The most dangerous conditions are projected for late Saturday afternoon between Oklahoma City and Salina, Kan. Forecasters say
other areas also could see severe storms with baseball-sized hail and winds of up to 70 mph.
The Storm Prediction Center in Oklahoma says the outbreak could be a "high-end, life-threatening event." Its warning covers parts of Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma and Texas.
Emergency workers focused their attention overnight on central
Oklahoma, where they said funnel clouds had been spotted though none had touched down. The area includes the small town of Piedmont, where a twister last May killed several people.