Candidate for main point of paper: El Nino blocking the formation of SSW? Large ENSO (El Nino) event duringg DNJ. Most significant since 1997/1998. When el nino: SSWs are more likely to come in late winter. (From Bell et al. 2008). Onset March 2nd 2016. Preceded by intense vortex. Consult G Harrison on this!