000 AGXX40 KNHC 150759 RRA MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 259 AM EST THU DEC 15 2016 Marine Weather Discussion for the Gulf of Mexico, Caribbean Sea, and Tropical North Atlantic from 07N to 19N between 55W and 64W and the Southwest North Atlantic including the Bahamas ...GULF OF MEXICO... MODEL PREFERENCE: Global model consensus. High confidence, except average confidence western gulf zones Sunday through Monday night. The 06Z surface analysis has a weak 1019 mb high centered over the eastern gulf waters at 25N86W. A weak cold front stretches from northeast Fl southwest to 27N86W and to 25N92W where it becomes stationary from there to inland Mexico near Tampico. Latest buoy observations reveal light to gentle anticyclonic winds over the eastern gulf south of 27N in association with the 1019 mb high center. Elsewhere south of the front, winds are generally light to gentle southeast to south in direction, except for moderate northeast to east winds over the eastern Bay of Campeche and just north of the Yucatan peninsula as noted in the buoy observations and in a partial Ascat pass from 0336Z last night. The observations from the buoys along with recent altimeter data show seas in the 2-3 ft range, except for lower seas of 0-1 ft to the east of 90W. A small pocket of 3-4 ft seas is in the northwest gulf from 26N to 28N west of 95W to the Tx coast. The cold front will continue to move south-southeast reaching a position from southeast gulf and Straits of Florida northwest to the northeast portion of Mexico this afternoon. The front is then forecast to become stationary and dissipate through Friday. Mostly moderate northerly flow with some pockets of fresh flow will follow in behind the front through this afternoon. The high pressure in the wake of this front will quickly shift eastward through Friday night. The winds will respond by veering around to an east to southeast direction over the central and eastern gulf, and to more of southerly direction in the western portion where they increase to the fresh to locally category on Saturday. Seas behind the front are expected to build to the range of 3-5 ft, except for higher seas of around 6-8 ft in the western gulf on Saturday. The strong return flow in the western gulf will occur in advance of the cold front to approach the area. Models depict this cold front as a rather strong that will be followed by a large area of strong high pressure. This high pressure will usher in arctic air into the gulf of Mexico behind this next front. There are differences in timing of the cold front as it approaches and moves into the northwest gulf over the weekend. Will favor a blend of the models for periods of Saturday night through Monday. Model ensembles indicate possibe gale conditions in cold arctic northerly flow mixing down behind the front as it moves across the western gulf zones Sunday and Sunday night. The front is forecast to quickly reach from the Fl panhandle to the southwest gulf on Sunday night, and become stationary from north/central Fl to the Bay of Campeche by late on Monday. Will highlight possible gale conditions for Sunday in the far western portion of zones GMZ017 and in the far southwest portion of GMZ023 for Sunday night and Monday. Seas are expected to build to around 12 ft with these conditions in the far western part of zone GMZ017, and to 13-15 ft in the far southwest part of zone GMz023 on Monday. Wavewatch and NWPS guidance suggests that these seas will be slow in subsiding late on Monday. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...corrected MODEL PREFERENCE: Global model consensus. High confidence. The 0152Z Ascat pass showed fresh to strong northeast winds between 72W and 78W. Seas are in the 8-10 ft range with these winds. Both buoy and Ascat data show moderate to fresh northeast to east winds elsewhere, with seas in the 5-7 ft range, except for 3-5 ft seas west of 81W and in the windward passage. As Atlantic high pressure continues to slide eastward through tonight, the tight pressure gradient producing the fresh to strong trades will slacken allowing for coverage of the fresh to strong winds to decrease some. On Friday, these winds decrease further. This trend will be short-lived as strong high pressure will re-established itself over the western portion of the SW Atlantic beginning late Friday afternoon and evening, and through early next week with the associated tight pressure gradient expected to initiate a widespread increase of the northeast to east trades across the Caribbean east of 81W, and over the tropical north Atlantic zones. Wavewatch guidance, including the ensemble guidance, suggests that related seas will build to around 11 ft with the trades affecting the Caribbean, and to a higher max of 12 or 13 ft in the eastern section of tropical north Atlantic zones AMZ127 and AMZ027. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: Global model consensus. High confidence. High pressure over the far eastern waters is sliding eastward. The 0154Z Ascat pass highlighted moderate to fresh south to southwest winds in the far northeast portion of the forecast area. Buoy observations reveal seas in the 4-6 ft range east of the Bahamas, except for higher seas of 6-8 ft southeast of a line from 26N65W to near 20N71W. Significantly lower seas of 0-2 ft are within and west of the Bahama island chain. Forecast is on track with current trend of the high pressure continuing to slide eastward through late tonight in response to a slow moving cold front that moved over the far northwest waters yesterday evening, and as of 06Z this morning extends from near 31N79W southwest to inland the northeast sector of Fl. The front is forecast to be increase its forward this afternoon as a large area of Canadian high pressure builds southeast to the north of the front. The front will move over the northern and central waters today and tonight, and reach the southern waters on Friday where it will become stationary from near 25N65W to the Straits of Fl by Friday evening. The large area of high pressure in its wake will encompass the entire basin. The associated tight pressure gradient between the high and the front will induce fresh to strong northerly flow over much of the northern and central waters beginning this afternoon, and into Friday. As the aforementioned high shifts eastward, the northerly flow will become northeast to east on Friday and into Saturday at which time the winds west of the Bahamas veer around to the east to southeast. A swath of strong northeast to east winds with seas in the 8-10 ft range is expected from 24N to 26N between 71W and the Bahamas Friday through Saturday afternoon, then become confined to the far southern waters east of 75W Saturday evening through Monday. Similar winds are expected through the windward passage and adjacent waters. The front is forecast to be preceded by fresh to strong southerly winds, and seas in the 8-10 ft range. Seas of up to 11 ft are expected behind the front Friday night in zone AMZ115, and around 9 or 10 ft in zones AMZ111 and AMZ113. Seas subside in zones AMZ113 and AMZ115 on Monday, but will be slow in subsiding in the waters east of the Bahamas south of 26N where wavewatch and TAFB NWPS guidance indicate seas in the 8-11 ft range there. Will make adjustments to NDFD wind and waveheight grids as needed with conditions associated with this cold front. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... .GMZ017...W CENTRAL GULF FROM 22N TO 26N W OF 94W... GALE CONDITIONS POSSIBLE W OF 96W Sun. and Sun. night. .GMZ023...SW GULF S OF 22N W OF 94W... GALE CONDITIONS POSSIBLE W OF 95W Sun. night into Mon. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *For detailed zone descriptions, please visit: http://www.nhc.noaa.gov/abouttafbprod.shtml#OWF Note: gridded marine forecasts are available in the National Digital Forecast Database (NDFD) at: http://www.nhc.noaa.gov/marine/grids.php For additional information, please visit: http://www.hurricanes.gov/marine $$ .Forecaster Aguirre. National Hurricane Center.