I believe @high risk explained this type of plot the other day. As I recall, it represents the total snow depth change through the time period (in this case through 54 hours from 12Z today). It's not the same as what TT and other sites show, which gives the snow depth of the event itself. Keeping in mind that today and tomorrow there will surely be a decent amount of snow melt (being above freezing), I can see a net of zero or not very much considering that. But that's not indicative of how much falls for this particular event by itself.
Of course, we may "only" see less than an inch or 1-2", but you get the idea.