What is a derecho? Massive, severe thunderstorms explained

The June 29, 2012 derecho socked the D.C. area, and it came quite suddenly. Photo: NWS

Many forecasters have been using the term derecho to describe what could impact the D.C. area in the next 36 hours. The violent storms are extremely hard to predict in the longer term.

A destructive derecho did hit the area on June 29, 2012, and with severe storms on the horizon this week, it's best to be prepared for any sort of weather that comes, derecho or not.

ABC7 meteorologist Brian van de Graaff explains exactly what comprises a derecho.