Iowa Derecho Was Nation's Most Costly Thunderstorm

The derecho that swept through Iowa on August 10 turns out to be very likely the most costly thunderstorm event in United States history. 

Debris from the August derecho in Iowa was covered
in unseasonable snow on Monday. Photo via Twitter
 from Rebecca Kopelman @KopelmanWX 

You think of thunderstorms causing local damage, since they're usually relatively small in area. 

But this derecho was so strong and so widespread, it ended up causing at least $7.5 billion in damage, according to reports from the Washington Post and NPR.

Yes, I am still a little obsessed with this Iowa derecho because it was so unusual. The length of its path was long - about 770 miles - which is pretty lengthy but not outstanding for a derecho.

The remarkable part of this storm was how intense it was.  

Widespread areas had gusts in the 80 to 100 mph range, with a peak wind estimated at 140 mph.  In any given place in most of Iowa, the worst of the storm lasted a half hour or more, which is an awfully long time to have such strong winds blowing from thunderstorms.

No wonder the destruction was so great.  In Cedar Rapids, about 90 percent of homes and businesses had at least some damage.  Roughly 1,000 homes in Iowa were destroyed. 

The storm came at the worst time of year for crops, NPR notes. Corn was tall before the storm, making it easier for the winds to slam the corn stalks to the ground.  Had this storm occurred in the spring or early summer, the corn would have been shorter and more able to withstand the winds.

At this point, it looks like the Iowa derecho is so far the second most expensive weather disaster in the United States this year.  Only Hurricane Laura in Louisiana was worse, with estimated damages there at around $14 billion. 

The closest comparable derecho in terms of destruction I could find was one that extended from Ohio and Michigan to the Mid-Atlantic States in June, 2012.  That one caused about $2.9 billion in damage. 

In Iowa, the amount of debris from the derecho is so immense that a lot of it hasn't been removed yet. Big piles of wreckage line city streets in Cedar Rapids and elsewhere. 

To add insult to injury, an unexpectedly heavy and early season batch of snow squalls Monday dumped up to seven inches of snow on some of the areas most affected by the August 10 derecho.