Chicago, IL

The Chicago area could be in for a wild tornado season this spring

Jennifer Geer

The arrival of the La Nina weather pattern might bring severe weather to the Midwest, including deadly tornadoes.

Photo by Nikolas Noonan on Unsplash

We're off to a slow start this year for the severe spring storms we usually see throughout northern Illinois and in the Chicago area. However, we had a similarly slow start in 2011 when an active jet stream combined with a moderate La Nina weather pattern to create a very severe tornado season.

2011 was the most dangerous tornado season in the U.S. since 1925, with over 550 deaths. And this year, weather experts say the La Nina effect combined with an active jet stream looks identical to 2011.

Guess what else happened in 2011 in part due to the La Nina weather pattern? Texas experienced unusually frigid temperatures in the winter that led to millions of Texans without power. It's the same scenario that occurred this February.

What is La Nina?

Derived from NOAA / PMEL / TAO diagrams, Public domain, via Wikimedia Commons

La Nina is a weather pattern that occurs over the Pacific Ocean. It's unlike during El Nino, where the Pacific Ocean waters are warmed. During La Nina, they are colder than average.

The cooler ocean temperatures can drive weather patterns across the U.S. During La Nina seasons there are temperature differences between cooler and drier air to the northern US and hotter and more humid air from the south. This results in a more active jet stream which drives severe weather in the Midwest and the Great Plains, such as hailstorms and tornadoes.

Weather experts are predicting an active spring

It's impossible to know for certain what weather to expect. However, meteorologists can make predictions based on overall weather patterns like El Nino, La Nina, and the Arctic Oscillation.

Studies have shown how La Nina behaves in the winter can help predict if it's going to be a rough year for hailstorms and tornadoes. According to the study, "La Niña, in contrast [to El Nino], concentrates hot, humid air over the region. The heat and humidity over the southern Plains states sets up a strong north-south temperature gradient, which in turn favors storm formation."

The severe storms that generate hail and tornadoes tend to strike in early spring for the south, the southern Plains in May and June, and the upper Midwest during the summer months of June and July. Of course, tornadoes and hailstorms can occur any time of the year, but in the Chicago area, we're more likely to see them starting in June.

A collapsed building caused by an EF1 tornado that traveled between Kendall County and Will County, Illinois NWS Survey, Public domain, via Wikimedia Commons

Predicting tornadoes has improved

Thanks to new technology like radar and computer models, meteorologists are better than ever at predicting when a dangerous storm is on its way. Soon, we may be able to get predictions two to three weeks out. Dr. Victor Gensini at Northern Illinois University is working on an experimental long-range weather forecast.

It wouldn't be able to pinpoint exact locations, like if a tornado was going to emerge in Chicago, for example. But it would give us an idea of dangerous weather patterns that might be brewing across the state.

Climate change and tornadoes

Experts believe that climate change is partly to blame for an increase in deadly storms across the U.S. Whether this will create more frequent tornadoes is hard to say.

What scientists do know is that tornado patterns are shifting. Research has shown Tornado Alley, an area of the U.S. where tornadoes are the most frequent shifting to the east. Though most tornadoes still occur through the Great Plains (Texas, Oklahoma, and Kansas) the frequency has been increasing in the Southeast and Midwest states, including Illinois.

How should you prepare for tornado season?

Although impossible to predict, when you live in an area with frequent, severe storms, you can be confident you will probably get a tornado watch or warning at some point during the spring and summer months.

Here in the Chicago area, the likeliest time for dangerous storms is in June and July, but they could strike at any time, and we need to be prepared.

Safety tips:

Don't let it take you by surprise. Set your phone up with alerts from apps such as NOAA Weather Service, Wireless Emergency Alerts, WeatherBug, and ABC7 Chicago Weather app.

Know where you will shelter whether you are at home, in school, or at work. Stay away from windows.

If you're driving, don't try to outrun the tornado. ReadyIllinois suggests that you lie flat in a low spot with your arms and hands over your head. Do not try to shelter from the storm in a highway underpass.

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Jennifer covers lifestyle content and local news for the Chicago area.

Chicago, IL

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