A shortwave trough will translate through the upper Mississippi River Valley and Great Lakes, dragging a cold front into Missouri by afternoon.
In addition, the outflow from ongoing convection over the plains along with the front will aid in the development of scattered thunderstorms as they interact with a moist and unstable atmosphere.
Effective shear values are not all that impressive only 20 to 25 knots, but steep low-level lapse rates and within a moist environment will likely result in the potential for damaging wind gusts and possibly some hail to the size of quarters.
This convection will wane during the evening hours as the front pushes south, with some drier dew points advecting in after midnight. Lows tonight will range from around 70 along the Arkansas border to the middle 60s across central Missouri.
A couple of quiet and less humid days are expected Thursday and Friday. Temperatures will drop back a few degrees with highs in the middle and upper 80s, but dew points will drop back into the 60s, and even some upper 50s at times, so temperatures will drop off into the lower 60s for overnight lows.