000 AGXX40 KNHC 300641 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 200 AM EST WED DEC 30 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W GULF OF MEXICO... A WEAK RIDGE OF HIGH PRES IS OVER THE MAJORITY OF THE GULF... WITH A TROUGH REMAINING NEARLY STATIONARY ALONG THE GULF COASTS OF MEXICO AND TEXAS. A WEAK AREA OF LOW PRES WILL DEVELOP ALONG THIS TROUGH NEAR GALVESTON BAY LATER THIS MORNING...THEN WILL MOVE TO THE NE-E JUST INLAND ALONG 30N...DRAGGING A COLD FRONT ACROSS THE GULF. THE LOW WILL BE NEAR 31N92W WITH THE FRONT TO 24N96W BY THIS EVENING...THEN WILL MOVE INLAND OVER FLORIDA BY THU EVENING. A NORTHERLY SURGE OF COLD AIR WILL DIVE DOWN ACROSS THE GULF THU NIGHT THROUGH FRI. HIGH PRES BECOMES CENTERED NEAR THE N CENTRAL GULF COAST BY LATE FRI NIGHT THROUGH SAT...AND WINDS WILL DIMINISH AS THE GRADIENT WEAKENS AND AS THE COLDER AIRMASS MODIFIES OVER THE RELATIVELY WARMER GULF WATERS. THIS PATTERN WILL CONTINUE THROUGH SUN. CARIBBEAN AND TROPICAL N ATLC W OF 55W... HIGH PRES REMAINS N OF THE AREA OVER THE E GULF OF MEXICO AND SW N ATLC...WITH LOW PRES LOCATED INLAND OVER S AMERICA. A TIGHT PRES GRADIENT IS IN PLACE BETWEEN THE TWO OVER THE CARIBBEAN... WITH NE-E TRADES IN THE 20-25 KT RANGE OVER THE MAJORITY OF THE BASIN W OF 68W...EXCEPT FOR 25-30 KT WINDS NEAR THE COAST OF COLOMBIA. THE PRES GRADIENT WILL WEAKEN THU THROUGH FRI ALLOWING FOR TRADES TO DIMINISH TO 15-20 KT. THE GRADIENT WEAKENS EVEN FURTHER FRI NIGHT THROUGH SUN WITH NE-E TRADES IN THE 10-15 KT RANGE (20 KT NEAR COAST OF COLOMBIA) EXPECTED DURING THAT PERIOD. OVER THE TROPICAL N ATLC...A COLD FRONT WILL PUSH SE OF 20N LATER THIS MORNING AND WILL STALL OUT ALONG 18N TONIGHT THROUGH FRI. NE WINDS OF 20-25 KT WILL ARRIVE BEHIND THE FRONT ALONG WITH A NEW SET OF LARGE LONG PERIOD NW-N SWELL OF UP TO 15 FT...WHICH WILL PROPAGATE THROUGH THE TROPICAL N ATLC WATERS THROUGH FRI. THIS SWELL WILL ALSO SEEP THROUGH THE EXPOSED PASSAGES OF THE ATLC THU THROUGH FRI...SIMILAR TO THE CURRENT SWELL EVENT...THEN WILL GRADUALLY DECAY SAT THROUGH SUN ACROSS THE BASIN. SW N ATLC S OF 31N W OF 55W... A COLD FRONT EXTENDS FROM 31N53W TO 24N58W TO 20N64W. A GALE WARNING REMAINS IN EFFECT AHEAD OF THE FRONT E OF THE OFFSHORE WATERS WITH A 0000 UTC ASCAT PASS CAPTURING A FEW 35 KT WIND BARBS NEAR 30N55W...ALTHOUGH THEY WERE RAIN-FLAGGED AND THUS SOMEWHAT SUSPECT. POST-FRONTAL NORTHERLY SURGE OF 20-25 KT WILL DIMINISH AND BECOME E-SE LATER TODAY AND TONIGHT. A COASTAL TROUGH WILL DEVELOP IN THE RETURN FLOW LATER TODAY AND TONIGHT ALONG THE FLORIDA AND GEORGIA COASTS...SHIFTING E ALONG AND N OF 28N THROUGH THU NIGHT. MEANWHILE THE AREA OF LOW PRES THAT IS EXPECTED TO DEVELOP ALONG THE GULF COAST WILL CROSS FLORIDA THU NIGHT...THEN WILL STRENGTHEN AS IS MOVES TO NEAR 33N77W WITH A COLD FRONT EXTENDING TO 30N80W BY EARLY FRI MORNING...THEN WILL MERGE WITH THE AFOREMENTIONED COASTAL TROUGH. SOUTHERLY FLOW AHEAD OF THE FRONT INCREASES TO MINIMAL GALE FORCE...WITH NORTHERLY FLOW BEHIND THE FRONT ALSO EXPECTED TO REACH MINIMAL GALE FORCE DURING THE DAY FRI. THE NORTHERN EXTENT OF THE FRONT AND STRONGEST WINDS WILL PUSH E OF 65W BY EARLY SAT MORNING WITH THE TAIL END REACHING FROM NEAR 27N65W TO 20N72W BY 12 UTC SAT. THE FRONT WILL THEN STALL OUT SAT NIGHT THROUGH SUN WITH W-NW WINDS OF 20-25 KT PERSISTING N OF 28N. LARGE LONG PERIOD NW SWELL OF UP TO 22 FT (HIGHEST NEAR 31N65W) WILL ALSO PROPAGATE SE THROUGH THE SW N ATLC BEHIND THE FRONT. WARNINGS... ATLC... .NONE. AMZ080...GALE CONDITIONS EXPECTED FRI N OF 29N ALONG FRONT. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER LEWITSKY