Stratospheric control of the extratropical circulation response to surface forcing

The transient atmospheric circulation response to fall season Siberia region snow forcing in an atmospheric general circulation model is investigated. The forcing generates a stratosphere‐troposphere interaction response whose coupling to the surface on multiple week timescales depends on the state of the stratosphere prior to the initiation of the forcing. An initially weak stratospheric polar vortex increases the likelihood of a negative Northern Annular Mode response at the surface. These results may provide useful insight for seasonal prediction of circulation anomalies arising from surface forcing in the extratropics.