Taking scale into account, I wouldn't bother with dedicated snow products myself.
Just a fine sand on the base, completely painted white, with maybe a extremely thin wash of a very light blue for some contrast. It's how I did my own winter/snow table. And I aim to keep my table surfaces as scale agnostic as possible to avoid having to make multiples of the same type.
On my table, mainly used with 28mm, I used regular sand, which I then painted over in several layers with some left over white wall paint mixed with PVA. Then the aforementioned wash and then several drybrushes of white over that.
For bases, the above should work just as well; at 6mm, sand, paint and glue will level out to about ankle height anyway, so no need to use different techniques on bases and boards...