Woodland scenics is what I've used for my snow effects. I generally make a paste with a generous helping of the snow and white glue with water, then heap it on. You can also add in a drop of white paint for that extra brilliant, freshly fallen snow look. Bicarb would be cheaper, but I've always worried about it yellowing.
That said, I think your bases look great. If anything, I'd maybe try getting the snow to have a muddier look, as if it had been trampled into the ground by hundreds of DKoK boots....
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