By Madeline Heim, Milwaukee Journal Sentinel
Unless thunderstorms dump rain on the Midwest in the coming months, there’s little chance of spring flooding on the upper Mississippi River this year, forecasters say.
That news is likely to bring relief to river communities, many of which were swamped with near-record floodwaters last spring. But it could have negatives too: The prolonged dryness that lingered over the winter could result in another summer of drought and low river flows.
“Compared to last year, it’s almost the polar opposite,” Jordan Wendt, service hydrologist for the National Weather Service in La Crosse, said during a flood outlook presentation in mid-February.
The Mississippi River basin has seen both droughts and increased rainfall and flooding in past years. Last spring’s flood on the upper river, when waters crested to the third-highest level on record in some communities, was followed quickly by drought over the summer. Scientists attribute extreme swings like these to human-caused climate change.
This year, a warm and virtually snowless winter across the upper basin means there’s little to no melting snow to cause water levels in the Mississippi and its tributaries to rise, according to an update to the flood outlook on February 29. Minneapolis and St. Paul, for example, have seen about 14 inches of snow so far this year. They had recorded nearly 90 inches of snow by the end of last winter.
The only thing that could change that outlook is if the region gets heavy precipitation in the next few months. More than one or two strong spring thunderstorms, depending on the amount of rain and where it falls, could trigger minor to moderate flooding in the river valley, said La Crosse meteorologist Todd Shea of the National Weather Service.
“It’s a strange year in the sense that (the flood risk) is all tied to future precipitation,” Shea said.
Flood risk is also low in the rivers across Wisconsin, Minnesota and Iowa that feed into the Mississippi, according to the National Weather Service outlook. Further downstream, the Missouri and Ohio rivers — both major tributaries of the lower Mississippi — are seeing normal to below-normal chances of spring flooding.
Other factors besides low snowfall are lowering flood risk, too. For example, relatively shallow frost depths will mean spring rains will be able to soak into the ground instead of running off into rivers and streams. While this forecast is a good sign for people with property along the river, and for the shipping industry, which typically pauses river travel during high-water events, it’s concerning to others who are watching drought conditions and river levels.
It was a dry fall in the Midwest, and while there was some recovery this winter, it wasn’t “as much as we’d like,” said Dennis Todey, director of the U.S. Department of Agriculture’s Midwest Climate Hub in Ames, Iowa. The states bordering the upper Mississippi are still experiencing at least abnormally dry conditions, with one pocket of eastern Iowa in extreme drought, according to the latest U.S. Drought Monitor. Even though soil moisture rebounded slightly over the winter, most soils are very dry deep down, Todey said.
“We are definitely very concerned,” he said.
One perk of early spring dryness: It allows farmers to get out into their fields early to plant. But it could come back to bite them if it sticks around through summer.
Low river levels, in turn, cause their own problems. When the mainstem of the Mississippi is low, the U.S. Army Corps of Engineers must dredge more frequently so that commercial shippers can pass through. In fall 2022, near-historic low river levels caused barges to run aground on the lower river.
This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, funded by the Walton Family Foundation.
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