000 AGXX40 KNHC 220927 AAA MIMATS MARINE WEATHER DISCUSSION...UPDATED NWS NATIONAL HURRICANE CENTER MIAMI FL 425 AM EST THU NOV 22 2012 UPDATE TO INCLUDE MENTION OF OSCAT DATA IN THE GULF OF MEXICO AND SW N ATLC SECTIONS 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... LATEST AND RECENT BUOY AND OIL RIG PLATFORM OBSERVATIONS SHOW N-NE 10-15 KT WINDS OVER JUST ABOUT THE ENTIRE AREA...EXCEPT FOR THE FAR NW PORTION WHERE WINDS ARE LIGHT AND VARIABLE AT 5-10 KT. THE 0340 UTC ASCAT PASS SHOWED NE WINDS OF 10-15 KT ACROSS THE MIDDLE PORTION OF THE GULF...WHILE THE OSCAT PASS FROM NEAR 06 UTC SHOWED N-NE WINDS OF 15-20 KT IN THE EASTERN PART OF THE GULF. LATEST SURFACE ANALYSIS SHOWS A 1024 MB HIGH CENTER OVER NORTHERN LOUISIANA WITH THE ASSOCIATED RIDGE STRETCHING SW HIGH PRES COVERING MAINLY THE WESTERN HALF OF THE GULF. THE BUOY OBSERVATIONS ARE REPORTING SEA HEIGHTS OF 3-4 FT... EXCEPT FOR A SMALL POCKET OF HIGHER SEAS OF 2-3 FT N OF ABOUT 27N...AND 3-5 FT S OF 27N. WATER VAPOR SATELLITE IMAGERY VIVIDLY SHOWS THE SHORTWAVE TROUGH THAT EARLIER PAST ACROSS THE NE GULF NOW PULLING E AWAY FROM THE AREA OVER N/CENTRAL FLORIDA. SUBSIDENCE ALOFT IN ITS WAKE IS NOTED OVER THE E GULF...AND MOST OF THE MIDDLE GULF ZONES. AS A RESULT...DRY STABLE CONDITIONS EXIST AT THE SURFACE DEPICTED BY THE CLEAR TO MOST CLEAR SKIES ACROSS JUST ABOUT THE ENTIRE E GULF. UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED THIN CLOUDS IS STREAMING EASTWARD FROM THE EASTERN PACIFIC ENE OVER A HIGHLY AMPLIFIED RIDGE NOW LOCATED OVER THE WESTERN GULF ...AND STRETCHING NNE TO THE UPPER GREAT LAKES REGION OF THE U.S. THIS RIDGE IS FORECAST TO SHIFT EASTWARD DURING THE NEXT 24-36 HRS WITH THE SURFACE RIDGE ALSO TRANSLATING EASTWARD. THIS WILL ALLOW FOR AN UPPER TROUGH...CURRENTLY WELL NW OF THE REGION...TO DIVE SE AND PUSH THE COLD FRONT INTO THE FAR NORTHERN GULF AND COASTAL PLAINS FROM THE FLORIDA PANHANDLE TO FAR SOUTHERN TEXAS FRI NIGHT INTO SAT. LATEST GFS/ECMWF/NOGAPS 10M WIND GUIDANCE INDICATES THAT STRONG HIGH PRES BEHIND THIS FRONT WILL INDUCE A PRES GRADIENT OVER THE FAR NW AND N CENTRAL WATERS ON SAT RESULTING IN N-NE 20 KT WINDS BEHIND THE FRONT. THIS GRADIENT THEN RELAXES DURING SAT AS THE FRONT BEGINS TO WEAKEN WHEN REACHING FROM NEAR TAMPA FLORIDA TO SW GULF ALLOWING FOR N WINDS TO DIMINISH TO 10-15 KT. THE FRONT CONTINUES TO WEAKEN AS IT MOVES TO THE FAR SE GULF WATERS LATE SAT INTO SUN...WITH ITS WESTERN SEGMENT LIFTING BACK N AS A WARM FRONT AS HIGH PRES SHIFTS EASTWARD ACROSS THE SE U.S. THIS WILL ALLOW FOR WINDS ACROSS THE GULF TO BECOME E-SE AROUND 10 KT...EXCEPT RETURN FLOW OF SE-S 10-15 KT SETS UP OVER THE FAR WESTERN GULF. THESE WINDS INCREASE TO 15-20 KT LATE SUN AND MON IN THE CONTINUING RETURN FLOW. THE SEAS OF 5-6 FT IN THE SE PART OF THE GULF ARE FORECAST TO SUBSIDE TO 3-5 FT FRI...TO 2-4 FT SAT THROUGH MON. SEAS BEHIND THE FRONT ARE FORECAST USING THE GRIDDED WWIII GUIDANCE TO BUILD TO AROUND 6 FT...THEN SUBSIDE TO 3-4 FT SAT NIGHT AND SUN. BY MON SEAS WILL BE LOW...IN THE 3-4 FT RANGE W OF 91W...EXCEPT 2-3 FT IN THE SW GULF AND 5-6 FT IN THE FAR WESTERN GULF WITH THE SLY RETURN FLOW OF 15-20 KT. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE HIGH RESOLUTION ASCAT SWATH FROM 0156 UTC LAST NIGHT REVEALED N-NE WINDS OF 10-15 KT OVER THE FAR WRN CARIBBEAN N OF 15N...AND HIGHER WINDS FROM THE NW-N AT 20-25 KT IN THE FAR SW PORTION FROM ABOUT 11N TO 15N AND W OF 81W. A 0156 UTC ASCAT PASS SHOWED E-SE WINDS OF 10-15 KT OVER THE EASTERN PART OF THE SEA S OF 15N AND SE-E WINDS OF 5-10 KT N OF 15N. SEA STATE...SEAS RANGE FROM 3-5 FT ACROSS MOST OF THE CARIBBEAN EXCEPT FOR 2-3 FT NE OF A LINE FROM THE WESTERN TIP OF CUBA TO TRINIDAD AND TOBAGO. A SMALL POCKET OF 6-8 FT SEAS IS CONFINED TO THE FAR W CARIBBEAN IN THE AREA OF NW-N 20-25 KT WINDS. THE CURRENT SYNOPTIC PATTERN WITH COMPLEX LOW PRES AND ASSOCIATED FRONTAL BOUNDARIES N OF THE AREA CONTINUES TO ALLOW FOR THE RELATIVE ELY LIGHT WIND CONDITIONS TO REMAIN ACROSS ALL ZONES EXCEPT IN THE FAR SW CARIBBEAN WHERE THE PRES DIFFERENCE BETWEEN HIGH PRES SURGING S FROM THE GULF OF MEXICO...AND LOWER PRES IN THE SW CARIBBEAN AND OVER COLOMBIA MAINTAINS THE SMALL POCKET OF NW-N WINDS OF 20-25 KT THERE. LITTLE CHANGE IS EXPECTED WITH THIS PATTERN THROUGH TONIGHT... THEN STRONGER HIGH PRES FROM THE GULF OF MEXICO BEGINS TO SURGE SE OVER THE WESTERN CARIBBEAN BEGINNING FRI WITH RESULTANT PRES GRADIENT INCREASING N WINDS TO 20 KT MUCH OF THE WESTERN CARIBBEAN SEA...WITH THE CURRENT POCKET OF NW-N 20-25 KT WINDS IN THE SW CARIBBEAN SEA INCREASING IN AREAL COVERAGE. SEAS BUILD TO 4-6 FT IN THE WESTERN CARIBBEAN FRI AND SAT...EXCEPT FOR HIGHER SEAS OF 6-8 FT IN THE SMALL POCKET OF NW-N 20-25 KT WINDS. THE GRADIENT ONLY WEAKENS SLIGHTLY IN THE NW CARIBBEAN MON ALLOWING FOR SEAS TO SUBSIDE A LITTLE THERE...BUT CONTINUE AT 4-6 FT ELSEWHERE IN THE WESTERN CARIBBEAN SEA...WITH THE EXCEPTION BEING THE 6-8 FT SEAS IN THE SW CARIBBEAN. OF MORE SIGNIFICANCE...THE PRES GRADIENT IS FORECAST BY THE MODELS TO TIGHTEN OVER THE REMAINDER OF THE SEA SUN AND MON AS ATLC HIGH PRES STRENGTHENS. THIS WILL BRING INCREASING NE-E TRADES OVER MUCH OF THE CENTRAL AND EASTERN CARIBBEAN WITH SEAS BUILDING TO 7-9 FT. THE LIGHT WIND CONDITIONS CURRENTLY NOTED ACROSS THE TROPICAL N ATLC ARE FORECAST BY THE GFS/ECMWF TO CONTINUE THROUGH MON. THE SOUTHERN PORTION OF A WEAKENING COLD FRONT WILL MOVE INTO THE NW CORNER OF THE TROPICAL N ATLC FRI...AND REACH FAR THE NE WATERS BY LATE SAT WHILE DISSIPATING. WINDS WILL BE LIGHT NE-E BEHIND THE FRONT...AND LIGHT SE-S AHEAD OF IT. ELSEWHERE ACROSS THE TROPICAL N ATLC WINDS WILL REMAIN NE-E AT 10-15 KT THROUGH MON. SEAS OF 3-5 FT OVER TROPICAL N ATLC WILL CONTINUE THROUGH TONIGHT...THEN BUILD TO 4-6 FT OVER MUCH OF THE TROPICAL N ATLC FRI AND TO 5-7 FT SAT THROUGH MON. A NW SWELL MOVING INTO THE FAR NORTHERN WATERS SAT WILL PRODUCE 6-8 FT SEAS THERE INTO SUN AFTERNOON BEFORE DIMINISHING TO 5-7 FT MON. SATELLITE IMAGERY SHOWS A PERSISTENT AREA OF SCATTERED SHOWERS AND TSTMS CONFINED TO THE SW AND FAR S CENTRAL PORTIONS OF THE SEA. THIS ACTIVITY IS EXPECTED TO CONTINUE THROUGH AT LEAST SAT. SW N ATLC W OF 55W... THE PRELIMINARY 0600 UTC SURFACE ANALYSIS HAS A DEVELOPING COLD FRONT EXTENDING FROM 31N68W TO 29N74W AND NW TO 31N80W. THE 0200 UTC HIGH RESOLUTION ASCAT PASS NOTED NW-N 15-20 KT WINDS S OF OF THE FRONT...AND MUCH STRONGER NW-N WINDS OF 20-25 KT N OF THE FRONT. THE 0414 OSCAT PASS ALSO INDICATED STRONG N WINDS OVER THE FAR NW WATERS. THESE WINDS WERE SHOWN WITH SPEEDS OF 25-30 KT N OF ABOUT 28N BETWEEN 76W-79W. BUOYS IN THE NW PORTION ARE REPORTING COMBINED SEAS OF 8-12 FT. OBSERVED SEAS ELSEWHERE ARE IN THE 4-6 FT RANGE IN A NE SWELL ...EXCEPT FOR SEAS OF 7-9 FT N OF 26N AND 1-2 FT SW OF BAHAMAS AND 4-6 FT STRAITS OF FLORIDA. THE COLD FRONT WILL SWEEP ACROSS THE AREA THROUGH FRI AND MERGE WITH A DISSIPATING OLD BOUNDARY IN THE FAR SE WATERS. GLOBAL MODELS ARE CONSISTENTLY DEPICTING THAT STRONG HIGH PRES BEHIND THE FRONT WILL BUILD SE OVER THE ENTIRE BASIN THROUGH FRI...AND WEAKEN MOST ZONES ON SAT. THE GFS/ECMWF/UKMET MODEL GUIDANCE CONSISTENTLY SUGGEST THAT A VERY TIGHT PRES GRADIENT SETS UP OVER THE NE WATERS ON FRI WITH NW-N WINDS OF 20-30 KT. BY LATE FRI AND INTO SAT...THE RESPONSIBLE PRES GRADIENT LIFTS NE AND THE NW-N 20-30 KT WINDS DIMINISH TO 20-25 KT. BY THIS TIME THE MODELS ALSO DEPICT THAT THE NEXT COLD FRONT ENTERS THE FAR NW WATERS. THIS FRONT WILL RACE EASTWARD ACROSS THE NORTHERN AND CENTRAL WATERS DURING SAT AND SUN FOLLOWED BY NW-N WINDS OF 20-25 KT UNDER STRONG HIGH PRES THAT BUILDS SE IN ITS WAKE. THESE WINDS QUICKLY DIMINISH TO 15-20 KT OVER THE WESTERN AND CENTRAL PORTIONS LATE SAT...AND NLY AT 10-15 KT IN THE EASTERN PORTION LATE SUN. THE WINDS IN THE WESTERN PORTION VEER TO THE NE-E AND CONTINUE TO DIMINISH TO 10-15 KT SUN AND MON WITH LIGHT N WINDS OF 5-10 KT NW OF THE BAHAMAS SUN...VEERING TO THE E MON. FOR SEAS...THE SEAS OF 8-12 FT IN THE NW PORTION WILL SPREAD THROUGHOUT THE BASIN WHILE BUILDING TO 15 OR 16 FT OVER THE N CENTRAL AND NE PORTIONS FRI AND SAT...AND WHILE BEING IN THE RANGE OF 8-13 FT ELSEWHERE TO THE N AND NE OF THE BAHAMAS. BEHIND THE SECOND COLD FRONT...SEAS ARE NOT EXPECTED TO BUILD MORE THAN THE HIGH VALUES ALREADY IN PLACE WITH THE FIRST COLD FRONT SWEEPING ACROSS THE BASIN. BY SUN ONCE THE SECOND COLD FRONT EXITS THE NE WATERS...THE STRONG HIGH PRES IN ITS WAKE WEAKENS LATE SUN AND MON WITH SEAS SUBSIDING TO 6-9 FT IN A NW SWELL OVER THE NE AND CENTRAL PORTIONS...AND TO 3-5 FT ELSEWHERE EXCEPT 2-3 FT SW OF BAHAMAS. 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