Saturday, December 8 Update

I think that we can expect the following in the Chicago metro area tonight:
Flurries will start after 3pm, increasing to light snow throughout the evening (really light, less than an inch).
Around midnight sleet will mix with the snow and continue through late morning.
As the temperatures rise tomorrow afternoon the sleet will change to freezing rain (it freezes as it touches the ground). As they fall again near sunset the rain will change to snow and gradually taper off.

It appears right now that all of this will be light and intermittent, but it will make for dangerous driving conditions. Because the exact location of the freezing line is very hard to predict, the timing of the different types of precipitation will vary from the north to the south of the city.