This is an advisory for a possible thunder-snow event in the Chicago area and areas around.
A meteogram is showing that the Chicago area may receive snow on December 7th to December 9th. Specifically, Thunder-Snow.
(See the previous Weather Explained for more info on Thundersnow.)
Accuweather is also showing that a snow event may occur in that time period.
However, the GFS model isn’t showing anything about Chicago. If anything, the thickness becomes too high to support a snow storm by what appears to be a high pressure.
I think that the probability is now 11% of occurring. But I would increase it to 20% for wiggle room.
This will be updated later today. Below you can see the snow bars and the red inside the blue, meaning thundersnow.