Widespread Storms Raise Flooding Risk Across U.S.

A broad stormy pattern this week will bring scattered showers and thunderstorms across multiple U.S. regions, with the main hazards being heavy, locally torrential rain, localized flash flooding and isolated damaging wind or hail rather than widespread severe outbreaks. In East Tennessee (Knoxville area), a marginal severe risk expected on Sept. 24 includes about a 15% chance of localized flash flooding and a 20–50% chance of receiving more than 2 inches of rain. Central Pennsylvania and nearby midstate counties face rounds of storms through Thursday, with some forecasts calling for 2–4 inches of rain in spots and isolated gusts up to 60 mph. Local NWS offices and regional outlets have warned that heavy rainfall and flash flooding are possible even where overall storm severity is low, and First Alert Weather Days are in effect in some markets. Elsewhere, Southern Colorado will turn cool, windy and unsettled with mountain snow and a frost advisory, Southeast Arizona will see scattered storms followed by significant heat later in the week, and parts of New York and Idaho expect mainly sunshine with only isolated showers. Authorities advise avoiding flooded roads and heeding local forecasts and warnings.