10/27/2021, 5:51 pm EDT
-WPO/-EPO climate signals regained recognition during the 2013-14/2014-15 “polar vortex” winter seasons in North America and again on single events such as last February’s ERCOT freeze. This time around, -WPO and -EPO (-EPO climatology shown) reach moderate intensity (-1.0 to -1.5) which typically produces a chilly pattern during autumn over west-central/central North America.