Two Cold Winters

The coldest winter months seen  in Europe over the last 150 years have been 1963 and 2010. They have remarkably similar temperature distributions due to strong negative Arctic Oscillations pulling Arctic air down over Europe and America. As a result of this flow, polar temperature anomalies appear warmer than the 30 year average. Warmer air over North Africa and Asia is also blocked from moving northwards.

Temperature anomaly distribution for January 1963

December 2010 saw a similar pattern with AO values reaching  very low values approaching  -5

Arctic Oscillation for winter 2010/11 produced by NOAA

 

In December 2010 the lowest ever temperatures were recorded at several  UK  stations. This  is how the global temperature anomaly distribution looked, not too different than 1963.

Temperature anomalies for December 2010

A negative phase of AO corresponds to high pressure at the pole.  The Jet Stream moves further south with large meanders, causing cold polar air to be dragged with it. As a result polar temperatures actually appear to be slightly warmer than normal.

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