WASHINGTON(7News) — If you lived in the Washington, D.C., area in the summer of 2012, chances are you remember exactly where you were on the evening of June 29. What started as another hot, humid June day quickly turned into one of the most destructive weather events the region has ever experienced.

The storm wasn't a tornado. It wasn't a hurricane. It was something many people had never even heard of before—a derecho.

A derecho (pronounced deh-RAY-cho) is a fast-moving line of powerful thunderstorms that can produce hurricane-force wind gusts over hundreds of miles. In fact, the word comes from the Spanish word for "straight ahead," referring to the straight-line winds that cause the damage.

Unlike tornadoes, which create narrow paths of destruction with rotating winds, derechos spread damaging winds across a much larger area. Think of it as an enormous wall of severe thunderstorms racing across the landscape.

The June 29, 2012, derecho began during the morning in Iowa before rapidly organizing into a massive line of thunderstorms. Fueled by extremely hot, unstable air, the storm kept strengthening as it charged eastward.

By the time it reached the Mid-Atlantic that evening, it had already traveled more than 700 miles—an incredible distance for a thunderstorm complex.

The storm was moving at nearly 60 miles per hour, giving communities very little time to prepare.

Around 10:30 p.m. June 29, the line of storms slammed into Northern Virginia and the D.C. metro area.

People first noticed the sky turning dark and an intense rush of wind. Then came torrential rain, nonstop lightning, and winds strong enough to snap trees like toothpicks.

Those numbers were measured at official weather stations. Some neighborhoods likely experienced even stronger gusts.