000 AGXX40 KNHC 120800 RRA MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 300 AM EST MON DEC 12 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. The 06Z surface analysis shows the western periphery of Atlantic high pressure extending westward into the northeast portion of the gulf. This feature is influencing the general wind flow across the area. A tight pressure gradient over the far western portion of the gulf is supporting fresh southerly flow north of 25N west of 92W as noted in the latest buoy observations, and confirmed in the 0258Z Ascat pass. Both the buoys and Ascat data indicated gentle to moderate southerly flow elsewhere, except for winds in an east to southeast direction south of 25N east of 93W. The observations from the buoys along with recent altimeter data show seas in the 5-6 ft range, except for higher seas of 6- 7 ft in the northwest gulf within the area of fresh southerly flow, and lower seas of 1-3 ft in the northeast and far eastern gulf north of the Florida Keys. Models indicate that the aforementioned high pressure is on track to shift eastward and weaken through Wednesday. A weaker gradient will set up over the area into Wednesday allowing for seas to subside to 2-3 ft throughout, except for 3-5 ft seas in the approach to the Yucatan channel, and in the Yucatan channel. The 3-5 ft seas then subside to 2-3 ft Wednesday through Thursday. A cold front is forecast to approach the northern gulf Tuesday night, then become stationary through Wednesday. Models indicate that strong high pressure surges south over the southeast U.S. pushing the cold front across the northern and eastern gulf Wednesday night through Thursday night. Northerly flow will increase behind the front during this time as the high pressure broadens, and increases the pressure gradient over much of the northern and eastern gulf into Friday. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: Global model consensus. High confidence. The 0254 Ascat pass showed fresh northeast winds between 68W and 79W and also from 12N to 15N between 79W and 82W. Strong northeast to east winds are noted in the Ascat pass to be within about 90 nm of the coast of Colombia, and in the Gulf of Venezuela. Seas are in the 8-10 ft range over the central Caribbean, except for 10-11 ft within 90 nm of coast of Colombia. 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 to 4 ft west of 79W and higher seas of 5-7 ft in the windward passage. The well-defined surface trough of the past few days that moved across the Caribbean with easterly wave characteristics has moved just inland the coast of Honduras and Nicaragua with an associated 1008 mb low over far southern Nicaragua. A tight gradient in the wake of the trough is helping to contribute to the aforementioned fresh to strong northeast to east winds. Satellite imagery is revealing numerous showers and thunderstorms north of 12N and west of 80W. This activity is capable of producing wind gusts to around 30 kt as it translates in a northwest direction through today. Scattered showers and isolated thunderstorms are elsewhere south of 19N and west of 79W. The fresh to strong northeast winds will continue to expand in coverage through today, then diminish tonight and Tuesday. Strong northeast to east trades across the tropical north Atlantic zone AMZ127 will continue through early on Tuesday. Combined seas up to 12 ft in zone AMZ031 will gradually subside through Tuesday. Seas of 8-10 ft in the tropical north Atlantic zone will begin to subside on Tuesday night. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: Global model consensus. High confidence. Strong high pressure over the north central and eastern portions of the basin is shifting eastward. A dissipating stationary front extends from 25N65W northwest to near 28N71W where it transitions to a warm front Northwest to the southern part of South Carolina. The 0256Z Ascat pass showed a large swath of fresh southeast winds west of 74W, and fresh northeast to east winds east of 74W. Seas are in the 8-11 ft range east of the Bahamas, and 5-7 ft elsewhere except for lower seas of 1-3 ft within and west of the Bahama island chain. The stationary front will dissipate during the morning as the warm front lifts northward. A weak cold front will move into the northwest portion this afternoon preceded by strong southerly winds within 180 nm to its east north of 29N, and generally gentle northerly winds behind it. The front will reach from near 31N74W to 29N80W tonight, then weaken as it reaches from near 31N71W to 28N80W Tuesday morning. At that time, the strong southerly winds are forecast to diminish to mainly moderate to fresh speeds. Seas are expected to build to 8 ft with the strong southerly winds before they subside to 4-5 ft Tuesday. Seas of 5-6 ft are expected behind the front. On Tuesday, strong east winds confined to the southeast portion of the basin will begin to diminish to fresh speeds. A stronger cold front is expected to move into the far northwest corner late Wednesday night, and reach the eastern waters late Thursday where it will begin to weaken into Friday. This front is forecast to be preceded by fresh to strong southerly winds, and seas possibly up to 8 ft. Northerly winds behind the front are forecast to be mainly in the fresh range, but this is subject to change based on guidance from future model runs. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.