Saturated soils add flood threat as rain falls and snowpacks melt
University of Missouri Extension
January 31, 2020
COLUMBIA, Mo. - Soil moisture, down to subsoil, normally helps farming. But as winter heads to spring, saturated soils become a concern for Missouri farmers.
"The pressing situation is exceptional wetness across the Missouri River and upper Mississippi River basins," says Pat Guinan, University of Missouri Extension climatologist, Columbia.
There's potential impact from spring rains plus melting snows in northern states. Saturated soils won't hold more water. Rain and snowmelt will run off, heading to Missouri.
A new report from meteorologists in the north-central U.S. raises flooding issues but refrains from firm forecasts. Guinan says.
A 2019 flood repeat isn't guaranteed, they say. There's time and factors to come together before they know how bad, or uneventful, it becomes.
Missourians farming along rivers recall last year's record floods, high rivers and super wet ground. They'll watch changes from winter to spring across the state this year.
Changes could include dry, warm weather allowing soils to drain and dry; little or no added snowfall with cold snaps; or a gradual move from winter to spring with mild temperatures making a slow snow melt.
All of those cut flood risks.
However, other possible changes between now and April are not good, the meteorologists report.
Above-normal snowpacks across the basins could grow. A long, widespread cold snap might freeze the ground and build thick layers of river ice. That increases ice jams. Or big rain on snowpack could rapidly release more water.
These changes could delay or prevent crop planting.
Guinan makes no forecast on how spring weather develops. As a climatologist, he says he's better at looking back. Past records help us understand conditions.
December 2019 showed above-normal temperatures during most of the month. Statewide temperature was almost 6 degrees above long-term average. That made it the ninth-warmest December on record.
In the tradition of Missouri's erratic weather, 2019 had six months each of below-normal and above-normal temperatures.
December was the state's driest since 2017, yet Missouri had eight wetter-than-average months during 2019.
January data isn't tallied. It surely won't match December's temperature departures, though it will be above normal.
Average precipitation for the year was 53.78 inches. That makes 2019 the state's seventh-wettest year on record.
Meanwhile, bottomland farmers keep watch on the weather heading into spring. They hope for no topping of 2019 records.
River data for Missouri is at agebb.missouri.edu/weather/river.htm.
Source: Pat Guinan, 573-882-5908