LOT mentions the below caveats In their discussion
1). The leading and secondary troughs phase more than currently
anticipated, leading to the surface low path much further northwest
than advertised. In this scenario, a much larger portion of area
would end up with a cold, wet rain with the southern edge of the
snow roughly along a line from Dixon to Waukegan. While displayed by
NAM/SREF guidance, we (as well as WPC) believe this outcome is
unlikely.
2). Convective episodes across the Lower Mississippi River Valley
muddy the surface low pressure pattern leading to a more "sheared"
out wave and less forcing overall. While this would not necessarily
shift the zone of anticipated accumulating snow, eventual amounts
would end up lower than in our forecast (more in the range of 3-5"
instead of 6"+). We saw this occur with a similar-looking storm
system in February 2020. Of the two possible failure modes, this
appears more realistic.