The 2020-22 La Nina has produced wide variation in ENSO diagnostics. Multi-variate ENSO index has consistently indicated a La Nina climate while Nino34 SSTA, the conventional ENSO phase diagnostic, has been choppy and subsurface upper ocean heat has varied widely during the 3-year period.

Latest 1-2 week outlooks indicate a dry and hot pattern developing across Argentina to far Southeast Brazil. In Northeast Argentina, a large area of deep layer soil moisture deficits is present. The combination of the forecast and deep layer soil moisture condition will lead to an Argentina flash drought by the middle third of January.

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.