We are working on a video to explain the definition of a derecho that we will share at some point, but in the meantime, here is a one-pager to explain the scientific rationale for defining one.
The damaging wind swath from Wednesday, June 10 has been preliminarily confirmed as a derecho.
The wind swath had a track length over 400 miles with a footprint just under 100,000 square miles. The strongest known gust was measured at over 94 mph.