000 AGXX40 KNHC 210800 RRA MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 255 AM EST WED NOV 21 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... 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 AND IN THE FAR WESTERN PORTION OF THE SW GULF WHERE WINDS ARE N-NE AT 10-15 KT. THE 0400 UTC ASCAT PASS NICELY CAPTURED THE WINDS IN THE FAR WESTERN PORTION OF THE GULF...AND THE 0218 UTC ASCAT ALSO CAPTURED THE N-NE 10-15 KT EASTERN GULF WINDS. THE PRELIMINARY 6 UTC SYNOPTIC SCALE ANALYSIS SHOWS HIGH PRES COVERING MAINLY THE WESTERN HALF OF THE GULF. AN ASSOCIATED 1022 MB HIGH CENTER IS ANALYZED JUST NW OF TAMPICO MEXICO. A TROUGH MOVING W 15-20 KT IS OVER THE SW GULF EXTENDING FROM NEAR 2N495W SE TO 19N92W...AND ITS SUBTLE CYCLONIC WIND SHIFT WAS ALSO NOTED IN THE 0400 UTC ASCAT PASS. 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 25N...AND 4-5 FT S OF 25N EXCEPT IN THE SE PART WHERE HIGHER SEAS OF 5-7 FT CREATED BY A PROLONGED NLY FETCH ARE NOTED. SATELLITE IMAGERY SHOWS SCATTERED TO BROKEN LOW LEVEL CLOUDS ASSOCIATED WITH THE AFOREMENTIONED TROUGH MOVING WITH POSSIBLE ISOLATED SHOWERS S OF 24N AND BETWEEN 92W AND 97W. BROKEN TO SCATTERED LOW CLOUDS MOVING S WITH POSSIBLE ISOLATED SHOWERS ARE THE EASTERN GULF S OF 26N AND E OF 85W. WATER VAPOR SATELLITE IMAGERY SHOWS THAT BROAD MID/UPPER LEVEL RIDGING OBSERVED YESTERDAY OVER THE MIDDLE AND EASTERN GULF HAS SHIFTED EAST TO E OF FLORIDA...AS A SHORTWAVE TROUGH CLIPS THE NE PORTION. WITH DRY SUBSIDENT CONDITIONS ALOFT OVER THAT PART OF THE GULF...THE TROUGH WILL HAVE LITTLE INFLUENCE ON WEATHER CONDITIONS. UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED THIN CLOUDS IS STREAMING EASTWARD FROM THE EASTERN PACIFIC NE OVER A HIGHLY AMPLIFIED RIDGE LOCATED OVER NRN MEXICO...THEN EASTWARD TO THE NW GULF AND TO NEAR 90W WHERE IT DISSIPATES IN THE DRY ALOFT. WITH THE MID/UPPER LEVEL RIDGING HAVING SHIFTED E OF THE AREA...THE SURFACE RIDGE OVER THE WESTERN HALF WILL WEAKEN THROUGH BUT BE REPLACED BY ANOTHER AREA OF HIGH PRES THAT BUILDS SE ACROSS THE SE U.S. AND THE GULF THROUGH THU AS MODELS DEPICT. AN UPPER TROUGH WILL THEN DRIVE THE NEXT 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 THE 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. HOWEVER...THE GRADIENT BEHIND THEN RELAXES DURING SAT AS IT BEGINS TO WEAKEN WHEN REACHING FROM NEAR TAMPA FLORIDA TO SW GULF ALLOWING FOR N WINDS TO DIMINISH TO 15-20 KT. THE FRONT CONTINUES TO WEAKEN AS IT MOVES TO THE FAR SE GULF WATERS LATE SAT INTO SUN. HIGH PRES N OF THE FRONT SLIDES EASTWARD OVER THE SE U.S. ALLOWING FOR WINDS ACROSS THE GULF TO BECOME E-SE AROUND 10 KT...EXCEPT RETURN FLOW OVER THE FAR WESTERN GULF COMPOSED OF AROUND 10-15 KT. THE SEAS OF 5-7 FT IN THE SE PART OF THE GULF ARE FORECAST TO SUBSIDE TO 4-6 FT THU...TO 3-5 FT FRI...TO 2-3 FT SAT AND SUN. SEAS BEHIND THE FRONT ARE FORECAST USING THE GRIDDED WWIII GUIDANCE TO BUILD TO AROUND 6 OR 7 FT IN THE FAR WESTERN GULF BEFORE SUBSIDING TO 3-4 FT SAT NIGHT AND SUN. SEAS ELSEWHERE BEHIND THE FRONT ARE EXPECTED TO BUILD TO 4-6 FT BEFORE SUBSIDING TO 2-3 FT SUN. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE HIGH RESOLUTION ASCAT SWATH FROM 0218 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 14N AND W OF 82W. A 0216 UTC ASCAT PASS SHOWED NE-E WINDS OF 10-15 KT OVER A PORTION OF THE EASTERN PART OF THE SEAS...AND AN 0038 UTC ASCAT PASS REVEALED ELY WINDS OF 10 KT OVER EASTERN PORTION OF THE TROPICAL N ATLC ZONES. 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 NEAR GRENADA. A SMALL POCKET OF 6-8 FT ARE CONFINED TO THE FAR W CARIBBEAN IN THE AREA OF NW-N 20-25 KT WINDS. THE CURRENT SYNOPTIC PATTERN WITH FRONT AND TROUGHS PASSING TO THE N OF THE CARIBBEAN IS ALLOWING 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 UNTIL THE WEEKEND WHEN STRONGER HIGH PRES FROM THE GULF OF MEXICO AGAIN SURGES SE OVER THE WESTERN CARIBBEAN WITH A 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 AROUND 7 FT IN THE WESTERN CARIBBEAN FRI AND SAT...AND STAY THE LIGHT WIND CONDITIONS CURRENTLY NOTED ACROSS THE TROPICAL N ATLC ARE FORECAST BY THE GFS/ECMWF TO HOLD THROUGH THE PERIOD... BUT VEER TO THE SE-S AT 5-10 IN THE NORTHERN WATERS LATE FRI AND SAT IN RESPONSE TO THE ATLC COLD FRONTS AND TROUGHS THAT ARE FORECAST TO MOVE OVER THAT PORTION OF THE TROPICAL N ATLC. THESE WINDS THEN BECOME NE AT 10-15 KT DURING SUN WITH THE WEAKENING OF THESE FEATURES AS HIGH PRES BUILDS SE OVER THE NORTHERN TROPICAL N ATLC. SEAS OF 3-5 FT OVER TROPICAL N ATLC WILL TODAY AND CONTINUE THROUGH THU NIGHT...THEN BUILD TO 4-6 FT OVER MUCH OF THE TROPICAL N ATLC FRI AND SAT TO 5-7 FT SAT AND SUN WITH A NW SWELL MOVING INTO THE FAR NORTHERN WATERS. SATELLITE IMAGERY HAS BEEN HIGHLIGHTING...AND IS CURRENTLY SHOWING AMPLE DEEP ATMOSPHERIC MOISTURE CONFINED TO THE SW SECTION OF THE CARIBBEAN. THIS MOISTURE IS IN THE FORM OF MULTILAYERED CLOUDS WITH SCATTERED SHOWERS AND TSTMS AIDED BY A PERSISTENT UPPER TROUGH IN THE NW CARIBBEAN THAT EXTENDS SWWD FROM CENTRAL CUBA TO GULF OF HONDURAS. THIS ACTIVITY IS EXPECTED TO CONTINUE THROUGH AT LEAST SAT. SW N ATLC W OF 55W... THE PRELIMINARY 0600 UTC SURFACE ANALYSIS HAS A WEAKENING COLD FRONT EXTENDING ALONG 30N BETWEEN 65W AND 76W WITH TROUGH TO ITS S ALONG 28N BETWEEN 68W AND 76W. THE 02200 UTC HIGH RESOLUTION ASCAT PASS NOTED GENERALLY LIGHT NW-N WINDS S OF OF THESE FEATURES...AND N WINDS OF 20-25 KT BEHIND THE FRONT. BUOYS IN THE NW PORTION ARE REPORTING COMBINED SEAS OF 7-12 FT. OBSERVED SEAS ELSEWHERE ARE IN THE 4-6 FT RANGE IN A NE SWELL. THE COLD FRONT WILL THEN SWEEP ACROSS THE AREA THROUGH FRI AFTER MERGING WITH THE PERSISTENT SURFACE TROUGH DESCRIBED ABOVE. 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 SAT AS YET ANOTHER COLD FRONT ENTERS THE FAR NW WATERS. THE N WINDS OF 20-25 KT BEHIND THE COLD FRONT WILL SPREAD SE AND E THROUGH FRI UNDER STRONG HIGH PRES. THESE WINDS ARE FORECAST TO DIMINISH TO 15-20 KT OVER THE WESTERN AND CENTRAL PORTIONS FRI AS THE HIGH PRES WEAKENS. HOWEVER IN THE NE PORTION OF THE EASTERN ZONES THE PRES GRADIENT WILL BE VERY TIGHT THU AND FRI. THE SEAS OF 7-12 FT IN THE NW PORTION WILL BE FURTHER REINFORCED BY ANOTHER BATCH OF LARGE N SWELLS THAT FOLLOWS IN BEHIND THE SECOND FRONT WITH THE HIGH PRES SURGE. A COMPLEX LOW PRES GYRE JUST N OF THE AREA FROM WHICH THE FRONT WILL BE TIED TO WILL CONSOLIDATE INTO ONE LOW BY FRI...AND WHILE DEEPENING. MODELS DIFFER ON EXACT PRES AND FORECAST PSNS OF THE LOW. THE MAIN THING TO NOTE IS THAT THE GFS MODEL GUIDANCE TO INDICATE THAT A VERY TIGHT PRES GRADIENT SETS UP OVER THE NE WATERS ON FRI WITH NW-N WINDS OF UP TO 30 KT...WHILE THE ECMWF ALSO DEPICTS NW-N WINDS OF 25-30 KT FOR THAT SAME PART OF THE BASIN ON FRI. THE GFS CARRIES A DEEPER LOW N OF THE AREA...WHILE THE ECMWF IS WEAKER AND FURTHER S WITH THE LOW. I AM THINKING THAT THE GFS WINDS MAY BE TOO HIGH FOR FRI ACROSS THAT PORTION OF THE FORECAST WATERS. WILL LEAN CLOSER TO THE ECMWF/UKMET FOR NOW AND FORECAST W-NW WINDS OF 20-30 KT FOR THE NE ZONE ON FRI. BY LATE FRI AND INTO SAT...THE RESPONSIBLE PRES GRADIENT LIFTS NE AND THE STRONG WINDS DIMINISH TO NW-N AT 15-20 KT OVER THE NE WATERS. FOR SEAS...THE SEAS OF 8-11 FT IN THE WRN PORTION N OF THE BAHAMAS WILL BE FURTHER REINFORCED BY ANOTHER BATCH OF LARGE N SWELLS THAT FOLLOWS IN BEHIND THE SECOND FRONT WITH THE HIGH PRES SURGE AS DESCRIBED ABOVE. IN REFERENCE TO THE CENTRAL AND NE PORTIONS OF THE BASIN MAX HEIGHTS ARE FORECAST BY THE GRIDDED NOAA III WAVEWATCH GUIDANCE AND TO NOT AS LARGE AN EXTENT THE ECMWF WAVE GUIDANCE TO BUILD TO HIGH LEVELS (POSSIBLY TO 16 OR 17 FT) OVER THE N CENTRAL AND NE WATERS THU AND SPREAD SSE ACROSS MUCH OF THE CENTRAL AND EASTERN WATERS FRI AND SAT. BY SAT THE SEAS SUBSIDE TO 13 FT IN THE NE PORTION...TO 8-11 FT ELSEWHERE TO THE NE OF THE BAHAMAS...AND TO 6-9 FT IN A NW SWELL IN THE FAR NW PORTION. ON SUN N WINDS WILL BE RATHER LIGHT OVER MOST OF THE AREA...EXCEPT FOR NW WINDS OF 20-25 KT IN THE NE PART. SEAS WILL BE IN THE 8 TO 10 FT IN A NW AND N SWELL N OF ABOUT 27N...EXCEPT TO 12 FT IN THE FAR NE CORNER. SEAS ELSEWHERE WILL BE 6-8 FT IN A NW-N SWELL AND 3-5 FT SW OF THE 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