The "Ring of Fire" Derecho

A lot of us just went through the effects of a Meteorological phenomenon called a derecho, defined as:

a widespread and long-lived, violent convectively induced straight-line windstorm that is associated with a fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo. Derechos blow in the direction of movement of their associated storms, similar to a gust front, except that the wind is sustained and generally increases in strength behind the "gust" front.

Over at Watts Up With That, Anthony Watts, a weatherman by profession, has a post up explaining derechos, with a couple of neat graphics.  First, a radar composite showing the June 29 derecho from its origin near Chicago, to its arrival at the Chesapeake Bay.

The traditional definition of a derecho is a thunderstorm complex that produces a damaging wind swath of at least 240 miles (about 400 km), featuring a concentrated area of convectively-induced wind gusts exceeding 50 kts (58 mi/h, or about 93 km/hr). Some studies add further criteria, such as a requirement that no more than 2-3 hours separate any two successive wind reports. Derechos typically possess a high or rapidly increasing forward speed. In addition, they have a distinctive appearance on radar (known as a bow echo) with several unique features, such as the rear inflow notch and bookend vortices, and usually manifest two or more downbursts.

He explains how, although you likely have not heard the term before, they are not an uncommon weather event, along with a history of some of the more damaging derechos in US history. I for one, am happy that me region is in the region expecting 1 derecho per 4 years as opposed to, say 4 in 3 years.

Major derechos get names, much like Hurricanes, and this one has been named the "Ring of Fire."

There is also an an excellent animated video of progressive radar images as it traveled across the country: