Flip a coin. Heads, you stay dry. Tails, your town floods.
A number of locations in Missouri have a 50% or greater chance of moderate flooding over the next three months, according to the most recent data from the National Weather Service.
All counties along the Missouri River, including Boone, have an above-average chance of flooding this spring, said Jud Kneuvean, chief of emergency management for the U.S. Army Corps of Engineers’ Kansas City District.
Nine gauges spread across northwestern Missouri and the state border with the Mississippi River show at least a 1-in-4 chance of major flooding that could require evacuation, according to weather service guidelines.
The weather service gives Jefferson City a 3-in-10 chance of major flooding between now and mid-June, with flood risk peaking in mid-May.
Some locations are expecting floods sooner rather than later. The Corps of Engineers anticipates late-April flooding on the eastern edge of the state and is bracing for impact.
“I would say that the likelihood of having some type of flooding in the spring is probably relatively high,” said Russell Errett, a hydraulics engineer with the Corps’ St. Louis District.
Some pockets of the state might have more time, but not much. The Missouri River gauge near St. Joseph shows peak flood risk at the beginning of May.
In the short-term, the corps is racing against nature, draining reservoirs such as Mark Twain Lake so they can catch more runoff from upstream.
But the beginning of 2020 was unusually rainy, and the reservoirs are accumulating water even as the corps tries to lower their levels.
The latest data from the corps shows that the Lewis and Clark Lake reservoir behind Gavins Point Dam in Yankton, South Dakota, is taking in water slightly faster than the dam is releasing it, even though the release rate is about twice the average for this time of year, Kneuvean said.
Gavins Point Dam began releasing more than 100,000 cubic feet of water per second in order to avoid a breach last year, contributing to the destruction of 45 levees and overtopping 65 more in the Kansas City District, according to previous Missourian reporting.
Though Errett assured the Missourian that the levee system is generally in “good shape,” repairs haven’t started on many of the levees that were damaged. Kneuvean said that just under 20 in the Kansas City District have completed repairs; another 21 are still seeking bids for repair contracts.
The communities protected by these levees will be vulnerable until repairs are done, Errett said.
In an email, Kneuvean said the Corps of Engineers is “working hard to ensure” these communities aren’t imperiled, “but once the water is released, all bets are off since lower basin flooding is very dependent on localized heavy rainfall. Flood control and life safety are our priorities.”
A meteorologist with the National Weather Service confirmed that the climate outlook for the Midwest this spring includes above-average rainfall.
But exactly when the rain will hit is hard to predict. Forecasts get dicier the farther out you look and are hard to pin down beyond two weeks at most, Errett said.
“The big wild card is always the rain, and that’s going to be really the determining factor of whether we see big, major flooding or not,” Osterhage said.
Soil is extremely wet for this time of year, meaning that the earth probably won’t be able to sponge up the rain when it hits. A report released by the Corps on March 5 forecasts that 2020 will have the ninth-highest runoff volume in 122 years of recording.
But exactly when and where the flood will come is the “million-dollar question,” Errett said. “I’d be making a lot more money if I could predict exactly when a flood starts,” he said.
It’s not all bad news. The outlook is better than 2019’s record-setting flood season.
Several metrics the weather service tracks in its flood models have begun to improve regionally, Mark Fuchs, a senior hydrologist with the weather service, said. Soil in northern Missouri has begun to dry out somewhat.
Whether those improving conditions are sufficient remains to be seen.
“It’s an improvement. Is it a significant improvement? I’d probably have to say it’s not,” Fuchs said.
Multiple gauges on the Missouri and Mississippi rivers and its tributaries indicate that minor flooding has already arrived, and water flow is significantly faster in many places.
“It’s not all sunshine and lollipops,” he said.
These kinds of flood events are likely to become more frequent as the planet warms. A recent study from the U.S. Department of the Interior projected a 10% increase in annual runoff in the Missouri River Basin by 2050 due to climate change.
While Fuchs declined to draw a straight line from global warming to flooding, he said the flooding is consistent with the theory.
The Corps’ emergency response branch is stockpiling materials to support direct assistance operations if and when the flooding hits, including pumps and sandbagging machines, Osterhage said. Levee districts can ask for help from the Corps in the event that the county and state are unable to handle the situation on their own.
Osterhage recommended Missourians develop their own evacuation plans, including how to get to safety and where to stay. He also suggested staying engaged with local levee districts and law enforcement, listening to their suggestions and figuring out how to get information during a flood.
“Each community’s a little bit different on how they handle flood response and putting out information,” he said. Figuring out how to get information from emergency response crews ahead of time is critical.
Osterhage also suggested flood-proofing homes and buying flood insurance before it’s too late.
To see the flood risk to your community, go to the National Weather Service’s website and find the nearest gauge station.