Chicago Double-Bow Echo Thursday Afternoon

Causing plenty of damage, two bow echoes moved through the Chicago area early Thursday afternoon. In their wake was left a mangled mess of trees, broken windows, and power outages.

Bow echoes, named after the formation they take on radar, are areas on a line of thunderstorms that bow outward. To the left, one bow can be seen just to the East of the "ORD" or Chicago marker over Lake Michigan, and another bow is pictured right along the Southern Lake Michigan shoreline. These are caused by strong winds that are pushing that portion of the line ahead of the rest.

As in this case, it's typical to see these winds transferred down to the surface, causing gusts of hurricane force (in the 70-mile-an-hour range) or greater as the echo passes. Many times, the damage caused by a bow echo can be confused as that caused by a tornado!

Jonathan Myers