Weekly Weather Event -Week of July 13th
July 17, 2020Severe thunderstorms will be impacting the Northern Plains tonight, bringing large hail and possibly a few tornadoes over parts of the Dakotas, Minnesota, Northern Wisconsin, and the Upper Peninsula of Michigan. In addition, it is possible that the storm system could evolve into a derecho, causing strong gusts and sustained straight-line winds throughout the region. Gusts from this system could be as strong as 75 miles per hour, capable of downing trees and power lines.
NOAA’s Storm Prediction Center defines derechos as “a widespread, long-lived windstorm associated with a band of rapidly moving showers or thunderstorms variously known as a squall line, bow echo, or quasi-linear convective system”. In order for a thunderstorm to be classified as a derecho, it must be a long-lived system, have wind gusts of at least 58 miles per hour (mph), extend at least 250 miles, and wind reports cannot be more than two and a half hours apart.
In the United States, derechos primarily occur in the late spring and summer, with more than 60% occurring between May and July. They are most commonly found in the Great Plains, Midwest, and South.