The KBGM Airport is the official measuring station which is on a 1630ft hill. The city is like 8 miles south and about 900ft ASL, and averages between to 65-70" I believe, which would be about 80-85% of what the airport receives.
The 730ft of extra elevation is definitely the biggest contributing factor to the disparity, but those 8 miles further north also tend to put the airport in a more favorable trajectory down wind of Cayuga Lake under NW Flow LES. Over the course of an average winter, I'd say we get about 6-10" of bonus snow from lake enhancement off Cayuga Lake that the river valley to the south largely misses out on.