That RAP run has 3-5” of snow down by 12z in a corridor from C IL into Chicago metro. That’s unlikely to happen, so shave a bit off the total at the end of the run. .
Have had -SN at ORD for a little over 2 hours now, but only a T of snow thus far.
More recently better -SN has developed, with some actual accumulation now.
Has a lot to do with what is going on aloft... How far north and when exactly the wave goes negative tilt has the say in if this ends up NW or SE. in addition to the amount of ridging ahead. .
Given the NW shift, ORD is now much more in the game for significant lake effect/enhancement.
If ORD were to miss out on the LE, it means noting to the official Chicago snowfall total then.