What's with this crazy, stormy weather lately (Plains states and east)?

This weather pattern is rather typical for the late spring/summer months across the northern half of the U.S. The primary contributor to this harsh weather is the jet stream. As you may know the jet stream is a "river" of air high in the atmosphere (around 30,000 feet high). It determines where most low pressure systems go and thus what the weather at a certain region will be like. Lately, the jet stream has been situated along the Canadian border, occasionally dipping south or north. Along with intense daytime heating, moisture availability, the jet stream is one of the important ingredients for the formation of strong thunderstorms. This placement of the jet stream is one of the main reasons for the inclement weather Michigan, as well as much of the northern U.S. has been seeing. It is not all that uncommon in the summertime. There will be years where activity will be higher or lower than normal, this year happens to be an active year. Not to worry, the pattern will shift southward eventually as we approach the autumn months.