Could there be a tornado in Illinois today? What to know about severe threat

Parts of the Chicago area and Illinois will be under a heightened risk for tornadoes as severe weather threatens a swath of the state Tuesday. But just how high is that risk?

The biggest threat for tornadoes sits south of Interstate 80 and extends into northwest Indiana, where several counties are now under a “moderate” risk for severe weather, a level four out of five. Such a high risk level is rarely seen in the Chicago area.

Suburbs like Joliet, Kankakee, Frankfort, Morris and more will be under that moderate category, with a tornado risk of 15%.

Several other counties are also under an “enhanced” risk of severe weather, which ranks as level three of five. The “enhanced” risk was also increased to include much of Cook County, according to the Storm Prediction Center.

“All weather hazards will be at play,” NBC 5 Storm Team Meteorologist Kevin Jeanes said.

Strong tornadoes are possible across the “moderate” and “enhanced” risk regions as the storm system moves through.

There is potential for the formation of one or two supercells, often considered one of the most dangerous types of storms, capable of producing “high winds, large hail, and strong tornadoes,” according to Jeanes and National Weather Service.

“A supercell is an often-dangerous thunderstorm with a very organized internal structure including a rotating updraft that allows it to keep going for up to several hours,” the NWS reports.

Additional hazards like large hail, flash flooding, damaging winds and more are also expected.

While the greatest tornado threat will stay south and west of Chicago, other parts of the area will also see the potential for stormy conditions.

According to the NWS, Lake County and counties to the north Tuesday will be under a “slight” risk of severe weather, which ranks as level two of five. There, the biggest weather threats will be large hail, flash flooding and strong winds, gusting as high as 60 miles per hour.

The system will be moving in from the southwest and could reach the Chicago area as early as 3 p.m., with one or two strong storms potentially developing.

The best timing for showers and storms begins between 4 p.m. and 5 p.m., potentially impacting rush hour commuters, the NBC 5 Storm Team said. By 7 p.m., scattered showers and storms with heavy downpours were expected across the Chicago area.

The tornado threat is expected to last through at least 10 p.m. for most locations, but could extend even later across northwest Indiana.

Steady rain and gusty winds are expected to continue into the evening and overnight, bringing a continued risk for flash flooding, Jeanes said.