So here's a little Chicago snowstorm climo.
 
	Officially, there have been 49 storms of 10"+ since records began. 
 
	If you narrow it down to 12"+ storms, there have been 26 of those.
 
	If you narrow it down to 14"+ storms, there have been 12 of those.
 
	So historically... when Chicago has had a 10" storm, a little over 50% of those have actually reached 12" (26 out of 49).