000 AGXX40 KNHC 310800 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EST MON DEC 31 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... THE LATEST SURFACE ANALYSIS HAS HIGH PRES CENTERED OVER THE SE U.S. WITH ASSOCIATED RIDGING SSW ACROSS THE ERN AND CENTRAL GULF. THE HIGH CENTER AND RIDGE IS SHIFTING EWD ALLOWING FOR SE RETURN OVER THE WRN GULF PORTION TO EXPAND EWD. LATEST BUOY OBSERVATIONS DEPICT THE SE RETURN FLOW AS SE-S WINDS OF 15-20 KT. THE OBSERVATIONS SHOW THAT WINDS ELSEWHERE ACROSS THE GULF ARE E-SE AT 15 KT...WITH THE EXCEPTION OF THE S CENTRAL WATERS WHERE WINDS THERE ARE GENERALLY NE-E AT 10-15 KT. SEA STATE REPORTS INDICATE THAT SEAS HAVE LOWER FROM THE PAST FEW DAYS...WITH SEA HEIGHT RANGES OF 5-6 FT W OF 91W...AND 3-5 FT E OF 91W EXCEPT HIGHER SEAS TO 8 FT IN THE FAR SE GULF AND STRAITS OF FLORIDA DUE TO NE 20 KT WINDS ACROSS THE STRAITS AGAINST THE CURRENT FLOW THERE. THE AREA OF HIGH PRES WILL SHIFT SEWD TO E OF THE FLORIDA PENINSULA OVER THE NW ATLC EARLY TONIGHT WHILE LOW PRES DEVELOPS W OF THE AREA. THE NE GULF WINDS VEER TO SE-S AT 10-15 KT BY THEN. THE LOW PRES W OF THE AREA WILL INTRODUCE THE NEXT COLD FRONT INTO THE WESTERN GULF WATERS TUE MORNING PER GLOBAL MODEL GUIDANCE AND SIMILAR DEPICTING ON THE GFS/ECMWF MODEL ENSEMBLES. THIS FRONT WILL THEN MOVE EASTWARD...BUT AT A SLOWER PACE THAN PREVIOUS FRONTS AS THE UPPER FLOW PATTERN BECOMES MORE FROM A SW DIRECTION. WILL MAINTAIN CONTINUITY WITH PREVIOUS FORECAST THINKING IN PROGGING THIS NEXT FRONT TO REACH A POSITION FROM PENSACOLA FLORIDA PANHANDLE SW TO NEAR TAMPICO MEXICO BY EARLY TUE EVENING. THE DETERMINISTIC MODELS ALONG WITH THE GFS/ECMWF ENSEMBLES ARE IN AGREEMENT THAT LOW PRES FORMS ALONG THE FRONT TUE AND INTO WED...AND TRACKS NEWD TOWARDS THE GENERAL VICINITY OF W CENTRAL FLORIDA BY THU AFTERNOON AND TO NE OF THE AREA THU NIGHT. INTERESTINGLY....THE GFS MEAN ENSEMBLE TAKES IT MORE TO THE BIG BEND OF FLORIDA AREA. THE EVENTUAL POSITION AND TRACK OF THE LOW ALONG THE FRONT WILL BE MORE RELEVANT TO INCREASING MOISTURE FOR THE WRN AND NRN GULF ZONES WED AND THU ENHANCING THE CHANCES OF RAIN ALONG WITH SCATTERED SHOWERS AND ISOLATED TSTMS. WITH RESPECT TO RELATED WIND FORECAST WITH THIS SYSTEM...HIGH PRES FORECAST TO BUILD SE BEHIND IT WILL INCREASE THE PRES GRADIENT OVER MUCH OF THE CENTRAL AND WRN GULF WED AND THU WITH NLY WINDS INCREASING TO 25 KT WITH POSSIBLE BRIEF INSTANCES OF 30 KT IN THE FAR WRN GULF ON WED. THE GRIDDED WAVEWATCH GUIDANCE FORECASTS SEAS TO BUILD TO 8-13 FT IN THE W CENTRAL GULF WED...THEN SHIFTS THESE SEAS INTO THE SW GULF BY FRI. THESE VALUES ARE HIGHER THAN NOTED IN PREVIOUS RUNS OF THE WAVEWATCH...AND IS MORE IN LINE WITH THE ECMWF WAVES. WILL FOLLOW THESE SOLNS FOR THIS PACKAGE AS THE HIGH VALUES SEEMS MORE PLAUSIBLE GIVEN EXPECTED SET UP OF NLY FETCH AND INCREASING DURATION BEHIND THE FRONT AND LOW. WINDS AHEAD OF THIS FRONT ARE EXPECTED TO BECOME S-SW AT 15 KR IN THE NE GULF ZONE WED AND THU WITH SEAS OF ABOUT 5-6 FT...AND SE-S 10-15 KT ELSEWHERE IN THE ERN GULF PORTIONS. WILL TWEAK WINDS/SEAS FOR DAYS 4 (WED) AND 5 (THU) BEHIND THIS NEXT FRONT AS NECESSARY AS UPDATED MODEL GUIDANCE BECOMES AVAILABLE. SW N ATLC S OF 31N W OF 65W... THE COLD FRONT THAT MOVED INTO THE AREA YESTERDAY NOW EXTENDS FROM 24N65W SW TO THE SE BAHAMAS WHERE IT BEGINS TO DISSIPATE TO ACROSS ERN CUBA. THE ERN PART OF THE GULF OF MEXICO HIGH PRES RIDGE NUDGES EWD ACROSS THE BASIN BEHIND THE FRONT. LATEST AND CURRENT BUOY OBSERVATIONS SHOW NW WINDS OF 20-30 KT BEHIND THE FRONT IN COLD AIR ADVECTION AS WERE NICELY CAPTURED IN THE 0152 UTC ASCAT PASS FROM LAST NIGHT. THESE WINDS EXTEND WESTWARD TO NEAR 70W WITH THE STRONGEST OF THE WINDS N OF 28N. SEAS WITHIN THIS AREA ARE 9 TO 14 FT. WINDS ELSEWHERE BEHIND THE FRONT ARE N-NE AT 20-25 KT WITH LIGHTER WINDS OF NE-E 15-20 KT W OF THE BAHAMAS...AND E 10-15 KT IN THE FAR NW PORTION. SEAS ELSEWHERE BEHIND THE FRONT ARE 8-12 FT IN NW SWELLS NE OF THE BAHAMAS...AND 6-8 FT ELSEWHERE EXCEPT LOWER SEAS OF 4-6 FT SW OF THE BAHAMAS AND 2-4 FT IN THE FAR NW PORTION. SE OF THE FRONT... WINDS ARE NE-E AT 10-15 KT WITH SEAS OF 5-6 FT IN MIXED N AND NE SWELL. SCATTERED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE FRONT. THE COLD FRONT WILL REACH THE FAR SE WATERS TO N CENTRAL CARIBBEAN ROUGHLY ALONG 20N BY LATER THIS AFTERNOON OR EARLY THIS EVENING AS A WEAKENING BOUNDARY. THIS BOUNDARY WILL THEN BECOME STATIONARY WHILE DISSIPATING ALONG 20N THROUGH WED WITH A POSSIBLE SHEAR LINE FORMING FROM IT INTO THU. THE LARGE SEAS BEHIND THE FRONT WILL CONTINUE TO PROPAGATE SEWD RESULTING IN A LARGE SWELL EVENT FOR THE REGIONAL ATLC WATERS AS WELL AS CARIBBEAN ISLANDS. AS MENTIONED IN PREVIOUS FORECASTS ...THE LEADING EDGE OF THE SWELLS ARE EXPECTED TO REACH THE N COASTS OF THE LESSER ANTILLES TONIGHT...AND INTO THE N LEEWARDS BY TUE MORNING...WITH 8-10 FT SWELL AT AROUND 15-16 SECONDS. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... WEAK HIGH PRES SLIDING ENE ACROSS THE W CENTRAL ATLC IS MAINTAINING FRESH TO STRONG NE-E TRADES ACROSS THE CENTRAL CARIBBEAN...WHERE 20-25 KT TRADES ARE CONFINED TO S OF 17N BETWEEN 70W-83W. THE PARTIAL ASCAT PASS FROM 0150 UTC LAST NIGHT NOTED THE ERN SWATH OF THESE WINDS. SHIP "C6SE3"...HUGGING THE COAST OF PANAMA NEAR 10N79W IS REPORTING NE WINDS OF 25 KT WITH COMBINED SEAS OF 12 FT. SEAS ELSEWHERE ARE IN THE RANGES OF 6-9 FT IN AN E SWELL S OF 17N BETWEEN 68W-82W AND 4-6 FT ELSEWHERE IN THE CENTRAL CARIBBEAN...AND LOWER ERN CARIBBEAN AT A RANGE OF 3-5 FT. SEAS HAVE BUILD IN THE NW CARIBBEAN SEA TO THE RANGE OF 7-9 FT IN A NW SWELL THAT IS FILTERING THROUGH THE YUCATAN CHANNEL. SEAS IN THE TROPICAL N ATLC ARE 5-7 FT IN A N-NE SWELL AS BEING REPORTED BY BUOYS 41300 AT 16N57.5W AND 41040 AT 14N53W. WIND AND SEAS ACROSS THIS PORTION OF THE CARIBBEAN WILL CHANGE VERY LITTLE THROUGH TUE ACROSS MUCH OF THE CARIBBEAN...BUT BEGIN TO SIGNIFICANTLY BUILD OVER THE NRN TROPICAL N ATLC AS QUITE AN IMPRESSIVE BATCH OF NW-N SWELLS MOVES INTO THAT PORTION OF THE TROPICAL N ATLC. SEAS THERE BEGIN TO BUILD TO 12 OR 13 FT TUE AS THE AFOREMENTIONED COLD FRONT UNDER THE SW N ATLC SECTION PUSHES S TO NEAR 20N MOST LIKELY AS A SHEAR LINE. THE SEAS THEN BEGIN TO GRADUALLY SUBSIDE TO 10 FT WED WHILE MIGRATING FURTHER S ACROSS THE TROPICAL N ATLC...BUT ALSO FILTER IN THROUGH THE EXPOSED ATLC PASSAGES INTO THE NE CARIBBEAN WATERS. THESE SWELLS WILL ALSO IMPACT THE NW COASTS OF EXPOSED LEEWARD ISLANDS. THE SHEAR LINE (REMNANT FRONTAL BOUNDARY) SHOULD BE DISSIPATING AT THAT TIME. BY FRI SEAS ACROSS THE TROPICAL N ATLC SHOULD BE IN THE 6-9 FT RANGE IN A N SWELL COMPONENT. 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