This kind of fast-moving, long-lived, large, and violent thunderstorm complex is known as a derecho.
Incredible radar loop of derecho from start to finish uploaded to YouTube by akrherz
Derechos are most common in the Midwest and Great Lakes between May and July. The National Weather Service indicates they occur about once every four years in the D.C. area.
Link: Facts about derechos
They often form along the northern boundary of a hot air mass, right along or just south of the jet stream - where upper level winds zip along at high speeds.
On Friday, a historic, record-setting heat wave covered a sprawling region from the Midwest to the Southeast. All-time high temperatures records of 109 were established in Nashville and Columbia, South, Carolina and tied in Raleigh and Charlotte which hit 105 and 104. Here in Washington, D.C., the mercury climbed to an astonishing 104 degrees (breaking the previous record set in 1874 and 2011 by two degrees), our hottest June day in 142 years of records.
71 mph near Dulles Airport
70 mph in Damascus, Md.
79 mph in Reston, Va.
65 mph in Rockville, Md.
70 mph at Reagan National Airport
76 mph in Seat Pleasant, Md. (Prince George’s co.)
77 mph in Swan Point, Md. (Charles co.)
70 mph in Ashburn, Va.
69 mph in Leesburg, Va.
In addition, an 80 mph gust was clocked in Fredericksburg. To the north and west, 91 mph and 72 mph gusts were measured in Ft. Wayne, Indiana and Columbus, Ohio.
This derecho event is likely to go down as not only one of the worst on record in Washington, D.C. but also along its entire path stretching back to northern Indiana.
As the intensity of the heat wave, without reservation, was a key factor in the destructiveness of this derecho event - it raises the question about the possible role of manmade climate warming (from elevated greenhouse concentrations). It’s a complicated, controversial question, but one that scientists will surely grapple with in case studies of this rare, extraordinary event.