Here & Now

Snowpack Brings Flooding

Frederica Freyberg:
It’s been one heck of a winter. Polar vortex, snow, rain, melting snow. It all adds up to flooding across Wisconsin. In tonight’s inside look, we check in with Andrew Mangham, hydrologist with NOAA’s Northcentral River Forecast Center. He joins us from Chanhassen, Minnesota and thanks very much for doing so.

Andrew Mangham:
Happy to be here.

Frederica Freyberg:
You know, we are seeing images right now from across Wisconsin of flooding and it looks like pretty significant flooding. After rain and snow this week, what is the flooding situation across Wisconsin?

Andrew Mangham:
Well, currently the flooding situation is rapidly developing. You know, you said it best when you said polar vortex, snow, rain on snow. We’ve got pretty elevated chances of significant flooding across the entire state because of the conditions on the ground. What we’re seeing right now is just the beginning of that. This rainstorm that passed over has brought down a lot of the snowpack. So you go outside, you see a lot of the snow has come down. However, that water is only just now starting to make it into the rivers all over the place. What we’re seeing instead is ice jamming and flooding from ice jams, where ice piles up into a big ice dam and causes a backup of water all over the place. So you will get flooding in a lot of unexpected areas and flooding that’s very difficult to forecast.

Frederica Freyberg:
How is this year different than others?

Andrew Mangham:
This year is different than others in that we just have an historic level of snow. In many places, February blew out the record for snow that fell in February. We also went into the winter with the rivers at fairly elevated levels in terms of flow and the soil is very, very wet. So what makes this year different, it’s not any one factor. It’s the fact that we have a combination of all of these factors that makes this year a little bit different and leads us to a situation where we have the potential for some very significant flooding.

Frederica Freyberg:
Does this year look like historic flooding? I mean is it that different?

Andrew Mangham:
There certainly could be some historic floods. Now, that is a misleading title sometimes. There could be historic floods in places where we have gauges there for a very long time and that’s a very serious situation. There’s an elevated chance of flooding at those kind of spots. There can also be historic floods in places where the gauges are very new and we don’t have a very long record. Just today we issued several forecasts along those lines, that are record floods not necessarily in Wisconsin yet, but around other parts of our area. They’re record floods, but the gauges are so new that the records aren’t quite as serious as some people might think. However, we are headed toward some record flooding in Ozaukee County, getting very close to that right around Cedarburg, because of ice jamming.

Frederica Freyberg:
We did extensive coverage of the flooding in Sauk County last year due to the Baraboo River overtopping its banks. What is the status of that area right now? Those people are still trying to recover from last year.

Andrew Mangham:
Absolutely. That river, we’re starting to see the runoff develop into actual flooding into that river. So far it doesn’t look like — because the rain was not as heavy as we thought it might be coming into this storm, so far we’re not headed towards major flooding. But certainly we could reach what we call moderate flooding, where county roads and things like that will be difficult to access and any homes close to the river might be impacted. For people that are living in that area, I would absolutely recommend contacting the weather forecast office, either in La Crosse or Milwaukee to ask about what kind of impacts they could expect and check what the forecast looks like. We are monitoring that river very, very closely. In fact, I am monitoring.

Frederica Freyberg:
You spoke of Ozaukee County. What are other critical spots?

Andrew Mangham:
Let’s see. I would say that a lot of the critical spots are happening in the Kickapoo area over in southwest Wisconsin. Certainly Sauk County with the Baraboo River is critical. All along the Wisconsin River heading up into Rhinelander. That snow has yet to fully develop into flooding so that’s kind of waiting in the wings. Northeastern Wisconsin we’re getting a lot of ice jamming, so up and down the Milwaukee River, all the way down to Milwaukee. So it’s a little hard to say there’s one spot in the state that is bad. It would be probably more accurate to say that there are many spots in the state that are at risk at least of some significant flooding.

Frederica Freyberg:
With about a minute left, given the snowpack and the frozen ground and these ice jams, how long could this go into the spring?

Andrew Mangham:
I would say at least another month of looking at this, of elevated chances. And then we should be able to get rid of much of the snowpack. I would say a month to six weeks, we’ll have everything flushed out, just in time for the big summer storms to come in. We’re hoping that what we get is a nice, maple syrup spring, where we get slightly warm days and cold nights that can bleed off the snowpack slowly. But we’ll see.

Frederica Freyberg:
All right. We will see. Andrew Mangham from NOAA, thank you very much.

Andrew Mangham:
Thank you.