The Southern Plains and Mississippi Valley are preparing for a significant weather event as heavy rain and thunderstorms are expected to intensify on Thursday and spread eastward. The National Weather Service has issued a Slight Risk of excessive rainfall for these regions, indicating a heightened potential for localized flash flooding. Urban areas, narrow canyons, gullies, and small streams are particularly vulnerable, as are areas recently affected by wildfires, where burn scars can exacerbate runoff.