Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 352 AM EDT Wed Sep 25 2024 Valid 12Z Wed Sep 25 2024 - 12Z Fri Sep 27 2024 ...Helene is forecast to rapidly intensify to a major hurricane in the Gulf and bring life-threatening impacts to Florida and the Southeast late today through Friday... ...A rare High Risk of excessive rainfall is in place for the southern Appalachians Thursday-Thursday night where considerable flash/urban/river flooding and landslides are possible... Current Tropical Storm Helene is forecast to quickly become a hurricane today and become a major hurricane before making landfall on Thursday. A Hurricane Warning is in effect over the Florida Big Bend for damaging hurricane-force winds. Helene will grow in size as it strengthens, spreading its impacts to much of Florida and the Southeast. There is a danger of life-threatening storm surge along the entire west coast of the Florida Peninsula and Florida Big Bend. The highest inundation levels are expected along the coast of the Florida Big Bend. Prepare now and heed instructions from local officials about evacuations in these areas. Please refer to the National Hurricane Center for the latest updates on the track and timing of Helene. Helene will also cause significant rainfall and flooding threats. Even ahead of Helene itself, tropical moisture will be pulled north into the Southeast to southern Appalachians today and tonight ahead of a slow-moving upper trough/low. This moisture will pool along and ahead of a stalling front at the surface and lead to excessive rainfall. A Moderate Risk is in place in WPC's Excessive Rainfall Outlook (ERO) across portions of Georgia into the southern Appalachians today into tonight within a broader Slight Risk, in addition to Slight Risks of flash flooding in parts of the Florida Peninsula and West Coast as Helene approaches. Today's rainfall is forecast to create wet antecedent conditions that should likely overlap heavy rain along Helene's track Thursday-Friday. Thus a High Risk of excessive rainfall is delineated across the southern Appalachians where upslope flow should increase rain totals and varying terrain could lead to landslides. Overall, 5 to 10 inches of rain with isolated totals around 15 inches is forecast over the Southeast. Considerable flash and urban flooding is expected across portions of Florida, the Southeast, southern Appalachians, and the Tennessee Valley Wednesday through Friday. This includes the risk of landslides across the southern Appalachians. Widespread minor to moderate river flooding is likely, and isolated major river flooding is possible. Additionally, there is a tornado threat with Helene, especially on the eastern side of the track. The Storm Prediction center is indicating a Slight to Enhanced Risk of severe weather, primarily for tornadoes, on Thursday into Thursday night for parts of Florida into Georgia and South Carolina. Elsewhere, showers and storms are also possible farther north in the eastern U.S. along the northern part of the frontal system over the next couple of days. A couple of fronts passing through the Northwest should lead to some precipitation there. Meanwhile the rest of the western U.S. stretching into the north-central U.S. can expect dry conditions with warmer than average temperatures. The Desert Southwest will see highs well into the 100s, and 90s are possible in the northern High Plains. Some record temperatures are possible for lows and highs. Tate Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php