Severe weather will begin Wednesday and continue through Thursday. Thursday will be the big day for severe weather when the system now coming into California moves into the Plains. While we will see a few storms in the Plains today that can produce hail and damaging wind gusts, storms that develop Wednesday can produce the same impacts plus may produce some tornadoes across parts of central Oklahoma into eastern Kansas.
As mentioned above, the big day for severe weather will be Thursday. I can see a dozen or more tornadoes Thursday centered around Illinois, Missouri and Arkansas.
I also add a map below showing where snow is possible Friday. The storm that develops may also produce a swath of 4-12 inches of snow from Nebraska to Wisconsin.
A blizzard will hit the West and northern Plains. After that, a shot of cold weather will bring lake snow this weekend.