932 AXNT20 KNHC 301800 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 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 1200 UTC surface analysis and satellite imagery through 1750 UTC. ...SPECIAL FEATURES... Hurricane Sam was centered near 22.6N 60.0W at 30/1500 UTC or 315 nm NNE of the Northern Leeward Islands moving NW at 11 kt. Estimated minimum central pressure is 937 mb. Maximum sustained wind speed is 125 kt with gusts to 150 kt. Numerous moderate scattered strong convection is from 20N to 27N between 56W and 63W. Maximum significant wave height near the center is estimated at 45 ft. On the forecast track, the core of Sam will pass to the east of Bermuda early Saturday. Some fluctuations in intensity are expected during the next couple of days, but Sam is forecast to remain a major hurricane through Saturday, with more significant weakening anticipated later in the weekend. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for more details. Tropical Storm Victor is centered near 9.5N 28.9W at 30/1500 UTC or 480 nm SW of the Cabo Verde Islands moving WNW at 12 kt. Estimated minimum central pressure is 1004 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Numerous moderate convection is from 04N to 15N between 24W and 33W. Maximum significant wave height near the center is estimated to be near 17 ft. A west-northwest to northwest motion over the eastern tropical Atlantic is expected through the weekend. Gradual strengthening is forecast, and Victor could be near hurricane strength on Friday. A weakening trend is expected to begin over the weekend. Please read the latest High Seas Forecast issued by Meteo-France at website https://www.weather.gmdss.org/II.html. Please also read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml for more details. ...TROPICAL WAVES... A tropical wave extends from 06N to 15N with axis near 48W, moving W near 10 kt. Scattered moderate convection is from 05N to 10N between 42W and 48W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the W coast of Africa near 16N16W and continues to 13N21W, then resumes west of Victor near 07N32W and contiunes to 06N38W. The ITCZ begins near 06N38W and extends to 05N53W. Aside from the convection associated with Victor and the tropical wave, scattered moderate convection is from 05N to 09N between 34W and 42W. GULF OF MEXICO... Microwave satellite imagery continue to show moisture inflow from the Caribbean to the western half of the gulf, which along with middle level divergent flow continue to support heavy showers and thunderstorms W of 95W and just to the N of Veracruz, Mexico. Similar convective activity is along the Texas and SW Louisiana coastal and offhshore waters. Model guidance indicate the continuation of shower activity in these regions through the weekend. Otherwise, a weak surface ridge covers the eastern half of the basin and provides mainly gentle to moderate E to SE flow basin-wide, except in the areas of convection where fresh winds are observed. Seas remains in the 1 to 3 ft range. For the forecast, a weak ridge of high pressure will persist north of the Gulf through Fri night, supporting tranquil conditions. Stronger higher pressure will build across the region Sat and Sun, allowing winds and seas to increase over the SE Gulf. Quiescent condition will prevail over the entire Gulf of Mexico beginning again on Mon. CARIBBEAN SEA... An upper level trough extending a base to the south-central Caribbean continue to support showers and isolated tstms over E Cuba and portions of Hispaniola. Diffluent flow to the E of the upper trough support similar convective activity over the SE Caribbean waters. With a weak pressure gradient across the region, latest scatterometer data continue to show gentle to moderate trades basin-wide. Seas are 3 ft or less across most of the Caribbean Sea, except in the northeast Caribbean passages, where swell from Hurricane Sam will peak today through tonight. For the forecast, Hurricane Sam well north-northeast of the Leeward Islands will continue to generate swells over Atlantic waters from off the N Leeward Islands to north of the Mona Passage through Fri. Meanwhile, tranquil trades will prevail over the Caribbean through Fri. As high pressure builds in behind Hurricane Sam, winds are expected to become moderate to fresh across the central and E Caribbean and tropical N Atlantic by Sat through at least Mon. ATLANTIC OCEAN... Please read the Special Features section above for details on Hurricane Sam and 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. Marine and aviation interests should monitor this ongoing situation by reading the latest 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 30/1500 UTC. A surface trough extends from 30N64W to 25N66W. Scattered moderate showers and tstorms are near the trough axis, especially within the area from 23N-31N between 61W-75W. A 1017 mb high pressure is located east of the NE Florida coast near 31N78W. Overnight ASCAT data show mostly gentle wind speeds covering the western Atlantic west of 65W. Seas are 2-4 ft west of 70W, but 4-6 ft between 65W- 70W due to easterly swell from Hurricane Sam. The east Atlantic is being dominated by a 1033 mb high pressure centered over the Azores. This is driving fresh to strong trade winds east of 40W from 20N-30N. Seas are 8 to 11 ft in the area. For the forecast, Hurricane Sam was near 21.5N 59.1W 937 mb at 5 AM EDT moving NW at 10 kt. Maximum sustained winds are 125 kt gusts 150 kt. Sam will move to 23.0N 60.2W this afternoon, 25.6N 61.4W Fri morning, 28.4N 61.8W Fri afternoon, 31.1N 61.3W Sat morning, and move east of Bermuda near 33.5N 59.9W Sat afternoon, and 35.5N 58.0W Sun morning. In addition to hurricane conditions northeast of the Leeward Islands today, expect rough seas in the form of swell from Sam to impact the area northeast of the Bahamas starting Fri and continuing through the weekend. Meanwhile, a weak pressure pattern will maintain light to gentle breezes and slight seas through tonight. A weak cold front will move from the Carolinas to the central Bahamas by Fri and dissipate by Sat. Stronger high pressure will build in to the area, which will bring moderate to occasionally fresh winds through the weekend. $$ Ramos