000 AXNT20 KNHC 271021 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Fri Sep 27 2024 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Newly downgraded Tropical Storm Helene is centered near 32.8N 83.0W at 27/0900 UTC or 30 nm E of Macon Georgia, moving N at 26 kt. Estimated minimum central pressure is 968 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. The 12 ft seas extend 380 nm in the southern semicircle and 240 nm in the NE quadrant with peak seas near 17 ft. Most of the convection is well inland, with an outer band noted from 24N to 31N between 76W and 80W. Helene will turn toward the north this morning, taking the center over central and northeastern Georgia. After that, Helene is expected to turn northwestward and slow down over the Tennessee Valley later today and Saturday. Continued weakening is expected, and Helene is expected to become a post-tropical low this afternoon or tonight. However, the fast forward speed will allow strong, damaging winds, especially in gusts, to penetrate well inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Swells generated by Helene will affect much of Florida and the coasts of Georgia and the Carolinas during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. Please, read the latest HIGH SEAS FORECAST, that is issued by the National Hurricane Center, at the website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, and the latest NHC Forecast/Advisory and Public Advisory, at www.hurricanes.gov, for more details. Gale Warning for AL98: Showers and thunderstorms associated with an area of low pressure located midway in between the Cabo Verde Islands and the Lesser Antilles continues to remain well organized. Environmental conditions are currently conducive for further development and a tropical depression or storm could form at any time today while the system moves generally westward to west-northwestward at 10 to 15 mph. The system is then forecast to slow down and turn north- northwestward by this weekend. This system has a gale warning in effect, with a high chance of formation within 48 hours. Please read the latest Tropical Weather Outlook issued by the National Hurricane Center at hurricanes.gov ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 26W from 19N southward, moving westward at 10 to 15 kt. Scattered moderate to isolated strong convection is noted from 12N to 18N between 21W and 26W. An Atlantic Ocean tropical wave is along 42W from 20N southward, moving westward at 10 to 15 kt. Scattered moderate to isolated strong convection is noted from 16N to 22N between 37W and 45W. Please see the Special Features section for more information on the Gale Warning on this system. A Caribbean Sea tropical wave is along 66W from 20N southward, moving westward at 15 kt. Scattered moderate convection is noted from 13N to 20N between 63W and 69W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal plains of Mauritania near 17N16W to 17N41W. The ITCZ extends from 08N43W to 07N50W. Scattered moderate convection is noted along the ITCZ from 06N to 09N between 42W and 52W. Please see the Tropical Waves section for convection information along the monsoon trough. GULF OF MEXICO... Please read the SPECIAL FEATURES section for details about Tropical Storm Helene. Strong to near gale force winds are likely continuing across the eastern and northeast Gulf of Mexico with seas from 13 to 17 ft. Outside of the periphery of Helene, the cyclonic circulation of the hurricane has been pushing a dry continental airmass into the western Gulf, especially from 88W westward, allowing for generally tranquil conditions. Gentle to moderate winds prevail in the central and western Gulf with moderate to rough seas. For the forecast, Newly downgraded Tropical Storm Helene is near 32.8N 83.0W at 5 AM EDT, and is moving north at 26 kt. Maximum sustained winds are 60 kt with gusts to 80 kt, and the minimum central pressure is 968 mb. Helene will move inland to 36.4N 84.5W this afternoon, weaken as an extratropical cyclone near 36.9N 87.3W Sat morning, 36.7N 87.3W Sat afternoon, 36.7N 87.0W Sun morning, 36.9N 86.0W Sun afternoon, and dissipate Mon morning. Winds and seas will improve over the eastern Gulf waters later this afternoon into tonight. Light to gentle winds and slight seas will prevail across the basin Sat through early next week. CARIBBEAN SEA... Please refer to the TROPICAL WAVES section for information about the 66W tropical wave. Scattered thunderstorms continue across the northwestern Caribbean Sea. Seas range 4 to 6 ft across this area. Additionally, the eastern Pacific monsoon trough extends along 06N from Colombia to Nicaragua in the SW Caribbean with scattered thunderstorms noted within 50 nm of the trough. Otherwise, gentle to moderate winds prevail across the basin with seas 3 to 5 ft. For the forecast, newly downgraded Tropical Storm Helene is well inland in the southeast US. Winds across the NW Caribbean are now gentle to moderate with seas slight to moderate. Gentle to moderate winds and slight seas will persist across the basin through early next week. ATLANTIC OCEAN... Please, read the SPECIAL FEATURES section for details about the INVEST-98L low pressure center with a gale warning. Across the western and central Atlantic outside of the periphery of Helene and AL98, gentle to moderate winds prevail with seas 4 to 7 ft. In the eastern Caribbean, moderate to fresh winds are noted north of the monsoon trough with seas 5 to 8 ft, with 8 ft seas close to the eastern Atlantic tropical wave. For the forecast W of 55W, newly downgraded Tropical Storm Helene is near 32.8N 83.0W at 5 AM EDT, and is moving north at 26 kt. Maximum sustained winds are 60 kt with gusts to 80 kt, and the minimum central pressure is 968 mb. Helene will move inland to 36.4N 84.5W this afternoon, weaken as an extratropical cyclone near 36.9N 87.3W Sat morning, 36.7N 87.3W Sat afternoon, 36.7N 87.0W Sun morning, 36.9N 86.0W Sun afternoon, and dissipate Mon morning. Winds off the Florida east coast will improve this afternoon into tonight, with seas subsiding below 8 ft by tonight. Elsewhere, newly upgraded Hurricane Issac, well N of the region, will continue moving away from the area, but generate N swell that will propagate into waters N of 29N and E of 65W, producing seas near 8 ft today. $$ AReinhart