SnOw

mix elmers white glue with some water to thin it as needed.......pour on some baby powder and presto!

if you want a light mist of snow just overspray paint from a distance


good luck,

Baking powder works well, also.
Gip Winecoff

You could also try a product from Woodland scenics which you just pour onto your dio etc,you can even sweep it back into the bottle and reuse it.
HTH
Peter