The atmospheric forcing for a stratospheric polar vortex displacement event is no longer there. The SHAL index is now negative. We want to see the SHAL index positive (strong Siberian High and Aleutian Low, together), to get that good upward wave flux from the Pacific side. pic.twitter.com/gyYws0ddMX

— Mike Ventrice (@MJVentrice) November 13, 2021