000 AGXX40 KNHC 030632 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 232 AM EDT Tue Oct 3 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 surface trough is in the western Gulf extending from 26N94W to the Bay of Campeche near 19N94W. Scattered showers and isolated thunderstorms are occurring near the trough which is moving westward. Otherwise, ridging dominates the basin with fresh to strong E to SE flow across the basin E of 94W and E of the trough, and moderate NE winds W of the trough. Seas are up to 6 to 9 ft E of the trough, and 3 to 5 ft W of the trough. The trough will shift W reaching the coast by this upcoming evening, then new troughing will develop from the NE coast of Mexico to the Bay of Campeche thereafter, which will remain nearly stationary with fresh to strong NW winds W of this troughing offshore of Veracruz by Thu afternoon. High pres ridging will continue to dominate the basin along with persistent fresh to locally strong winds and 6 to 9 ft seas. Model guidance diverges by the end of the week with respect to a feature that may move and or develop in the eastern Gulf. Some guidance develops a closed low near or E of the Straits of Florida, while other guidance merely shows an open trough or northern portion of a tropical wave moving into the eastern Gulf from the SW N Atlantic. In either case, the pressure gradient across the central and western portion of the basin will weaken allowing for winds to relax there. Plentiful moisture and convection will also likely accompany the feature. Model guidance also shows elongated low pressure that may move from the NW Caribbean Sea or the Yucatan Peninsula into the southern Gulf by the start of the upcoming weekend. Thus, plenty of uncertainty exists during the extended period of the forecast. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A tropical wave extends from eastern Jamaica southward to northern Colombia. This tropical wave along with a vigorous middle to upper low near 16N78W is supporting numerous showers and scattered thunderstorms, mainly between 70W and 80W. Another tropical wave has entered the Tropical N Atlantic near 55W/56W. Most of the associated convection is E of the wave axis. Mainly moderate to locally fresh trades dominate the waters, except fresh to strong in the Gulf of Honduras. Seas are mainly 3 to 5 ft, except 4 to 6 ft in the Gulf of Honduras, and 1 to 3 ft in the SW Caribbean where the lightest winds are present. The tropical wave will continue to move W through the middle part of the week and become difficult to identify as it slowly becomes absorbed into a developing Central American gyre. Very active weather is expected across SW and W portions during this time. The tropical wave in the Tropical N Atlantic will also eventually merge and become absorbed within the gyre. The combination of all of these features may lead to the development and consolidation of low pressure over Central America or the NW Caribbean by the end of the week, which would then likely move NW toward the Yucatan Peninsula into the upcoming weekend. There remains uncertainty with regard to the development of this low pressure in the western Caribbean. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The remnants of a front, now having more of the appearance of a shear line, extend from 27N65W to the central Bahamas. High pres continues to build down from the N and support fresh to strong NE to E flow to the N of this boundary, with mainly moderate easterly flow S of the boundary. Seas are 8 to 13 ft N of the boundary, and 4 to 7 ft S of the boundary. Broad surface troughing is S of the boundary, extending from roughly 26N76W to eastern Cuba with scattered thunderstorms in its vicinity. The northern portion of a tropical wave has entered the far SE portion with additional convection entering eastern portions of zone AMZ127W. Little change in these marine conditions is likely through the middle part of the week. The trough will slowly shift to the NW and W approaching the Straits of Florida by Wed evening. Weak low pressure may develop along the trough prior to it shifting westward, although model guidance varies with the development of a low. The feature will exit the area by Fri with weak ridging and a significantly weaker pres gradient left across the basin in its wake. The weak ridging currently looks to hold in place for the upcoming weekend, with much more tranquil marine conditions possible. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.