As far as my understanding, the snow maps just take QPF falling as snow and then multiply it by a calculated ratio and that's it. I could be very wrong on this, but I've always assumed they don't really factor in much else. While I do think the snow maps can be very useful to aid in pinpointing where the gradient between rain/snow will be, oropgraphic influences, and what max totals may be, I don't think they provide any other value. As we know, during an event snowfall ratios are not constant and there are many factors which influence ratios; (snowgrowth, lift, moisture) and I don't believe the algorithms behind these maps incorporate these.