Chip Somodevilla/Getty Images
SILVER SPRING, MD - JULY 02: A hand-written sign about local power company Pepco hangs on a pole in a residential neighborhood July 2, 2012 in Silver Spring, Maryland. About 445,000 businesses and households in the metropolitan area surrounding the nation's capital remain without electricity three days after a deadly storm ripped a path from Illinois to the Mid Atlantic region. Almost 40-percent of Pepco customers in Montgomery County, just north of the District of Columbia, are still without electricity and the power company does not expect to have full service restored until Friday. (Photo by Chip Somodevilla/Getty Images)
A storm last Friday hit a huge area of the east coast, bringing winds of 60-80 miles per hour and knocking out power in several states. Already 18 people have died and Virginia, West Virginia, Maryland and Washington D.C. have all declared states of emergency.
Power is still out for millions of people and with temperatures topping 100 degrees, the situation is pretty miserable. KPCC's Meghan McCarthy joins the show to explain the weather phenomenon that caused this - called a derecho.
A derecho is similar to a tornado in that it has strong winds. But where the winds of a tornado are spinning, the winds of a derecho are straight line winds. It's a warm weather storm phenomenon that strikes commonly in the Midwest.
Generally, the thunderstorms resulting from a derecho fan out over a hundred miles or so. In this case though, the storms spread over 600 miles of the Atlantic seaboard all the way to Chicago.
While the west wasn't affected by the derecho, it wasn't immune from the web outage that these storms caused. They hit a data center in Virginia which housed the servers for popular web services like Instagram, Netflix and Pinterest. The backup power at the data center failed and those services were unavailable from Friday night through Saturday afternoon.
That problem was resolved fairly quickly, but 2.2 million people are still without power. Officials say it might not be restored until Friday.