Damaging Winds, Potential Derecho Possible Overnight

The National Weather Service says conditions are developing which could lead to a possible derecho or strong damaging winds overnight Monday into Tuesday.

Meteorologist Donna Dubberke says it’s an “evolving situation” and she’s warning everyone across the region to keep a very close ear on the forecast and an eye on the sky. She says they expect storms to develop in South Dakota into Minnesota late this afternoon into early evening and then start to track to the east or southeast. “The questions are where exactly that’s going to track, and then the other question is, how strong is it going to be?” says Dubberke.

The Storm Prediction Center has upgraded a portion of eastern Iowa to a Level 3 out of 5 Enhanced Risk for severe storms from Cedar Rapids up north through Delaware and Clayton counties (and points to the west) tonight into early Tuesday. Areas southeast are under a Level 2 out of 5 Slight Risk for severe weather. Delaware County Emergency Management encourages everyone to have a warning method that will wake you up. You can sign up for Delaware County Alerts at this link: https://www.smart911.com/smart911/ref/reg.action?pa=DelawareCountyAlerts

Iowa took the brunt of a powerful derecho in August of 2020 that packed winds which, based on the damage, may’ve hit 140 miles an hour. That’s the equivalent to a Category 4 hurricane. It was one of the most destructive storms ever to hit the Midwest, with damage in multiple states estimated at over 11-billion dollars.

Dubberke says it does NOT appear tonight’s events will be anywhere near as severe. “There is potential for it to be strong enough to be a derecho, but at this point we don’t expect it to be the same as what we had, for example, in 2020, which is the one that so many people remember because it was a high-end, extreme case, even for a derecho,” Dubberke says. “We are worried about severe thunderstorms with damaging winds being the main threat.”

A derecho is a widespread, long-lived, straight-line wind storm that’s associated with a fast-moving group of severe thunderstorms, and Dubberke says they’re rare, and they can be exceptional devastating. “Once you get it moving, it just keeps going and so it makes the storm very strong,” she says. “And the thing with a derecho is you get an enhanced wind threat, so damaging wind that lasts for a long time, covers a long area, and is stronger than your average thunderstorm, so we’re talking winds of 75 to 80 miles an hour or stronger.”

The winds that hit Iowa in 2020 were much stronger – flattening crops, ripping roofs off houses, and destroying more than half of the tree canopy in Cedar Rapids. Cleanup took a full year.

However, Dubberke is concerned about toppling trees as Iowa has had so much rain lately, noting that a powerful wind storm could knock over trees with compromised or shallow root systems in the moist soil.

partial story contribution courtesy of Radio Iowa