Boy that's a tough question. If an increase of 1C holds 7% more water vapor and we have been increasing 0.15C-ish per decade across the CONUS (give or take here).....I don't know how you can assert that into snowfall. To me it's more at the mercy of hemispheric nuances that are dictating storm track and temps. Obviously things don't work linearly in nature. In other words, you can't just say an increase in temps by X-amount means an increase in snowfall by Y-amount. To some degree there likely is an element of AGW...but I remain in the camp that our fortunate run is a result of nuances far beyond AGW.