000 AGXX40 KNHC 171947 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 245 PM EST MON DEC 17 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 SHOWS THE PREVIOUSLY COLD FRONT NOW HAVING MOVING OFF THE TEXAS/SW LOUISIANA COAST INTO THE NW GULF ALONG A POSITION FROM S CENTRAL LOUISIANA SW TO INLAND FAR NE MEXICO JUST S OF BROWNSVILLE TEXAS. WEAK HIGH PRES IS OVER THE EASTERN PART OF THE GULF. CURRENT BUOY AND PLATFORM OBSERVATIONS SHOW S-SW 15-20 KT WINDS OVER THE EASTERN AND CENTRAL GULF AHEAD OF THE FRONT...EXCEPT SE-S 10-15 KT WINDS S OF 25N E OF 89W. WINDS HAVE BECOME N AT 15-20 KT. THE LATEST AND CURRENT OBSERVATIONS ARE REPORTING SEAS OF 2-3 FT E OF 87W...3-5 FT BETWEEN 87W AND THE FRONT AND ALSO W OF THE FRONT AS SEEN IN THE REPORTS FROM BUOYS 42020 AT 27N97W AND 42019 AT 28N95.5W. LATEST NWS RADAR ANIMATIONS AND SATELLITE IMAGERY REVEAL ABUNDANT MOISTURE ASSOCIATED WITH THE FRONT AND AN UPPER JET STREAM BRANCH THAT STRETCHES FROM THE SE U.S. SW TO FAR INLAND NRN MEXICO. THE MOISTURE IS IN THE FORM OVERCAST MULTILAYERED CLOUDS WITH AREAS OF RAIN WITH EMBEDDED SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 100 NM EITHER SIDE OF THE COLD FRONT. THE UPPER PATTERN HAS CONTINUED TO TRANSFORM INTO A RATHER PROGRESSIVE ONE WITH ACROSS THE AREA AS THE LARGE DOME OF HIGH PRES IN THE UPPER LEVEL THAT WAS ANCHORED OVER MUCH OF THE AREA HAS BEGUN TO SLIDE EASTWARD IN RESPONSE TO A DEEP LAYER TROUGH PROGRESSING EASTWARD OVER THE UPPER MID-WEST TO EASTERN PART OF TEXAS REGION. THESE FEATURES WILL CONTINUE TO ADVANCE EASTWARD OVER THE NEXT FEW DAYS. KEEPING THIS IN MIND WILL BASE THIS FORECAST ON HOW THESE FEATURES AND UPCOMING SIMILAR BUT STRONGER ONES IMPACT WINDS AND THE SEAS IN THE TAFB FORECAST DOMAIN. IN THE VERY NEAR SHORT TERM...THE RIDGE OVER THE EASTERN GULF WILL SHIFT E OF THE GULF TONIGHT ALLOWING FOR THE COLD FRONT TO CONTINUE EASTWARD TO A POSITION FROM NEAR TAMPA SW TO 25N88W THEN WEAKENING TO CENTRAL BAY OF CAMPECHE EARLY TUE...THEN EXIT THE AREA TUE EVENING. THE N 15-20 KT WINDS BEHIND THE FRONT WILL DECREASE QUICKLY TO 10-15 KT LATER DURING THE AFTERNOON AS WEAK HIGH PRES BEHIND IT QUICKLY MOVES E TO THE FAR NE GULF AND NE FLORIDA AREA TUE NIGHT AND WED. THE HIGH WILL THEN MOVE FURTHER E TO THE WESTERN ATLC TO THE NE OF NE FLORIDA BY LATE WED. THE SEAS TO 5 FT BEHIND THE FRONT WILL SUBSIDE TO 3-4 FT BY EARLY THIS EVENING. THE CLOUDINESS AND PRECIPITATION ASSOCIATED WITH THE FRONT AND UPPER LEVEL JET STREAM/TROUGH PATTERN WILL SHIFT TO THE EASTERN GULF TONIGHT INTO TUE MORNING...THEN BEGIN TO LOSE IMPETUS LATER TUE AS THE FRONT WEAKENS BEFORE EXITING THE AREA. SLY FLOW WILL DEVELOP JUST ABOUT ACROSS THE ENTIRE GULF WED AND THROUGH THU IN ADVANCE OF YET ANOTHER COLD FRONT...STILL PROGGED BY THE MODELS TO BE ON THE STRONG SIDE. THE FLOW WILL INCREASE THE MOST IN THE FAR WRN PORTION WED...THEN DIMINISH WED NIGHT WITH THE APPROACH OF THIS NEXT COLD FRONT. SEAS WILL CHANGE LITTLE IN THE EASTERN AND CENTRAL GULF THROUGH THE PERIOD. WITH THE INCREASING SLY WINDS IN THE FAR WESTERN GULF...EXPECT SEAS THERE BUILD TO AROUND 7 OR 8 FT WED. MODELS IN RATHER GOOD AGREEMENT THAT THE FRONT WILL PUSH OFF THE TEXAS COAST THU MORNING. WITH RESPECT TO THE TIMING AND FORECAST OF THE FRONT AFTER IT EMERGES INTO THE GULF...THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE TIMING AND FORECAST POSITIONS ACROSS THE GULF. THE GFS REMAINS A BIT FASTER THAN THE OTHER MODELS AND ALSO WITH GFS MEAN GUIDANCE. SIMILAR TO PREVIOUS FORECAST THINKING...WILL FOLLOW CONSENSUS FOR THIS FORECAST WHILE MAINTAINING CLOSE CONTINUITY WITH PREVIOUS FORECAST COLD FRONT POSITIONS ACROSS THE GULF...AND WILL FORECAST THE FRONT TO REACH FROM NE FLORIDA TO EASTERN BAY OF CAMPECHE LINE BY LATE THU NIGHT...AND TO SE OF THE GULF FRI MORNING. A COLD AND STRONG HIGH PRES AREA...THE FIRST OF THE UPCOMING EARLY WINTER SEASON... WILL BUILD E ACROSS THE SE U.S. AND ENTIRE GULF THU...THEN BEGIN TO WEAKEN FRI AND SAT AS IT SLIDES ENE OVER THE FAR NRN PORTION. THE HIGH WILL VERY LIKELY CREATE A STRONG PRES GRADIENT BRINGING N WINDS OF 20-30 KT ACROSS THE WESTERN AND CENTRAL GULF ZONES DURING THU AND INTO FRI WITH EXPECTED GALE NLY WINDS IN THE SW GULF ZONES W OF 94W. THIS IS WHERE MODELS SUGGEST THE GRADIENT WILL BE THE TIGHTEST. CANNOT RULE OUT THE POSSIBILITY OF GALE WINDS OVER A PORTION OF THE NW GULF AS WELL FOR THU INTO FRI. MAY HAVE TO INCLUDE AN AREA WORDING SUCH AS "S OF 28N W OF 95W" IN THE FUTURE FORECAST UPDATES. THE HIGH PRES AREA WILL BUILD EWD ACROSS THE GULF THU...THEN BEGIN TO WEAKEN FRI AS IT SLIDES ENE OVER THE FAR NRN PORTION. THE STRONG N WINDS OVER THE WRN GULF WILL OVERSPREAD THE ENTIRE GULF THROUGH FRI WHILE BECOMING MORE N-NE IN DIRECTION WITH THE EWD PROGRESS OF THE HIGH. WINDS ARE FORECAST TO BECOME NE 20-25 KT ACROSS MUCH OF CENTRAL AND EASTERN GULF BY FRI AFTERNOON... AND NE-E AT 15-20 KT ELSEWHERE WITH WINDS DIMINISHING TO LIGHTER SPEEDS E AT 10-15 KT IN THE NW PART BY LATE FRI THEN VEER AROUND TO THE SE SAT WITH THE EASTWARD TRANSLATION OF THE HIGH OVER THE NORTHERN GULF. FOR SEAS BEHIND THE SECOND FRONT WILL LEAN TOWARDS THE MIDDLE OF THE GRIDDED WWIII AND ECMWF WAVES FOR MAX SEAS ON THU AND FRI WITH VALUES OF 13-14 FT IN THE SW GULF LATE THU INTO FRI...AND IN THE RANGE OF 8-12 FT ELSEWHERE. SEAS SLOWLY DECREASE FROM NW TO SE LATER DURING FRI AND INTO SAT. SW N ATLC S OF 31N W OF 65W... THE 18 UTC PRELIMINARY ANALYSIS DEPICTS HIGH PRES ACROSS THE BASIN. LATEST BUOY OBSERVATIONS ALONG WITH A SEVERAL SHIP REPORTS NOTE E-SE WINDS OF 10-15 KT S OF 27N W OF 67W EXCEPT SE-S 10-15 KT W OF THE BAHAMAS. NE-E 15-20 KT WINDS ARE SEEN IN THE FAR SE PART BETWEEN THE SE BAHAMAS AND PUERTO RICO. THE OBSERVATIONS REVEAL SEAS OF 6-7 FT IN NE SWELLS N OF 27N E OF 66W...AND 4-6 FT ELSEWHERE EXCEPT 5-7 FT S OF 24N E OF 73W ...AND 3-5 FT SW OF THE BAHAMAS. WIDELY SCATTERED SHOWERS ARE S OF 22N E OF 70W. MODELS ARE ON TRACK WITH FORECAST OF HIGH PRES ACROSS THE BASIN SLIDING EASTWARD TO E OF THE FORECAST ZONES ON TUE. THIS WILL ALLOW FOR A COLD FRONT TO MOVE OFF THE SE U.S. AND NE FLORIDA COAST TONIGHT INTO EARLY TUE. THE FRONT WILL REACH FROM NEAR 31N73W TO SE FLORIDA BY EARLY TUE AFTERNOON THEN BEGIN TO WEAKEN. THE FRONT WILL PUSH SE TO ACROSS THE FAR SE WATERS AS A DISSIPATING STATIONARY FRONT BY LATE WED. HIGH PRES WILL BUILD ACROSS AREA BEHIND THE FRONT. SW WINDS OF 20-25 KT WILL PRECEDE THE N OF ABOUT 29N AS SUGGEST BY THE GFS/ECMWF GUIDANCE. THE FRONT WILL BE FOLLOWED BY W-NW WINDS OF 20-25 KT WITH POSSIBLE WINDS TO 30 KT N OF 30N WED. SEAS ARE FORECAST TO BUILD TO AROUND 6-9 FT AHEAD OF THE FRONT AND TO AROUND 8-12 FT BEHIND IT ON WED...BUT WITH THE HIGHEST OF THE SEAS N OF 29N PER WWIII/ECMWF/UKMET WAVE GUIDANCE. THE GFS AND ECMWF SHIFT THESE SEAS QUICKLY TO THE E BY LATE WED SIMILAR TO THE UKMET BUT LATER DURING THE WED. HIGH PRES WILL THEN BUILD ACROSS THE ENTIRE AREA IN THE WAKE OF THE FRONT...AND ALSO SHIFT ESE THU AND FRI AS YET ANOTHER COLD FRONT IS EXPECTED TO MOVE OFF THE NE FLORIDA COAST LATE THU. THIS FRONT...APPEARING TO BE STRONGER THAN THE AFOREMENTIONED ONE...WILL BE PRECEDED BY SW 20-25 KT WINDS AND FOLLOWED BY STRONGER NW WINDS OF 20-30 KT. PER GFS/ECMWF CONSENSUS WITH GALE FORCE JUST N OF 31N. WAVEWATCH GUIDANCES BUILD SEAS TO MUCH HIGHER LEVELS THAN THAT ASSOCIATED WITH THE FIRST FRONT WITH MAX VALUES OF 15 OR 16 FT PER THE GRIDDED WWIII GUIDANCE AND UP TO 20 FT PER THE ECMWF GUIDANCE ON SAT OVER THE N CENTRAL AND NE WATERS. WILL ADJUST FORECAST WAVE HEIGHTS FOR FRI AND SAT BY PERHAPS BLENDING THESE GUIDANCES. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... A RELATIVELY WEAK PRES GRADIENT CONTINUES AS WEAK ATLC HIGH REMAINS IN PLACE. HOWEVER...THE ASCAT PASS FROM 1412 UTC FROM THIS MORNING REVEALED A POCKET OF NE-E 20-25 KT WINDS FROM 11N-14N BETWEEN 73W-77W WITH SEAS TO 8 FT. THE ONGOING PRES GRADIENT WILL MAINTAIN GENTLE TO MODERATE TRADE WINDS THROUGH WED EXCEPT OVER THE S CENTRAL PORTION OF THE CARIBBEAN WHERE A TIGHTER GRADIENT IS RESULTING IN HIGHER WINDS THERE. THESE WINDS ARE EXPECTED TO DIMINISH SOME TUE AFTERNOON. STRONGER HIGH PRES WILL BUILD EASTWARD ACROSS THE WESTERN ATLC LATE WED THROUGH FRI INCREASING TRADES ACROSS MUCH OF THE CENTRAL CARIBBEAN WATERS. LARGE NW TO N SWELLS IN THE RANGE OF 8-14 FT ARE EXPECTED TO BEGIN TO IMPACT THE NORTHERN TROPICAL N ATLC THU AND FRI... AND SLOWLY SUBSIDE FROM THE NW ON SAT. A WEAK SURFACE TO LOW TROUGH ALONG 64W FROM 14N-18N WILL CONTINUE WESTWARD ACROSS THE EASTERN CARIBBEAN THROUGH THE NEXT 48 HRS ...THEN ACROSS THE CENTRAL CARIBBEAN THU WHILE GRADUALLY BECOMING DIFFUSE ONLY ISOLATED SHOWERS ARE ALONG AND WITHIN 180 NM E OF THE TROUGH. THE SRN PORTION OF THE ABOVE MENTIONED SECOND COLD FRONT IS FORECAST TO PUSH SE ACROSS THE NW PORTION OF THE TROPICAL N ATLC WATERS LATE SAT...BUT WILL BE IN THE DIFFUSING STAGE AS ATLC HIGH PRES BRIDGES SE ACROSS IT. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .GMZ017...GALE CONDITIONS EXPECTED THU W OF 96W... .GM023...GALE CONDITIONS EXPECTED THU AND FRI S OF 22N W OF 94W... CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE