In one of my PhD papers, we found that -- of the four North American regimes -- the Pacific Trough can most 'easily' transition into the Greenland/Arctic High regime if the lower-stratospheric vortex weakens. That seems to be what happens at the end of this GEFS run. pic.twitter.com/UA9cVFtA59

— Dr Simon Lee (@SimonLeeWx) December 8, 2023