000 AGXX40 KNHC 220844 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 340 AM EST SUN FEB 21 2010 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W GULF OF MEXICO... WEAK COLD FRONTAL BOUNDARY HAS MOVED SE ACROSS THE NW GULF TONIGHT...CURRENTLY EXTENDING FROM NEAR ATCHAFALAYA BAY LOUISIANA TO THE UPPER MEXICAN COAST NEAR 23N. NW TO N FLOW AROUND 10 KT WAS OCCURRING BEHIND THIS BOUNDARY...WITH A SECONDARY AND REAL FRONT MOVING THROUGH TEXAS BEHIND IT...WHERE THE COLDER AIR IS FOUND. S TO S-SE FLOW AROUND 20 KT IS FOUND ACROSS THE NE GULF E OF THE FRONT E OF 90-91W...WHERE SEAS HAVE BUILT 5-8 FT. AS FORECAST BY MODELS PAST SEVERAL DAYS...A LLVL WEAKNESS HAS DEVELOPED ACROSS THE SE GULF FROM THE STRAITS OF FLORIDA W-NW TO NEAR 25N87W...WITH AN UPPER LEVEL S/W MOVING ACROSS IT AND INDUCING SCATTERED DEEP CONVECTION. THIS FEATURE WILL GRADUALLY MOVE E ACROSS THE BAHAMAS AND INTO THE SW N ATLC DURING THE NEXT 48 HOURS AND IS DISCUSSED BELOW. THE NEXT S/W IN THE VERY PROGRESSIVE PATTERN WILL MOVE E ACROSS THE MS VALLEY AND SE U.S. DURING THE NEXT 36 HOURS AND DRAG THE LEADING FRONTAL BOUNDARY ACROSS THE E HALF OF THE GULF TODAY...REACHING THE E SIDE OF THE FLORIDA BIG BEND TO NEAR 25N85.5W THIS EVENING AND THEN MOVING ACROSS THE FLORIDA PENINSULA AND INTO THE W ATLC BY TUE MORNING. ACTIVE WEATHER IS FORECAST ALONG THE LEADING EDGE OF THIS BOUNDARY DURING THE NEXT 24 HOURS AS JET ENERGY ALOFT COMBINES WITH AMPLE LLVL MOISTURE CURRENTLY ACROSS THE NW CARIBBEAN AND ADVECTING N INTO THE SE AND CENTRAL GULF. LOOK FOR 20 KT OF SLY FLOW TO PREVAIL E OF THE FRONT WITH LOCALIZED AREAS TO 25 KT...WITH HIGHEST WINDS AND SEAS N PORTIONS AS INFLOW INCREASES INTO DEVELOPING CONVECTION LATER TODAY. WINDS BEHIND THE FRONT WILL QUICKLY VEER N TO NE TONIGHT GENERALLY AROUND 15 KT...AND THEN NE TO E 15 KT ON TUE. THE NEXT S/W MOVING SE INTO TEXAS TUE NIGHT WILL BE SUPPORTED BY A DEEP LAYERED UPPER TROUGH ACROSS THE GREAT LAKES DIGGING S INTO THE CENTRAL U.S. WITH VERY STRONG COLD AIR ADVECTION DIVING DOWN FROM CANADA. THIS WILL BLAST A STRONG COLD FRONT OFF THE NW GULF COASTS TUE EVENING AND NIGHT...WITH COLD AIR DIVING DUE S ALONG THE LOWER TEXAS AND MEXICAN COASTLINES LEADING TO GALES TO 40 KT. SEAS WILL RESPOND RAPIDLY AND PEAK 18-20 FT ACROSS THE BAY OF CAMPECHE BY LATE WED AFTERNOON-EVE. THE FRONT WILL MOVE SE AND ACROSS THE ENTIRE GULF BY WED EVENING...WITH GALES LIKELY SPREADING E ACROSS SRN PORTIONS OF THE GULF...CONFINED TO A NARROW BAND OF 90-120 NM BEHIND THE BOUNDARY...AND POSSIBLY SPREADING AS FAR E AS THE YUCATAN CHANNEL. ELSEWHERE NW TO N WINDS OF 25-30 KT WILL OCCUR ACROSS THE REMAINDER OF THE BASIN BEHIND THIS FRONT. CARIBBEAN SEA... WINDS HAVE BEGUN THE EXPECTED WEAKENING TREND ACROSS THE BASIN AS THE WEAK HIGH OFF THE SE U.S. COAST SLIDES E-SE THIS MORNING. RETURN SLY FLOW IS OPENING UP ACROSS THE FAR NW CARIB OUT AHEAD OF THE APPROACHING GULF COLD FRONT...ACCELERATING TO 15-20 KT THROUGH THE YUCATAN CHANNEL. ELY FLOW AROUND 15 KT PREVAILS ACROSS MUCH OF THE REMAINDER OF THE BASIN...WITH 20-25 KT S OF 15N OFF THE COAST OF COLOMBIA...AND NE TO E FLOW NEAR 20 KT THROUGH THE MONA AND ANEGADA PASSAGES AND SMALLER GAPS BETWEEN P.R. AND THE V.I. THIS OCCURRING N OF THE OLD LINGERING FRONTAL TROUGH STILL S OF P.R. LOOK FOR WINDS TO ABATE FURTHER DURING THE NEXT 24 HOURS AS THE GULF FRONT REACHES THE W COAST OF FLORIDA AND WINDS ACROSS THE NW 0NE-THIRD OF THE CARIB VEER SE-S. THERE REMAINS UNCERTAINTY WITH THE DEVELOPMENT OF A POTENTIAL SURFACE LOW ACROSS THE BAHAMAS SHIFTING E OR NE INTO THE ATLC TUE MORNING...WHICH COULD INCREASE THE FLOW ACROSS THE N CENTRAL AND NE CARIB TO BEYOND 15-20 KT...AND 20 KT THROUGH THE PASSAGES IS A GOOD BET REGARDLESS. OTHERWISE REDUCED TRADES AND THIS VEERING OF THE FLOW MON NIGHT AND TUE WILL LEAVE ELY TRADES NEAR 20 CONFINED TO THE FAR SRN CARIB...WITH SEAS ACROSS THE BASIN SUBSIDING TO BELOW SEASONAL NORMS. THE FOLLOWING STRONG COLD FRONT FORECAST TO BLAST THROUGH THE GULF TUE NIGHT AND WED IS EXPECTED TO REACH THE NW CARIB WED EVENING...WITH POTENTIAL FOR BRIEF GALES BEHIND IT THROUGH THE YUCATAN CHANNEL. THIS FRONT IS FORECAST TO REACH FROM CENTRAL CUBA TO NICARAGUA BY THU MORNING...WITH SEAS IN THE NW CARIB 9-12 FT...AND BUILDING BY THAT TIME. SW N ATLC AND TROPICAL ATLC W OF 55W... AS INDICATED ABOVE...WEAK 1018 MB HIGH CONTINUES TO SLIDE E-SE AWAY FROM THE SC AND GEORGIA COASTS...WITH SE TO S FLOW GRADUALLY INCREASING FROM THE SE BAHAMAS THROUGH THE NE FLORIDA COAST. THIS FLOW HAS INCREASED TO 15-20 KT S OF THE NW BAHAMAS DURING THE PAST FEW HOURS...WITH STRONGEST FLOW TO 25 KT THROUGH THE STRAITS OF FLORIDA...WITH GUSTS IN EXCESS OF 30 KT LIKELY. A FEW RECENT SHIP OBS THERE CONFIRM EVENING SCATTEROMETER PASSES. THIS FLOW WILL SPREAD N TO 30N AND E TO 73W BY THIS AFTERNOON AS THE GULF COLD FRONT MOVES INTO THE ERN GULF. AREAS OF 25 KT FLOW WILL BE SEEN THROUGH GAPS AND PASSAGES IN THE BAHAMAS AND ALONG THE SE FLORIDA COAST. SEAS ARE LIKELY TO BUILD BEYOND WWIII FORECASTS OF 3-5 FT...AND COULD REACH 5-7 FT BETWEEN CENTRAL CUBA...THE BAHAMAS...AND SE FLORIDA BY SUNSET...AND BUILD 7-9 FT WELL OFFSHORE OF NRN FLORIDA ACROSS FAR NW PORTIONS. MODEL CONSENSUS SUGGESTS THAT UPPER LEVEL S/W ENERGY WILL OUTRUN THE COLD FRONT AS IT IS MOVING ACROSS FLORIDA MON NIGHT AND TUE...WITH A SEPARATE TROUGH MOVING E WELL IN ADVANCE OF THE COLD FRONT. VERY ACTIVE CONVECTION AND SQUALLY WEATHER SHOULD BE EXPECTED ALONG THIS TROUGH AS IT MOVES E ACROSS THE BAHAMAS MON NIGHT AND THEN BEYOND 70W BY TUE AFTERNOON. THE LLVL WEAKNESS ACROSS THE SE GULF AND INTO THE STRAITS OF FLORIDA ATTM WILL BE PUSHED EWD AHEAD OF THE FRONT AND MODELS HAVE BEEN FORECASTING VARIOUS SCENARIOS OF A SURFACE REFLECTION WITH THIS FEATURE. ENHANCED 20-25 KT SLY FLOW IS LIKELY TO THE S AND SE OF THIS FEATURE AS IT MOVES E T0 E-NE ACROSS THE STRAITS THIS EVENING AND THEN ACROSS BAHAMAS TONIGHT...AND WILL LIKELY BE THE FOCUS OF VERY STRONG CONVECTIVE ACTIVITY. MODELS HAVE GENERALLY BACKED OFF ON DEVELOPMENT OF A WELL ORGANIZED LOW WITH THIS FEATURE...BUT AN E-NE MOVING LOW TO MID LEVEL PERTURBATION WILL BE SEEN MOVING ALONG A TRAJECTORY THROUGH THE SRN BAHAMAS AND INTO THE SUBTROPICAL ATLC. WLY FLOW OF 15-20 KT WILL OCCUR BRIEFLY BEHIND THE COLD FRONT TUE AS IT MOVES E OFF OF FLORIDA...WITH WINDS QUICKLY DECREASING TO LESS THAN 15 KT IN ADVANCE OF NEXT STRONGER FRONT MOVING ACROSS THE GULF. THIS FRONT IS FORECAST TO MOVE ACROSS FLORIDA WED NIGHT AND WILL BRING ANOTHER ROUND OF VERY ACTIVE CONVECTION ALONG THE FRONT...AND MUCH COLD AIR. 20-25 KT NWLY FLOW WILL INITIALLY OCCUR BEHIND THE FRONT THU...WITH SW TO S WINDS OF 20-30 KT OUT AHEAD OF IT ACROSS THE OPEN ATLC. ALL THIS ENERGY IS FORECAST TO EVENTUALLY WRAP UP INTO A DEEP LOW OFF THE NE U.S. COASTLINE FRI. WARNINGS... ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER STRIPLING