Just a note too when purchasing winter specific tires:
Winter tires/snow tires come with a Q rating vs. S, H, T, V, Z (W, Y)
This Q rating means the tires stay soft at sub-freezing temps...(Notice how the high-performance tires become practically worthless at anything below 40 degrees F.) M+S rating means almost the same. The tire will stay pliable at 40 degrees.
Anything below 40 degrees and Q ratings are preferred.
But.. the Q rated tires are somewhat worthless at anything above 60 degrees. They will experience greater tire wear. They have a super soft compound. This is not to say that everyone run out and get Q rated tires for racing. They are not designed to handle super high speeds at high temps.
A dedicated snow tire will have more sipes (the little grooves in each tread block). The more sipes that better the ability to bite into the snow.
Nokian Hakkapelittas are probably the best snow tire you can find anywhere. There are also Michelin Alpins (for cold weather but not necessarily a lot of snow). Dunlop Graspics, Pirelli Scorpion Ice&Snow, etc. You can get tires that are designed specifically for your climate... whether you get a lot of snow or a little and a lot of cold weather.