Causal of the recent polar vortex event into the U.S. was the combination of persistent high latitude blocking high pressure related to the warming influence of the upper atmospher caused by farther north open water during winter, warm water zones of the Northeast Pacific and western North Atlantic basins whose attendant upper air patterns force susceptibility of polar vortex events in North America and cross-polar flow of frigid Siberian arctic air making this polar vortex event even stronger.

An MJO-inspired pulse of wet monsoon weather shifts into Northern Australia to start the New Year. However, the MJO may shift eastward later in January with a goal of eroding La Nina and shifting the Australia climate drier as indicated by ECMWF in 3-4 weeks.

Stratospheric cooling over Alaska motivated a tropospheric "ridge bridge" across Alaska to the polar region motivating cross-polar flow of arctic air into an emerging polar vortex over the Midwest U.S. resulting in a frigid arctic outbreak for the U.S.

In one of today's Climate Impact Company market reports, noted was the vast sharp warming of the ocean water off the West Coast of South America. Indicated is a potential weakening of the Humboldt Current. If so, this is one diagnostic suggesting La Nina's demise is ahead.