~Winter 2018-19 main atmospheric circulation main feature was driven by sea ice morphology and snow on ground or lack thereof
A common basic meteorological mis-concept is to ignore sea ice having anything to do with weather. To the contrary it has everything to do with world wide weather.
2012 sea ice extent minima was all time lowest, so the weather following mid September 2012 was marked by split Cold Temperature North Poles during winter 2013, while 2018 minima extent was characterized by a great depletion or wide open water North of Beaufort sea, 100% driven by summer time circulation, given a remainder sea ice core close to the North Pole :
2019 sea ice strong near North Pole remainder made the vortex more unified but elongated. Here at 600 mb, we see the Vortex true configuration difference, coming from the conclusion at sea ice minima. WD March 31 2019