639 AGXX40 KNHC 201910 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 310 PM EDT Thu Sep 20 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... Water vapor imagery and model analyses indicate the presence of an upper-level cyclonic shear axis stretching from the Florida Straits to southeast Louisiana. At the surface, a trough extends from near Ft. Myers, FL southwestward to near 24N86W. Another trough extends through the central Bay of Campeche from 24N91W to the coast of Mexico near 18N93W. Locally fresh winds are possible with this trough. Isolated showers and thunderstorms are noted over the Bay of Campeche. This trough and associated moisture will move westward, reaching mainland Mexico by late Fri. Otherwise, high pressure building over the eastern United States will produce mainly gentle to moderate E to SE breezes and 1 to 4 ft seas across the Gulf through Sun. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A tropical wave along 70W-71W will move west across the central Caribbean through Fri, and then over central America Sun. Strong wind gusts are possible near showers and thunderstorms associated with this tropical wave across the eastern Caribbean through Fri. 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 now through Fri, before winds diminish slightly Sat and then more significantly on Sun. A 1008 mb low along the monsoon trough is located in the southwest Caribbean near 11N82W. These features are producing numerous moderate to strong convection over the southwest Caribbean from 10N-13N between 77W-86W. This activity is affecting parts of northern Costa Rica and Nicaragua, including the city of Bluefields, where heavy thunderstorms are currently being reported. Plenty of moisture will persist over the southwest Caribbean through Saturday as the tropical wave, currently along 70W, reaches the area and moves inland into central America late Sat or early Sun. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A cold front enters the forecast area near 31N69W and continues southwestward to 29N73W to 29N79W. Scattered showers are within 120 nm ahead of the frontal boundary between 70W-78W. East of the front, a surface trough is analyzed from 29N62W to 23N70W. Scattered showers and thunderstorms are located within 150 nm east of the trough. Scatterometer data indicate winds of 20-25 kt are currently occurring north of 29N between 64W-69W. This area of 20-25 kt winds will move eastward over the area for the next 12 hours before gradually weakening. The aforementioned front will sink SE to the waters north of 27N through Fri before the front dissipates. Low pressure north of the area is forecast to drop southeast and bring 20 to 25 kt winds, accompanied by NE swell over the upcoming weekend W of 70W and N of 28N. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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 Latto. National Hurricane Center.