EEE 2014: How Unusual was the Cold Winter of 2013/14 in the Upper Midwest?

Main finding:

The frigid 2013/14 Midwestern winter was 20–100 times less likely than in the 1880s due to long-term warming, while winter temperature variability has shown little long-term change.

Longer report:

EEE 2014 = Explaining Extreme Events of 2014 from a Climate Perspective