Breakdown: Derecho, What is it and why it causes major damage

Published: Aug. 19, 2020 at 11:44 AM CDT
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MEMPHIS, Tenn. (WMC) - On August 10th, 2020, a complex of storms rolled across the Midwest and Great Lakes region. This complex system was considered a derecho. In this episode of the Breakdown, we will explain what a derecho is and why it can cause major damage.

Starting around 8 a.m. in the morning on August 10th and not dissipating until after 7 p.m. at night, the long wind event known as a derecho carved a path of damage across the Midwest, from Omaha, NE across Iowa, Northern Illinois, and into Indiana and Michigan.

According to the National Weather Service in Chicago, over 700 severe wind reports were taken once the event was done. This line caused widespread damage and even spun up tornadoes.

A derecho or damaging wind thunderstorm complex has very unique features to gain its title. It has to have a large line of storms, in a bowing shape, which means strong winds.

There is often a comma-head shape on the northern end of the storm system, which is usually well-organized, helping sustain the path of the storm.

It usually has large area of rain on the backside of the system, which is rain cooled air helping it sustain the momentum of strong winds. Right behind the initial line of heavy rain are higher rain bands, usually meaning descending air from the rear inflow of the jet supporting damaging winds.

It also can have rather jagged-like front edges, those will signify embedding rotation in the line with a broader severe wind threat and tornado potential.

This complex is usually called a derecho. What makes it different is derechos will be intense organized storms tracking over a wide area, producing winds nearly 100 miles per hour.

For it be considered a derecho it has to have severe gusts of 58 mph or higher for its entire corse, with several significant gusts of 75 mph or higher in the path. It must cover an area of 250 mph long and will be primarily classified as straight-line winds but can have numerous tornadoes in the line.

Science shows that derechos are more common in the Upper Midwest to the Great Lake region, where this 2020 storm system impacted.

The Mid-South has been impacted by derechos before, back in July of 2003 a line of storms impacted the region causing major damage and deaths, this storm has been coined “Hurricane Elvis” by locals in the region.

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