000 AGXX40 KNHC 130829 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 429 AM EDT Thu Apr 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... High pressure ridge persists over the northern waters this morning. An inverted llvl trof can be seen across E gulf along about 84w shifting slowly WSW and weakening. Otherwise, latest data indicates gentle to moderate NE to E winds prevailing over the forecast waters, except fresh ENE wind through the Straits. Seas are in the 2-3 ft range over the northeast Gulf, 3-4 ft over the northwest Gulf, and 4-6 ft over the southern Gulf. The ridge will continue nearly E to W across the northern Gulf waters through the weekend. Reinforcing high pres will briefly freshen winds to strong Fri night through Sat night across E and SE portions, especially through the Straits. A trough will develop each evening over the Yucatan peninsula. This trough will shift westward into the southwest Gulf each night where it will dissipate each morning. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... Latest data depicts moderate to locally fresh winds over the central Caribbean and gentle to moderate winds over the remainder of the Caribbean, and moderate E to SE winds across the tropical north Atlantic forecast waters. Nocturnal maxes of 20+ kt area seen through the Windward Psg and in lee of Ern Dom Rep per recent ASCAT data. Seas are in the 4-6 ft range across the southern Caribbean, possibly to 7 ft off of Colombia, 3-5 ft over the north central Caribbean, 4-6 ft over the western Caribbean and Windward Psg, 2-3 ft over the eastern Caribbean, and 5-6 ft over the tropical north Atlantic waters. Fresh tradewinds will continue to pulse to strong over the south central Caribbean as well as the lee of Cuba and windward passage the next couple of night. Low pressure north of Hispaniola has begun to drift southward overnight and is expected to drift ENE next 24 hours, and will loosen the pressure gradient over the W half of the basin with little change elsewhere. This will limit the strength of nocturnal pulsing in the lee of Cuba and the windward passage by Friday. The low will shift northeast and begin to accelerate late Fri through the weekend with high pressure building into the Atlc north of the area in its wake. This will quickly tighten the pressure gradient over the forecast waters Sat night through Sun and increase winds across the Caribbean. ...SW N ATLANTIC INCLUDING THE BAHAMAS... Broad upper low across the Ern waters has cutoff from mean flow and drifting ESE attm, with sfc low now just SSE near 26N68.5W. Occluded front remains draped across the N and NW of low with gales still assumed to be occurring along this boundary between about 65-70W. Afternoon altimeter data yesterday showed seas to 13 ft near gales occurring at that time and 12 ft seas are assumed to still persist in the gale area. Upper trough has also aided in formation of a trough or convergence line wrapping into Ern side of low that is kicking off cnvtn in Mona Psg and across Puerto Rico and adjacent waters, where isolated cells will produce very heavy rain in the short term. strong cyclonic winds prevail elsewhere generally N of 26N across N semicircle and NW quad, between 59W and 73W, where seas area 8-10 ft outside of the gales. Seas to 8 ft have spread into SW quad of low which was not forecast by wave models and will propagate towards Turk and Caicos and Hispaniola next 24 hrs. Gentle Nly flow is spreading across far SE waters into back side of convergence line across Mona Psg, while fresh NELy flow extends W of 73W into much of FL coastal waters and into Straits, where seas are generally 4-6 ft N of Bahamas and 3-5 ft in lee of Bahamas. The ECMWF appears to have verified very well with this event, while the GFS has finally come in line. Models suggest the cyclonic motion of sfc low is now moving toward the S and SE and then should commence an E to ENE drift tonight into Fri and then begin to shift NE and gradually accelerate into the N central Atlc over the weekend. Strong high pres will reinforce the ridge to the NW, and produce a quickly tightening pres gradient across the area waters from N to S over the weekend. The exiting low will drag a cold front across the SE forecast waters Sat and Sun while a reinforcing front will sink S across most of the area with building high pressure. Strong NE wind and building windsea will maintain seas 8-10 ft E of the Bahamas through the entire weekend. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... .AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W... Gale Warning early today. $$ *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 Stripling. National Hurricane Center.