I think the seasonality of the polar environment is a critical factor - while warming is expect to decrease the average equator-to-pole temperature gradient (as

I think the seasonality of the polar environment is a critical factor - while warming is expect to decrease the average equator-to-pole temperature gradient (as all models predict faster polar warming than equatorial warming by a large margin), winter is still winter as the polar axis is tilted, so steep atmospheric gradients are expected over that seasonal period.