A major GFS/GEFS divergence continues for Arctic height anomalies in the medium-range: GFS shows top-down polar vortex strengthening, but GEFS shows bottom-up weakening. Recall these are fundamentally different models: GFS was upgraded to FV3 in June, GEFS not yet. pic.twitter.com/BRO76ms48i

— World Climate Service (@WorldClimateSvc) November 14, 2019