firstly you need cold enough air to cause snow to fall in the clouds and ground level water and moisture is needed to form clouds and precipitation. the moisture is called water vapour to make the clouds a source of water vapour is cold air blowing across large lakes or the sea but the cold air doesn't actually make too much snow, its a combination of cold and warm air that does it. the warm air normally meets the cold air if the wind is being pulled towards the equator when they are brought together a front is formed and precipitation is formed and the warm air can go up to the clouds and the blizzard forms from there.