This was from a project they did years ago that used both snowfall reports and estimates using a model that factored in geography to come up with an accurate snowfall map.  I lost the key years ago but you can figure it out from what known locations get in each color code.  Love how my ridge shows up on the map.  Shame I can't find the whole project online anymore, it had really cool maps like average first and last day of snow, average days of snowcover, and average largest storm.