m3orm5,
I am actually working on a Bulge dio too, but this product is what you want to use (IMO). It is the best choice--that I know of--for making snow. It is a little pricey as you can see from the picture, but well worth the price and will last you a long time. It is actually made up of tiny styrene bits. Don't try to take a shortcut and go cheap with anything organic like baking soda--it will rot, turn yellow, stink and attract bugs.
I've used this product a couple times now on dioramas and vignettes and have had great results! Basically, paint your base/groundwork under the snow white, then after that dries, give the area where you want the snow to be with a liberal coating of white glue (I use Elmer's school glue). I thin the glue with a little bit of water to make a slimey paste which allows the glue to spread out more, rather than glom together. Then sprinkle this Woodlands Scenics Soft Flake Snow on top of the white glue--I sometimes like to tamp the "snow" down into the glue to get a better hold. Let it dry completely, then shake off the excess that didn't get attached to the glue. Then, if you want more snow in a particular spot--to build up a little more snow thickness, add more white glue, then more snow and let dry. I've found that 2 layers of snow looks best--first layer tamped down, the second layer left naturally "fluffy."
If you want deep drifts, I build them up like I would if I was making a little hill in my groudwork. It will save you time and effort--rather than having 1/2" thick Woodland Scenics snow & glue.
If you're adding footprints, make them when the glue is still wet. I use a spare figure leg to make the tracks in the snow, then add the final figures in their desired places.
I then seal it all in with a quick spray coat of Testor's Dullcoat, just to make sure it all stays put.
Hope this helps! Would like to see some pics of the WIP and finished dio if you care to share!