Pace is convinced snow does not stick to airframes. Well it might, but by then it has subtly changed to ice.
I and most other pilots have no idea at what that point is.
It is however interesting that many helicopters have limitations on flying in snow. (there is a bunch of stuff about the engines as you might expect) but the rotor systems have exposure limits to snow. So presumably the manufacturers are worried about the effect on the aerofoils. Of course I'm sure that is probably ice - but if it looks white and flurry and there is an exposure limit - it can stick.