The National Weather Service has issued a winter storm warning and a wind chill warning for Will, Grundy and Kendall counties. Both warnings also includes the counties of Cook, LaSalle, Kane and DuPage.
The winter storm warning will continue through 6 p.m. Sunday, Jan. 5. Snow will develop Saturday afternoon, continuing into Sunday, and computer models are now indicating we may get 5 to 10 inches of new snow.
The Weather Service has been updating its predictions frequently since Friday night. The previous weather advisory issued earlier on Saturday has been replaced with this new warning, which was posted Saturday at 10:45 a.m.
Periods of moderate to heavy snow could lead to hazardous travel conditions, and airport delays are likely, according to the Weather Service. Brisk northwest winds of 15 to 30 miles per hour also could result in blowing and drifting snow, further reducing visibility.
The wind chill warning is in effect from 6 p.m. Sunday through noon Tuesday.
Temperatures, while remaining mild all day Saturday, will drop dramatically on Sunday. Expect to wake up to about 13 degrees and end the day at about -5 degrees. Wind chills will make that feel like about -30 degrees.
The deep freeze continues into Monday, which will see a high of -12 and a low of -15, and Tuesday, which will "warm up" to only 4 degrees. Both days are predicted to be windy, making the wind-chill factor extremely dangerous for anyone outdoors.
"The most extreme wind chills are likely to be late Sunday night through Monday afternoon," according to the Weather Service. "A prolonged period of wind chills colder than 30 below zero is expected, with wind chills of 40 to 50 below zero expected late Sunday night into Monday afternoon. This will result in frostbite and lead to hypothermia or death if precautions are not taken."