000 AGXX40 KNHC 241932 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 330 PM EDT MON SEP 24 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... OBSERVATIONS FROM BOTH BUOYS AND OIL PLATFORMS HAVE SHOWN LITTLE OVERALL CHANGES TO WINDS AND SEAS SINCE THE LAST FEW DAYS. WINDS ARE NE 15 KT...EXCEPT SE OF A LINE FROM SARASOTA FLORIDA TO 23N98W WINDS ARE HIGHER IN THE 15-20 KT RANGE. LIGHT E-SE WINDS OF 5 KT ARE BEING OBSERVED IN THE FAR NW PORTION OF THE GULF. SEAS ARE IN THE RANGE OF 3-5 FT WITHIN THE AREA OF 15-20 KT WINDS...AND 2-3 FT NW OF THE SAME LINE. THE 18 UTC PRELIMINARY SURFACE ANALYSIS HAS A WEAKENING STATIONARY FRONT EXTENDING FROM FORT MYERS FLORIDA TO 24N88W AND NW TO NEAR 25N93W...WHILE HIGH PRES IS BUILDING SEWD TO THE N OF IT. THE ASCAT PASS FROM 1628 UTC THIS MORNING CAPTURED N-NE WINDS OF 15-20 KT TO THE W OF THE TROUGH...AND E WINDS OF 15-20 KT TO ITS E AND NE OVER THE SW AND S CENTRAL PORTIONS OF THE AREA. IN THE UPPER LEVELS...A PERSISTENT DEEP LAYER TROUGH IS OVER THE WESTERN GULF. UPPER LEVEL DIFFLUENCE TO THE E OF THE UPPER TROUGH IN COMBINATION WITH THE SURFACE TROUGH IS HELPING TO TRIGGER OFF EXTENSIVE DEEP LEVEL ATMOSPHERIC MOISTURE ACROSS THE VAST MAJORITY OF THE MIDDLE AND EASTERN GULF PRODUCING NUMEROUS SHOWERS AND SCATTERED TSTMS OVER THESE PORTIONS OF THE GULF. LITTLE CHANGE IS EXPECTED IN THE OVERALL PRESENT PATTERN THROUGH EARLY TUE. AFTER THEN THE UPPER TROUGH SHIFTS FURTHER E ALLOWING FOR ATMOSPHERIC INSTABILITY TO THEN BECOME MORE CONCENTRATED OVER THE SE PORTION OF THE MIDDLE GULF...AND IN THE SE PORTION AS WELL. THIS WILL LEAD TO SCATTERED SHOWERS AND TSTMS PRIMARILY OVER THOSE AREAS THROUGH AT LEAST TUE NIGHT BEFORE DIMINISHING. HIGH PRES FROM THE EASTERN UNITED STATES WILL CONTINUE TO BUILD SW ACROSS THE NORTHERN GULF THROUGH TUE NIGHT PRETTY OVERRIDING THE WEAKENING STATIONARY FRONT AND DISSIPATING IT. THE HIGH PRES WILL THEN WEAKEN AS IT MOVES NE OF THE AREA WED THROUGH SAT AND THE TROUGH IN THE SW GULF MOVES TO JUST ALONG THE COAST MEXICO BY TUE NIGHT WHILE DISSIPATING. AS FOR WINDS...THE NE 15-20 KT WINDS WILL DIMINISHING TO 10-15 TUE. WINDS ELSEWHERE WILL BE IN THE SAME RANGE THROUGH AT LEAST WED NIGHT BEFORE DIMINISHING FURTHER TO 10 KT THROUGH SAT. WIND DIRECTION VEER AROUND MORE TO THE SE OVER THE WESTERN GULF DAYS 3 THROUGH 5. THE 3-5 FT SEAS SUBSIDE TO 2-3 FT WED NIGHT...AND WILL BE THE SAME ELSEWHERE THROUGH SAT. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE PRELIMINARY 18 UTC SURFACE ANALYSIS HAS A COLD FRONT EXTENDING FROM NEAR 31N72W SW TO S FLORIDA...WHILE GENERALLY WEAK PRES IS ANALYZED ELSEWHERE. THIS FEATURE IS AGAIN PARTLY RESPONSIBLE FOR ATMOSPHERIC INSTABILITY...FURTHER INDUCED BY RIPPLES OF JET STREAM ENERGY...RIDING NEWD AHEAD OF THE GULF OF MEXICO DEEP LAYER TROUGH. WIDESPREAD SHOWER AND TSTM ACTIVITY ARE OVER MUCH OF THE AREA S OF 29N AND W OF 69W. GUSTY WINDS AND OCCASIONAL TO FREQUENT LIGHTNING STRIKES ARE POSSIBLE WITH THIS ACTIVITY. ASCAT DATA FROM AROUND 15 UTC THIS MORNING ALONG WITH BUOY REPORTS ARE SHOWING RELATIVELY LIGHT E-SE WINDS THROUGHOUT...EXCEPT FOR N-NE 15-20 KT BEHIND THE FRONT. SEAS ARE 2-3 FT...EXCEPT FOR 5-6 FT IN A NE SWELL E OF 68W AND 5-7 FT BEHIND THE FRONT. BUOY 41047 AT 27.5N71.5W AND BUOY 41046 AT 24N68W HAVE SEAS OF 3-5 FT IN A NE SWELL. BOTH THE GFS AND ECMWF 12 UTC MODEL RUNS WERE IN CLOSE AGREEMENT WITH THE POSITIONS OF THE COLD FRONT AT BOTH 12 AND 18 UTC TODAY. BASED ON THIS GUIDANCE WILL FORECAST THE FRONT TO REACH FROM NEAR 31N69W TO NEAR 26N75W WHILE SLOWING DOWN BY TONIGHT...AND CONTINUING AS A STATIONARY FRONT TO S FLORIDA. THE COLD FRONT PORTION THEN STALLS AND BEGINS TO WASH OUT THROUGH TUE NIGHT AS HIGH PRES BEHIND IT BUILDS S ACROSS THE AREA. THE N-NE WINDS OF 15-20 KT BEHIND IT DIMINISH TO 10-15 KT WHILE VEERING TO THE NE TONIGHT AND TUE...AND SHIFT FURTHER TO THE E THROUGH DAY 5. THE 5-7 FT SEAS IN THE NW PORTION SUBSIDE TO 3-5 FT TUE. SEAS ELSEWHERE WE BE THE SAME THROUGH DAY 5...EXCEPT FOR 5-6 FT IN THE EASTERN PORTION DUE TO A NE SWELL. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE ASCAT PASS FROM NEAR 15 UTC THIS MORNING SHOWED NE-E WINDS OF 20-25 KT IN THE S CENTRAL PORTION. ELSEWHERE BUOYS ARE SHOWING LIGHTER NE-E WINDS OF 10-15 KT...AND E 10 KT IN THE FAR WESTERN PORTION. SEAS ARE UP TO 8 FT IN THE S CENTRAL PORTION NEAR THE COAST OF S AMERICA...AND 4-6 FT ELSEWHERE EXCEPT FOR 2-3 FT IN THE WESTERN CARIBBEAN SEA. A TROPICAL WAVE IS ANALYZED IN THE FAR SW PORTION OF THE TROPICAL N ATLC ON THE 18 UTC PRELIMINARY ANALYSIS. THE COMBINATION OF THE WAVE AND AN UPPER LEVEL LOW TO ITS NW AT 17N63W IS RESULTING IN ENHANCED TSTM ACTIVITY ACROSS THE EASTERN PART OF THE CARIBBEAN...AND OVER MUCH OF THE TROPICAL N ATLC ZONES. THE WAVE IS MOVING W NEAR 15 KT...AND BASED ON THIS MOTION IT IS FORECAST TO REACH THE POSITION ALONG 62W/63W BY TUE MORNING...FROM JUST SE OF PUERTO RICO TO 10N68W WED MORNING ...FROM HISPANIOLA TO COLOMBIA BY THU MORNING AS IT BECOMES LESS DEFINED. SEAS AT BUOYS 41101 AT 15N56W...AND BUOY 41040 AT 14.5N53W HAVE LOWERED TO 5-7 FT. EXPECT THESE SEA CONDITIONS TO LOWER TO 3-5 FT BY THU AND CONTINUE TO SAT. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE