A notable early-winter SSW was 8 Dec 1987. An "absorbing"-type vortex split, the event was non-downward propagating. The SSW was also a PJO (polar jet oscillation) event, and was followed by a very strong vortex in Jan-Feb 1988 which also refused to couple downwards strongly! pic.twitter.com/GRKs8xSQTM

— Dr Simon Lee (@SimonLeeWx) November 13, 2019