000 AGXX40 KNHC 220758 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 255 AM EST THU NOV 22 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 AT 5-10 KT. THE 0340 UTC ASCAT PASS SHOWED NE WINDS OF 10-15 KT ACROSS THE MIDDLE PORTION 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 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. THE WESTERN PORTION OF THE FRONT THEN LIFTS BACK N AS A WARM FRONT LATE SAT AND SUN AS HIGH PRES MOVES E ACROSS THE SE U.S. THIS WILL ALLOW 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. WINDS IN THE FAR WESTERN GULF INCREASE TO 15-20 KT FROM THE SE TO S LATE SUN AND MON IN THE RETURN FLOW THAT SETS UP THERE. 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 FAR SW GULF AND 5-6 FT IN THE FAR WESTERN UNDER THE 15-20 KT S WIND RETURN FLOW. 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 ARE 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 PACKET OF NW-N 20-25 KT WINDS. THEN GRADIENT ONLY WEAKENS SLIGHTLY IN THE NW CARIBBEAN MON ALLOWING FOR SEAS TO SUBSIDE A LITTLE IN THE FAR NW PORTION BUT CONTINUE AT 4-6 FT ELSEWHERE IN THAT PART OF THE SEAS...WITH SEAS OF 6-8 FT IN THE SW CARIBBEAN. OF MORE SIGNIFICANCE...THE PRES GRADIENT TIGHTENS 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 OVER THOSE PORTIONS OF THE SEA. THE LIGHT WIND CONDITIONS CURRENTLY NOTED ACROSS THE TROPICAL N ATLC ARE FORECAST BY THE GFS/ECMWF TO CONTINUE THROUGH SUN. THE SOUTHERN PORTION OF WEAKENING COLD FRONT WILL MOVE INTO THE NW CORNER OF THE TROPICAL N ATLC FRI...AND REACH FAR 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 DAY 5. 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. 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 0200 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