The National Weather Service sent experts to Marion, Jasper and Poweshiek Counties Wednesday to conduct a preliminary survey on damage caused by Tuesday’s severe weather. According to their findings, a very strong thunderstorm moved northeast through Marion County at speeds of up to 60 miles per hour and included damaging straight line winds with embedded large hail.
Large hail broke windows and punched holes in siding on homes northwest of Knoxville and west of Pella, and isolated strong winds were identified 5 miles northwest of Pella. The greatest damage was incurred by a garage that had two walls blown out by winds coming inside the open door. The walls were only attached with nails into the concrete foundation.
Additionally, an open-ended farm shed lost a roof near the same area, which was blown approximately half a mile. Wind speed estimates in the area were consistent with 75 to 85 mile per hour straight line winds. The storm reached its peak just west of Grinnell, where wind speeds were estimated at 95 to 105 miles per hour.