The current major #SSW is likely now at maximum intensity, using the 10 hPa 60°N zonal wind metric. So how did we get here? Here's an animation of GFS 00Z analyses & T+12 forecasts from Dec 18th - Jan 10th. pic.twitter.com/IgkqoXMlwM

— Dr Simon Lee (@SimonLeeWx) January 10, 2019