5 feet of record lake-effect snow in Pennsylvania, New York on Christmas!
Erie, Pennsylvania, racked up over 65 inches of lake-effect snow on Christmas Day and the day after.

(Photo:Twitter/jerksa41)
We have photos from the event, and the NWS in Cleveland has posted this list of final snowfall totals and Erie records from this lake-effect event:

The state of Pennsylvania's two-day record snowfall was broken, as well as Erie's one-day snowfall, Christmas Day snowfall and December snowfall records. This is what the final map looks like:

How did this happen? Very simply, a continuous west, cold wind for over 48 hours, which drew moisture up to form clouds and snow, which kept tracking east, "training" over the same areas.
It wasn't just Pennsylvania -- the favored lake-effect area around Oswego County, New York, also got over 5 feet of snow... breaking records there too. These webcams show before-and-after pictures from New York state, courtesy NorthernChateau.com:


And finally, the Erie newspaper from Dec. 26:

