I was checking out the 12z GFS, and it seems to point to pretty nice system Sunday here in the Midwest/Lower Lakes. From 0z-12z Monday (Sunday evening), a 1002 mb low will move from SE IA, deepen to 997 mb, and end up in NE IN. There will be SE winds ahead of the the low pressure at the sfc, with SWly LLJ of up to 60 kts. That's nearly 90Â° of directional shear in the first 2000'! Add a 60kt 500mb jet, and I see the distinct possibilty for supercells in IL and IN. There is still a big question as to whether the instability will be there, so this isn't yet appropriate for the chase forecast thread.