Diminished Polar Ice Cap Affects Sensible Weather Created By The Major Teleconnection Patterns

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The arctic oscillation was -1.7 in December and (traditionally) representative of blocking high pressure in the polar latitudes while a split in the polar vortex southward causes widespread mid-latitude chill. But! December 2020 was mild across most of North America and Europe and only Central Eurasia was (very) cold (about as far away from a maritime influence as possible). The additional open water in the northern latitudes is affecting the sensible weather normally created by the major climate teleconnection patterns. The same negative arctic oscillation produced historic cold in North America and Eurasia in December 1985. Until recently and since September the northern hemisphere sea ice extent has rivaled 2016 for lowest extent on record.