NOAA: Historic, widespread flooding to continue through May

March 21, 2019 0 Comments

Historic flooding continues in parts of Nebraska and Iowa, but it could get worse and more expansive over the next two months, including in our neck of the woods. According to NOAA, 25 states, including Wisconsin, have an elevated risk for moderate to major flooding through May. This flood outlook map produced by NOAA, has portions of Wood, Portage, Juneau, and Adams counties under the risk for major flooding, with moderate flooding possible around all of central Wisconsin. Minor flooding will be possible in the Northwoods.

Many locations in the Upper Midwest just had their wettest and/or snowiest meteorological winters on record, including Wausau, and there is plenty of water in the snow. After losing 20 inches over the last week and a half, Wausau’s snow depth is currently sitting at 7 inches. Snow depths are much lower south of Wausau, and range between 10 to 25 inches in the Northwoods. The liquid water equivalent of the remaining snow is around 2-4 inches in Wausau and between 4-9 inches in the Northwoods! All of this water will have to go somewhere, and the longer the ground stays frozen, the worse flooding could become if we quickly warm up and get a lot of rain.

Credit: NOHRSE

 

Due to the heavy February snow followed by warmth and heavy rain, soil moisture is high in much of the Midwest. In many locations farther north, such as north central Wisconsin, the ground is still frozen so none of this water is currently able to soak in. To make matters worse, the Climate Prediction Center released their 3 month outlook for April – May – June, and it has a majority of the country in a risk for above normal precipitation. Compound this with the melting snow, and floods will continue and become more widespread as river basins become waterlogged.

CPC Precipitation Outlook Apr-May-June

The best case scenario to minimize the flooding would be for a gradual warm up over the next several weeks. Last week, temperatures were above freezing for 72 hours and during that time most of the area picked up between .75 – 1.5″ of rain. This is what caused the worst of the flooding that is only now beginning to improve. Since then, temperatures have fallen below freezing almost every night, which puts a pause on the melting process for several hours a day. Even though we all want the warm weather, as long as temperatures keep cooling below freezing at night and rising above freezing during the day, it should mitigate much of the severe flooding risk.

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