August 10, 2020 Derecho: A look back at the costliest thunderstorm event in US history

Published: Aug. 10, 2023 at 2:51 PM CDT
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QUAD CITIES, Iowa/Ill. (KWQC) - August 10th, 2020 is a day many soon won’t forget as a powerful line of thunderstorms, known as a derecho, brought 60 to 130 mph winds to parts of the TV6 viewing area.

Trees toppled onto homes and power lines, leading to more than 100-thousand power outages in the hours and days following the devastating storms.

While the Quad Cities started the day with sunshine, head and high humidity a line of severe thunderstorms began producing damage in parts of South Dakota and Nebraska around 8 o’clock that Monday morning.

The thunderstorms strengthened and expanded in coverage as they raced to the east, approaching eastern Iowa and western Illinois between 1 p.m. and 2 p.m.

The strongest winds, out of the more than 700-mile-long path of destruction, occurred in Cedar Rapids area, where 140 mph wind gusts destroyed an apartment complex on the south side of the city.

The 140 mph winds are equivalent to an EF-3 tornado, although the derecho’s wind speeds lasted a half hour tow 45 minutes as opposed to just a few minutes for a tornado.

While the winds weren’t as strong as the derecho tracked through the TV6 viewing area, they were strong enough to cause the widespread damage. Many areas had 80 mph+ winds including in Davenport, where the airport had wind gusts up to 86 mph.

There was an estimated 130 mph wind gust in Clinton, causing a 400 foot radio tower to collapse.

Farther east toward Princeton, Illinois, 110 mph winds snapped numerous power poles.

Derecho was first classified as a meteorological occurrence in the late 1800s by a University of Iowa physics professor. It’s a widespread, long-lived wind storm with a swath of damage at least 250 miles long and 50 miles wide.

The storm reports must include wind gusts of 58 mph or greater, with several 75 mph or great wind gusts embedded in the line. While many hadn’t heard of a derecho before 2020, they are more common than you might think.

Climatology from the Storm Prediction Center shows there is at least one derecho every year in eastern Iowa and western Illinois. The derecho in 2020 was one of 22, separate billion-dollar disasters that year. In fact, the derecho has become the costliest thunderstorm disaster in US history, causing $11 billion in damages and losses. Four people were killed.

Click here for a summary from the National Weather Service Quad Cities.