000 AXNT20 KNHC 201744 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Thu May 20 2021 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1640 UTC. ...SPECIAL FEATURE... A 1012 mb non-tropical low is located about 600 NM east of Bermuda. The low is expected to develop gale-force winds later today while it moves generally northward. The low is then forecast to move westward and southwestward over warmer waters tonight and Friday, and it will likely become a subtropical cyclone near and to the northeast of Bermuda on Friday. The system is expected to move toward the north and northeast into a more hostile environment by late Sunday into Monday. Currently S strong winds are associated with the low in our marine area north of 29N between 46W and 52W with seas to 9 ft. These conditions should diminish south of 31N by tonight. For more information on this developing low pressure area, please see High Seas forecasts issued by the NOAA Ocean Prediction Center ocean.weather.gov/shtml/NFDHSFAT1.php. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Senegal near 14N16W to 10N22W. The ITCZ continues from there to 04N52W along the coast of NE Brazil. Scattered moderate convection is noted between 01N and 06N west of 43W. GULF OF MEXICO... Scattered moderate convection is occuring north of 20N between 90W and 96W in association with a sharp upper-level trough over Texas and NE Mexico as well as a surface trough over the NW Gulf from 25N94W north-northwestward to the Texas coast near 29N95W. While the prevailing winds are gentle or weaker west of the trough, winds will be gusty in the vicinity of the thunderstorm activity. East of the trough and north of 23N, a strong NE-SW pressure gradient is forcing E to SE winds of fresh to strong. Seas are 8 to 10 ft in the NE Gulf as well as the Straits of Florida. Elsewhere seas are generally 5 to 7 ft. Strong thunderstorms are expected to continue across W Gulf of Mexico through Fri and will be capable of producing locally near- gale force winds and seas to 10 ft. Meanwhile, a strong ridge stretching from eastern seaboard to the NE Gulf will continue to dominate the Gulf waters through the remainder of the week. The pressure gradient between the ridge and deepening low pressure across the Southern Plains and northern Mexico will result in fresh to strong SE winds and high seas across the Gulf region through Sat. Seas will peak 10 to 13 ft today through Fri in the Straits of Florida and 12 ft in the N central Gulf on Fri. CARIBBEAN SEA... A moderate N-S pressure gradient between ridging north of the Bahamas and a 1010 mb Colombian low is promoting fresh to strong E winds over the S central Caribbean and over the Gulf of Honduras. Elsewhere the trades are gentle to moderate. Seas are peaking 6-8 ft just north of Colombia and 5-7 ft in the Gulf of Honduras. Elsewhere seas are generally 4-6 ft. Scattered showers are present across the N Caribbean and Greater Antilles in association with a stationary front that extends over the SE Bahamas to central Cuba. Elsewhere very scattered moderate convection is noted south of 12N in the SW Caribbean in association with the NE Pacific monsoon trough that extends from Costa Rica to NE Colombia. High pressure off the U.S. East Coast will continue to build across the western Atlantic west of 70W through Fri. This will bring fresh to strong winds across the central Caribbean through Sat. Fresh to strong winds will also occur in the lee of Cuba through Sat. Expect fresh to strong easterly winds in the Gulf of Honduras mainly at night through tonight. ATLANTIC OCEAN... See above Special Feature for a non-tropical low centered just north of our marine area of responsibility. A cold front extends from the 1012 mb non-tropical low at 33N52W southwestward to 22N70W where it transitions to a stationary front to 23N79W. Scattered moderate convection is located within 120 NM southeast of the front east of 65W and scattered showers are present within 120 NM south of the front west of 65W. Strong ridging north of the front is causing fresh to strong NE to E winds between 19N and 30N west of 70W. Seas are up to 9 ft east of the Bahamas and NE Florida. Elsewhere across the tropical N Atlantic, the NE to E trades are moderate to fresh south of 20N and gentle elsewhere. Seas are up to 8 ft south of 20N and 4 to 7 ft elsewhere. In the forecast west of 65W, the front will weaken and dissipate through Fri as it sinks southward and approaches the Windward Passage and Hispaniola. Meanwhile, the pressure gradient between high pressure off the eastern seaboard and the frontal boundary will support an area of fresh to strong easterly winds N of the front and W of 68W through late Fri. Seas will peak around 9 ft E of the Bahamas today. Large NE swell will enter the NE waters early Sat and spread across the area waters through Mon. In the forecast east of 65W, winds and seas are anticipated to have little change through Saturday, then diminish slightly on Sunday and Mon. $$ Landsea/Rivera-Acevedo