OKLAHOMA CITY, Okla. — In an unusually early and strong warning, national weather forecasters cautioned Friday that conditions are ripe for violent tornadoes to rip through the nation’s midsection from Texas to Minnesota this weekend.
As states across the middle of the country prepared for the worst, storms were already kicking off in Norman, Okla., where a twister whizzed by the nation’s tornado forecasting headquarters but caused little damage.
It was only the second time in U.S. history that the Storm Prediction Center issued a high-risk warning more than 24 hours in advance, said Russ Schneider, director of the center, which is part of the National Weather Service. The first such warning was issued in April 2006 before nearly 100 tornadoes tore across a large swathe of the southeastern U.S.
The latest warning covers portions of Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma and Texas. The worst weather is expected to develop late Saturday afternoon between Oklahoma City and Salina, Kan., but other areas also could see severe storms with baseball-sized hail and winds of up to 70 mph, forecasters at the Storm Prediction Center said Friday.
The outbreak could be a "high-end, life threatening event," the center said.
The strongly worded warning came after the National Weather Service announced last month that it would start using terms like "mass devastation," "unsurvivable" and "catastrophic" in its warnings in an effort to get more people to take heed. It said it would test the new warnings in Kansas and Missouri through the late fall before deciding whether to expand them to other parts of the country.
Forecaster Daryl Williams confirmed Friday that a tornado had touched down about 4 p.m. near the University of Oklahoma campus in Norman. The weather service is housed at the university, and a university spokesman said non-essential personnel there as well as students were ordered to take shelter.
Video from television helicopters show several buildings damaged in the city of about 100,000 about 20 miles south of Oklahoma City, but Oklahoma Department of Emergency Management spokeswoman Keli Cain said there were no reports of injuries.
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, a meteorologist at the NWS.
"This is a very powerful weather situation," Schneider said. "The environment is extremely favorable for violent, long-track tornadoes.
"The only question is when and where these storms will initially develop."
With the worst storms expected in Oklahoma and Kansas, emergency management officials 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," said Keli Cain, a spokesman for the Oklahoma Department of Emergency Management. "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