000 AGXX40 KNHC 200730 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 230 AM EST WED JAN 20 2010 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W GULF OF MEXICO... 1019 MB HIGH PRES NEAR 27N83W DOMINATES THE GULF AT THIS TIME...WITH LIGHT ANTICYCLONIC FLOW ACROSS THE EASTERN GULF. SOUTHERLY WINDS HAVE PICKED UP TO 20 KT IN THE NW GULF AS THE PRES GRADIENT BUILDS BETWEEN THE HIGH AND A NEW LOW PRES SYSTEM PASSING THROUGH THE CENTRAL PLAINS TONIGHT. WHILE THE MODELS AGREE ON TURNING THE UPPER LEVEL FLOW MORE ZONAL AND PROGRESSIVE...THEY DIVERGE WITH THE SURFACE LOW TRACK FROM THE PLAINS INTO THE MID MISSISSIPPI VALLEY TONIGHT THROUGH THU AS A NEW SURFACE LOW BEGINS TO DEVELOP ON THE CAROLINA COAST ALONG THE WARM FRONT AHEAD OF THE MAIN LOW. THE GFS CARRIES THE MOST SOUTHERLY TRACK WITH BOTH THE MAIN LOW AND THE CAROLINA COASTAL LOW. AS A RESULT...IT IS STRONGER WITH THE WIND FIELD OVER THE FORECAST AREA...BUT IT HAS TRENDED WEAKER WITH ITS WIND FIELD OVER THE PAST FEW DAYS WORTH OF RUNS. A FEW DAYS AGO...IT CARRIED GALE FORCE WINDS IN THE N CENTRAL AND NE GULF. NOW...WINDS PEAK AT 25 KT. THE NOGAPS ALSO BRIEFLY ALLOWS WINDS OF 25 KT AHEAD OF THE PRE-FRONTAL TROUGH PASSING THROUGH THE GULF THU...BUT THE ECMWF AND UKMET TOP IT OFF AT 20 KT. FORECAST WILL SHOW PEAK WINDS TO 25 KT. HIGH PRES QUICKLY SHIFTS E ACROSS THE GULF BEHIND THIS SYSTEM FRI/SAT. THE MODELS AGREE ON INCREASING RETURN FLOW IN THE WESTERN GULF FRI NIGHT INTO SAT IN RESPONSE TO THE NEXT SYSTEM EMERGING IN THE PLAINS. THE ECMWF AND GFS AGREE ON TAKING THE COLD FRONT ASSOCIATED WITH THIS SYSTEM TO THE COAST SAT AFTERNOON WITH WINDS TO 25 KT AHEAD OF IT. CARIBBEAN AND TROPICAL N ATLC W OF 55W... 1019 MB HIGH PRES CENTERS JUST W OF SARASOTA BAY AND JUST E OF THE NORTHERN BAHAMAS HAS CREATED A STRONG PRES GRADIENT BETWEEN IT AND THE 1007 MB LOW PRES OVER COLOMBIA...ALLOWING FOR GALE FORCE EASTERLY TRADES OFF THE COAST OF COLOMBIA. ASCAT PASS FROM 0252 UTC SHOWED TRADES JUST BELOW GALE FORCE NEAR THE COAST OF COLOMBIA. WHILE THERE HAVE NOT BEEN SHIP REPORTS IN THIS AREA FOR SEVERAL HOURS...KNOWING THE ASCAT RUNS LOW HERE AND THE PRES GRADIENT HAS INCREASED JUSTIFIES THE GALE WARNING AT THIS TIME. THE HIGH PRES TO THE NORTH SHIFTS EAST INTO THE CENTRAL ATLC THU...DIMINISHING THE WINDS BELOW GALE FORCE. MEANWHILE...SE FLOW IN THE NW CARIBBEAN INCREASES TO 20 KT TONIGHT AND THU AHEAD OF THE NEXT SYSTEM IMPACTING THE GULF OF MEXICO. THE HIGH PRES BEHIND THIS SYSTEM WILL BE FAST MOVING AND CENTERED WELL N OF THE AREA...PREVENTING A RETURN OF STRONG TRADES. ANOTHER SYSTEM MOVES THROUGH THE U.S. PLAINS STATES SAT AND SE RETURN FLOW IN THE NW CARIBBEAN AGAIN BUMPS UP ABOVE 20 KT AHEAD OF IT ON SUN. SW N ATLC S OF 31N W OF 55W... 1019 MB HIGH PRES NEAR 27N76W IS THE DOMINATING WEATHER FEATURE OVER MUCH OF THE AREA TODAY AND TONIGHT WITH LIGHT ANTICYCLONIC FLOW DOMINATE OVER MUCH OF THE AREA N OF 23N AND TRADES TO 15 KT S OF 23N. MODEL DIFFERENCES COME IN TO PLAY BY THU NIGHT OVER THE CAROLINA COAST...WITH THE GFS MOVING A LOW OFFSHORE ON A MORE SOUTHEASTERLY TRACK THAN THE OTHER MODELS. WHILE ALL OF THE MODELS AGREE ON DEVELOPING THIS LOW AND MOVING IT OFFSHORE WELL NORTH OF THE AREA...PREFER TO SLOW DOWN THE GFS DEVELOPMENT OF THE SYSTEM BY 6 TO 12 HOURS TO BE MORE IN LINE WITH THE MODEL CONSENSUS. GALE FORCE WINDS ARE POSSIBLE IN THE SOUTHERLY FLOW SE OF THE SYSTEM. HOWEVER...THE OTHER MODELS DO NOT DEVELOP GALE FORCE WINDS AS EARLY OR AS FAR E AS THE GFS...ALL WAITING TO SHOW GALES E OF THIS FORECAST AREA. THE GFS ENSEMBLES SHOW ONLY A 10 PERCENT CHANCE OF GALES OCCURRING IN THIS ZONE N OF 30N E OF 66W AND NOT UNTIL SAT AT 0600 UTC. THE SREF ENSEMBLES ALSO SHOW A 10 PERCENT CHANCE OR LESS OF GALE FORCE WINDS N OF 29N E OF 70W FROM 2100 UTC FRI TO 0900 UTC SAT. HESITANT TO BRING DOWN THE MENTION OF POSSIBLE GALES WITH MANY OF THE MODELS SHOWING 30 KT. THEREFORE...WILL HEDGE CLOSER TO THE MODEL CONSENSUS AND START THE MENTION OF GALES FOR LATE FRI NIGHT AND EARLY SAT IN FAR NE WATERS. HIGH PRES PASSES E THROUGH THE AREA QUICKLY SAT EVENING THROUGH SUN...WITH SOUTHERLY RETURN FLOW PICKING UP IN E WATERS SUN NIGHT AHEAD OF THE GULF FRONT. WARNINGS... ATLC... .NONE. CARIBBEAN... .GALE WARNING FROM 11N TO 15N BETWEEN 72W AND 77W...AMZ084 AND AMZ086. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER LEWITSKY