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Members of the science community say it's a matter of when, not if, a major tornado comes through Chicago

Chicago needs to improve tornado awareness

by Andrew Holik
May 21, 2013

Chicago is due for a major tornado and the public may not be prepared.

In the wake of the Oklahoma tornado that killed at least 24, experts said city safety measures are continually improving, but Chicagoans must be aware of the risk and plan it.

“Chicago is absolutely not immune from deadly tornadoes like we saw yesterday,” said Eric Lenning, science and operations officer at the Chicago area office of the National Weather Service. “Some areas might see it more frequently, but it’s absolutely going to happen in the Chicago area some day.”

Tornadoes are formed from a combination of strong instability - when very warm, humid conditions near the surface mix with relatively cool air above 20,000 feet to create thunderstorms, Lenning said.

Differences in wind speed and direction in atmospheric depth organize those thunderstorms, and as the wind turns, the storms convert into super cells that are associated with tornadoes.

Bob Rauber, head of the University of Illinois atmospheric department, said the Midwest’s proximity to the cold air from Canada and warm air off the Gulf of Mexico makes it the prime location for tornadoes.

While the concentration of people in the city would lead to more injuries, Rauber said, the buildings are sturdier to withstand natural disasters and leave a lower percentage of damage in their path.

While oceans and large bodies of water can help temper tornadoes, he said the path tornadoes take negate any benefits a major lake would provide.

“When super cell thunderstorms form, they typically move from southwest to northeast,” he said. “When you think of that trajectory, the storm would form well before it got to Chicago.”

According to the National Weather Service, 92 significant tornadoes hit the Chicago area between 1855 and 2008. A tornado is considered significant if its winds are 113 mph or greater, caused any fatalities or injured at least 10 people.

The largest tornado in Chicago-area history hit west suburban Plainfield, 40 minutes outside the city, in 1990. The storm killed 29, injured 353 and caused $165 million in damage.

The mayor of North Utica, about 90 miles southwest of Chicago, wasn’t there when the tornado struck his town in 2004 and killed nine, but he remembered its impact.

“My wife and I are both at the hospital and we go, ‘Oh my God, there goes our house,’ thinking it would go high ground,” said Fred Esmond. “When we got the call it hit downtown, it was horrible when we got there.”

After the tornado in North Utica, Illinois implemented the School Safety Drill Act that enforces drills ensuring students know how to handle natural disasters.

Thompson said the agency has worked with regional planners to establish preparedness, including efforts to get weather alert radios into schools and public buildings.  

Lenning said Chicago has done a solid job recently of developing precaution.

“I have to say there has been a lot of effort by our office to reach out to various officials in the city and I think those efforts have been effective,” Lenning said. “Numerous venues in Chicago have been certified as storm ready.”

Still, they said the most important thing Chicagoans can do is develop an emergency strategy and find a safe place away from doors.

“Every second counts when you have a tornado bearing down on you,” said Patty Thompson, communications manager of the Illinois Emergency Management Agency. “It’s important to have a plan and practice it.”

“The problem with major tornadoes is even if you know it’s coming there may be no place to go,” Lenning said. “That’s why being able to plan ahead is so important.”

He also emphasized the weather radio.

“It’s basically a smoke alarm for weather,” Lenning said. “It’s the only thing that will wake you up in the middle of the night.”

“There’s no reason not to have a weather radio by your bedside.”