With a lot of talk about the upcoming Polar Vortex disruption and a potentially official SSW (Stratospheric Warming) event, most people cant see what makes this event "unprecedented" as its often called. And for a good reason, as a single map of the #polarvortex can be vague in context. I decided to visualize that context. The official criteria for an SSW event is the reversal (0 or negative value) of the stratospheric winds at the 10mb level along the 60N polar circle line. We are still on the edge if we will reach a reversal with this event, but there are forecast runs that suggest its likely. Link to those live forecasts is in the comments 👇 Most of the SSW events occur in January and February. I decided to look at every first SSW of each season (some seasons had two) and when it occurred. As you can see, a reversal in the current event would break the record for the earliest SSW on date by at least 3 weeks! This is really a strong outlier, and having an SSW this early in the season is what makes this event unprecedented in itself, perhaps more so than any temperature or pressure anomaly in the stratosphere. Its likely not a coincidence we get this with a very strong Super El Niño ongoing in the Pacific. So overall, this is truly a very interesting season for anyone that is into monitoring the weather and seasonal development.

86% of runs in the latest ECMWF ensemble have a major sudden stratospheric warming event around 6th Nov, which AFAIK would be the earliest on record (WRT Nov-Mar). It appears it'll be a mainly wave-1 driven event if it occurs, greatly displacing & distorting the polar vortex.

My 92 year old mum had a go at presenting the weather yesterday! The @BBCWales weather team had better watch out! 😉

Very wet Cromer Pier a little while later