000 AXNT20 KNHC 292322 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Sep 30 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 2300 UTC. ...SPECIAL FEATURES... Hurricane Sam is centered near 20.2N 57.6W at 29/2100 UTC or 330 nm ENE of the Northern Leeward Islands moving NW at 8 kt. Estimated minimum central pressure is 945 mb. Maximum sustained wind speed is 115 kt with gusts to 140 kt. Seas are peaking to 41 ft. Numerous strong convection is within 90 nm of the center in the NE semicircle and within 50 nm of the center in the SW semicircle. Scattered moderate convection is noted farther N from 21N to 22N between 55W and 58W, and farther SE from 18N to 21N between 54W and 56W. Swells generated by Sam will continue to impact the Leeward Islands for the next few days, and reach Puerto Rico and the Virgin Islands early Thu morning. These swells are expected to reach Bermuda and the Bahamas in a day or two, and then spread to the United States east coast by this weekend. These swells could cause life-threatening surf and rip current conditions. On the forecast track, Sam will continue to pass well to the east-northeast of the northern Leeward Islands through tonight. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT3.shtml, Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml, and the NHC High Seas Forecast at www.hurricanes.gov for more details. Newly formed Tropical Storm Victor is centered near 8.3N 25.5W at 29/2100 UTC or 470 nm S of the Cabo Verde Islands moving WNW at 11 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Seas are peaking at 12 to 15 ft near the center. Numerous moderate to isolated strong convection is evident up to 200 nm in a NW semicircle from the center. Scattered moderate convection is seen up to 190 nm in a SE semicircle from the center. Victor will continue on a WNW course for the next several days with a slight increase in forward speed on Thu afternoon, staying away from the Cabo Verde Islands. Steady strengthening is forecast, and Victor is expected to become a hurricane in a day or two. Please read the latest High Seas Forecast issued by Meteo-France at website https://www.weather.gmdss.org/II.html and the latest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... An Atlantic tropical wave is along 43W from 17N southward and moving W near 10 to 15 kt. Scattered showers are found from 06N to 10N between 40W and 43W. A western Caribbean tropical wave is near 83W from 18N southward across W Panama into the E Pacific Ocean, and moving W at 5 to 10 kt. Scattered moderate convection is present over the SW corner of the Caribbean Basin mainly south of 14N and west of 80W. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic through the coast of Mauritania near 18N16W to a 1009 mb low near 18N17W to 09N24W to 1009 mb low pres near 07N34W to 06N40W. The ITCZ extends from 07N45W to 08N55W. Scattered moderate to isolated strong convection is present from 02N-11N between 20W-41W. ...GULF OF MEXICO... A surface trough extends across the northern portion of the basin from 30N85W to 27N97W. Scattered moderate convection is noted along the trough mainly west of 87W. Moderate to locally fresh winds and seas up to 5 ft are possible near these showers and thunderstorms. Otherwise, a broad surface ridge extending southwestward from N Florida to central Mexico should sustain light to gentle winds and seas at 1 to 3 ft across the E and central Gulf. Moderate SE to S winds and seas of 2 to 4 ft prevail across the rest of the Gulf, including the Yucatan Channel. For the forecast, weak high pressure will persist over the Gulf through Thu night, supporting moderate southerly winds across the western Gulf with mostly gentle winds in the eastern Gulf. A weak cold front will move southward over the eastern Gulf Fri, then stall and dissipate over the southeast Gulf through late Sat. Stronger higher pressure will increase across the region behind the front, allowing winds and seas to build over mainly the southeast Gulf. Seas may build to 7 ft over the Straits of Florida by Sat night. Light to gentle breezes and slight seas will follow over most of the Gulf through early next week. ...CARIBBEAN SEA... Light easterly trade winds allow island heating to generate isolated thunderstorms over Cuba and Hispaniola. Farther S, convergent trades are causing scattered showers and thunderstorms near the Colombia-Venezuela border and adjacent waters, and also over NE Venezuela and nearby waters. Refer to the Tropical Waves section above for additional convection in the basin. Light to gentle trades and seas of 2 to 3 prevail across the entire Caribbean Basin. For the forecast, Hurricane Sam will move to 21.2N 58.9W Thu morning, 23.1N 60.4W Thu afternoon, then continue north of the region to southeast of Bermuda by Sat then into the north central Atlantic. Swells generated by Sam are forecast to continue over Atlantic waters from off the northern Leeward Islands to north of the Mona Passage through Fri. Meanwhile, gentle trades will prevail over the Caribbean through Fri. Winds are expected to increase moderate to fresh across the basin by the weekend. ...ATLANTIC OCEAN... Please read the Special Features section above for details on Hurricane Sam and newly formed Tropical Storm Victor. The Cumbre Vieja volcano on the island of La Palma in the Canary Islands near 28.6N 17.8W has been erupting since September 19th. High concentration of volcanic ash is found near the volcano up to 9,000 m ASL. Marine and aviation interests should monitor this ongoing situation by reading Volcanic Ash Advisory issued by Meteo-France at http://vaac.meteo.fr/volcanoes /la- palma/ for details. The next advisory will be issued no later than 30/0300 UTC. A surface trough meanders east-northeastward from 31N58W to 23N78W. Light to gentle with locally moderate winds and seas of 2 to 4 ft are evident N of 24N between 33W and the Georgia- Florida coast. Fresh to strong with locally near-gale NE trades and seas at 8 to 12 ft exist N of 19N between the NW African coast and 33W. Outside the influence of Hurricane Sam, gentle to moderate trades and seas of 4 to 6 ft are found from the Equator to 24N between 35W and the Lesser Antilles. Outside the influence of Tropical Storm Victor, gentle to moderate monsoonal winds and seas at 5 to 7 ft prevail across the rest of the basin. For the forecast, Hurricane Sam was near 20.2N 57.6W 945 mb at 2100 UTC, moving NW at 8 kt. Maximum sustained are winds 115 kt, with gusts to 140 kt. Sam will move to 21.2N 58.9W Thu morning, 23.1N 60.4W Thu afternoon, 25.6N 61.4W Fri morning, 28.3N 61.9W Fri afternoon, and 31.0N 61.3W Sat morning. Sam will change little in intensity as it moves into the north central Atlantic early next week. In addition to hurricane conditions northeast of the Leeward Islands through Thu, expect rough seas in the form of swell from Sam to impact the area northeast of the Bahamas starting Thu. Meanwhile, a weak pressure pattern will maintain light to gentle breezes and slight seas through Thu. A weak cold front will move from the Carolinas to the central Bahamas by Fri and and dissipate by Sat. Stronger high pressure will build in to the area, which will bring moderate to occasionally fresh winds through the weekend. $$ ERA