000 AGXX40 KNHC 261808 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... LATEST SURFACE MAP SHOWS WEAK HIGH PRESSURE EXTENDING FROM THE SOUTH CENTRAL STATES TO A WEAKENING FRONTAL BOUNDARY EXTENDING FROM THE FLORIDA STRAITS SOUTHWEST THROUGH THE CENTRAL BAY OF CAMPECHE. NOW THAT THE PRESSURE GRADIENT OVER THE NORTH HAS RELAXED...SO HAVE THE STRONG WINDS FROM YESTERDAY. IN FACT ...SHIP AND BUOY REPORTS N OF 25N INDICATE NO MORE THAN 10 TO 15 KT OF N TO NE WINDS WITH 4 TO 7 FT SEAS IN NE SWELL OF THE CENTRAL AND W CENTRAL GULF AND 2 TO 4 FT SEAS OVER THE FAR N. IMMEDIATELY BEHIND THE FRONT...HOWEVER...THE CONTRAST BETWEEN LOW PRESSURE OVER CENTRAL AMERICA AND THE HIGH PRESSURE TO THE NORTH IS RESULTING IN MODERATE TO STRONG N TO NE WINDS OF 20 TO 25 KT S OF 23N AND N OF THE FRONT. NOAA WAVEWATCH III SUGGESTS SEAS OF 6 TO 10 FT IN NE SWELL...IN ADDITION TO SCATTERED TO NUMEROUS SHOWERS AND TSTMS ACROSS THE BAY OF CAMPECHE. OVER THE NEXT FEW DAYS...GLOBAL MODELS ARE IN GENERAL AGREEMENT ON WEAK LOW PRESSURE REMAINING OVER THE NORTHWEST CARIBBEAN AND CENTRAL AMERICA...WHILE HIGH PRESSURE TO THE NORTH ONLY SLOWLY WEAKENS. AS A RESULT...LIGHT N TO NE WINDS OF 10 KT OR LESS SHOULD COVER A LARGE PART OF THE GULF AND BE COLLOCATED WITH GRADUALLY SUBSIDING SEAS. MEANWHILE...A TIGHTER GRADIENT OVER THE FAR SOUTHWEST AND BAY OF CAMPECHE SHOULD MEAN A CONTINUATION OF N TO NE WINDS OF 15 TO 20 KT WITH SEAS OF 5 TO 8 FT SLOWLY SUBSIDING BY SUN AND MON. OVER THE NORTHEAST WATERS...BROAD LOW PRESSURE ASSOCIATED WITH THE OLD STORM SYSTEM OFFSHORE THE SE CONUS COAST SHOULD MEANDER AROUND AT LEAST THROUGH MON AND CAUSE A W TO NW 10 KT OR LESS FLOW OVER THE FAR NE WATERS...GENERALLY N OF 28N WITH SEAS 2 FT OR LESS. LONGER-TERM...SEVERAL GLOBAL MODELS SHOW THE REMAINS OF THE FRONT NOW OVER THE GULF LIFTING NORTHWEST INTO THE SE GULF WATERS LATE SUN INTO MON AND TUE NEXT WEEK. ALTHOUGH WINDS WILL BE LIGHT AROUND THIS FEATURE ...IT WILL MARK BE ASSOCIATED WITH A WIND SHIFT BETWEEN NE AND E FLOW TO THE NORTH AND SE TO S FLOW TO THE EAST. IN ADDITION...THERE MAY BE SOME SCATTERED SHOWERS AND TSTMS NEAR OR ALONG THIS FEATURE WHICH COULD PRODUCE SOME LOCALLY HIGHER WINDS AND SEAS. OTHERWISE...MODEL GUIDANCE INDICATES A HEALTHY FALL COLD FRONT APPROACHING THE NORTHERN GULF WATERS LATE TUE AND EARLY WED...WITH THE FRONT LIKELY ENTERING THE AREA BY WED MORNING. COMPARED TO THE REMAINDER OF THE 12Z SUITE OF GUIDANCE...THE GFS IS THE LONE MODEL NOT TO HAVE A CUT-OFF FEATURE DIGGING INTO THE MIDWEST AND OHIO VALLEYS BY MID-WEEK NEXT WEEK. THE GFS MEAN...SEVERAL RUNS OF THE ECMWF...UKMET...AND CMC ALL HAVE THIS CUT-OFF FEATURE...THOUGH THE CMC IS THE MOST AMPLIFIED. ASSUMING A MORE MIDDLE-OF-THE-ROAD APPROACH LIKE THE ECMWF AND GFS ENS MEAN...THERE WOULD LIKELY BE A LOT MORE WIND AND INCREASING SEAS THAN SHOWN IN THE 12Z GFS. ON THIS BASIS...WILL INTRODUCE NW TO N 15 TO 20 KT WINDS IN THE WAKE OF THE FRONT OVER THE NORTHERN GULF WATERS WED AFTERNOON AND EVENING SPREADING N TO S. WILL INCREASE SEAS TO AT LEAST 5 TO 8 FT ALSO. CARIBBEAN AND TROPICAL N ATLC... THE WEAK PRESSURE PATTERN WHICH HAS DOMINATED THE CARIBBEAN BASIN FOR MUCH OF THIS WEEK IS IN THE PROCESS OF CHANGING...AS THE LOW-LEVEL ATLANTIC SUBTROPICAL RIDGE BEGINS TO BUILD INTO THE EASTERN WATERS THIS AFTERNOON. AS A RESULT OF THE EXTREMELY LIGHT WINDS CARIBBEAN-WIDE...LATEST BUOY AND SHIP REPORTS INDICATE 1 TO 2 FT SEAS OVER A LARGE PORTION OF THE CARIBBEAN ...WITH THE HIGHEST SEAS OF ONLY 3 TO 4 FT OVER THE EAST OR EAST CENTRAL WATERS. BY TONIGHT...HOWEVER...MODELS SHOW THE TRADES BEGINNING TO RESUME TO NEAR NORMAL OR SLIGHTLY BELOW NORMAL LEVELS OVER THE EASTERN AND CENTRAL AREAS...BUT THE TRADES WILL NOT HAVE A CHANCE TO RECOVER FULLY THERE UNTIL SUN. EXPECT SEAS TO BUILD BACK CLOSER TO CLIMATOLOGICAL NORMS OF 5 TO 8 FT IN E SWELL S OF 15N AND ROUGHLY BETWEEN 69W AND 77W. THE NEW EASTERLY SWELL SHOULD BEGIN TO SPREAD W OVER THE WESTERN CARIBBEAN SUN AND MON...CAUSING WAVE HEIGHTS THERE TO ALSO BUILD. ALSO OF NOTE...SEVERAL MODELS PERSIST THE REMNANTS OF THE FRONT NOW OVER THE EXTREME SOUTHERN GULF OF MEXICO AND DEVELOP LOW PRESSURE OVER CENTRAL AMERICA OR NEAR THE YUCATAN INTO EARLY NEXT WEEK. ALTHOUGH NO TROPICAL CYCLONE DEVELOPMENT APPEARS LIKELY...THERE IS A CHANCE THAT SOME WEAK LOW PRESSURE... POSSIBLY FRONTAL IN NATURE...AND MORE UNSETTLED CONDITIONS MAY DEVELOP OVER THIS AREA BETWEEN SAT AND TUE. GIVEN THE LACK OF MODEL AGREEMENT HERE...THIS TYPE OF SCENARIO HAS NOT BEEN BUILT INTO THE CURRENT FORECAST PACKAGE EXPLICITLY. FINALLY...SIGNIFICANT LONG PERIOD NE SWELL COMING OUT OF THE NORTH ATLANTIC WILL BE ARRIVING OVER THE NORTHERN TROPICAL ATLANTIC WATERS LATER THIS WEEKEND...SUBSIDING A BIT...AND THEN REBUILDING BY TUE NEXT WEEK. WAVE HEIGHTS SHOULD PEAK OUT OVER THE TROPICAL N ATLC TUE...WITH VALUES OF 6 TO 10 FT. THE SWELL WILL ALSO BE IMPACTING THE NE CARIBBEAN ISLANDS AND BLEEDING THROUGH NE ATLANTIC PASSAGES STARTING LATE SAT INTO SUN. SUN THROUGH TUE...EXPECT SEAS FROM THE NORTH COAST OF PUERTO RICO THROUGH THE NORTHERN ANTILLES TO AVERAGE BETWEEN 6 AND 9 FT. SW N ATLC...MAIN CONCERN OVER THE SHORT-TERM IS TROPICAL STORM KYLE OVER THE EAST CENTRAL WATERS WHICH IS BEGINNING TO ACCELERATE NORTHWARD. LATEST NHC FORECAST CALLS FOR KYLE TO EXIT THE FORECAST WATERS BY SAT MORNING...THOUGH RESIDUAL WINDS AND SEAS WILL TAKE AT LEAST ANOTHER 12 TO 24 HOURS TO WIND DOWN. QUIKSCAT DATA AND A HOST OF SHIP DATA INDICATE THAT STRONG WINDS OF 20 KT OR GREATER SURROUNDING KYLE EXTEND AT LEAST 360 NM OVER THE NE QUADRANT AND 270 NM SE. ON THE WEST SIDE...HOWEVER... STRONG WINDS ARE LIMITED TO RIGHT NEXT TO THE CENTER...IF AT ALL. IN ADDITION...SIGNIFICANT LONG PERIOD NE SWELL FROM STRONG WINDS EARLIER IN THE WEEK OF THE U.S. EAST COAST CONTINUES TO ARRIVE OVER ALL AREAS N AND E OF THE BAHAMAS. ALTHOUGH THE SWELL HAS BEEN DECAYING GRADUALLY...SHIP AND BUOY REPORTS ARE STILL INDICATING 7 TO 11 FT SEAS N OF 23N E OF THE BAHAMAS AND ROUGHLY N OF 28N W OF THE BAHAMAS. HOWEVER...SEAS ARE 2 TO 4 FT OR 3 TO 5 FT IMMEDIATELY OFFSHORE THE NE FLORIDA COAST...THANKS TO AN OFFSHORE FLOW. ON THE OTHER HAND...N TO NE SWELL HAS MADE IT ALL THE WAY DOWN TO THE SE FLORIDA COAST AND WESTERN BAHAMAS...WITH SEAS OF 4 TO 7 FT NOW SUBSIDING TO ABOUT 3 TO 5 FT. GOING INTO THE WEEKEND...THE LOW-LEVEL SUBTROPICAL RIDGE IS FORECAST TO REASSERT ITSELF AND EXTEND FROM 29N65W TO THE STRAITS OF FLORIDA EARLY SAT AND THEN ALONG 27-28N SUN THROUGH TUE. NE SWELL STILL ARRIVING ACROSS THE AREA WILL CONTINUE TO SLOW SUBSIDE...WITH SEAS ABOVE 8 FT CONFINED TO THE FAR N SAT AND THEN GONE EXCEPT OVER THE NE WATERS SUN. ADDITIONAL NE SWELL COMING OUT OF THE NORTH ATLANTIC TODAY AND SAT WILL OVERSPREAD THE EXTREME EASTERN WATERS SUN AND MON...WITH SEAS OF UP TO 8 FT S OF 24N E OF 68W SUN AND MON. AS MENTIONED IN THE CARIBBEAN SECTION...THERE EXIST SOME POSSIBILITY THAT WEAK LOW PRESSURE COULD FORM ALONG THE OLD FRONT NEAR THE YUCATAN OR SE GULF LATE THIS WEEKEND AND SHOOT NE ACROSS FLORIDA BY EARLY NEXT WEEK. LONG-TERM...MODELS SHOW A SIGNIFICANT FALL COLD FRONT ENTERING THE GULF WATERS EARLY WED...WITH THE FRONT LIKELY APPROACHING OR ENTERING THE FAR NW WATERS LATE WED. REGARDLESS OF WHETHER IT DOES OR NOT...AS THE RIDGE AXIS SHIFTS SOUTHWARD IN ADVANCE OF IT...INCREASING SW TO W FLOW SHOULD PREVAIL GENERALLY N OF 27N...WITH THE STRONGEST LIKELY W OF 75W. THE 12Z GFS WAS UNUSUALLY WEAK WITH THE TROUGH DIGGING INTO THE EAST AND A SOLUTION MORE AKIN TO THE ECMWF/GFS ENS MEAN IS CONSIDERED MORE LIKELY AT THIS POINT. GIVEN THIS...WILL EMPHASIZE INCREASE WIND AND SEAS OVER THE NORTHERN WATERS LATE THIS PERIOD. WARNINGS... ATLANTIC... .TROPICAL STORM WARNING S OF 24N E OF 70W...AMZ080 CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER KIMBERLAIN. TROPICAL PREDICTION CENTER.