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How can continental polar air be responsible for lake-effect snowstorms in the Great Lakes region?

This question has to do with air masses. It's for my honors earth science homework.

Public Comments

1. I'm no expert in the field, but it seems like it should have something to do with the Rossby waves coming down from the Arctic. If this is for your Honors degree, you probably know more about it than me, but just in case, Rossby waves are the borders between warm tropical air masses and cold Arctic air masses. I believe the edges of the Rossby waves often fall around the Great Lakes region in the winter, so the warm air from the south meets the cold air from the north, causing heavy updrafts and snowstorms in the winter. In summer the boundary between warm and cold moves further north so you don't have a lake-effect rainstorm.
2. It might also be due to the fact that the polar air mass is pretty dry and is thus able to pick up a lot of water vapor from the lakes. Lake effect snow involves picking up moisture over a lake and then precipitating that as snow.
3. When the polar air is dragged down because of the jet stream moving further south, it brings extremely cold air. The Great Lakes do not completely freeze over so therefore the temperatures of the lakes are above freezing and are warmer than the polar air. The cold Polar air moves across the warmer lake water, providing energy and picking up water vapor which freezes and is deposited on the shores in the form of snow.