000 AGXX40 KNHC 160804 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 404 AM EDT Wed Aug 16 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... The main feature continues to be the western extension of the Atlantic sub-tropical ridge that reaches across the central Gulf, with a 1017 mb center at 27N84W. The associated anticyclonic flow consists of light to gentle winds in the basin as confirmed by current buoy observations and by an Ascat pass from 0246Z last night. Moderate to fresh southerly winds being observed over the far western Gulf will diminish this afternoon, then briefly materialize tonight before diminishing again on Thursday. Seas to 6 ft associated with these winds will lower to around 4 ft on Thursday. The ridge will lift northward to the northern Gulf on Friday, and remain nearly stationary through the weekend. Moderate NE to E winds over the eastern Bay of Campeche will pulse to fresh to strong at night through the period. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A tropical wave is analyzed near 81W at 06Z, moving westward at 20-25 kt. The wave will move across the remainder of the western Caribbean through Thursday. A broad tropical wave approaching the Lesser Antilles at 06Z is moving westward near 25 kt. This wave will move quickly through the Tropical N Atlantic waters early this morning, then pass across the eastern Caribbean later this morning and through Thursday afternoon, across the central Caribbean Thursday beginning late Thursday afternoon through Friday afternoon, and the western Caribbean Friday night through Saturday evening. The next tropical wave or low pressure system will move across the eastern Tropical N Atlantic waters Thursday afternoon, and the rest of the Tropical N Atlantic through Friday morning, then across the eastern Caribbean Friday afternoon through Saturday night and the central Caribbean Sunday and Sunday night. Fresh to strong winds, locally gusty at times, will accompany this system along with scattered to numerous showers and thunderstorms. Scattered showers and thunderstorms in the far SW Caribbean will continue to pulse from time to time through the forecast period. ...SW N ATLANTIC INCLUDING THE BAHAMAS... Now with Hurricane Gert well to the north of the forecast waters, winds and seas over the NE portion of zone AMZ 113W will continue to subside through today. A trailing band of mostly low to middle level clouds is noted over much of the waters between 70W-76W and N of 26N. Widely scattered showers and isolated thunderstorms are present over the northern portion of zone AMZ 113 to the east of 75W. This activity should linger through the afternoon and possibly the evening. In the wake of Gert, the sub-tropical Atlantic ridge will become established along along 27N through tonight. It will then shift N to near 28N Thursday through Friday, and shift N to 29N on Saturday and to along 31N on Sunday. The northern portion of a broad tropical wave is passing across the far SE portion of the area. Associated scattered showers and isolated thunderstorms cover most of that zone. The wave will quickly move into the eastern Caribbean later this morning, but the pressure gradient between it and the Atlantic ridge will increase the winds and wave heights over the far southern waters tonight through at least early Friday afternoon, with easterly winds reaching the fresh to locally strong range and seas expected to build to around 6 or 7 ft. Guidance indicates that easterly winds begin to increase again beginning Saturday evening over these same waters as another broad large tropical wave or tropical low pressure system moves through the Tropical N Atlantic waters. Expect similar winds and seas with this wave or low pressure system, but may be significantly larger if it is a stronger system. Stay tuned to future updated text forecasts as well as updated NDFD forecast data. E winds will pulse to fresh, maybe with brief instances to strong, between the SE Bahamas and Hispaniola in the afternoons and at night through the forecast period. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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 Aguirre. National Hurricane Center.