Updated spring flood outlook keeps risk near or below average

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CEDAR RAPIDS, Iowa (KCRG-TV9) - The National Weather Service has issued its second spring flood outlook of the season, updating the one from mid-February. The risk of springtime flooding is still near or somewhat below the long-term odds on the smaller rivers such as the Cedar, Iowa, Wapsi, and the others that are in eastern Iowa. The Mississippi River has an above-average risk of flooding.

Soil Moisture
The moisture in the soil across most of eastern Iowa is near or below normal. In fact, about the southeastern third of Iowa is in abnormally dry conditions or moderate drought. In central and southern Minnesota, the ground is wetter than normal, affecting mainly the Mississippi River. As the ground thaws, drier ground is able to absorb rainfall and snowmelt better than wet ground.

Frost Depth
Even though temperatures have been warmer lately, frost remains deep in the ground. Frost still exists roughly a foot-and-a-half down. Because the ground is frozen so deeply, water will run off into streams and rivers more than it otherwise would.

Streamflow is the amount of water moving through the river at a given place. Streamflow is near or above normal because of the rain and snowmelt not long ago. Because some of the rivers area already carrying an above-normal amount of water, they won’t be able to take in as much until they return to more typical levels.

Water in the Snowpack
Very little, if any, snow remains over most of our river basins. There’s still up to a few inches of water in the snow in Minnesota that would affect mainly the Mississippi River. However, its effect would be quite limited.

These are all general factors and are a broad indication of the most likely scenario. A situation such as a small-scale heavy rain event, or a significant ice jam, are too localized to be able to predict far in advance or include in this type of outlook. Because there is still ice on some of the rivers, ice jam flooding is still possible.