With one round of thunderstorms causing power outages for thousands of MidAmerican Energy customers and more storms on the way, some Iowans may be worried about a derecho.
The powerful storms can bring hurricane-strength winds to Midwestern states like Iowa and leave a wide path of damage.
Here's what we know about the storms and the risk in Iowa.
What is a derecho?
Derechos can pack lethal gusts of wind in excess of 100 mph — which is hurricane strength — and stretch for many miles, lasting for hours.
Storms that have sustained winds of at least 58 mph and leave a path of damage at least 250 miles long qualify as derechos, according to the National Weather Service.
Derechos develop in the northern hemisphere during warm weather and may be accompanied, or preceded, by violent thunderstorms. A derecho may also create tornadoes.
Parts of the Midwest see a derecho roughly once or twice every year, Accuweather said in a news release.
Are derechos common in Iowa? When have they hit the state?
Derechos are less commonly occurring in Iowa than tornadoes, but occur regularly in the Plains states. Among years with notable derechos in Iowa: 1983, 1986, 1991, 1998, 2004, 2011, 2014 and 2020.
In August 2020, a derecho caused significant damage across the Des Moines metro and central and eastern Iowa. As the system moved across Iowa, winds of 99 mph were recorded at the Marshalltown airport and 75-mph winds were recorded at the Des Moines International Airport, according to previous NWS reports.
Previously: Marking 2 years since devastating Aug. 10 derecho slammed Iowa
The storm ripped through central Iowa during the mid-morning, taking down trees and leaving at least 480,000 Iowans without power that afternoon. Tuesday morning, the next day, there were still more 400,000 people without power.
Is a derecho possible in Iowa?
Aside from unbearable heat, Iowans could also see some severe weather sweep the state in the evening on July 28 and into the morning.
Storms will begin in South Dakota or Minnesota in the afternoon and move east toward Iowa. Damaging winds are the main concern, according to the National Weather Service. Northwestern Iowa has the greatest likelihood of damaging winds ranging from 60 to 80 mph. There is also a chance for large hail.
The Des Moines metro could see some damaging winds, but is only under a marginal (level 1 out of 5) risk, according to the National Weather Service.
The storms have the potential to evolve into a destructive derecho, AccuWeather warned in a mid-day news release on Monday.
The greatest risk for severe weather is just slightly west of the track of the 2020 derecho that caused more than $11 billion in damages, said AccuWeather Meteorologist Brandon Buckingham.
“The extreme heat in place, combined with an ample amount of available moisture, will result in an immensely unstable atmosphere for thunderstorms to develop and feed off on Monday," Buckingham said.
Was Monday morning's storm event a derecho?
Monday morning's weather event will not be characterized as a derecho, said Mike Fowle, the science and operations officer at the National Weather Service. Wind gusts did not reach 75 mph and widespread damage was not significantly observed.
Severe thunderstorm warnings were issued in some parts of northern Iowa, but storms stayed below those limits in the Des Moines area. Rainfall totals of more than an inch were reported across the northern half of the state.
More: See rainfall totals from overnight storms that caused 25,000+ MidAmerican power outages
A derecho is not officially determined until after the event has occurred, Fowle said. This is so NWS officials can confirm the extent of the damage as well as wind gust reports.
(This story was updated to correct a typo.)
Des Moines Register staff Bill Steiden and Kate Kealey contributed to this report.
Victoria Reyna-Rodriguez is a general assignment reporter for the Register. Reach her at [email protected] or follow her on Twitter @VictoriaReynaR.
This article originally appeared on Des Moines Register: What is a derecho? Iowa at risk for destructive storm
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