This is my update for the Winter weather for New Years Day.
There is still some model disagreement with the winter storm tomorrow morning. Overall a good swath of ice in the mid Mississippi River valley as well as some snow as well.
First I will discuss what causes Freezing Rain/Sleet/Snow.
Here in the first weather sounding shows Freezing Rain. In all pictures, the diagonal purple line shows the freezing line, and the red circle shows temperatures above freezing and the blue circles show below freezing temperatures. With this one (compare this with the others), this shows a large warm, inversion layer above the surface with a slim area of below freezing at the surface. Here's the picture below
Next I have the sounding with Sleet. This shows a small inversion layer in the mid levels, barely above freezing, with the rest after it between that and the surface below freezing, as seen below
Here is a sounding with snow, which shows the temperatures below freezing the entire sounding!
NOW for the forecast:
This is still very tricky to do but I'll give it a shot.
Generally across central IL, totals for ice will be .1-.3 with some high totals possible/likely. There's a lot of factors that go into this so a small change can be the different between a glaze and an inch of ice. These totals are the amount of ice accumulated before rain changes and settles in. Here is the ice and snow totals below. The large snow amounts of snow is where snow is the main form of precipitation, and the lesser amounts in central IL is snow that falls Friday afternoon after the rain.
Here are the forecast start times of freezing precipitation as well
Thanks for reading and hopefully this does not become as bad as some models are showing it at the moment!