I think I have seen some heavy snows before, maybe 2-3 feet in a 24-48 hour period but it is rare. Maybe once I saw that much. I think an average of snow fall for parts of the Northern USA are indeed, around 60 inches. So, they got this in two days.
It happens every so often, I posted a picture once where Indiana had some weird snow that went up all the way to the top of telephone polls. That was their 79 blizzard or something.