000 AGXX40 KNHC 111758 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 155 PM EDT SAT OCT 11 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS... STATIONARY CUT-OFF CYCLONE JUST NW OF THE NW PORTION OF THE SW N ATLC NEAR 32N80W HAS DEEP LAYER TROUGH EXTENDING S TO CENTRAL CUBA. IT IS MOVING SLOWLY W AS BROAD RIDGING BOTH AT THE SURFACE AND ALOFT BUILDS ACROSS THE EASTERN UNITED STATES...MUCH OF THE ATLC OFFSHORE WATERS AND THE EASTERN AND CENTRAL GULF OF MEXICO THROUGH TUE BEFORE WEAKENING LATE TUE THROUGH THU. MID/UPPER LEVEL CYCLONE OVER PUERTO RICO HAS A TROUGH EXTENDING SW INTO THE EASTERN CARIBBEAN SEA NEAR 15N70W. A TROUGH EXTENDS NE FROM THE CYCLONE TO WELL NE OF THE AREA. ABUNDANT MOISTURE IS PREVALENT THROUGH ALL LEVELS OF THE ATMOSPHERE AROUND THIS CYCLONE AS WELL AS TO ITS SE...WHILE DRY AND AND STABLE AIR HAS INTRUDED INTO THE FAR WESTERN PART OF THE SW N ATLC BEHIND THE DEEP LAYER TROUGH. DRY AIR ALOFT IS ALSO NOTED WITHIN ABOUT 420 NM TO THE W OF THE MID/UPPER LEVEL CYCLONE CENTERED OVER PUERTO RICO. A SMALL UPPER LEVEL ANTICYCLONE IS NEAR 23.5N70W WITH A RIDGE NE THROUGH 26N68W TO 29N67W TO A CREST N OF THE AREA AT 32N65W. SURFACE... SURFACE LOW NEAR 31N78W 1012 MB IS A REFLECTION OF THE CUT-OFF CYCLONE MENTIONED ABOVE. AN ASSOCIATED TROUGH EXTENDS FROM THE LOW SW TO CENTRAL FL AT THE PRESENT TIME. BOTH OF THESE FEATURES ARE DRIFTING W...AND ARE EXPECTED TO DISSIPATE TONIGHT INTO SUN MORNING. A WIND SHIFT FROM NE TO SE IN THE RANGE OF 10-15 KT DEFINES THE TROUGH AXIS AS NOTED IN BOTH BUOY OBSERVATIONS FROM THIS MORNING AND EARLY AFTERNOON. MODEL GUIDANCE CONTINUES TO BE CONSISTENT IN DEPICTING A RATHER SUBSTANTIAL INCREASE IN ELY WINDS OVER MUCH OF THE SW N ATLC WATERS BEGINNING ON SUN AS STRONG SURFACE HIGH PRES BUILDS S AND SE OVER THE SE UNITED STATES THROUGH TUE...THEN WEAKENS WED AND THU AS IT SINKS FURTHER SE TO ROUGHLY ALONG 31N. WINDS OVER THE SW N ATLC N OF ABOUT 23N W OF 70W ARE EXPECTED TO INCREASE INTO THE 20-25 KT RANGE THEN DIMINISH WED AND THU TO 10-15 KT...EXCEPT 15-20 KT OVER THE FAR S WATERS. WAVEWATCH GUIDANCE SUGGESTS SEAS WILL BUILD POSSIBLY UP TO 11 FT TUE. THIS WILL DEPEND ON JUST HOW JUST HOW MUCH AREAL COVERAGE THESE WINDS WILL AFFECT. SEAS WILL THEN GRADUALLY SUBSIDE TO 8 FT WED AND THU. SEAS MAY LINGER UP TO 10 FT IN N SWELL OVER THE FAR NE PART INTO THU. CARIBBEAN TRADE WINDS ARE RATHER LIGHT FOR THE MOST...EXCEPT IN THE EASTERN PORTION WHERE A TROPICAL WAVE ALONG 63W/64W WITH ASSOCIATED LOW PRES ON THE WAVE AXIS NEAR 13N IS PRESENT. ALTHOUGH WINDS WITHIN 240 NM TO THE W OF THE WAVE ARE LIGHT NE ...WINDS TO THE E OF THE WAVE ARE E-SE 15-20 KT TO THE 12N. ALSO TO THE E OF THE WAVE...NUMEROUS SHOWERS AND TSTMS ARE ENHANCING SEA STATE PRODUCING LOCALLY GUSTY WINDS. GLOBAL MODEL GUIDANCE IS IN PRETTY GOOD AGREEMENT THAT LOW PRES...POSSIBLY A TROPICAL CYCLONE...ORIGINATES FROM THE WAVE AND TRACKS NW THEN N OR NE OVER THE NE CARIBBEAN WED AND THU OF NEXT WEEK. HOWEVER...EVEN BEFORE THIS WOULD OCCUR THE LOW...PROBABLY THE ONE BEING OBSERVED NEAR 13N63W...MAY HAVE ALREADY DEVELOPED INTO A TROPICAL CYCLONE AS LATEST VISIBLE SATELLITE IMAGERY SHOWS CYCLONIC TURNING OF THE LOW CLOUD FIELD AROUND THIS FEATURE. THERE IS ALSO SOME INDICATION IN THE MODEL GUIDANCE THAT SOME FORM OF LOW PRES...WHETHER PART OF THE LOW THAT MOVES ACROSS THE NE PART OR A SEPARATE LOW ALTOGETHER...LAGS BEHIND OVER THE WESTERN CARIBBEAN WED AND THU. THIS LEADS TO SOME UNCERTAINTY IN THE LATTER EXTENT OF THIS FORECAST. ANOTHER TROPICAL WAVE WELL E OF THE AREA ALONG 50W IS MOVING W 10 KT. THIS WAVE SHOULD ENTER THE TROPICAL N ATLC SUN MORNING...THEN MOVE ACROSS THE EASTERN CARIBBEAN SEA MON AND TUE...THE CENTRAL CARIBBEAN WED AND THE WESTERN CARIBBEAN THU. THE SAME STRONG HIGH PRES THAT BUILDS OVER THE SW N ATLC INTO EARLY NEXT WEEK WILL INCREASE ELY WINDS TO 20-24 KT IN THE E GULF N OF 28N SUN THROUGH MOST OF TUE...THEN DIMINISH TO 15-20 KT N PART LATE TUE AND TO 10-15 KT WED AND THU. WINDS WILL REMAIN E 20-25 KT IN THE MIDDLE GULF S OF 26N WED...THEN DIMINISH TO 15-20 KT THU. EXPECT SEAS TO BUILD UP TO 9 FT...MAYBE 10 FT...IN THE MIDDLE GULF S OF 27N WED THEN SUBSIDE TO 5-7 FT THU UNDER MUCH WEAKER PRES GRADIENT. WINDS OVER REMAINDER OF GULF WILL BE IN THE RATHER LIGHT RANGE (10-15 KT) THROUGH THE FORECAST PERIOD...BUT AN E SWELL OF 5-8 FT WILL SPREAD W THROUGH THE NW PART. A NE SWELL OF 3-6 FT MAY SLIDE S INTO THE SW PART WED AND THU. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER AGUIRRE. TROPICAL PREDICTION CENTER.