The large air mass that is moving into the area is a continental polar one. As we can see on the map, the air mass is moving in from the northern part of North America toward the Central part of North America. It is an air mass that has been formed over land, thus it is a continental one, and since it has been formed on a very high latitude it is a polar one too. This type of air mass brings in very cold weather, often resulting in large amounts of snowfall as well, thus it is causing severe snow storms.
