After the August 10 Derecho
Monday at 6:48 pm
A week ago today, on August 10, a line of storms raced through Iowa and central Illinois and headed for Chicago. Over 100 mph winds were reported in the Quad Cities. There were flight delays at Midway and O’Hare airports, and Metra trains were halted. It was fast and furious! A line storm. A derecho.
What is a derecho? Here is Tom Skilling’s explanation–
by: Tom Skilling
Posted: Aug 15, 2020 / 07:48 PM CDT / Updated: Aug 17, 2020 / 10:48 AM CDT
What are the atmospheric conditions that produce derechos?
John Podulka, Wolverine, MI
A derecho develops from an organized cluster of thunderstorms that evolves into a bow echo. Thunderstorm development requires warmth, moisture, instability and lift and bow echoes can form when the winds aloft are strong with little change of direction with height. As rain-cooled thunderstorm downdrafts strike the surface, they spread out in the direction of the storm movement forming a gust front, generating wind gusts in excess of 60 mph and sometimes in excess of 100 mph. The storm complex must travel at least 250 miles to be called a derecho and the length of the line can range from about 50 to several hundred miles. While most derecho damage is from straight-line winds, small tornadoes are often embedded in the storms.
This line of storms produced several tornadoes, including one in Rogers Park, and a waterspout over the Lake.
In the wake of the storm, there was a lot of damage–whole trees and tree limbs knocked down, hundreds of thousands without electric power, corn fields flattened and grain silos twisted into something Frank Gehry would have designed. Counties in Iowa have been declared disaster areas.
As I write this, one week later, they are still assessing the extent of the damage. Most of the corn will not recover. There are still power outages.
There is a big tree in my yard that will have to be removed from the roof of the garage. The tree service will be coming out later this week. Fortunately, the power stayed on. It could have been so much worse!
We are realizing how much we depend on electric power. How much we depend on internet connection. How much we depend on each other.
And in these pandemic and uncertain times, Com-Ed crews have been working. The Postal Service, too. Neither snow nor rain, not even a derecho can stop the mail from getting through!