Different predictability and surface impacts of two recent split stratospheric vortex events

Two recent occurrences of a dynamic split in the Northern Hemisphere stratospheric polar vortex in February 2018 and January 2019 are compared in terms of their predictability and surface impacts. Though the evolution of these two events in the stratosphere were somewhat similar, they occurred in different background states of the atmosphere and were likely driven by different wave forcing. Subsequently, while the 2018 split persistently coupled to surface climate weeks after the event, the 2019 split did not. Here we compare how the different states of the El Nino-Southern Oscillation, the Quasi-biennial Oscillation, and Madden-Julian Oscillation may have influenced these split events, including their predictability and their influence on surface weather.