Minor SSW event: Impacts of a weak polar vortex

A sudden stratospheric warming event has occurred, but what does that mean for our weather?

In recent days, a minor sudden stratospheric warming event occurred. ECMWF weather models had been predicting an SSW event around this date, though they had been angling for a major warming, rather than a minor one.

The zonal winds have weakened, rather than reversed, meaning a minor warming event. However this does mean that it can be followed still by further vortex disruption, with further cold spells possible later down the line.

Weather models are already indicating at the chance of another SSW event in mid-late January, again attempting a major warming event.

Despite this one being classed a minor warming, temperatures rose to 2°C, which is 60°C above normal! So don't be fooled by the word "minor", as it can still have dramatic impacts on our weather pattern. For now, the event increases, but still does not guarantee, the risk of cold weather.

The weak polar vortex also likely brings a welcome respite from the relentless rain. As the jet stream weakens and wobbles, atmospheric rivers are less likely, resulting in a greater chance of drier conditions.