A derecho is a storm system that brings widespread wind damage. To be classified as a derecho, it has to have wind damage reports of at least 250 miles in length, and common wind gusts to 58 mph or greater.
The June 29, 2012, derecho sure lived up to that definition — tracking over 700 miles in distance over a 12-hour window. The storm system developed on an abnormally warm day across the East. In Norfolk, the high temperature hit 100 degrees. That set the stage for a wild evening of storms. When the storms reached our area around 10 p.m., they packed winds of 60 to 75 mph.
Historically, our region sees impacts from a derecho event about once every four years. Often times, they’re not as significant as the June 2012 storm was – but they can still bring widespread wind damage.
The 2012 event serves as a good reminder that you should always take severe t-storm warnings seriously – as they can cause just as much damage as tornadoes.
The National Weather Service in Wakefield has a nice website with historical images and charts. You can view it here. Another link you may want to checkout is this one, with more charts, pics and historical satellite data.