Skip Talbot
EF5
A quick glance at the 12z NAM shows a favorable shear and instability combination over west central Illinois into Indiana. Pretty substantial 1km EHI in my backyard makes me excited for a tornado chase, but I'm not sure we've got the lift over the warm sector to initiate storms in this favorable environment. A cold front sweeping in from the northwest looks like the dominant player here shown on the surface plot. A positively tilted trough with the bulk of its energy north of the warm sector, and weaker zonal flow south of there (shown on the 500 mb chart), looks like it will confine most of the lift to north and along the cold front. Midlevel flow relatively in line with the orientation of the cold front may yield a messy training line along the cold front. Surface winds veer along this boundary, so the nice helicity we have out ahead of the front, won't be there for our cold front storms. Ongoing convection aided by that strong midlevel flow looks to limit instability on the warm front up by Michigan, and maybe into the warm sector as well as the precip plot is showing on going activity there as well. Timing looks a little off on this one too, as the best shear and instability combinations look to be in the late morning and early afternoon when cool surface temps may yield elevated storms, with surface winds veering even more by mid afternoon and evening as the cold front sweeps through. I'm not expecting too much in the way of tornadoes across Illinois tomorrow as I'm not seeing the lift needed to initiate discrete storms in the warm sector unless there is a shortwave hiding in that midlevel flow or some outflow boundaries to work with. We'll probably just be dealing with some damaging winds from a messy line as that cold front pushes through Illinois and Indiana tomorrow.
