I had great success in capturing snow flakes falling, by locating a dark background.
With a dark(ish) background, be it foliage or buildings, the light coloured falling snow, is a breeze to capture.
Given that I live in a country where snow isn't all over the place, I thought long and hard, on how I would capture falling snow.
In Germany last Christmas, I also discovered that you can capture the essence of falling snow under street lights. The falling snow becomes dark(ish) generally, exposures with which I obtained good pictures, were around the 1/4 to 1/8 of a second. Snow falls a lot slower than rain, wet snow falling in the 0C to -5C falls quite fast, dry snow falling around -14C was a completely different kettle of fish. It fell really slowly, swirling in the slightest of breezes. Things, I never knew about.
I was using a 24mm lens wide open at 2.8 and using Fuji Neopan 400 rated at 320 ASA. for the night shot.
The daylight pictures can be quite successful when taken with a 105mm lens, whilst tracking a moving subject with a dark background.
People walking through the frame under the street light, added a terrific quality to the moodiness.
The only downside was the cold factor, I don't really have the correct clothing for the temperatures!
Mick.