At that temperature, it is technically "too cold" to snow as the air at that temperature is too dry to support moisture. Maybe you were referring to wind chill.
Yes, typically 40 below is too cold to support moisture, but it does happen. Most blizzards there does not have to be fresh snowfall. Snow drifts tend to pile up on the negative pressure side of buildings, fences, trees, etc. When the wind changes direction, the snow drifts become airborne again and reform elsewhere. Typically these are ground blizzards that can be only a foot off the ground, or 2 or 3 feet high. With the Alberta Clippers that go on for days, it all gets worked up into a very fine powder creating the zero visibility.