Central US Braces for Severe Tornado Outbreak and Widespread Storms.

St. Louis and surrounding regions are under a tornado watch until 8 p.m. as a cold front brings severe weather threats, including thunderstorms, large hail, damaging winds, and the possibility of "violent, long-track tornadoes." The National Weather Service warns residents to secure outdoor objects and exercise caution while driving. Areas north of St. Louis are expected to face the severe weather first, with threats increasing in other places later in the afternoon.