A small complex of severe thunderstorms developed near Sioux City, IA very early Monday morning (July 21, 2008). As the storms slid southeast, they strengthened and began producing very strong straight-line winds measured as high as 78 mph in Glidden. In some locations in Central Iowa, wind speeds were estimated to be near 100 mph. Farther east, as the storms reached the Mississippi River, a wind gust of 94 mph was measured in Moline, IL. This type of severe thunderstorm is called a derecho. Additional information on derecho's can be found by clicking here.
The extreme winds produced widespread wind damage, leaving a swath of downed trees and powerlines up to 25 miles wide.