While tornadoes are the most noted feature of severe thunderstorms, there are other destructive wind features. As the recent events in Shawnee County show, not all destruction came from the tornadoes. What was the culprit? The most likely is straight line winds that are formed by outflow from the thunderstorm. Straight line winds lack the rotation that is characteristic of a tornado, but may easily be in excess of 100 miles per hour. In fact, most of the wind damage from severe storms comes from straight line winds, not from tornadoes. This is another good reason to secure outdoor equipment when severe thunderstorms are forecast. With winds of these speeds, items like lawn furniture can quickly become airborne missiles.
Mary Knapp, Weather Data Library