Email Communication: Dr. Jennifer Francis, 01/02/2018
The pattern that has prevailed across N. America the past few weeks (ridging and dry over CA and SW along with troughing and cold in the eastern 2/3) is entirely consistent with research suggesting that a warm Arctic, especially in the Pacific sector, tends to intensify this jet-stream pattern and make it more persistent. We know that when this pattern is in place, nor'easters are likely to form along the boundary between the cold air and the warm Atlantic, fueled by the dynamics in the SW flow of the jet stream along the eastern seaboard. It appears all the ingredients are in place for a whopper of a storm. We can't say this particular storm is caused by global warming, but we can say that the persistent ridge/trough pattern that is one factor in causing nor'easters is likely to occur more frequently.
While extreme cold should wane as global warming progresses, thepersistence of cold spells (and all weather patterns) should increase, which will likely have a larger impact on society than a reduction in record-breaking cold snaps.