Central and Northeast U.S. Deep Freeze

Donald Trump is taking the opportunity of the extreme cold weather in the Northeast and Central U.S. to claim it is proof against global warming.  Such a claim is disingenuous.  Due to vagaries in the jet stream, the extreme Arctic weather has moved to Canada and the U.S.  The result is that the Arctic is far warmer than usual. 

Near surface temperatures on December 28th as generated by the Climate Reanalyzer online software tool


 WMAZ-Macon Meteorologist Matt Daniel summed it up this way,

The comment I dislike the most is when people talk about cold weather and people type "So much for global warming..." Not really a joke to me. Also, it proves someone doesn't have the understanding of the definition of weather vs climate. You'll see people type that a lot in the next week or two on professional meteorologists' social media pages.
Now having said that, our weather is governed by a series of undulations or wave patterns. The "valleys" (troughs) in those waves allow cold, dense air to ooze into the U.S. The "hills" (ridges) in the waves are typically associated with warm conditions. If you search Arctic Amplification on the Internet, there is some evidence that climate change is causing more wavy, high amplitude "valleys" and "hills" in the jet stream pattern. This could be associated with more extreme cold events and more extreme heat/drought events. The science is still emerging on this process, but it should be monitored and not dismissed.
The other thing to point out is that because one part of the world is cold (in that valley), there is likely another part of the world experiencing abnormally warm conditions (in the hill part of the wave pattern). In the temperature map tweeted by long-time weather observer Joe Stepansky, it is clear that on December 28th the United States and parts of Canada are experiencing the anomalously cold weather. If you need a visual of how our three-dimensional atmospheric wave patterns work, consider what happens when you press down on a water bed mattress (for us older folks) or an inflatable bouncy house. One part goes down, another part goes up. 
 Oh, and to throw a another counterintuitive thing out there, there are some studies that suggest that a warming climate (because more water vapor is available to a warmer atmosphere) may fuel bigger blizzards or snowstorms. That science is also emerging.
Ok, it's unusually cold in the Northeast, but it's unusually warm somewhere else as a result.  And that cold air cruising over the Great Lakes, and you have intense snowfalls in areas downwind of them.


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