000 AXNT20 KNHC 300500 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Thu Sep 29 2022 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 0000 UTC surface analysis and satellite imagery through 0500 UTC. ...SPECIAL FEATURES... Hurricane Ian is centered near 30.2N 79.3W at 30/0300 UTC or 160 nm S of Charleston South Carolina moving NNE at 9 kt. Estimated minimum central pressure is 986 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Tropical storm force winds extend up to 360 nm from the center. Peak seas over Atlantic offshore waters east of NE Florida are 26 ft. 12 ft seas extend up to 300 nm NE of the center. Numerous moderate convection is N of 30N between 74W and 82W. A weakening outer rainband covers the offshore waters between 74W and 77W, including the central Bahamas. On the forecast track, Ian will approach the coast of northeastern South Carolina mid-day Friday. The center will move farther inland across the Carolinas Friday night and Saturday. Ian is expected to maintain intensity before landfall tomorrow, when it will rapidly weaken over the southeastern United States late Friday into Saturday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more details. ...TROPICAL WAVES... An eastern Atlantic tropical wave extends along 17W, from 02N to 17N, moving W at 15 kt. Scattered moderate convection is observed from 05N to 15N, between the coast of Africa and 20W. A central Atlantic tropical wave extends along 33W, from 07N to 20N, moving W at 10 kt. There is no significant convection associated with this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Mauritania near 17N16W to 07N34W and from 11N40W to 09N47W. The ITCZ continues from 09N47W to 11N58W. Convection is isolated and weak along these boundaries. GULF OF MEXICO... The gradient between high pressure over northern Mexico and Hurricane Ian east of northern Florida is supporting moderate to fresh northerly flow across the basin. Seas are 6-8 ft on an abating trend. For the forecast, the pressure gradient between high pressure over the Gulf waters and Hurricane Ian located E of Florida supports an area of fresh northerly winds over the eastern Gulf, mainly E of 85W, with seas in the 8 to 9 ft range. Fresh NW to N winds and seas of 8-9 ft are also noted over the SW Gulf, including the Veracruz area. Winds and seas are forecast to gradually diminish over the Gulf region overnight. Looking ahead, a cold front may enter the NE Gulf late Sat or Sun then stall and dissipate across the area early next week. CARIBBEAN SEA... An upper-level trough over the eastern Caribbean is supporting scattered moderate convection from 11N to 18N, between the Lesser Antilles and 63W. Similar convection is noted south of Hispaniola. Otherwise, Hurricane Ian to the north is actually improving conditions by interrupting the usual pressure gradient. Winds are gentle to moderate across the basin with slight seas. The only exception is in the extreme NW basin, where 4-8 ft northerly swell is propagating through the Yucatan Channel from the Gulf of Mexico. For the forecast, large N swell produced from Ian will continue to spread through the Yucatan Channel through tonight. A surface trough is forecast to persist over the NW Caribbean through at least Sun. Moderate to fresh N winds are expected W of the trough through Fri night. Elsewhere gentle to moderate winds and slight to moderate seas will persist across the basin. ATLANTIC OCEAN... For details on Tropical Storm Ian, centered just offshore Jacksonville, FL, please read the Special Features section above. Winds of 20 kt or greater associated with the circulation of Ian currently extend over the waters to the west of 72W and north of 26N. Seas of 8 ft or greater associated with Ian extend over the waters west of 72W and north of 27N. In the central Atlantic, winds are mainly gentle to moderate from the east with 4 to 6 ft seas. The only exception is a small area of decreasing fresh winds and abating 6-8 ft seas in the vicinity of Post-Tropical Depression Eleven near 20N37W. In the eastern Atlantic, a tighter pressure gradient is supporting moderate to fresh NE winds with 6-8 ft seas. For the forecast west of 55W, Hurricane Ian near 30.2N 79.3W 986 mb at 11 PM EDT moving NNE at 9 kt. Maximum sustained winds 70 kt gusts 85 kt. Ian will move to 31.7N 79.1W Fri morning, move inland and weaken to a tropical storm near 34.0N 79.6W Fri evening, weaken as an extratropical cyclone near 36.0N 80.4W Sat morning, 37.5N 81.0W Sat evening, and dissipate Sun morning. $$ Flynn