Now that the 0z soundings are in... BNA was a nice sample of the pre-storm environment, and it indicated ~500 sbCAPE with ~600 0-3km SRH. Meanwhile, the ILN sounding is stable for a surface parcel, though appears to have about 500 j/kg CAPE for a parcel centered near 850mb. Oh yeah, the 0-3km SRH is 1100 m2/s2! Since the environment appears stable to a surface parcel, I don't think any storms near ILN would be surface-based (though that was at 0z, so it may destabilize a bit with time before the front moves through). Most of the SRH is in the 0-1km range, so I'm not sure elevated convection would have the advantage of high SRH that characterizes the area. It's a very good thing we didn't have steeper lapse rates today, as 2000+ CAPE in the kinematic environment (i.e. incredible shear) in this part of the US is amazing.