After record snowfalls and many winter storms Iowans are likely looking forward to the spring thaw — but the National Weather Service says the warmer weather could bring a new set of problems to the state. National Weather Service senior hydrologist, Jeff Zogg, says there’s a good chance of spring flooding.
“Right now we’re looking at a high risk of significant flooding, especially across the northwest half of Iowa this spring,” Zogg says, “the streams of most concerns right now are the Des Moines, the Racoon, the Floyd, the Little Sioux and Big Sioux Rivers as well as part of the Cedar/Iowa river basin.”
Zogg issue his first flood outlook for the period from February through April. He says there’s a high risk of “moderate” flooding which is more than what is typical and he says there’s also a chance of major flooding, especially in northwest Iowa, which is at a higher risk than some areas. Zogg says a lot of things are pointing toward flooding this spring.
Zogg says the most obvious is the snowpack, which he says is very deep in the northwest and has a lot of water in it. And he says streams are running very high across much of the state, and that combined with high soil moisture, leads to an enhanced risk of flooding. Zogg says while things are building toward the possibility of flooding, the weather from here on out is a big factor that’s unknown.
“Flooding is not a certainty, although it appears pretty likely. We could get lucky for example and have a prolonged period of snow melt that would not overwhelm our rivers and keep them lower than we are thinking. It’s one of those things we are going to have to watch very closely,” Zogg explains. He says the storms systems that move into the state in the next few months hold the key to the amount and severity of flooding.
He says a quick warm up or a prolonged or heavy period of snowfall or rainfall would be especially important, as it would boost the risk of flooding. Zogg says timing is also important as a heavy rain on top of snow melt would result in more flooding. One other wildcard in the flooding mix is the potential for ice jams.
Zogg says we’ve had colder temperatures, which has led to thick ice on the rivers. He says the flood outlook they’ve issued today does not take into account flooding from ice jams, and says ice jams could make the flooding even higher than what they are calling for in the outlook. You can see the entire flood outlook on the National Weather Service website here.