000 AGXX40 KNHC 121854 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 254 PM EDT Sat Aug 12 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... Showers and thunderstorms are active over the northeast and north central Gulf along a surface trough reaching from 30N83W to 29.5N 88.6W. 1018 mb high pressure is centered over the central Gulf near 26N88W, maintaining calm to light winds and nearly flat seas over much of the northern Gulf north of 25N. Isolated thunderstorms are active over the northeast Gulf near 26.5N85W, associated with divergent flow aloft on the eastern edge of an upper ridge. Farther south, a coastal trough reaches along the coast of Veracruz. Gentle to moderate winds and 2 to 4 ft seas south of the ridge. The ridge will shift eastward early in the week, allowing moderate to fresh return flow to set up over the western Gulf. A thermal trough will develop over the Yucatan Peninsula during the late afternoons and evenings, move slowly westward during the overnight hours, and dissipate over the southwest Gulf by late each morning. A brief surge of fresh to locally strong winds with seas of 3-5 ft will accompany this trough. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A recent scatterometer pass indicated strong winds off the central Colombian coast have diminished to 10 to 15 kt as a tropical wave moves across the area. The tropical wave reaches from eastern Panama to Jamaica, and will move across the remainder of the Caribbean through late Sunday. Fresh to strong trades are already starting to pulse in the wake of the tropical wave over the south central Caribbean, off the Guajira peninsula of Colombia and likely over far northwest Venezuela. Scattered thunderstorms persist over the waters north of Panama, south of 13N, related to the interactions of the monsoon trough and the tropical wave. Farther east, a large tropical wave well east of the area will pass 55W Sun evening, then pass through the eastern Caribbean Tue through Wed. Trade winds and seas will build between this wave and another one that is expected to pass 55W Tue and reach the eastern Caribbean Wed. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The main feature of interest continues to be broad low pressure centered near 23N68W, or about 150 nm northeast of the Turks and Caicos Islands. The low is still struggling to become organized, but there is enough convection at times to indicate tropical cyclone development is possible over the next 48 hours. The low pressure will likely continue to move NNW around 10 kt, eventually turning N and NNE through late Monday. Strong winds, seas to 8 ft, and scattered thunderstorms within 150 nm will accompany the low pressure on the northeast semicircle of the low pressure. Ridging will build along roughly 27N/28N by Tue in the wake of the low pressure, allowing winds and seas to diminish north of 22N. South of 22N, moderate to fresh winds will persist, pulsing to strong during the late afternoons and evenings Tue through mid week, enhanced by the northern portion of a tropical wave moving through the eastern Caribbean. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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 Christensen. National Hurricane Center.