000 AGXX40 KNHC 231904 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT SUN SEP 23 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-E 10-15 KT THROUGHOUT...EXCEPT N-NE OVER THE NE PORTION OF THE GULF WHERE EVEN THE 1510 UTC ASCAT PASSED CONFIRMED THESE WINDS. COMBINED SEA HEIGHTS RANGE FROM 2-4 FT S OF 25N W OF 90W TO 1-2 FT ELSEWHERE. A RATHER WEAK PRES PATTERN REMAINS OVER THE AREA...EXCEPT IN THE NORTHERN PORTION WHERE STRONGER HIGH PRES IS ANALYZED. THE SURFACE ANALYSIS FROM THIS MORNING AS WELL AS THE PRELIMINARY 18 UTC ANALYSIS FROM THIS AFTERNOON STILL REVEAL A SURFACE TROUGH IN THE SW GULF FROM 24N97W TO 19N96W WITH A HIGH CENTER OF 1021 MB AT 21N97W. A PERSISTENT SURFACE TROUGH EXTENDS FROM S FLORIDA SW TO 21N89W...WHILE IN THE UPPER LEVELS PERSISTENT BROAD SCALE TROUGHING STRETCHING FROM THE EASTERN UNITED STATES SW TO THE NORTHERN GULF REMAINS IN PLACE. THE COMBINATION OF THE UPPER LEVEL TROUGH AND THE SURFACE TROUGHS WILL CONTINUE TO BRING ABUNDANT DEEP ATMOSPHERIC MOISTURE AND SCATTERED SHOWERS AND TSTMS OVER MUCH OF THE SE AND SW SECTIONS OF THE GULF THROUGH MON NIGHT...THEN BE MAINLY IN THE SE PART OF THE GULF TUE THROUGH WED BUT PERHAPS NOT AS SCATTERED AS PRESENTLY OBSERVED AS SHORTWAVE ENERGY DIVES SE INTO THE BROAD TROUGH HELPING TO NUDGE E OF THE GULF WED NIGHT INTO THU. AT THE SURFACE...A WEAK COLD FRONT PRESENTLY JUST ALONG THE FLORIDA PANHANDLE COAST WILL MOVES S TO VICINITY OF CENTRAL FLORIDA TONIGHT AND BECOME STATIONARY AS HIGH PRES BUILDS SWD OVER THE GULF BEHIND IT. THIS PROCESS WILL CAUSE THE FRONT TO WEAKEN FURTHER AND GRADUALLY WASH OUT THROUGH WED. WINDS BECOME NE-E 10-15 KT ACROSS MUCH OF THE ZONES OF THE NORTHERN AND CENTRAL GULF SUN NIGHT THROUGH TUE WITH A BRIEF INSTANCE OF N-NE WINDS OF 15 KT IN THE NE PART OF THE GULF SUN NIGHT AND MON BEFORE DIMINISHING TO 10-15 KT. WINDS BECOME NE-E 10-15 KT THROUGHOUT MUCH OF THE GULF DURING TUE THROUGH THU. SEAS REMAIN IN THE LOW RANGE THROUGH THE FORECAST PERIOD...EXCEPT FOR SEAS BUILDING SLIGHTLY TO 3-4 FT IN THE NE PART TONIGHT SUBSIDING TO 2-3 FT MON THROUGH FRI. THE TROUGH IN THE SW PART OF THE GULF WILL DISSIPATE AFTER ABOUT 48 HRS. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE PRELIMINARY 18 UTC SURFACE ANALYSIS HAS A SURFACE TROUGH EXTENDING FROM NEAR 31N74W SW TO A WEAK LOW OF 1016 MB ON THE TROUGH AT 29N77W. THE TROUGH RESUMES SW TO ACROSS S FLORIDA. THIS FEATURE IS PARTLY RESPONSIBLE FOR ATMOSPHERIC INSTABILITY... FURTHER INDUCED BY RIPPLES OF JET STREAM ENERGY...RIDING NEWD AHEAD OF THE GULF OF MEXICO UPPER TROUGH. RESULTANT SCATTERED SHOWERS AND TSTMS ARE ALONG AND WITHIN 90 NM SE OF THE TROUGH. GUSTY WINDS AND OCCASIONAL TO FREQUENT LIGHTNING STRIKES ARE POSSIBLE WITH THIS ACTIVITY. A WEAK COLD FRONT IS JUST BEGINNING TO EMERGE OFF THE NE FLORIDA COAST AND INTO THE FAR NW WATERS. ELSEWHERE WEAK HIGH PRES IS ANALYZED. BOTH ASCAT DATA AND BUOY REPORTS ARE SHOWING RELATIVELY LIGHT WINDS THROUGHOUT...MAINLY FROM THE NE IN DIRECTION. SEAS ARE 2-3 FT...EXCEPT FOR 4-6 FT IN A NE SWELL E OF 72W. BUOY 41047 AT 27.5N71.5W IS SHOWING 5-6 FT...AND BUOY 41046 AT 24N68W HAS 3-5 FT IN A NE SWELL. A COUPLE OF SHIP OBSERVATIONS BETWEEN THE SE BAHAMAS PUERTO RICO ALSO HAVE A NE SWELL OF 5-6 FT. LATEST RUN OF THE GLOBAL MODELS ARE IN REASONABLE AGREEMENT THAT COLD FRONT WILL REACH A POSITION FROM NEAR 31N76W TO S CENTRAL FLORIDA TONIGHT...THEN SLOWLY MOVES S THROUGH MON NIGHT FROM NEAR 31N71W TO THE NW BAHAMAS AND SE BAHAMAS AND BEGIN TO BECOME DIFFUSE AS HIGH PRES BUILDS BEHIND IT BUILDS S ACROSS THE AREA. THE UKMET MODEL RUN FROM 12 UTC IS A BIT FASTER THAN THE OTHER MODELS WITH THE FORECAST POSITION OF THE FRONT THROUGH TONIGHT BUT THEN SEEMS REASONABLE TO THE OTHER MODELS INTO MON NIGHT AT WHICH TIME THE FRONT IS FORECAST BY THE MODELS TO BECOME STATIONARY AND GRADUALLY THROUGH WED. MODELS IN AGREEMENT THAT WINDS BEHIND THE FRONT WILL BE FROM THE NW-N 10 TO 15 KT TONIGHT...THEN QUICKLY VEER AROUND TO THE NE EARLY MON AND INCREASE TO 15-20 KT OVER THE FAR NRN WATERS. THE WINDS THEN BECOME MORE ELY IN DIRECTION MON NIGHT THROUGH FRI AT 10-15 KT THROUGHOUT. LITTLE CHANGE WILL BE EXPECTED WITH SEAS INTO DAY 5 (FRI) WITH THE ONLY CHANGE EXPECTED IN THE NW PORTION MON NIGHT THROUGH TUE NIGHT WHERE SEAS ARE EXPECTED TO BUILD TO THE 4-6 FT RANGE...BUT THEN DIMINISH TO 3-5 FT THERE WED AND TO 2-4 FT THU AND FRI AS GENERALLY WEAK HIGH PRES BECOMES ESTABLISHED ACROSS THE AREA. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... GENTLE TO MODERATE TRADE WINDS PREVAIL ACROSS THE CARIBBEAN WATERS AND THE TROPICAL N ATLC WATERS...EXCEPT FOR FRESH NE-E WINDS IN THE S CENTRAL CARIBBEAN WATERS WHERE SEAS ARE UP TO 8 FT BASED ON A MORE DEFINITIVE WAVEWATCH MODEL CONSENSUS. SEAS ELSEWHERE ARE IN THE 3-5 FT RANGE...EXCEPT 2-3 FT BETWEEN 19N AND CUBA. SEAS ARE EXPECTED TO BUILD SLIGHTLY IN S CENTRAL CARIBBEAN OVER THE NEXT 24 TO 36 HRS. A TROPICAL WAVE HAS MOVED INTO THE FAR SE PORTION OF THE TROPICAL N ATLC AS OF EARLY THIS AFTERNOON. 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 20 KT...AND BASED ON THIS MOTION IT IS FORECAST TO REACH THE POSITION ALONG 60W/61W BY MON MORNING...FROM THE VIRGIN ISLANDS TO 10N65W BY TUE MORNING...THEN SHOULD BECOME LESS DEFINED AT THE SURFACE AS IT MOVES ACROSS THE CENTRAL CARIBBEAN WED THROUGH THU AND THE WESTERN CARIBBEAN FRI. SEAS OF 8-9 FT ARE BEING CURRENTLY REPORTED BY BUOYS 41101 AT 16N56W ...AND BUOY 41040 AT 14.5N53W. EXPECT THESE SEA CONDITIONS TO CONTINUE THROUGH AT LEAST MON MORNING BEFORE SUBSIDING. ACTIVE CONVECTION WILL PRECEDE THE WAVE AND LAG WITHIN ABOUT 240 NM E OF THE WAVE AS IT MOVES ACROSS THE EASTERN AND CENTRAL CARIBBEAN OVER THE NEXT 24-48 HRS. 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