000 AGXX40 KNHC 201539 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 1139 AM EDT Thu Apr 20 2017 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... A few showers and thunderstorms are noted over the south-central and southwest Gulf in association with an upper-level low spinning over the SW Gulf. The latest observations indicate mainly moderate E to SE flow across the basin around weak high pressure located in the NE Gulf, except near and through the Straits of Florida where winds are fresh. Seas are mainly 2-4 ft, except 4-6 ft near and through the Straits of Florida, and 1-3 ft in the SW Gulf. The high and ridging extending westward from it will remain in place through Friday. A thermally induced trough will develop over the Yucatan Peninsula late each afternoon. This trough will shift into the southwest Gulf each evening accompanied by moderate to fresh northeast winds, then it will dissipate each morning. Expect fresh southerly return flow across the northwest Gulf by late Friday ahead of a cold front forecast to enter the NW Gulf by Saturday afternoon. Fresh to strong northerly winds are expected behind the front, with seas building to 6-8 ft by Sunday morning. The front will extend from the Florida Panhandle to near Tampico, Mexico by Sunday morning, then from Tampa Bay, Florida to the northern Yucatan Peninsula Monday morning, pushing SE of the Gulf Monday night. A reinforcing trough or cold front may move through the N central and NE Gulf Monday night into early Tuesday. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A relatively tight pressure gradient over the central Caribbean that was supporting fresh to strong winds including across the approach to the Windward Passage, has weakened slightly allowing for winds to diminish to 20 kt or less. Mainly moderate to locally fresh trades will prevail, except gentle to moderate in the SW and NW Caribbean. Seas are 2-4 ft in the NW and SW Caribbean, and 4-7 ft elsewhere. Seas are 5-7 ft in the tropical N ATLC. Fairly tranquil marine conditions will prevail across the western half of the basin through the upcoming weekend. A decaying cold front may slip SE of the Yucatan Channel Monday with little impact. Moderate to fresh trades will prevail across the eastern half of the basin as well as across the tropical N ATLC through the next several days. Seas will be mainly 2-4 ft W of 72W and 4-6 ft E of 72W. Seas will subside to 4-5 ft in the tropical N ATLC tonight through Saturday, with northerly swell building seas back to 5-7 ft Sunday into next week. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A weak cold front is moving across the N central and NE waters. Building high pressure in the wake of the front is producing locally fresh easterly winds across the waters between the Bahamas and Cuba, including the approaches to the Windward Passage, along with seas of 4-6 ft. Gentle to moderate anticyclonic winds prevail elsewhere around the building high, along with 3-5 ft seas. The parent high of the ridging will sink S into the weekend with a NW to SE ridge prevailing across the waters. Moderate to fresh E-SE will prevail across the SW half of the basin with gentle to moderate winds elsewhere. Seas will be pulsing to 4-7 ft across the waters outside of the Bahamas through the next several days as sets of northerly swell manage to propagate through the area. Southerly winds will increase to 15-20 kt off NE Florida by late Sunday ahead of a cold front approaching from the W. The front is forecast to enter the forecast region by Sunday night, then stall across the NW waters on Monday. The general consensus among global models is weak low press forming off the northern Bahamas Monday, although there remains some uncertainty regarding exact position and intensity at this time. This may enhance southerly flow over the waters northeast of the Bahamas between the developing low pressure and a high pressure center located east of Bermuda. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.nhc.noaa.gov/marine $$ .Forecaster Lewitsky. National Hurricane Center.