Broad cloud shield associated with a low in the deep south causes moisture advection over the Ohio Valley. Weak low and moisture advection causes destabilization of the atmosphere.
IHL plots show a good match in time and height with the MOG PIREP as a broad patch of IHL=SLW='yes icing'. The modified single-pol SLW algo does a decent job identifing IFI in this case. NIRSS also identifies MOG severity icing around the time and height of the PIREP.