A traditional approach to making snow onstage is with the use of theatrical "snow" dropped from a snow cradle (also known as a snow bag). You can purchase snow cradles ready-made that will last you for years, or you can quickly and inexpensively make your own.
Typically a snow cradle is made out of a piece of muslin with small holes covering about 1/3 of an end. Hung from two adjacent battens and filled, snow is released by moving one end of the cradle up and down slightly to allow snow to filter through the holes.
Make a Snow Cradle
If you plan to sweep up and reuse the snow after the production, please take care to sift though it before reloading it into the snow cradle. Nothing interrupts a performance like an actor unexpectedly getting hit on the head with a screw.