000 AGXX40 KNHC 130755 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 355 AM EDT Sun Aug 13 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 extends west across the central Gulf. The associated anticyclonic flow consists of light to gentle winds over the basin, with the exception of the eastern portion of the Bay of Campeche where there northeast to east moderate winds are present due to the tighter gradient with the Yucatan Peninsula thermal trough that has moved to just offshore that peninsula. A partial Ascat pass from 0348Z depicted these winds. The buoys are reporting rather low seas in the 1-3 ft range throughout. Only isolated showers and thunderstorms are noted over the far southeastern part of the Gulf at this time. For this forecast, the only foreseeable changes will be seen in regards to a tightening of the pressure gradient over the far western part of the Gulf beginning on Tuesday due to the interaction between deepening low pressure over northern Mexico and W Texas and the already in place ridge axis across the Gulf. This is expected to increase the southerly winds over some areas of the western Gulf to the moderate to fresh range with seas building to around 6 or 7 ft in some spots over those areas of the Gulf. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... Latest Buoy and available scatterometer data show generally gentle to moderate NE to E trades throughout, except for stronger trades of fresh to strong intensity confined to the far south- central waters S of about 12.5N and between 70W and 74W. The buoys and latest altimeter data indicate seas in the range of 4-6 ft, except for lower seas of 3-4 ft over the western Caribbean, and seas of 2-3 ft over much of the NW Caribbean section. A tropical wave is analyzed along 84W S of western Cuba at 06Z moving westward at 20 kt. This wave will move across the rest of the western Caribbean through this afternoon, and inland central America tonight. A large and well-defined tropical wave currently over the central Atlantic along 52W S of 20N is expected to begin to move across the eastern portion of the Tropical N Atlantic waters this evening, then move across the rest of those waters through tonight, and across the eastern Caribbean Monday through Tuesday night, the central Caribbean Wednesday and Wednesday night and the western Caribbean Thursday into Thursday night. A tightening of the pressure gradient will accompany this wave bringing an increase to the trades across much of the eastern and central Caribbean Monday through Thursday. Expect scattered showers and thunderstorms, some with gusty winds to also accompany the wave and follow in behind it. Yet another large tropical wave will quickly move through the Tropical N Atlantic waters Tuesday night into Wednesday, and across the eastern Caribbean from about Wednesday afternoon through Thursday night. A NE to SE wind shift of moderate to locally strong winds will accompany this wave. Scattered to numerous showers and thunderstorms with gusty winds are expected as well with this wave. The fresh to strong trades over the far south-central waters are forecast to shrink in coverage this afternoon, then re-develop late this afternoon and evening and continue through tonight before expanding N to near 16N between 70W and 77W early on Monday before diminishing some on Monday night. With passage of the aforementioned tropical waves, expect for winds of this intensity range to encompass a good majority of the eastern and central Caribbean through just about the entire week beginning late on Monday night. Numerous showers and thunderstorms noted over the SW Caribbean from 11N to 14N between the NW coast of Colombia and 83W are being activated by the eastern segment of the E Pacific monsoon trough that runs southern Costa Rica to just west of NW Colombia. The presence of speed convergence along the trough is helping to activate this activity. It should remain quite active through the next few days. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The main feature of interest is now Tropical Depression Eight that formed late last night. As of 03Z, the center of Tropical Depression Eight was located near 25.3N 70.3W moving NNW at 11 kt, with maximum sustained winds 30 kt with gusts to 40 kt. The 0120Z Ascat pass nicely depicted an area of 20-30 kt winds over the eastern semicircle of the within a distance of around 150 nm. The depression is forecast to intensify to a tropical storm near 27.0N 71.2W this morning with maximum sustained winds 35 kt gusts to 45 kt...reach near 29.0N 71.9W this evening with maximum sustained winds 40 kt gusts to 50 kt...and continue to gradually intensify as it moves northward reaching near 30.7N 72.0W Monday morning with maximum sustained winds of 45 kt gusts to 55 kt. The tropical storm is then forecast to track northeastward to N of the forecast waters near 32.2N 71.4W Monday evening with maximum sustained winds of 50 kt gusts to 60 kt. In the wake of the tropical storm high pressure will build westward along 27N through Thu. The northern portion of a strong tropical wave interacting with central Atlantic ridging is expected to increase winds and seas over the far southeastern waters of the basin beginning on Wednesday. E winds will pulse to fresh to strong between the SE Bahamas and Hispaniola in the afternoons and at night beginning on Monday night. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... .AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W... Tropical Storm Warning Sun into Mon. .AMZ119...ATLANTIC FROM 22N TO 27N E OF BAHAMAS TO 70W... Tropical Storm Warning Sun. $$ *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.