A comparison of the evolution of the zonal-mean zonal winds at 100 hPa 60N for major SSWs in ERA5, and analysis & forecast from NASA GEOS. The 9 Feb 2010 SSW was the weakest at 10 hPa MSSW onset, but 2020-21 looks to be one of the extremes...https://t.co/qIDJD9Abki pic.twitter.com/r4d4wM8NvR

— Dr Simon Lee (@SimonLeeWx) December 30, 2020