDANCE SHOWS THIS FIRST PIECE OF SHORTWAVE ENERGY SHEARING E THU...WHILE THE BULK OF THE TROUGH REMAINS W OF THE SOUTHERN PLAINS. HOWEVER...THE SHORTWAVE SHOULD BEGIN SLIDING E FRI IN RESPONSE TO A NORTHERN STREAM SYSTEM PUSHING THROUGH THE GREAT LAKES. AS THIS OCCURS...A FAIRLY HEALTHY COLD FRONT IS EXPECTED TO PUSH OFF THE TX COAST FRI MORNING TO AFTERNOON...WITH A BRISK NW TO N FLOW OF 20 TO 30 KT BEHIND. WHILE SEAS CALM DOWN OVER THE EASTERN GULF FRI...BEHIND THE FRONT SEAS SHOULD BUILD TO 5 TO 8 FT BY SAT MORNING. SW N ATLC...THE SAME COLD FRONT MENTIONED ABOVE IS BEGINNING TO ENTER THE FAR NW WATERS. THE GRADIENT BETWEEN HIGH PRESSURE NE OF THE ANTILLES AND DEEP LOW PRESSURE OVER THE MID-ATLANTIC IS PRODUCING S TO SW 20 TO 30 KT WINDS OVER A BROAD AREA GENERALLY N OF 27N W OF 70W AS OF 03Z. AN EVENING QUIKSCAT PASS DID SHOW 30 KT WIND VECTORS RIGHT ALONG THE NORTHERN BORDER...BUT SHORT- TERM GUIDANCES KEEP GALE FORCE CONDITIONS N OF THE AREA THROUGH TODAY. SEAS AREA ALREADY BUILDING N OF 27N AND E OF THE FRONT ...WITH 6 TO 9 FT SEAS IN DEVELOPING NW SWELL W OF IT. SATELLITE AND RADAR IMAGERY OUT OF JAX ALSO SHOW A WELL-DEFINED SQUALL LINE NEAR AND ALONG THE FRONT...WITH THE SOUTHERN END OF THE CONVECTIVE LINE ROLLING IN JUST N OF THE FAR NW WATERS. ELSEWHERE OVER THE AREA...SEAS OF 3 TO 5 FT ARE COMMON E OF THE BAHAMAS IN A 10 TO 15 KT S TO SW FLOW...WHILE 1 TO 3 FT SEAS ARE PRESENT W OF THE BAHAMAS IN A LIGHTER SW FLOW. SHORT-TERM MODEL GUIDANCE SHOWS THE DEEP CUT-OFF LOW OVER THE MID-ATLANTIC STATES MOVING SLOWLY E AND DEEPENING OVER THE WESTERN ATLANTIC EARLY THIS WEEK. IN RESPONSE...A DEEP-LAYERED CYCLONIC FLOW SHOULD DOMINATE THE REGION THROUGH AT LEAST MID-WEEK BEFORE DIMINISHING LATER WED AND THU. A STRONG SW FLOW OF 20 TO 30 KT SHOULD CONTINUE TO PREVAIL E OF THE FRONT AS IT MOVES ACROSS THE NORTHERN HALF OF THE AREA TODAY...WHILE A SIMILAR W TO NW FLOW W OF THE FRONT CHURNS SEAS. NOAA WAVEWATCH III GUIDANCE INDICATES SEAS BUILDING FROM 9 TO 13 FT BY THIS AFTERNOON E OF FRONT IN SW WIND WAVES...WHILE 9 TO 15 FT SEAS BUILD W OF THE FRONT...HIGHEST WELL NE. AS DEEP LOW PRESSURE MOVES AWAY FROM THE COAST TUE...PEAK SEAS ARE EXPECTED OVER THE NE PART OF THE AREA TUE AFTERNOON AND EVENING...WITH 14 TO 18 FT SEAS LIKELY N OF 28N E OF 70W IN NW SWELL. FARTHER W...SEAS SHOULD BEGIN TO SUBSIDE BUT STILL REMAIN 6 TO 12 FT IN NW SWELL...HIGHEST N AND E. BY WED...WEAK HIGH PRESSURE SHOULD TAKE OVER...CAUSING WINDS TO RELAX CONSIDERABLY. IN FACT...GENERALLY NO MORE THAN 15 KT OF WIND SHOULD BE PRESENT OVER THE AREA BY WED EVENING EXCEPT PERHAPS OVER THE FAR NW. NEVERTHELESS...SEAS OF 8 TO 15 FT IN NW SWELL WILL PREVAIL N OF 23N N AND E OF THE BAHAMAS...WITH THE HIGHEST AGAIN TO THE NE. AS MENTIONED IN THE SECTION ABOVE...SHORTWAVE ENERGY COMING OUT OF THE SOUTHERN PLAINS IN THE GFS THU APPEARS TOO PROGRESSIVE COMPARED TO THE OTHER GUIDANCE AND LEADS TO ENHANCED SW FLOW N OF 28N W OF 73W BY FRI MORNING. ALTHOUGH OTHER MODELS HAVE SW WINDS RETURNING TO NEAR 20 KT BY FRI...THE GFS IS INDEED THE STRONGEST...GIVEN ITS FASTER/FARTHER E SOLN. ACCORDING TO THE MODEL CONSENSUS OF THE 18Z NCEP ENS MEAN/12Z ECMWF...SURFACE LOW PRESSURE SHOULD APPROACH THE CAROLINAS FRI AFTERNOON...WITH A TRAILING COLD FRONT MOVING THROUGH THE SERN STATES. THIS SHOULD EVENTUALLY LEAD TO AN INCREASING SW FLOW OVER THE NORTH CENTRAL AND NW WATERS LATE FRI...WITH SEAS POSSIBLY BUILDING UP TO 8 FT. CARIBBEAN AND TROPICAL N ATLC...THE DEEP CLOSED LOW OVER THE WESTERN ATLC EARLY THIS WEEK SHOULD LEAD TO A BREAK IN SUBTROPICAL RIDGING ACROSS THE CARIBBEAN BASIN....WHICH SHOULD MEAN DECREASED TRADES COMPARED TO THOSE OBSERVED LAST WEEK. STILL THOUGH...MODELS DO SHOW THE WESTERN EDGE OF THE SUBTROPICAL RIDGE POKING INTO THE EASTERN CARIBBEAN...WHICH COULD LEAD TO OCCASIONALLY FRESH TO STRONG TRADES S OF ABOUT 13N NEAR AND ALONG THE NORTHERN SOUTH AMERICAN COAST. ELSEWHERE... TRADES SHOULD BE MUCH LIGHTER...BLOWING 10 TO 15 KT. QUIKSCAT DATA TONIGHT DID...HOWEVER...INDICATE E TO SE WINDS OF 20 KT OVER THE GULF OF HONDURAS AND A GENERAL E TO SE WIND OF 20 KT AND OCCASIONALLY 25 KT SHOULD PREVAIL OVER THIS AREA FOR MUCH OF THE WEEK. SEAS OF 4 TO 7 FT SHOULD COVER THE SOUTHERN CARIBBEAN S OF 15N...EXCEPT LOCALLY TO 8 OR 9 FT OFF OF THE COLOMBIA COAST. OVER NORTHERN WATERS N OF 15N...SEAS OF 3 TO 5 FT WILL BE MOST COMMON...EXCEPT LOCALLY TO 8 FT IN THE GULF OF HONDURAS. BY THU...HIGH PRESSURE OVER THE SW ATLC SHOULD REASSERT ITSELF...THOUGH TRADES SHOULD GENERALLY CONTINUE AT PRESENT LEVELS. THERE COULD BRIEFLY BE SOME LOCAL ENHANCEMENT TO THE TRADES OVER THE WINDWARD PASSAGE LATE WED THROUGH THU AFTERNOON...IN RESPONSE TO THE SURFACE HIGH BUILDING N OF THE AREA. THE GULF OF HONDURAS TOO...ALONG THE WESTERN PERIPHERY OF THE WEAK SURFACE RIDGE...SHOULD CONTINUE OBSERVING SE WIND UP TO 25 KT. OTHERWISE...NW SWELL COMING OUT OF THE WESTERN ATLANTIC SHOULD REACH THE NORTHERN CARIBBEAN LATE WEEK...WITH 6 TO 8 FT SEAS NOTED ALONG THE NORTHERN HISPANIOLA AND PUERTO RICAN COASTS FRI. THE NW SWELL SHOULD ALSO ENTER THE NORTHERN TROPICAL ATLANTIC WATERS LATE WEEK...WITH 6 TO 8 FT SEAS ALSO NOTED THERE FRI AFTERNOON. WARNINGS... ATLC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. .FORECASTER KIMBERLAIN. TROPICAL PREDICTION CENTER.