Derocho That Slammed Iowa Took Bite Out Of St. Louis

by Don Corrigan

The massive derocho storm that slammed Iowa on June 10, and that flattened large parts of the state, also took a bite out of northern Missouri and the St. Louis area. A derocho is a widespread straight-line wind storm that can rival tornadoes and hurricanes with its wind velocities.The June 10 squall line that ripped through Iowa destroyed more than a quarter of the state’s corn crop and left $4 billion in damages and several fatalities. St. Louis was hit with the southern edge of the storm that began in the Dakotas and moved across Iowa, Illinois and Lake Michigan.

The St. Louis suburb of Kirkwood, which is the only city in the metropolitan area that owns and operates its own electric utility, is still assessing the impact of the June 10 storm on its electrical operation.

“We’re still reviewing all the numbers,” said Mark Petty of Kirkwood Electric.  “But this may have been the worst storm for us since 2006.”

In Iowa, the storm packed straight-line winds of up to 100 mph. Winds in the St. Louis area were clocked in the 40 to 50 mph range. Power outages and lightning strikes affected much of the St. Louis metro area.

“At the onset of the storm, we had over 1,500 customers, about 15% of our system without service,” said Petty.  “Our crews worked thru Monday and into late Tuesday to get everyone back on. And we spent the next couple of days cleaning up  all the debris.

“The team did a great job restoring power under the circumstances,” added Petty. “The Covid-19 Virus complicated things because we needed to maintain separation while making sure we had adequate resources for the repair work.”

There were trees downed and power interruptions throughout Kirkwood. Some major damage was reported in the Kirkwood Farmers Market area of the St. Louis suburb.

“For us, those downed trees damaged our distribution system just like a major tornado,” said Petty. “And these downed trees were totally uprooted.

“Those kind of wind forces always create very difficult situations for us.  Thankfully, we had crews ready and able to respond as quickly as possible,” Petty added.  “And since we’re part of the city organizational structure, we were able to work with police, fire, public works and the city forester to get things done.”

Does record heat & global warming get the blame?

Some climate scientists argue that stifling heat and humidity, drought and wildfires in the West, and even this month’s unusual derecho storm can be attributed to global warming and climate change.

As U.S. temperature records fall again this year, the average surface temperatures worldwide again are rising. The Southwest U.S. has been particularly hard hit this year with a record 130 degree temperature in California’s Death Valley.

Scientists argue contend the heating planet is likely caused by the emission of greenhouse gases from human activities, and this poses significant changes in the atmosphere. Some types of extreme weather look inevitably more common in a warming climate, including heat waves, extremes of both flooding rainfalls and drought, and possibly derocho storms.

Derechos are freak events because of their size and sweep, but they do seem to be occurring more often since the turn of the century. A storm in southern Missouri in 2006 destroyed millions of trees that were worth hundreds of millions of dollars as lumber.

This August’s derecho was characterized by a series of thunderstorms accompanied by downbursts that unleashed 120 mph wind gusts in Iowa. Derechos don’t happen very often, but with heat waves more common under climate projections, they are likely to increase in frequency and severity.

Forest ecologist Chris Peterson of the University of Georgia in Athens points to a 2000 study that predicts these extreme weather events will take an increasing toll on forests and on agriculture.

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