010 FXUS01 KWBC 182001 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Fri Jul 18 2025 Valid 00Z Sat Jul 19 2025 - 00Z Mon Jul 21 2025 ...Heightened flash flooding risk across portions of the Great Basin, Southwest, Northern/Central Plains, Midwest, Central/Southern Appalachians, Gulf Coast and Mid-Atlantic this weekend... ...Severe weather potential over parts of the Northern/Central Plains, Midwest and Mid-Atlantic this weekend... ...Major to Extreme HeatRisk expands across the Southeast and Mississippi Valley... A very active week of weather continues for much of the country this weekend. A trough-y pattern across the northern stream and shortwaves circling the periphery of an upper ridge stationed over the Southeast will interact with instability and relatively substantial moisture to produce scattered thunderstorms and heavy rainfall in many areas over the next couple of days. There are several regions with slight risks (at least 15% chance) of excessive rainfall leading to flash flooding through tonight. Those areas include portions of the Great Basin, Southwest, Upper/Middle Mississippi Valley, Ohio Valley, Central/Southern Appalachians, Mid-Atlantic and Central Gulf Coast. There's a targeted moderate risk (at least 40% chance) of excessive rainfall over portions of the Shenandoah Valley, Potomac Highlands and Virginia Piedmont, where soils are already very moist, meaning that additional rain will likely immediately runoff. Scattered to isolated storms capable of producing instances of flash flooding in the Central Gulf Coast should wrap up early this evening. The Storm Prediction Center issued slight risks (level 2/5) for parts of the Northern/Central Plains and Upper/Middle Mississippi Valley, as well as another area over central-southern Virginia into North Carolina tonight. An MCS is expected to produce large hail, damaging winds and a couple tornadoes across the corn belt late tonight, while scattered damaging winds are expected in Virginia and North Carolina early this evening. The threat of severe thunderstorms and excessive rainfall focus along and ahead of a low pressure system extending from the Central Plains to the Mid-Atlantic on Saturday. The continued abundance of moisture and instability along a lifting mechanism such as a moving surface front will generate rounds of thunderstorms with areas affected by recent rainfall especially susceptible to flash flooding. A broad slight risk area of excessive rainfall is in place due to continued uncertainty on where storms will pop up prior to the arrival of tonight's corn belt MCS. A broad slight risk of severe thunderstorms is also in effect from the Middle Mississippi Valley to Ohio Valley on Saturday where areas of damaging winds and hail will be possible. Supercells are expected to develop along a stalled front over portions of the Front Range/Central High Plains Saturday afternoon. Areas of damaging winds and hail will be possible from these storms. A retrograding ridge over the Southeast/Gulf will promote warm and humid conditions across the southern U.S. this weekend. There is high confidence in heat reaching levels that would affect anyone without effective cooling and/or adequate hydration. Long duration heat waves that last multiple days in a row, with little to no overnight relief and high humidity levels, often pose a greater danger. That is expected with this heat wave, especially over the Mid-Mississippi and Lower Ohio Valleys, and Mid-South region. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$