Flooding not to be an issue after ‘above average’ snowfall

Six to 12 inches of snow was reported across Southwest Iowa as of this morning, with Creston receiving 6 inches as reported by Justin Glisan, state climatologist with the Iowa Department of Agriculture and Land Stewardship.

"This kind of snow, it's the heavy wet stuff, so when it falls it compacts also, so that could introduce some measurement bias," said Glisan.

Glisan said at his home in Des Moines, he had two inches, but after reviewing CoCoRaHS (Community Collaborative Rain, Hail and Snow) gauges in the central region, they showed anywhere from 3 to 4 inches.

"I also have a lot of big trees in my yard, so with the size of the snowflakes, that can impact how much you get," he said.

The statewide average for snowfall in April is 1.6 inches and Creston's is 8/10 of an inch for this month. Glisan said the latest snowfall to occur in Creston was May 4, 1917, in which the city received 5 inches of snow.

"This is an above average event but it's not out of the realm of possibility," said Glisan.

Glisan said the system that moved across the region Thursday was caused by a transition between wintertime circulation, or large-scale atmospheric air flow, and normal springtime precipitation produced by showers and thunderstorms.

The National Weather Service was calling for chances of thunder snow – a thunderstorm that produces snow – but Glisan said he has not had any thunder reported, but for the type of system that appeared, the rate and type of snow was expected.

"When you get that type of system that sets up in the springtime, since we're shifting dynamics, you can get these elevated systems that you're feeding moisture into it and you're getting snowfall rates of 1 to 2 inches per hour.

As the forecast shows a high of 60 degrees Fahrenheit Saturday, some residents are worried about flooding, which Glisan does not anticipate.

"Southwest Iowa is actually the driest part of the state right now," he said.

Glisan said subsoil moisture is running in the 80 to 90th percentile and expects some of the moisture to absorb into the ground.

"If you think of a sponge, anywhere to 10 to 20% holding capacity," said Glisan. "You might get some run-off from it. You might get some rises in the streams, but I wouldn't see any kind of major flooding issues. Just a lot of wet fields."