The St. Louis region has been upgraded to a level 4 out of 5 threat for severe weather, as a multiday severe storm outbreak builds toward a dangerous peak on Monday. Millions are under threat of strong tornadoes and severe thunderstorms across the Midwest, including Missouri, Illinois, and Indiana, which are at high risk. As storms are forecast to pass through early Monday morning, the main severe threat is expected to intensify in the afternoon. Alerts are in place for significant weather impact, with forecasters predicting damaging winds, heavy rain, and isolated tornadoes. The Midwest is on high alert as communities brace for potential severe weather, including long-track EF-3+ tornado threats. Monday could see thunderstorms and severe storms spreading across the region, prompting officials to advise residents to prepare for hazardous conditions.