I´m doing this for my Loss Fest entry in the moment.
I call it the "Ridley Scott Snow" as he is using this pretty often.
Get a bag of film snow made out of potato or corn starch and blow it around with a fan.
The snow consists of starch flakes that dissolve in heavy rain, meaning the snow can be left to ‘melt’ rather than having to be scooped up and disposed of like conventional artificial snow made with white polyethylene chips.
The starch flakes have other attractive properties including their stickiness, where a slight moistening makes the flakes more adhesive.
look in dj shops, they usually sell snow machines that work with a special liquid. The resulting snow dries fast and (as far as I know) doesn't leave any mark.