Norman Regional Hospital and an affiliate treated 19 people for mainly "bumps and bruises," and one patient remained hospitalized in fair condition late Friday, hospital spokeswoman Kelly Wells said.
Storms were developing as cold air from the west hit low-level moisture coming up from the Gulf of Mexico. The difference in wind direction and speed was creating instability in the atmosphere that can spawn tornadoes, said Scott Curl, another weather service meteorologist.
Emergency management officials in Kansas and Oklahoma warned residents to stay updated on weather developments and create a plan for where they and their families would go if a tornado developed.
"We know it's a Saturday and that people are going to be out and about, so stay weather aware," Cain said. "Have your cell phone on you, keep it charged and make sure you're checking the weather throughout the day so you don't get caught off guard."
People also should put together an emergency preparedness kit that includes a pair of boots, rain gear, flashlight, battery-operated radio, first-aid kit and a few days' supply of food and water.
"It seems like it's kind of a big deal this time," said Monte Evans, a 42-year-old middle school teacher in Wichita, Kan., who said he planned to keep a close eye on the weather and take shelter in his basement with his wife and four children, ages six to 11, if tornadoes hit. "But they always say it's coming and then ends up somewhere else. You just do the best you can and get ready if it happens."
Medical officials in Oklahoma warned residents not to seek shelter at hospitals or other public buildings, but rather to stay inside their homes in a basement or interior closet.
During a tornado outbreak last spring, hundreds of residents packed Oklahoma City hospitals seeking shelter from a violent series of twisters that killed seven people in Oklahoma and Kansas.
"We had people actually lining the halls," said Michael Murphy of the Emergency Medical Services Authority. "Had we experienced a mass casualty incident, it really could have placed a strain on our resources."
Sean Murphy can be reached at www.twitter.com/apseanmurphy