After much experimentation, I am not a fan of the Woodland Scenics stuff, or any of the micro balloon products. The particles look much too large and awkward in any scale below 120mm, in my opinion... unless you want to replicate some hail. I got loads of it, and am gonna get rid of it.
You haven't mentioned where you want to place the snow. If it's covering a vehicle, I might consider working with white pastels or pigments. Very fine power. Position it as desired, and then seal it.
if it is groundwork, I use Plaster of Paris or Hydrocal. This is not only the most realistic looking method in my opinion, plaster is the cheapest as well. Place it where you want it, and then spritz it from above with a water bottle or an airbrush. Don't need to completely soak it, it'll do it's job. You can come back later with an air can or empty airbrush and gently blow away any excess. I like the results:
HTH