Hey,
I have done some snow bases. I use the snow flock and add white glue (PVA) to it to make a paste. I them put white glue down onto the area I want to cover with snow and then I stick the snow paste down on the white glues.
Making a paste makes the snow look a bit more natural, as it sorta looks like a snow bank as opposed to simply flakes of snow (which doesn't look all that good imho). Once it hardens it stays very hard as well, so it is quite sturdy.
Hope that helps.
n.