000 AGXX40 KNHC 180755 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 250 AM EST SUN NOV 18 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 NE-E WINDS OF 10-15 KT W OF 91W...AND NE WINDS OF 15-20 KT E OF 91W. THE ASCAT PASS FROM 0332 UTC LAST NIGHT CAPTURED THE MOST OF THE E GULF WINDS...BUT ALSO SHOWED A SWATH OF NE 20 KT WINDS CONFINED TO THE FAR SRN PORTION OF THE E GULF S OF 25N...AND ALSO E OF A LINE FROM PENSACOLA FLORIDA TO 25N85W. THE NE GULF BUOYS ARE REPORTING SUSTAINED NE 20 KT WINDS. THE PRELIMINARY 06 UTC SYNOPTIC SCALE ANALYSIS FEATURES A STRONG HIGH PRES RIDGE THAT STRETCHES FROM A VERY STRONG HIGH CENTER OVER MAINE SW TO THE WESTERN GULF. THE INTERACTION BETWEEN THE RIDGE AND BROAD LOW PRES E OF FLORIDA IS ALLOWING FOR THE TIGHTER PRES GRADIENT TO PERSIST OVER THE MUCH OF THE E GULF. THE BUOY OBSERVATIONS ARE REPORTING SEA HEIGHTS OF 3-5 FT... EXCEPT FOR A SMALL POCKET OF HIGHER SEAS OF 5-7 FT IN THE SRN PORTION OF THE E GULF WITH THE NE 20 KT WINDS...AND MUCH LOWER SEAS OF 2-3 FT IN THE FAR NW PART. IN THE ADDITION TO THE RIDGE MENTIONED ABOVE...THE PRELIMINARY 06 UTC SYNOPTIC ANALYSIS HAS A WEAK TROUGH OVER THE FAR SW GULF ALONG A PSN FROM JUST NE OF TAMPICO SE TO VERACRUZ. SATELLITE IMAGERY SHOWS A SOLID BANK OF BROKEN TO OVERCAST LOW/MID LEVEL CLOUDS OVER THE SW GULF W OF A LINE FROM JUST S OF BROWNSVILLE TEXAS TO 19N93W. ISOLATED SHOWERS ARE POSSIBLE WITH THESE CLOUDS. THE WATER VAPOR SATELLITE IMAGERY DEPICTS BROAD UPPER TROUGHING THAT EXTENDS FROM CAROLINAS SW TO 26N85W AND TO THE CENTRAL YUCATAN PENINSULA. MODERATE TO STRONG SUBSIDENCE ALOFT IS ASSOCIATED WITH THE TROUGH MAINTAINING RATHER DRY AND STABLE ATMOSPHERIC CONDITIONS OVER THE E GULF...WITH THE ONLY EXCEPTION BEING A SPEED MAX CROSSING THE BASE OF THE TROUGH OVER THE FAR SRN PORTION OF THE E GULF. AT THE SURFACE THIS WHERE A TROUGH LIES FROM THE WESTERN STRAITS OF FLORIDA SW TO JUST N OF WESTERN CUBA. THESE FEATURES ARE PRODUCING PATCHES OF LOW LEVEL MOISTURE IN THE FORM OF SCATTERED SHOWERS AND ISOLATED WEAK TSTM CELLS PRIMARILY S OF 26N E OF 86W. OTHER PATCHES OF LOW LEVEL MOISTURE BRINGING BROKEN LOWS WITH LIGHT RAIN AND ISOLATED SHOWERS ARE OVER THE REMAINDER OF THE E GULF...AND OVER PARTS OF THE MIDDLE GULF. THE BROAD UPPER LEVEL TROUGH IS FORECAST TO SWING E OF THE AREA TONIGHT THROUGH MON...FOLLOWED BY LARGE AMPLITUDE UPPER LEVEL RIDGING. THIS TRANSLATES TO OVERALL LITTLE CHANGES TO PRESENT OBSERVED CONDITIONS THROUGHOUT. THE NE 20 KT WINDS IN THE E GULF WILL DIMINISH TO 15 KT MON AS THE RIDGE WEAKEN SOME...AND THE AREA OF LOW PRES E OF FLORIDA LIFTS N. SEAS WILL BE ABOUT 3-5 FT MON THROUGH MOST OF WED...EXCEPT FOR 5-6 FT IN THE SRN PORTION OF THE E GULF. HOWEVER...MODELS FORECAST HIGH PRES TO STRENGTHEN OVER THE MID-WEST LATE TUE THROUGH THU WHILE MOVING SE AND THEN E. THIS WILL DRIVE A DRY COLD FRONT...OR SURGE OF NLY FLOW ACROSS THE E PART OF THE GULF INCREASING THE NLY WINDS THERE ONCE AGAIN TO 15-20 KT. WITH THIS SURGE SEAS ARE EXPECTED TO BUILD TO 7 OR 8 FT IN THE CENTRAL AND SRN PORTIONS OF THE E GULF WED AND THU. SEAS ELSEWHERE WILL BE IN THE 3-5 FT RANGE LATE WED AND THU. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE HIGH RESOLUTION ASCAT PASS FROM 0320 UTC LAST NIGHT REVEALED NLY WIND FLOW OF 10-15 KT OVER THE NW CARIBBEAN...AND HIGHER WINDS OF 20-25 KT S OF 16N W OF 81W. THE PRES GRADIENT IS TIGHTER ACROSS THE SW CARIBBEAN DUE TO THE PRES DIFFERENCE BETWEEN HIGH PRES FROM THE GULF OF MEXICO THAT EXTENDS TO THE NW CARIBBEAN SEA...AND A WEAK LOW PRES OF 1010 MB JUST NW OF COLOMBIA. ANOTHER ASCAT PASS FROM 0140 UTC SHOWED LIGHT NE-E WINDS OVER THE CENTRAL PART OF THE CARIBBEAN AS WELL AS OVER THE CENTRAL AND SRN HALF OF THE TROPICAL N ATLC WITH E WINDS OF 15-20 KT IN THE NRN HALF. SEA STATE...SEAS RANGE FROM 3-4 FT ACROSS MOST OF THE CARIBBEAN EXCEPT FOR 2-3 FT N OF ABOUT 17N...AND A SMALL POCKET OF 6-8 FT IN THE FAR SW CARIBBEAN WHERE THE 20-25 KT N WINDS ARE NOTED. THE CURRENT SYNOPTIC PATTERN IS FORECAST BY MODELS TO REMAIN IN PLACE THROUGH LATE TUE NIGHT. THEREAFTER...STRONGER HIGH PRES SURGES S FROM THE GULF OF MEXICO TO OVER THE WESTERN CARIBBEAN WED AND THU BRINGING INCREASING N WINDS OF 20 KT MUCH OF THE NW CARIBBEAN WATERS WITH SEAS BUILDING TO AROUND 7 FT. THE N 20-25 KT WINDS OVER A PORTION OF THE SW CARIBBEAN WILL VARY LITTLE...IF AT ALL...THROUGH DAY 5. THE 15-20 KT E WINDS OVER THE NORTHERN PART OF THE TROPICAL N ATLC ARE FORECAST BY THE MODELS TO BEGIN TO DIMINISH TO 10-15 KT TONIGHT AND HOLD THROUGH DAY 5 WHILE VEERING TO THE SE-S AS THE ATLC TROUGH MOVES E. LONG PERIOD NE SWELLS THERE RESULTING IN COMBINED SEAS OF 9 FT ARE FORECAST BY THE GRIDDED WWWIII GUIDANCE TO SUBSIDE TO 7 FT MON...TO 6 FT TUE AND TO 5 FT WED AND THU. SATELLITE IMAGERY HAS BEEN HIGHLIGHTING...AND IS CURRENTLY SHOWING AMPLE DEEP ATMOSPHERIC MOISTURE CONFINED TO THE SW AND CENTRAL PORTION OF THE CARIBBEAN AND ALSO ACROSS THE CENTRAL CARIBBEAN SEA. THIS MOISTURE IS IN THE FORM OF MULTILAYERED CLOUDS WITH SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH UPPER LEVEL DIFFLUENCE E OF LARGE UPPER TROUGH OVER THE NW CARIBBEAN...AND CONFLUENT FLOW FOUND IN THE LOWER LEVELS. CONVECTION IS FURTHER ENHANCED ALONG AND JUST OFFSHORE NW COLOMBIA DUE TO WEAK SURFACE LOW PRES THERE ALONG WITH ALREADY PRESENT DEEP ATMOSPHERIC MOISTURE. SW N ATLC W OF 55W... THE PRELIMINARY 0600 UTC SURFACE ANALYSIS HAS A WEAK 1016 MB LOW JUST N OF THE AREA AT 32N78W WITH A STATIONARY FRONT EXTENDING FROM IT SSW TO THE NW BAHAMAS. A LARGE TROUGH EXTENDS FROM E OF THE AREA AT 30N64W SW TO NEAR 21N70W. SATELLITE IMAGERY SHOWS ABUNDANT DEEP ATMOSPHERIC MOISTURE WITH SCATTERED SHOWERS AND TSTMS CONTINUING ACROSS MOST OF THE CENTRAL AND EASTERN PORTIONS OF THE FORECAST ZONES. THE 0140 UTC HIGH RESOLUTION ASCAT PASS NOTED GENERALLY LIGHT ELY NE-E WINDS OVER THE CENTRAL AND WRN PORTIONS OF THE BASIN... WITH THE EXCEPTION OF THE FAR NW CORNER OF THE BASIN BEHIND THE FRONT WHERE N-NE 20-25 KT WINDS ARE NOTED N OF 28N DUE TO A PERSISTENT VERY TIGHT PRES GRADIENT THERE AS A RESULT OF HIGH PRES RIDGING WEDGED BETWEEN THE FRONT AND THE SE U.S. COAST. MAX SEAS THERE ARE IN THE 8-12 FT RANGE PER 41012 BUOY DATA. SEAS ELSEWHERE ARE 5-7 FT IN A NE SWELL...EXCEPT 4-6 FT SW OF THE BAHAMAS. GLOBAL MODELS CONSISTENTLY SUGGEST THAT LOW PRES DEVELOPS ALONG THE NORTHERN PORTION OF THE SURFACE TROUGH THAT EXTENDS FROM 30N64W TO 21N70W OVER NEXT 24-48 HRS. THE PRES DIFFERENCE BETWEEN THIS LOW AND THE STRONG HIGH PRES RIDGE OVER THE FAR NW PORTION BEHIND THE FRONT WILL KEEP THE NLY WINDS ELEVATED BEHIND THE STATIONARY FRONT THROUGH TUE AT SPEED OF 20-25 KT. GIVEN THE INCREASING WIND SPEEDS OVER A LARGE ATLC FETCH AREA AND THE EXPECTED LONG DURATION...THE SEAS IN THE FAR NW PORTION E OF NE FLORIDA SHOULD MAX OUT TO AROUND 12 FT THROUGH MON PER WAVEWATCH GUIDANCES...THEN ONLY SLOWLY SUBSIDE TUE AND WED AS YET ANOTHER SURGE OF NLY WINDS PUSHES S INTO THE NW PART OF THE BASIN USHERING IN A LARGE SET OF LARGE NLY SWELLS ELEVATING THE SEAS TO 12 OR 13 FT OVER THE FAR NW PORTION WED AND THU. ONCE THE LOW PRES FORMS ON THE SURFACE TROUGH IT WILL PULL FURTHER AWAY FROM THE AREA LATE SUN AND INTO MON AS ADVERTISED BY GENERAL MODEL CONSENSUS. THE LOW WILL LEAVE BEHIND A TROUGH OVER THE SE PORTION OF THE AREA TUE AND WED. THE NEW NLY SURGE WILL MOST LIKELY BE DEPICTED AS DEVELOPING COLD FRONT ON FUTURE PROGS. THIS NE COLD FRONT THEN OVERTAKES THEN SWEEPS SE ACROSS THE REMAINDER OF THE WESTERN PORTION OF THE BASIN BY THU. RESIDUAL NE SWELLS WILL SPREAD SEAS MAXING OUT TO 9 FT N OF 27N OVER THE E PORTION THU. 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