Central US Braces for Severe Tornado Threat.

More than 75 million people in central and southern states are under a severe storm threat, with the possibility of strong tornadoes, large hail, and damaging winds. The Lower and Mid-Mississippi Valleys are under a moderate risk, while the Midwest is also under a moderate risk. The main threats in the moderate risk area are long-track strong tornadoes, large hail, and intense wind gusts. The storms are expected to begin Friday afternoon and last through the overnight hours, with the potential for flash flooding. Cities in the storm's path include Des Moines, Cedar Rapids, Little Rock, and Memphis.