During the early afternoon hours of Friday, June 29, thunderstorms developed near Chicago and quickly intensified as they moved into northern Indiana. Producing a wind gust to 91 MPH in Fort Wayne, Indiana, the storms matured into a derecho as they entered the NWS Wilmington OH forecast area. Over the next few hours, the derecho produced widespread significant wind damage across the majority of the NWS Wilmington OH forecast area, with measured wind gusts of over 80 MPH in a few locations. The derecho moved quickly across the area (which is typical and helps push high winds out ahead of the system), entering the northwest corner of the area around 3:15 PM and exiting to the southeast by 7:00 PM, with average storm speed in excess of 60 MPH. During the event, NWS Wilmington OH issued 19 Severe Thunderstorm Warnings.
What is a Derecho?
The word derecho is a Spanish word, meaning "straight" or "right." In meteorology, the term is used to describe a long-lived, violent straight-line convective wind storm. A derecho usually takes the form of a squall line or large bow echo, travelling hundreds of miles. Derechos produce widespread wind gusts to severe criteria (50 knots or 58 MPH), and wind gusts to 80 MPH (and even 100 MPH in rare cases) are possible. Derechos are not very common, as many atmospheric conditions have to come together perfectly for one to form. Sometimes, extreme winds caused by derechos are mistaken for tornadoes, due to their violent and turbulent nature, the appearance of swirling vortices of wind that can sometimes be observed along the leading edge of the gust front, and the significant amount of damage they cause.