Thunderstorm Wind in Poweshiek County, Iowa

Trailers blown over at a dealership south of Grinnell. Report via social media.

Convection began in early afternoon in eastern Iowa along a subtle boundary across the state. This was fueled by high CAPE exceeding 3000 J/kg with deep layer shear sufficient to support large hail growth. Later in the evening a secondary round of convection moved across the area producing additional hail in the form of a cold pool driven MCS, driven along the plume of higher instability. The result was dozen of hail reports up to baseball sized across much of central and southern Iowa, damaging homes and vehicles and taking down power lines. As storms crossed Interstate 80 an accident resulted in significant delays.