The climatological mean 10 hPa 60°N zonal-mean zonal wind at this time of year is ~20 m/s (though inter-annual variance is large). This year, the 20 m/s contour is all the way down beneath 150 hPa! #DeepWesterlies pic.twitter.com/UIrMRdCuN0

— Dr Simon Lee (@SimonLeeWx) February 27, 2020