Enormous Derecho Causes Historically Notable Power Failure in US


Millions of people across nine states were reeling without power Saturday to deal with thermostat-popping temperatures after fierce thunderstorms pounded parts of the Midwest and Atlantic Seaboard.

Joseph Rigby, president of electric company Pepco, said it could be a week before power is fully back up in some areas of Washington D.C. “Given the damage, you can understand this is going to take some time,” he said. “The wild card is the weather.”

The storms raced east Friday from Indiana through Ohio and into West Virginia and the nation’s capital.In all, 3.6 million homes were without power Saturday morning; nearly 1 million in Virginia alone.

This all happens as a piece of the picture during a June heat wave with only a couple of precedents. Now we have a super-derecho in that context.

Let’s hope the statistics never get sound enough to solve THAT attribution problem. Because if super-derechos start to become even a an occasional habit of the system over the US (or some other region), that would be a huge climate change. If they become frequent enough to build statistical arguments about, well, then the “settled” question of science will be a secondary concern to coping with the damn things.

My question for the P3 community: Has a derecho ever cause widespread electrical outages across a dozen states before?


  1. Peculiar that such a weather system would not be the harbinger of cooler temperatures; usually one would expect such a line to be the edge of a cold front?

    Must go read about these. Just like the "Spanish plume," never heard of a "derecho" before yesterday...

  2. "“settled” question of science will be a secondary concern to coping with the damn things" has a wide application, and I'd bet that whatever blame-seeking is done will include a lot of time and energy wasting efforts to blame the messengers.

    The whole NOAA site with links is good:

    with useful embedded cross links such as downbursts:

    and bow echoes:

    This one in produced sustained winds measured at an airport in southern Illinois (h/t Tenney Naumer) well over 100 mph:

    In summary, the "Super Derecho" of May 2009 traveled more than a thousand miles in twenty-four hours, causing untold millions of dollars of damage, numerous injuries, and several deaths. It produced widespread destruction, especially over southeast Kansas, southern Missouri, and southern Illinois, and was responsible for electrical outages that affected many millions. Power in some areas was not restored for nearly a week. The associated convective system also produced widespread flash flooding. Of particular note was the long-lived mesoscale convective vortex spawned by the parent convective system. This feature produced an extensive swath of intense damage independent of that caused by the more traditional large-scale bow echo with which it was associated.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.