Spring outlook: Flood risk minimal for Eastern Iowa

This year’s first spring flood outlook shows little risk of major flooding in Eastern Iowa.

But areas along the Mississippi River could see slightly above-normal risks of flooding, the report from the National Weather Service’s Quad Cities bureau stated.

The outlook considers seasonal temperatures and precipitation, snow cover, soil moisture and stream flows in projecting flood risks.

Snow pack

Widespread snowpacks stretch from the upper half of Iowa to Minnesota, varying from trace amounts to 2 inches of “snow water equivalent” — this is, the amount of water that would cover the ground if the snow was in a liquid state.

Much of the region’s snow cover is below normal. The deepest portions further north hold 4 to 8 inches of snow water equivalent.

These snowpacks have begun to melt, given the warmer temperatures.

Going forward, much of the Midwest may see above average temperatures, ranging between 1 and 3 degrees warmer than normal. Eastern Iowa is mapped to be warmer than western Iowa, which may see marginally cooler temperatures.

Northern snowpacks lay over frozen ground, which could lead to flooding along the Mississippi River if rapid snowmelt occurs. The flood threats in the NWS Quad Cities’ service area, however, appear mild.

“With little snowpack remaining locally, not much flooding impact is currently expected,” according to the outlook. “Any new snowfall can impact this in the future.”

If the frost in the ground — less than a foot locally, for the most part — thaws early, the ground can soak up snowmelt and rain.

That will come in handy since the winter precipitation across most of the Upper Mississippi River basin, particularly in Minnesota and Wisconsin, is well above normal.

Near-normal soil moisture levels will give the ground even more capacity to absorb water, especially with the abnormally dry to severe drought conditions the state has been experiencing.

“These conditions have persisted for months now, with no big indication of change yet,” the Thursday outlook report stated.

Nearly all of Iowa should encounter more precipitation than average — up to 300 percent in the northwest part of the state.

River levels

Runoff that makes it to nearby waterways shouldn’t threaten flooding, though, with most Iowa rivers at normal or below-normal levels. Some rivers in north-central Iowa are above normal.

The outlook found no Eastern Iowa locations with high chances of flooding, according to the outlook.

Some locations along the Mississippi River — generally near and downstream of the Quad Cities — have a 50 percent or higher chance of some flooding, along with the lower Wapsipinicon and Rock rivers.

The stretch of the Cedar River near Cedar Rapids shows a very slim risk for flooding. The Iowa River shows a small chance of flooding.

The forecasters noted that flood chances “may fluctuate,” based on snow melt and how much it rains this spring.

A second spring flood outlook for Eastern Iowa will be issued by the National Weather Service on Feb. 23.

Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com