I think this line from the article you linked to is probably the most important/relevant:

damaging thunderstorms may only affect a fraction of this zone and tornadoes are likely to only affect a tiny fraction
Severe Thunderstorms impact a small area, and usually for a brief period of time. I've never once in my life stopped travel for an entire day because of the chance of a storm. There have been times where I've pulled over and/or stopped for a bit to let a storm pass, but that's something you can judge by paying attention to your surroundings.

Not to mention, if you're now going through Chicago, then it would seem you'll be traveling north of the area highlighted in the link you provided.