A sagging cold front will nearly stall out across these regions today, prompting the potential for storms at any given time of the day. 12z soundings from across the severe weather potential area show vast areas of instability, with over 7000 j/kg of CAPE located in the most unstable part of the lowest 700mb of the atmosphere. Today, the most unstable part of the lower 700mb is roughly in the 900mb level, which is very close to the surface, indicating that storms that fire could have a lot of energy right off the bat.
I am not going to use the RAP for today's forecast because it has severely underestimated CAPE values for 12z in its soundings forecasts. However, the HRRR model does fire a mesoscale convective system (MCS) around 1:00 PM CDT and shifts it south and east into the night as it works across the severe weather potential area delineated above by the SPC.
As for what the SPC put out, it appears the main threats are damaging wind and hail, and the center of those threats should be in northern Indiana and Ohio.