Radar Tutorial
Chapter 3, Page 1: Derecho: A Thousand Mile Super Storm
A Derecho is a rare storm that is known for its strong straight line winds that cause damage for hundreds of square
miles. A Derecho is formed occasionally in a large storm called a Mesoconvective System (MCS). For unknown reasons,
Derechos are more common in Minnesota than anywhere else on earth. This particular storm rolled on through Chicago
, Detroit, Toronto, Buffalo, NY into Maine.
The diagram at right and some of the following information is courtesy the June 2, 1998 Star Tribune. On May 30, 1998,
a scattering of thunderstorms in Western Minnesota evolved into a one large storm (MCS) over about four hours. A
mid-level jet (very strong winds aloof) of dry air was drawn to the ground (not caused as the image indicates) by the
storm development around Hutchinson. The storm surged in the center causing a radar image called a bowecho in the
southern most part of the storm.
The radar loop on the left shows in dramatic fashion, the formation of the bowecho, the storm surging ahead through
south Metro. Winds were clocked consistently at 70 MPH, but damage indicated some winds caused by small microbursts
may have reached 120 to 130MPH causing the damage that is similar to tornado damage.
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