I thought of two days immediately when I saw this with one being the Roanoke day that Hoosier mentioned and the other being 8/4/08 from DVN and ILX roab soundings with the 2nd one from ILX just huge....the most I've ever seen, amazing.
This needs to be a rude awakening for others, and more so people that live in big cities. This is going to happen in Chicago, ITS going to happen and people here are not ready for a violent tonado.
just some numbers right now in central/northern AL
0-6km shear of 60-80kts
0-1km SRH of 600-1000 m2/s2
SBCAPE around 3000 j/kg with dew points above 70
sup comp at 44 and sig tor at 10-11 with