A true Arctic air mass has settled into the Stateline bringing temperatures at night down below zero and daytime highs not much above the low to mid teens. With this cold air mass also comes dangerously cold wind chills, the first of which arrive Saturday evening.
A WIND CHILL WARNING will go into effect for Stephenson, Jo Daviess and Carroll counties beginning Saturday evening and lasting through Noon Sunday. A WIND CHILL ADVISORY will go into effect for Winnebago, Boone, McHenry, Ogle, Lee DeKalb, Green, Rock and Walworth counties also beginning Saturday evening, lasting through Noon Sunday. This means wind chills could drop as low as -30 degrees, down to -35 degrees, by Sunday morning. Actual air temperatures could fall as low as -15 degrees. Frostbite can occur within a matter of 10 minutes to exposed skin if proper precautions are not taken.
Along with the bitterly cold temperatures, another round of snow is expected Saturday afternoon and evening. A WINTER WEATHER ADVISORY will go into effect beginning at Noon Saturday for Ogle, Lee and DeKalb counties, lasting through 12am Sunday. Snow accumulations of 2-4 inches will be possible for the areas within the advisory, with lighter amounts to the north. The very cold air mass means that the snow could be very flurry and light – higher snow to liquid ratios. This will allow the snow to accumulate quickly once it does begin to fall. Not only that, but with the very cold temperature in place, road treatments become less effective from keeping the snow sticking to the road and ice from building up. Road conditions later today could become very slick once the snow begins to fall. Even though lighter snow amounts will be found to the north, the impacts from the snow could be felt everywhere. Be careful if out this afternoon and evening.
The cold and snowy pattern looks to continue into next week with another chance for light snow Sunday, and then again for Monday into Tuesday.