Skies darkened across the Midwest on Tuesday as severe thunderstorms targeted the cities of Chicago, Indianapolis, and Cincinnati. Across Illinois, Indiana, Ohio, and Kentucky, over one million people were without power as of Tuesday evening as clusters of strong storms persisted across the Ohio Valley.

While Tuesday’s storms left many cleaning up damage from strong winds, further heavy rain and severe thunderstorms struck the Midwest and Ohio Valley on Wednesday.

Potential derecho on Tuesday

During the very early morning hours of Tuesday, scattered thunderstorms started forming across northern Iowa. By dawn, a strong cluster of thunderstorms had organized across eastern Iowa, and it was tracking east into northern Illinois. Observed wind gusts near 80-85 mph were being reported in northeast Iowa as it moved through.

Around 11:00 am CDT on Tuesday, a strong line of thunderstorms struck the Chicago metro, and it produced wind gusts near 70–80 mph. Building damage and uprooted trees were reported across the Chicago metro. The highest reported gust was near Sugar Grove, Illinois, where a home weather station reported a 97-mph wind gust.

Image: Storm reports from Tuesday, August 11, 2026. Source: NOAA / SPC.

While storms were ongoing across northeast Illinois, severe storms started forming in northern Indiana. Baseball-sized hail, or hail near 2.75–3 inches in diameter, hit northern Indiana. A large cluster of showers and thunderstorms extended from northeast Illinois into southwest Michigan, central Indiana, and western Ohio by early Tuesday afternoon. Around 2:00 p.m. EDT, a line of strong thunderstorms extended from Indianapolis to Columbus, Ohio.

Eventually, the line of storms in central Indiana and central Ohio shifted south, impacting Cincinnati and eastern Kentucky later Tuesday afternoon. Behind this line of storms, additional severe storms redeveloped across central Illinois and central Indiana.

Numerous tornadoes were reported on Tuesday, with the SPC registering a total of 11 tornado reports that included an EF-2 near Frankfort, IL. This rating was confirmed by a National Weather Service survey.

With wind damage stretching from northeast Iowa to eastern Kentucky and southern Ohio on Tuesday, there is a possibility that this storm system will get classified as a derecho.

Derechos are classified as long-lived thunderstorms that produce widespread wind damage, and they can sometimes lead to straight-line wind damage. Typically, the swath of wind damage needs to extend more than 240 miles and include wind gusts of at least 58 mph. To read more about derechos and how they form, visit the Louisville, Kentucky, weather forecast office’s website here: https://www.weather.gov/lmk/derecho.

Thunderstorm threat continued Wednesday

Multiple rounds of storms continued over the Midwest and Ohio Valley on Wednesday. While storms were less widespread than Tuesday, the SPC received more than 300 storm reports on Wednesday, including tornado reports from Wyoming, Indiana and Colorado.

Heavy rainfall and flooding were also widespread across the Ohio Valley on Wednesday, which was exacerbated for areas that also saw heavy rain on Tuesday.

Image: Storm reports from Wednesday, August 12, 2026. Source: NOAA / SPC.

A stationary front was one of the main culprits for these clusters of storms forming in the Ohio Valley this week. However, it takes more than just a stationary front to produce severe storms. A warm, humid airmass also contributed to these storms, creating a ripe environment for severe weather.