“We Gotta Get Outta Here”: Derecho Dashcam Drama

August 24, 2020

Guaranteed Iowa-whasca flashbacks for years for this stoic Mom with a carload of kids, and a roaring Derecho incoming.

Washington Post:

When the derecho tore through Iowa on Aug. 10, it unleashed winds gusting up to 140 mph, equivalent to a major hurricane. The vicious storms arrived with little warning, ravaging the state’s corn crop and devastating communities. The damage is expected to rise well above $1 billion.

More than a week later, upward of 30,000 customers remain without power, down from 590,000, as residents continue the lengthy recovery process.

The storm’s ferocity caught many Iowans off-guard, but the Hawkeye State is surprisingly vulnerable to these violent tempests. While the storm’s intensity was on the high end of derechos, this wasn’t some freak event. Destructive derechos are as common in Iowa as hurricane strikes are in Florida.

The derecho damaged or destroyed 10 million acres of crops while many structures in communities such as Cedar Rapids, Marshalltown, Ankeny and Iowa City lay in shambles. The historical record indicates these violent, fast-moving storm complexes will continue to torment the state most years into the future.

Alex Gibbs, a lead meteorologist at the National Weather Service in the Quad Cities, said that his office, which serves central and eastern Iowa and western Illinois, inspected and rated the storm’s intensity using damage indicators traditionally reserved for tornado surveys. His office found evidence of 110-to-140-mph winds.

In Atkins, Iowa, about 10 miles northwest of Cedar Rapids, a wind gust of 126 mph was measured. That’s near where the WMT Cedar Rapids transmitter tower was toppled.

A nearby tower’s antenna was snapped 340 feet above the ground. The tower had originally been rated to withstand 125 mph winds.

Rich Kinney, the warning coordination meteorologist for the Quad Cities office, said damage observed at an apartment complex, where the winds caused the removal of the roof, most exterior walls and some interior walls, led them “to come up with the 140 mph estimate for the max wind gusts.”

Gibbs said that, on average, his forecast areas see one derecho per year.

The scope of the devastation had many comparing the damage to that of an “inland hurricane,” with wind gusts similar to those of a major Category 3 or 4 storm.

While the 140-mph gusts were extreme, they are not unprecedented in a part of the country some have labeled Derecho Alley

A comparably strong derecho struck Iowa during the early morning hours of July 11, 2011. Vinton and Garrison, about 20 miles northwest of Cedar Rapids, saw wind gusts of up to 130 mph. That’s the same area that bore the brunt of the Aug. 10 storms. Marshall County, Iowa, gusted above 80 mph in 2011. Last week’s storms buffeted them with 100-mph gusts.

Weaker derecho events are even more common. Based on the distribution of observed wind gusts over time, the National Weather Service’s Storm Prediction Center has found that, in central Iowa, winds greater than 74 mph are likely to occur within 25 miles of any given point an average of once or more per year. Some weather stations in Iowa recorded 10 or more instances of 60 mph thunderstorm winds in six years’ time.

“[A]t least one piece of Iowa will end up in a derecho every year. But that is a different piece of info than the frequency at a point/city,” wrote Bill Gallus, an atmospheric scientist at Iowa State University in an email. “It is probably more like once every 10 years or more at any particular spot.”

He said winds of the magnitude of the most recent derecho, however, are unusual. “Winds above 85 mph which were common in this event, [are] very rare. Probably a first in most people’s lifetimes, and in the lifetimes of many cities and towns,” Gallus wrote.

3 Responses to ““We Gotta Get Outta Here”: Derecho Dashcam Drama”

  1. dumboldguy Says:

    Great video and a great job by the mom—-of she had driven another 100 yards, they would have been in big trouble.

  2. rhymeswithgoalie Says:

    It seems to me that one advantage of moving away from maize (“corn” in the US) to more traditional physically flexible grain crops (wheat, rye, barley, maybe even sorghum) is their greater survival of wind events.

    Of course, we’d have to remove the tangle of artificial supports like Federal subsidies for growing corn (including ethanol), and undo its spread across the midwest. Maybe we could even wean the cattle industry from relying on maize for feed.

    Hey, I can dream!

  3. J4Zonian Says:

    And we’ll be helped by the permaculture-adjacent move toward perennial crops including perennial grains like those being developed at the Land Institute in Kansas. But between droughts, floods, fires, heat waves, crop failures, tornadoes, and simple unbearable temperature increase I wonder if there will be any significant population in the region in fifty or a hundred years.


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