How likely is it, given the forecast La Niña AND a westerly Quasi-biennial Oscillation (QBO), that a sudden stratospheric warming (SSW) event will occur this winter? Our experts break down these odds in the Polar Vortex Blog: https://t.co/cnyPRUZVYz https://t.co/Ya9osMQ6nZ NOAA Climate.gov Climate Change Science on Telegram by @ClimateChangeScience A @grttme project - Other backups: @Hallotme