I don't like Scenic snow (or any other man made snow) as I have no idea what the fine particles are actually made out of.
So, I made my own.
Firstly I mixed together some water, PVA and some Selley's Spakfilla (an Australian product and I don't know the equivalent) which is a white, fluffy filler. I mixed that into a nice paste and blob it on to the areas I want snow. The last step is to dust the area with bi-carb soda several times as it dries to get nice fluffy snow.
If you want crunchy snow, get some white scenery rocks to mix into your original gloop. Then, as it dries, sprinkle more to get the crunchy effect, with some bi carb to make sure it goes white (the original gloop mixture may go off-white).
Hope this helps. If you would like some pictures let me know!