Winter waves in the polar jet stream are associated with extreme cold outbreaks and can modulate longer-term winter temperature trends in the mid-latitudes. Recent research has highlighted a positive trend in jet stream waviness from 1990 to 2010, with a hypothesized connection to Arctic amplification of anthropogenic warming. However, an increase in jet stream waviness has also been hypothesized to contribute to the winter “warming hole” (WH) in eastern North America, a cooling phenomeno...
