Wet February Increases Chance of Spring Flooding

Mar 2, 2018

The last two weeks of February were rainy, and that's changed the spring flood outlook.

Credit submitted / National Weather Service

Hydrologist Jessica Brooks, from the Quad Cities National Weather Service, says the ground has thawed and absorbed water that collected in low places. But Illinois got a lot more rain than Iowa.

The chance of flooding along the Mississippi River also increased. Brooks say in Minnesota and Wisconsin, the snow pack is holding a lot of liquid, up to six inches in some areas. And the snow is sitting on ground that's frozen two to four feet deep. If that snow melts quickly, it'll run into tributaries north of the Quad Cities, then into the Mississippi River. And heavy spring rainfall would exacerbate flooding.

This map shows how much liquid is contained in the snow that hasn't melted yet north of the Quad Cities.
Credit https://www.weather.gov/images/dvn/Hydro/FloodOutlooks/2018/SWE_0301.PNG / National Weather Service Quad Cities

In the Quad Cities through May, minor to moderate flooding is possible on the Mississippi. The chance of the river reaching flood stage in Rock Island is now 80%.

For the Rock and other tributaries, Brooks says they're already above flood stage and the ground is saturated from last month's rainfall. The chance of continued minor flooding on the Rock at Moline has increased to 70%, with the chance of moderate flooding now at 40%.