Creating them is do-able but involves a bit of work and of course they are then permanent.
The best temporary solution I have seen recently was a beautiful SYW game in 15mm possibly Lutzen?(not my period I'm afraid). The guys had used TSS boards and liberally sprinkled them with 'snow scatter' from Woodland Scenics(ABOUT £8 a jar - get it from D&F Models in the Trongate). It looked superb.
I bought a jar of it in the States (at Historicon last year) and used it to create a light snow effect on my
Panzer Ace demo (see pic in Gallery).
Best and cheapest solution David - low risk, quick and not messy(remember the Hoover afterwards
)