000 AXNT20 KNHC 250558 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 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 0000 UTC surface analysis and satellite imagery through 0600 UTC. ...SPECIAL FEATURES... Tropical Storm Helene is centered near 20.4N 85.9W at 25/0600 UTC or 60 nm E of Cozumel Mexico, moving NW at 9 kt. Estimated minimum central pressure is 991 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Seas 12 ft or greater are occurring within 120 NM in the NE quadrant, 150 NM in the SE quadrant, and 30 NM in the SW and NW quadrants, with peak seas near 20 ft. Strong convection is occurring within 250 NM to the north, east and south of the center, and additional moderate to strong convection is noted across much of the western Caribbean and southeastern Gulf of Mexico. Strengthening is forecast, and Helene is expected to become a hurricane later tonight or early Wednesday. The storm is forecast to rapidly strengthen over the eastern Gulf of Mexico and become a major hurricane on Thursday. Helene will strengthen to a hurricane near 21.1N 86.3W Wed morning, move to 22.7N 86.4W Wed evening, then be near 25.4N 85.5W Thu morning. Hurricane Helene will be at 29.5N 84.2W Thu evening, then move inland and weaken to a tropical depression near 34.0N 84.5W Fri morning. Tropical Depression Helene will be well inland in the southeastern U.S. by Friday evening. 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 4 to 8 inches with isolated totals around 12 inches. This rainfall will likely result in areas of 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: A tropical wave in the eastern Atlantic has its axis along 30W from 06N to 19N, moving westward at 10-15 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 53W from 17N southward, moving westward at 10-15 knots. Scattered moderate to strong convection is occurring from 11N to 18N between 50W and 60W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 12N17W, then curves southwestward to near 07N40W. The ITCZ extends from 06N43W to 07N50W. Scattered moderate to locally strong 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. Fresh to strong E winds and seas are increasing in the far SE Gulf of Mexico, including the Florida Straits and Yucatan Channel, in association with Helene. Seas are around 6 to 10 ft in this region. Weak ridging across the rest of the basin supports light to gentle winds and slight seas. For the forecast, Tropical Storm Helene will strengthen to a hurricane near 21.1N 86.3W Wed morning, move to 22.7N 86.4W Wed evening, then be near 25.4N 85.5W Thu morning. Hurricane Helene will be at 29.5N 84.2W Thu evening, then move inland and weaken to a tropical depression near 34.0N 84.5W Fri morning. Tropical Depression Helene will be well inland in the southeastern U.S. by Friday evening. ...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 21.1N 86.3W Wed morning, move to 22.7N 86.4W Wed evening, then be near 25.4N 85.5W Thu morning. Hurricane Helene will be at 29.5N 84.2W Thu evening, then move inland and weaken to a tropical depression near 34.0N 84.5W Fri morning. ...ATLANTIC OCEAN... Please refer to the Tropical Waves section for information on potential tropical development in the eastern Atlantic this week. A pair of surface troughs extend into the forecast waters south of 31N, one trough from 31N54W to 23N70W, and the other from 31N64W to 25N70W and then to 30N79W. Scattered showers are observed just ahead of these troughs. Elsewhere, a 1022 high dominates eastern portions of the Atlantic. Moderate to fresh NE winds are occurring north of 15N and east of 40W including the Canary Islands, along with seas of 6 to 8 ft in this area. 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 21.1N 86.3W Wed morning, move to 22.7N 86.4W Wed evening, then be near 25.4N 85.5W Thu morning. Hurricane Helene will be at 29.5N 84.2W Thu evening, then move inland and weaken to a tropical depression near 34.0N 84.5W Fri morning. As Helene moves across the eastern Gulf of Mexico, expect strong winds and rough seas just E of the Florida Peninsula to about 78W. $$ Adams