000 AXNT20 KNHC 212024 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sat May 22 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 1800 UTC surface analysis and satellite imagery through 2200 UTC. ...SPECIAL FEATURES... A 1008 mb gale-force non-tropical low is located near 35N60W, or about 260 nm NE of Bermuda, moving W at 15 kt. Scattered moderate convection is within 270 nm NE semicircle and 180 nm SW semicircle. The strongest winds of about 45 kt are located in the northern semicircle. Any increase in organization would result in the formation of a subtropical cyclone later today or tonight as it moves westward to west-southwestward to the northeast of Bermuda. By Saturday night or Sunday, the low is forecast to move NE into a more hostile environment. The potential for subtropical cyclone formation during the next two days is high. Please see High Seas forecasts issued by the Ocean Prediction Center at ocean.weather.gov/shtml/NFDHSFAT1.php for more details on this developing low pressure area. A well-defined 1009 mb surface low pressure is centered in the western Gulf of Mexico near 26.5N95W and is moving NNW at 10 kt. A recent ASCAT pass shows winds of 25 kt in the eastern semicircle of the low. Scattered shower and thunderstorm activity remains disorganized from 23N-29N between 90W-96W. Any increase in organized thunderstorm activity near the center could result in the formation of a short-lived tropical depression or storm. This system has a medium chance of becoming a short-lived tropical depression or storm before it moves inland over the northwestern Gulf coast tonight. Regardless of development, the system could produce heavy rainfall over portions of southeastern Texas and southwestern Louisiana through Saturday, which could lead to flooding across the region. See the NHC Tropical Weather Outlook at hurricanes.gov for more information. Gale Warning for the Canary Islands: According to the forecast from Meteo France, localized winds to gale force are possible near and in between the Canary Islands tonight. On Saturday, gale force winds will continue near the Canary Islands, and gales will expand toward the coast of Morocco, including the marine zones Agadir and Tarfaya. Outside of the gales, strong to near gale force winds will cover the area north of 26N and east of 24W by Saturday. Expect seas to build to 12-14 ft offshore Morocco this weekend, with 9-11 ft seas elsewhere north of 22N and east of 32W. See the High Seas Warning and High Seas Forecast products from Meteo France at weather.gmdss.org/II.html for more details. ...TROPICAL WAVES... The axis of a tropical wave is near 46W south of 12N, moving W at 20 kt. Scattered moderate convection is within 120 nm either side of the wave axis from 03N-07N. The wave could enhance showers over the southern Windward Islands and SE Caribbean on Sunday. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Africa near 11N15W to 08N19W. The ITCZ continues from 08N19W to 05N27W to 03N44W, then resumes W of a tropical wave from 04N48W to 03N51W. Isolated moderate convection is noted from 01N to 06N between 22W and 41W. GULF OF MEXICO... See the Special Features section above for information on a tropical disturbance with a medium chance of formation. East of 90W, scattered tstorms are noted from 23.5N-26N between 87W-90W. High pressure ridging stretching from the Carolinas to the NE Gulf of Mexico is leading to mainly clear skies in the NE corner of the Gulf. Fresh to strong winds prevail over the eastern and east- central Gulf of Mexico, where seas are 8-11 ft. Light to gentle winds, and seas of 3-5 ft prevail over the SW Gulf of Mexico. A strong ridge stretching from the eastern seaboard to the NE Gulf will continue to dominate the Gulf waters into Sat night. The pressure gradient will support fresh to strong SE winds and high seas across the Gulf region through Sat. Seas of 10 to 11 ft will continue over portions of the east-central and north-central Gulf through this evening. CARIBBEAN SEA... A stationary front extends over the NW Caribbean, south of Cuba, along 21N. Scattered moderate tstorms are along and south of the front, from Hispaniola to Jamaica to the Yucatan Channel. Similar convection is seen over the Gulf of Honduras. Most of the open waters of the eastern and central Caribbean south of 17N are free of any significant precipitation. Fresh to strong E winds prevail over the central Caribbean, as well as in the lee of western Cuba. Moderate to fresh winds are noted elsewhere. Seas of 6-9 ft prevail over the central Caribbean, with 4-6 ft seas elsewhere. For the forecast, high pressure across the western Atlantic will continue to support fresh to strong winds across the central Caribbean, and south of Cuba, through Sun morning. A tropical wave approaching from the east may increase moisture and rain chances over the southern Windward Islands and SE Caribbean on Sunday. ATLANTIC OCEAN... See the Special Features section above for details on a low pressure system NE of Bermuda that has a high chance of becoming a subtropical cyclone. A cold front extends from 31N57W to 25N65W to 26N74W. Isolated showers are along the cold front. A stationary front extends from 31N47W to 21N64W to the Windward passage and into the NE Caribbean. Scattered showers and isolated tstorms are within 120 nm of the stationary front. Fresh NE winds in the western Atlantic, between Florida and 70W, with strong E winds in the Florida Straits and south of the Bahamas. Winds are gentle to moderate north of 20N between 30W- 65W. Fresh to locally strong winds prevail south of 20N. Fresh to strong winds are noted north of 25N and east of 26W, with localized areas of near gale to gale force in between the Canary Islands. For the forecast west of 65W, the stationary front will slowly dissipate through tonight. The pressure gradient between high pressure off the eastern seaboard and the frontal boundary will support fresh to strong easterly winds N of the front and W of 68W through early Sat. Seas of 6 to 8 ft will prevail across the region through Sat. Large NE swell will enter the waters from 27N-31N between 65W-75W on Sat, and spread across the forecast area through Sat night before beginning to subside on Sun. $$ AL