For the past 48 hours, electric companies have been working nonstop to restore power to roughly 4.3 million customers after unusually severe and long-lasting thunderstorms—known as a "super derecho"—swept across the Midwest and Mid-Atlantic regions on Friday night.

A derecho is a long-lived wind storm that can travel for hundreds of miles with damage generally following a straight path. This is where the term "straight line winds" come from. The powerful thunderstorms travel very fast and as they accelerate, the storms sometimes tend to "bow." That can result in wind gusts between 60 and 100 mph. The super derecho that devastated 10 states and the District of Columbia on Friday traveled close to 700 miles in 10 hours.

The highly destructive nature of the super derecho presents unique challenges to EEI’s affected member companies during their restoration efforts. Company and state officials are characterizing the storm as similar to or even greater than a hurricane—but one that hit without warning.

Member company Dominion Virginia Power put it this way in a recent Facebook post: "Unlike a hurricane, this storm could not be forecasted well ahead of time by the National Weather Service. When we plan for hurricanes we have time to secure and position people and supplies. We couldn't do that with this storm.” The storm produced the largest number of non-hurricane-related power outages in Virginia’s history.

Electric companies are moving quickly to complete the restoration process, but this is complicated by the sheer magnitude of damage caused by the super derecho. Companies have reported hundreds upon hundreds of destroyed or badly damaged distribution circuits, each carrying power to hundreds or thousands of customers. And because of the nearly dozen states and millions of customers impacted, there is a huge demand for outside help. Further complicating the situation are communications infrastructure problems and the possibility of more severe weather in affected areas.

The entire electric power industry is committed to the safe and swift restoration of power to our customers. We appreciate your patience and understanding as emergency relief crews work around the clock to get your lights back on.

• To learn more, check out EEI’s press release about the electric power industry response.
• During power outages, safety is a priority for our crews and customers. Read about safety precautions you can take on the EEI Web site.