BOW ECHOES

The figure above is a prototype of the evolution of a "bow echo" (from Fujita 1978). Dr. Theodore Fujita, a professor at the University of Chicago, coined the term "bow echo" in the late 1970s. The terminology was based on how bands of rain showers or thunderstorms "bow out" when strong damaging winds reach the surface and spread out like pancake batter. The bowed rain band is near the leading edge of the damaging winds. The storm system that Dr. Fujita based the "bow echo" terminology on was the one that resulted in a strong derecho affecting northern Wisconsin and adjacent states on July 4, 1977.

Derechos are typically associated with a long lived bow echo or a series of bow echoes. These bow echoes may vary in scale, but they typically go through an evolution that has at least some of the aspects of the prototype shown in the figure above.

Back to the Derecho Facts Page