Did some skimming of SSTA data tonight and I'm intrigued by that warm pool centered at ~150˚W and 30˚S to the south of the cold SSTAs with the Nina. Based on looking into some previous analogs around this time, it seems like that strong meridional dipole is not present in years such as 2006, 2009, 2012, 2017, and 2018 (generally quieter severe seasons especially late season). It is more prevalent in several big Nina springs though, including 1974, 1976, and 2011.
It's probably to some degree why this CDAS-derived SSTA analog product from Tropical Tidbits is essentially grouping a who's who of Nina springs with a lot of tornadoes/severe weather, including some with very large outbreaks.
You can see the SSTA dipole present in the Southern Hemisphere in the mean here.