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. .