694 AGXX40 KNHC 181901 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 301 PM EDT Tue Sep 18 2018 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... Weak 1015 mb high pressure persists over the northwest Gulf near 27N94W, directly under an upper low, with an upper trough extending southward to Tampico. Divergent flow aloft related to the upper level trough is supporting isolated thunderstorms off the coast of Veracruz. A weak surface trough reaching from the Carolinas to the Lower Mississippi Valley is supporting scattered thunderstorms near the entrance to Mobile Bay. No significant showers or thunderstorms are noted elsewhere. Farther south, a weak trough is noted off the coast of west Yucatan. The light pressure pattern is allowing only light breezes and 1 to 3 ft seas, as observed in buoy observations and altimeter satellite data. A trough over the northwest Caribbean will move across the Yucatan Channel through Wed, into the southwest Gulf Thu and Fri, then dissipating Sat, with little change in winds and seas. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A few showers and dissipating thunderstorms are observed west of Grand Cayman Island, along a trough reaching from central Cuba to near Cabo Gracias a Dios in eastern Honduras. The trough is the remnant of what was T.S. Isaac. The trough will move west of the area through Wed. Farther east, a tropical wave currently approaching Barbados will move into the eastern Caribbean tonight, the central Caribbean Thu into Fri, and pass west of the area through late Sat into Sun. Meanwhile high pressure building from the central Atlc into the central Bahamas will support moderate to fresh trade winds and building seas across the entire basin late Wed through Fri. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A surface trough reaches from roughly Bermuda to the southern Bahamas. Divergence aloft on the southeast side of an upper low centered near 28N66W is supporting scattered thunderstorms within 90 nm to the east of the surface trough south of 24N. The surface trough will shift slowly NW and weaken through tonight as the central Atlantic ridge builds into the central Bahamas. Low pressure moving off the Carolinas will drag an attendant frontal trough across the waters north of 27N Thu and Fri. Winds may reach 20 to 25 kt associated with the low pressure on Thu, impacting primarily AMZ115. The low will move to near 31N71W Fri evening then drift W and slowly weaken through Sat, allowing winds and seas to weaken. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.