Just as a side note about the cold. I saw a live news broadcast where there was steam coming off the Chicago River. The steam seems counter-intuitive to some. That is water vapor created by the sunlight. That is actual subliming of the ice to water vapor.

When in the Arctic and crossing glaciers while the sun is out, scientists can wear shorts while cross country skiing. Why? it is plenty cold, however, the reflection of the sunlight off the ice heats the air enough to be comfortable in shorts.

Polar vortex: -46C temperatures as Chicago River turns to ice (click here)

I was in northwest Michigan during the winter of 2012-2013 and the Polar Vortex displaced for the first time. A bubble of air came over Traverse City with a temperature of -60 F. I am not saying -46 F is not significant, but, it is 14 degrees warmer than 2013's winter in northwest Michigan.