The Storm Prediction Center had issued only a slight risk for severe weather that day, with the threat for a tornado or two limited to parts of Kansas, Missouri, Iowa, and Illinois.

That morning, the Storm Prediction Center (SPC) issued a level 2/Slight risk of severe weather stretching from northeastern Kansas into western Illinois.

With convective available potential energy (CAPE) values around 2,000 J/kg, dewpoints in the low to mid-70s °F, and sufficient vertical wind shear along the boundary, the environment seemed supportive of severe thunderstorms, prompting the SPC to expand the Slight risk eastward into southern Illinois and Indiana.

In this case, however, the line of storms broke down into individual supercells as they tracked across northern Indiana and northwestern Ohio, marking the start of a short-duration but significant tornado outbreak.

[8] In addition to the rare convective evolution and unexpected nature of the event, it was notable in that large tornado outbreaks are an unusual occurrence in late August.