000 AGXX40 KNHC 231753 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 153 PM EDT Sun Jul 23 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 weak sfc ridge continues from high pressure in the E central Gulf extends W to about 95W and dominates the basin. The ridge has built slightly westward in the past 18-24 hrs and moderate to locally fresh winds are expected to currently be developing across much of the SW and W Gulf, assisted by the approach of a tropical wave moving across the Gulf of Honduras and into the Srn Yucatan Peninsula. Seas expected to build 3 to 5 ft across this area. Otherwise, gentle to moderate winds and seas of 1 to 3 ft will prevail. These conditions will then persist through Tuesday night. The pressure gradient will slacken thereafter as a trough sinks into the NE Gulf. Gentle winds and seas of 2 ft or less will then prevail across the basin by the end of the week. The typical thermal trough will develop over the Yucatan Peninsula each late afternoon-evening through midweek, before pushing offshore into the SW Gulf each night, drifting westward during the overnight hours, then dissipating over the SW Gulf each morning. A surge of mainly fresh NE winds will accompany this trough while seas briefly build to 4 to 6 ft. 12Z GFS suggests strongest winds with the trough will occur tonight, again assisted by the N part of wave moving into the Yucatan. A weaker thermal trough is expected by the end of the week. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... Recent obs and scat passes show trades have diminished slightly to fresh across the central Caribbean, as the complex tropical wave has shifted across the Gulf of Honduras and central America. Strongest winds overnight through this morning will N of typical coastal Colombia location, at about 13-14N and buoy 42058 showed peak seas to 9 ft this morning. This surge has shifted Wwd and will move into NE Nicaragua this afternoon/evening. Elsewhere mainly moderate to fresh trades prevail, with an increase in the lee of the Lesser Antilles from 24 hours ago. Seas are 6 to 9 ft in the central Caribbean, and mainly 3 to 5 ft elsewhere, except 2 to 4 ft in lee of Cuba. A weak low lat El wave moving across the Windwards will drag the ITCZ across the islands of the SE Carib through tonight and into the ABCs by Mon. This in combination with another piece of wave energy from Hispaniola Nwd along 70W will allow for the Atlantic ridge to build slightly across the basin behind these 2 features tonight through Mon night, with more easterly flow basin wide. Latest GFS runs suggest peak nocturnal winds will approach 30 tonight and likely reach 30 kt and 10-13 ft seas on Mon night, and spread a broad wind and wave field across the S central Carib into Tue. ...SW N ATLANTIC INCLUDING THE BAHAMAS... High pressure ridging W across the area and into the NW Bahamas will combine with SAL to will to control the sensible weather for the next several days. Associated SAL can be seen in GOES-16 Ch2 imagery moving around the NW periphery of the ridge and across Bermuda, as supported in their 12Z sounding. Mainly moderate anticyclonic winds around the ridge will linger between 27N and 29N, except in the waters S of 22N and W of 65W where trades will pulse to fresh to strong from N of Hispaniola to the Windward Passage during the evening hours through midweek. Seas will be mainly 3 to 5 ft, except 2 ft or less in the lee of the Bahamas, and 5 to 7 ft occasionally N of Hispaniola to the Windward Passage. A piece of tropical wave energy and moisture has moved WNW across the SE waters overnight and is entering the SE Bahamas and adjacent Atlc waters and will continue WNW next few days. This to bring modest increase in showers with and behind the perturbation, with with a slight increase in winds and seas behind it. The pressure gradient will weaken slightly by the end of the week allowing for gentle to moderate winds and seas of 3 to 5 ft to dominate across the open waters 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 Stripling. National Hurricane Center.