Despite new snow, Iowa experts predict ‘below normal’ spring flood risk

CEDAR RAPIDS — Even with new snowfall this week — and more expected Friday — the National Weather Service is predicting that flood risks for Eastern Iowa will be below normal this spring.

“The bottom line up front here is that the spring flood threat is below normal for the Mississippi River, and near to below normal for our tributary rivers,” said Timothy Gunkel, meteorologist with the weather service’s Quad Cities Bureau in a webinar Thursday.

Gunkel said that as of now, there is only a 10 to 15 percent chance for major flooding to occur along the Mississippi River.

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Rich Kinney, a warning coordination meteorologist with the National Weather Service Quad Cities, said the service considered the state’s recent snowstorm when making the flood outlook. He said the outlook also incorporates the snowfall Eastern Iowa is expected to receive both Friday and Saturday as well.

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“The moisture content of the snow we received and will receive is relatively low and will not have a significant impact on the risk for spring flooding,” Kinney said.

The majority of Iowa was blanketed in snow this week from a winter storm that marked the first significant snowfall the region has seen all season. According to data collected by the weather service, Cedar Rapids received about 8 inches of snow. Iowa City had about 4 inches and Dubuque saw about 6 inches.

But there will be more snow to come, meteorologists say.

It is projected that Eastern Iowa will see about another inch of snow — more north of Interstate 80 — that will likely start Friday afternoon. Light snow also is expected Saturday.

But with much of Iowa’s ground frozen, Gunkel said the recent snow likely will become runoff and go into the region’s rivers and streams.

“For the most part, there are plenty of dry areas in the Upper Mississippi Valley, so that means when the ground thaws, it does have room for more water to soak in and help prevent any future flooding,” Gunkel said.

Gunkel said the water levels in most of the state’s Eastern streams and rivers will have room for runoff, too.

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“There's no blaring high flood threat with the current stream flows. If anything, if we keep decreasing the stream flows and trend below normal even more, I might get more concerned with the stretch of the cold weather for the potential ice jams,” he said.

Ice jams occur when there are pieces of floating ice being carried by a stream’s current and obstruct the water’s flow. The water that is held back by the ice could cause flooding or flash flooding.

But when it comes to flooding risks, Jeff Zogg, senior service hydrologist with the National Weather Service, said the water equivalent of the snowpack is more important than the snow depth.

“Snow water equivalent values are generally 1/3 inch or less across the state,” Zogg wrote Thursday in an email to The Gazette.

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He said that over the past several years, spring rainfall across Iowa has become a bigger factor in spring flooding than snow.

“Whereas the snowpack has historically been a major driver of the spring flood risk, it has become less of a factor over time and the spring rainfall has become more of a factor,” Zogg said.

One exception to this is the Mississippi River, he said.

“The Mississippi River can still be significantly impacted by the snowpack in its drainage area which extends from Eastern Iowa northward into northern Minnesota and Wisconsin,” Zogg said. “Currently the snowpack in the Mississippi River drainage basin above Iowa is generally near to below normal for this time of year.”

Looking forward

Thursday’s outlook was the first of three flood reports by the National Weather Service. They will be hosting two more webinars about flooding outlooks on Feb. 27 and March 13.

Although the flood risks are low as of now, Gunkel said this spring’s outlook could look different if more major weather comes along.

“Many things can impact this, as we know one system can change this drastically,” Gunkel said.

The Wapsipinicon River is the only Eastern Iowa river with a slightly higher chance of flooding. As of now, the Wapsi, which is a tributary of the Mississippi River that runs through northeastern Iowa, has about a 25 percent or higher chance of reaching “major flooding.”

But Gunkel said that the Wapsi is a “trouble child every year, so it’s to be expected.”

“This is good news,” he said. “Hopefully it could stay this way for all of us, and we have a quiet spring.”

Iowa’s drought conditions

According to Thursday’s U.S. Drought Monitor update, about 60 percent of Iowa still is experiencing moderate drought conditions. Parts of Woodbury, Plymouth and Sioux counties are experiencing “severe” drought conditions. Parts of the state, however, have no drought or dry conditions reported, including parts of southern and southeastern Iowa.

But this week’s precipitation might not help the dry conditions since the ground still is frozen.

Current drought conditions in Iowa

According to the U.S. Drought Monitor's latest drought report on Thursday, Feb. 13, 60 percent of the state is experiencing "moderate drought" conditions. Compared to this time last year, Iowa is seeing less significant drought statewide, as in February 2024 nearly 20 percent of the state was facing extreme drought.

Source: U.S. Drought Monitor data released on Thursday, Feb. 13

“The snowfall this week will help alleviate drought if it can stick around long enough during melting to infiltrate into the soils,” said Keith Schilling, geologist with the Iowa Geological Survey. “If we get a warm spell and the snow melts quickly while frost is in the ground, we won’t get much soil moisture or groundwater recharge.”

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Schilling said that late winter and early spring snowfall often have “greater potential” to replenish soil moisture conditions if they occur as the frost is coming out of the ground.

Previously, Schilling said that soil moisture conditions are like a clock that continually needs to be rewound with precipitation.

“We routinely receive snow every winter and snowmelt is part of our recharge cycle for replenishing soil moisture conditions and the water table,” he said.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues. Comments: olivia.cohen@thegazette.com