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Weather Blog: Why snow totals are still in question for this weekend's storm

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Posted at 2:39 PM, Dec 11, 2020
and last updated 2020-12-11 16:26:51-05

WISCONSIN  — Our first accumulating snowfall event of the season will take place Friday night into Saturday.

The National Weather Service has issued a Winter Weather Advisory for Fond du Lac, Sheboygan, Dodge, Washington, and Jefferson counties. This is the area, as of now, that will see the best potential for 3-6 inches of accumulating snow.

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Exact snow amounts are still somewhat in question, and there are lots of factors to consider when it comes to this snowfall forecast.

For now, we think there will be less accumulating snow for much of the lake shore and higher amounts inland.

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Strong northeast winds Friday into early Saturday are one of the factors that will likely lead to lower snow amounts near the lake.

Lake Michigan water surface temperatures are still in the mid-40s. The wind blowing over the lake will add a bit of warmth to the air within a few miles of the lake, helping this zone see more of a rain and snow mix.

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However, by Saturday afternoon winds will turn more northerly. That will allow cooler air to settle in and transition the rain/snow mix to all snow.

Temperatures are another factor to consider. While atmospheric temperatures are cool enough to support snow, at the ground level, temperatures look to hover just above freezing through Saturday afternoon. That could aid in melting some of the snow as it makes contact with the ground.

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Also, we must consider the mild November and early December in SE Wisconsin, which has helped to keep ground temperatures near or just above freezing. And we are starting this event with rain, so the wet ground could aid in a little initial melting.

A cause for higher amounts - banding. This is where locally heavy areas of snow develop in "bands" and can cause narrow areas to see heavy snow and higher snow totals.

The bottom line, regardless of exact amounts, this will be a messy system with wet, heavy snow.

We will see slushy and slippery conditions on local roadways, especially bridges and overpasses. Strong winds will cause areas of blowing snow and reduced visibility.

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Stay with TMJ4 through the weekend for the latest thinking on this winter weather system. Things could still change as we get new models runs and assess new data.

As always, we appreciate your weather reports. We love to know what's happening where you live, send us snow reports or weather pictures that we can use on air! Share them with us on social media, or email the team at weatherteam@tmj4.com.

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