From the 13Z Day 1.
...Midwest/Lower Ohio Valley/Mid-South...
A mid-level dry slot on the southern fringe of the Cristobal should
continue to develop east-northeastward over southeast Missouri and
western portions of Kentucky/Tennessee toward Illinois/Indiana
through the afternoon. With a very moist air mass (low 70s F surface
dewpoints) also developing northward, dry slot-related cloud breaks
and diurnal heating will contribute to weakening inhibition and
moderate buoyancy by afternoon, particularly across Illinois into
western/central Indiana. The north/northeastward-expanding core of
strongest low/mid-level winds will also reside within this same
corridor, including an increasing mid-level westerly component this
afternoon, which could boost the potential for somewhat longer
duration/semi-discrete updraft rotation. A few tornadoes may occur
across the region, along with isolated thunderstorm-related wind
damage. Portions of Illinois (roughly the eastern half) into Indiana
will be reevaluated in subsequent outlooks for a possible
tornado-related risk upgrade (10% Enhanced).