000 AGXX40 KNHC 300709 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 309 AM EDT Sat Sep 30 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 middle to upper level low is located in the E central Gulf near 26N87W. Deep tropical moisture continues to feed up from the NW Caribbean Sea to across the Gulf E of 87W with scattered showers and isolated thunderstorms. Surface troughing is in the western Gulf extending from near the Texas/Mexico border to offshore of Veracruz near 18.5N94W. Scatterometer data showed fresh to strong NW winds offshore of Veracruz W of the trough axis, where seas are 6 to 8 ft. Another surface trough is analyzed across the eastern Yucatan Peninsula. Light to moderate winds are across the Gulf E of 90W, with moderate to fresh winds elsewhere W of 90W. Seas are 1 to 3 ft E of 90W and in the Bay of Campeche, and 4 to 6 ft elsewhere W of 90W. Strong high pressure is forecast to build across the NE Gulf this evening behind a stationary front, increasing winds to fresh to strong N of the front which will spread across the waters N of 27N/28N through early Monday, then will continue to expand across the waters N of 23N E of 91W by mid-week. Seas will build to 8 to 11 ft through early next week as a result. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... An upper level low in the E central Gulf of Mexico extends a trough southward to central Honduras. Deep tropical moisture continues to move across the waters W of 80W. This pattern is forecast to persist through the weekend. A tropical wave over the eastern Caribbean extending southward from the Mona Passage to northern Venezuela is interacting with an upper low over the Dominican Republic with widespread showers and scattered thunderstorm activity over the eastern Caribbean resulting in localized flash flooding, including across Puerto Rico and the Virgin Islands. This tropical wave and accompanying upper low will move westward to the central Caribbean through the weekend, then the western Caribbean early next week, bringing accompanying unsettled weather. Moderate to fresh trades in the central Caribbean between these two areas will diminish as a frontal system intrudes on the SW N Atlantic N of the area weakening the pressure gradient. Moderate trades will dominate the entire basin for the early part of the upcoming week into mid-week, except expect gentle to moderate southerly flow in the SW Caribbean S of the monsoon trough which will continue to be lifted slightly northward extending from NW Colombia to eastern Nicaragua. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A surface trough extends across the northern portion from near 30N75W to weak low pressure over central Florida near Orlando. Scattered showers and isolated thunderstorms persist across much of the basin N of 23N with the area under upper level diffluence. Mainly gentle to moderate easterly flow dominates the basin, except locally fresh winds N of Hispaniola. Seas are mainly 4 to 7 ft, except 1 to 3 ft inside protected areas SW and W of the Bahamas. A front is forecast to sag southward into the NW portion this afternoon and tonight with fresh to strong NE flow behind is as high pressure builds in. Seas will quickly build to 8 to 12 ft as a result. The front will extend from near Bermuda to 30N70W to E central Florida by Sunday evening, then will wash out from near 30N65W to the northern Bahamas early next week while high pressure continues to build southward. Fresh to strong NE flow will persist across the NW half of the basin, with moderate to fresh trades across the SE half through mid-week. The persistent NE fetch will maintain 8 to 11 ft seas, except 5 to 7 ft across the SE half of the basin. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.