LAUSR

The warm Arctic‐cold continent pattern was of record strength in October 2016, providing the opportunity to test its proposed influence on large‐scale atmospheric circulation. We find a record weak polar stratospheric vortex and negative North Atlantic Oscillation in November–December 2016 and link them to increased planetary wave generation associated with cold Siberian anomalies followed by troposphere‐stratosphere dynamical coupling. At the same time the warm Arctic anomalies, in particular those over the Barents‐Kara Seas, do not appear to play an important role in forcing the atmospheric circulation. Long‐range forecasts initialized on 1 October 2016 reproduced both the weak polar vortex and negative North Atlantic Oscillation, as well as their link with the Siberian temperatures. Our results support the stratospheric pathway for atmospheric circulation forcing associated with Siberian surface anomalies and uncover a source of skill for subseasonal forecasts from October to December.