000 AXNT20 KNHC 251008 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Wed Sep 25 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 0930 UTC. ...SPECIAL FEATURES... Tropical Storm Helene is centered near 20.7N 86.2W at 25/0900 UTC or 40 nm ENE of Cozumel Mexico, moving NW at 8 kt. Estimated minimum central pressure is 985 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Seas of 12 ft or greater are occurring within 180 nm in the E semicircle and 60 nm in the W semicircle. Numerous strong convection encompasses a broad area of the western Caribbean and SE Gulf of Mexico, extending from 16N to 24N between 78W and 88W. Rapid strengthening is forecast, and Helene is expected to become a hurricane today. Helene is then forecast to intensify into a major hurricane in the eastern Gulf of Mexico Thu morning. Major Hurricane Helene is likely to make landfall in the Florida Panhandle by Thu night. Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. Over the Southeastern U.S., Helene is expected to produce total rain accumulations of 5 to 10 inches with isolated totals in excess of 15 inches. This rainfall will likely result in considerable flash and urban flooding, with areas of significant river flooding. Landslides are possible in areas of steep terrain in the southern Appalachians. The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline, with impacts felt from the Florida Keys to the panhandle of Florida, as well as northeastern Florida through the central South Carolina coast. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Helene NHC Forecast Advisory and Public Advisory at www.hurricanes.gov for more details. Eastern Atlantic Tropical Wave: Broad low pressure is developing in association with a tropical wave with an axis around 33W. The low pressure is centered around 15N33W and is moving W at around 15 kt. Scattered moderate convection is noted from 12N to 17N between 27W and 35W. Environmental conditions appear favorable for gradual development of this system, and a tropical depression is likely to form in a few days while it moves westward to west- northwestward across the eastern and central tropical Atlantic. There is a medium chance of tropical formation in the next 48 hours and a high chance of formation in the next seven days. ...TROPICAL WAVES... A tropical wave approaching the Lesser Antilles is near 55W from 17N southward, moving westward at around 10 kt. Scattered moderate to isolated strong convection is occurring from 11N to 18N between 50W and 60W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 13N17W, then curves southwestward to near 07N40W. The ITCZ extends from 06N43W to 07N51W. Scattered moderate convection is noted generally along and within 300 nm south of the monsoon trough. ...GULF OF MEXICO... Please refer to the Special Features section above for details on Tropical Storm Helene. Strong E winds and rough to very rough seas continue to increase in the SE Gulf of Mexico, including the Florida Straits, this morning in association with Helene. In the Yucatan Channel, tropical storm force winds and seas of up to 20 ft are ongoing. Moderate to fresh winds and seas of 3 to 6 ft are also increasing in the NE and south-central Gulf of Mexico. Elsewhere over the northern and western basin, weak high pressure supports light to gentle winds and slight seas. For the forecast, Tropical Storm Helene will strengthen to a hurricane near 21.9N 86.5W this afternoon, then move to 24.1N 86.2W Thu morning. Hurricane Helene will be near 27.4N 85.0W Thu afternoon, then make landfall and be near 32.0N 84.2W Fri morning. ...CARIBBEAN SEA... Please refer to the Special Features section above for details on Tropical Storm Helene. Away from Helene, moderate to locally fresh E winds and slight to moderate seas are occurring across much of the basin. For the forecast, Tropical Storm Helene will strengthen to a hurricane near 21.9N 86.5W this afternoon, then move to 24.1N 86.2W Thu morning. Hurricane Helene will be near 27.4N 85.0W Thu afternoon, then make landfall and be near 32.0N 84.2W Fri morning. ...ATLANTIC OCEAN... Please refer to the Special Features section above for details on Tropical Storm Helene as well as low pressure forming in the eastern Atlantic that is likely to have tropical development this week. Convection has dissipated overnight in association with two surface troughs, one from 28N64W to 28N75W and the other from 27N56W to 23N70W. The only other significant areas of convection in the basin are discussed above in the Special Features, Tropical Waves, and Monsoon Trough sections. Elsewhere, most of the basin is dominated by an Azores- Canary Islands high pressure. Moderate to fresh NE to E winds are occurring from 15N to 25N E of 40W, along with seas of 6 to 8 ft. Gentle to moderate E winds and seas of 4 to 7 ft prevail across the remainder of the Atlantic. For the forecast W of 55W, Tropical Storm Helene will strengthen to a hurricane near 21.9N 86.5W this afternoon, then move to 24.1N 86.2W Thu morning. Hurricane Helene will be near 27.4N 85.0W Thu afternoon, then make landfall and be near 32.0N 84.2W Fri morning. $$ Konarik