The extensive damage sustained from two separate lines of thunderstorms on Monday, June 30th has been officially determined to be from two separate derecho events. During these two events, 80--100 MPH straight line winds along with several tornadoes of EF-1 intensity produced wind damage from Central Iowa east into Michigan and Ohio.
Derecho Events of June 30, 2014
What is a derecho?
A derecho (pronounced similar to "deh-REY-cho" in English) is a widespread, long-lived wind storm. Derechos are associated with bands of rapidly moving showers or thunderstorms variously known as bow echoes, squall lines, or quasi-linear convective systems.
Although a derecho can produce destruction similar to that of a tornado, the damage typically occurs in one direction along a relatively straight path. As a result, the term "straight-line wind damage" sometimes is used to describe derecho damage. By definition, if the swath of wind damage extends for more than 240 miles (about 400 kilometers), includes wind gusts of at least 58 mph (93 km/h) along most of its length, and several, well-separated 75 mph (121 km/h) or greater gusts, then the event may be classified as a derecho.
For more info on derecho events: www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm
For more on June 30th, visit our event page.