We're currently in a stronger than average Stratospheric Polar Vortex state; but there are some indications for that to change in our medium-range models. Model guidance indicate a displacement of the Polar Vortex & associated warming about the North Pole; 50mb U to shift -1sigma pic.twitter.com/CMRZZbTEOc

— Mike Ventrice (@MJVentrice) November 20, 2017