MARION, Iowa - The National Weather Service was able to use the wind-load rating for an iHeart Radio tower that was blown down during last week's storm to estimate the likely top wind speed.
Meteorologists have surveyed the the path from the August 10 Derecho storm, and put that peak wind speed at 130 miles per hour when the AM 600 WMT Radio broadcast tower was blown down north of Marion. Wind speeds were likely 110-130 in a path through Benton and Linn Counties
The strongest wind gust measured with wind speed equipment is 112 mph at Midway in Linn County. In Central Iowa, the Des Moines region the top speeds were 99 at the Marshalltown Airport, and 106 measured by an emergency manager.
Information and graphic from the National Weather Service Quad Cities. Photo of WMT tower by Raleigh Rubenking.