000 AXNT20 KNHC 211219 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Fri May 21 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. ...Updated at 1215 UTC for Special Features... Based on 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Updated: A 1009 mb storm-force non-tropical low is located near 35.5N 58W, or about 390 nm ENE of Bermuda. Strongest winds are in the northern semicircle. Showers and thunderstorms have become better organized during the past several hours. If current trends continue, advisories could be initiated on the system later today or tonight as a subtropical storm as it moves westward to west-southwestward to the northeast of Bermuda. Subsequently, the low is forecast to move NE into a more hostile environment by Saturday night or Sunday. 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. Updated: Recent satellite imagery suggests that a low-level circulation is forming associated with the mid- to upper-level disturbance over the western Gulf of Mexico. However, shower and thunderstorm activity remains disorganized. Environmental conditions are expected to be marginally conducive for development, 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 during the next few days. See the NHC Tropical Weather Outlook at hurricanes.gov for more information. Gale Warning for the Canary Islands: The forecast from Meteo- France is for gale-force winds near the Canary Islands, starting on 21 May, at 0600 UTC. Strong to near gale-force winds, surrounding this area, will expand on Saturday, to cover the area north of 26N and east of 24W, with the possibility of gale force winds continuing near the Canary Islands. 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. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal areas of Guinea near 11N15W to 05N20W to 03N26W. The ITCZ continues from 03N26W to 03N51W. Scattered moderate convection is noted from 02N to 06N between 38W and 52W. GULF OF MEXICO... A disorganized area of showers and thunderstorms over the western Gulf of Mexico is associated with a surface trough along 95W north of 21N. Conditions are expected to be marginally conducive for some development over the next day or so before the disturbance moves inland over the Texas coast by tonight. The system could produce heavy rainfall over portions of SE Texas and SW Louisiana through Saturday. This trough is spreading a large area of cloudiness and showers over the west- central and NW Gulf of Mexico. East of the trough, strong E to SE winds prevail across a large portion of the east-central Gulf of Mexico, from the Florida Straits to the Mississippi River delta, with seas 8 to 10 ft seas. Moderate winds prevail over the western Gulf, west of the trough, with 5 to 7 ft seas. For the forecast, showers and thunderstorms will continue across the western Gulf of Mexico today, with strong gusty winds and seas to 10 ft. 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 will peak at around 10 to 11 ft in the north-central Gulf this evening. CARIBBEAN SEA... A stationary front extends north of the region along 20N. High pressure in the wake of the front is north of Cuba. Scattered showers are noted across the northern Caribbean north of 17N between the Mona Passage and 84W. Similar convection is north of Honduras. Most of the open waters of the eastern and central Caribbean are free of any significant precipitation. Fresh to strong E winds are in the south-central Caribbean and in the Gulf of Honduras, with moderate to fresh winds elsewhere. Seas are 6-8 ft in the central Caribbean and 4-5 ft elsewhere. For the forecast, high pressure building north of the area across the western Atlantic will support fresh to strong winds across the central Caribbean, and south of Cuba, through Sun morning. ATLANTIC OCEAN... A cold front passes through 31N47W to 25N50W to 22N57W, then stationary to 20N63W to 20N79W. A large area of is west of the frontal boundary to a line from 31N56W to 21N70W. A second cold front trails from a complex low pressure area north of the area through 31N59W to 27N63W to 28N75W. A narrow band of showers is along the frontal boundary. Scatterometer data shows moderate to fresh trade winds across most of the western Atlantic. Seas are 6 to 8 ft east of the Bahamas, and 4 to 7 ft elsewhere. For the forecast west of 65W, the stationary front along 20N 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. 6 to 8 ft seas will prevail across the region through Sat. Large NE swell will enter the NE forecast waters Sat, and spread across the forecast area through Mon. For the forecast between 35W-65W, little change in winds and seas is expected through Saturday. See the Special Features section above regarding the forecast east of 35W. $$ Mundell/Hagen