Meteorologists wary as storms sweep in from South Dakota

Local meteorologists are growing increasingly concerned about storms capable of producing damaging winds and torrential rainfall throughout Iowa on Tuesday evening, particularly for areas north of Highway 20. The storm crossed into Iowa around 4 p.m. Tuesday.

The complex of thunderstorms with 65 mph wind gusts had crowded northwest of Sioux Falls, S.D., as of 1:45 p.m. Tuesday. Peter Speck, a meteorologist in the National Weather Service’s Quad Cities bureau, said the storms had been rumbling as early as 6 a.m. in the state’s northwest portion. The strongest reported wind speed reached 90 mph in Pierre, S.D.

Beyond the threat of high winds, meteorologists are also eyeing the amount of rain the storms may drop on regions already drenched by rains on the Fourth of July. If too much precipitation falls, flash flooding could be a concern upon saturated soils.

Although the complex is raising concerns, it doesn’t match up to the derecho that swept through Iowa in 2020, which sported multiple storm updrafts and wind speeds over 100 mph.

“This is not like what we had in 2020,” Speck said.

The line of storms was moving southeast, he said, and is expected to reach Cedar Rapids and the surrounding areas between 8 and 10 p.m. Tuesday.

The region’s excessive heat warnings and heat advisories introduce some instability to the complex’s path, which had defied earlier modeling forecasts as it survived overnight and passed over hot and humid environments, Speck said.

“There's a lot of juice and a lot of moisture to tap into as these storms move into the area,” he said.

He encouraged Iowa residents to keep an eye on the weather forecasts going into Tuesday night, particularly those in northern parts of the state and along Highway 20, which are expected to get hit harder than those in Linn County.

B.J. Dvorak, the coordinator for the Linn County Emergency Management Agency, said officials were communicating with the National Weather Service to track the impending weather. In case the storms pick up into the evening, he urged county residents to take safety precautions, including monitoring weather radios and having a plan for seeking shelter.

“If things started to pop up, we'll be in close contact with the National Weather Service and we'll send out the information that we get from them,” he said. “That's kind of what we do to try to keep everybody safe.”

The Des Moines bureau of the National Weather Service tweeted Tuesday afternoon that a weather radio serving Waterloo residents had degraded quality, although it can still transmit alerts, according to the Twitter account.

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Brittney J. Miller is an environmental reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com