If you read my 2021-22 winter forecast below, you’ll see how I explain why a sudden stratospheric warming (SSW) has a greater chance of occurring late December ’21/early January ’22 compared to others.

European Winter Forecast 2021-22

Interestingly, the models are sniffing at ‘potentially’ just that towards the end of December early January.

Initial

Wed 29th Dec

Tue 4th Jan.

This could be in response to the projected ‘strong high latitude blocking’ now developing in response to the phase 7 MJO.

GFS ensemble shows the development of a classic Greenland/high latitude block with southward displaced jet which looks to try and keep under cutting lows firing towards the UK, SW Europe which adds complication.

Regarding any possible SSW, we must throw caution to the wind, STILL A LONG WAY OFF and models are subject to backing off, so it’s only worth taking a ‘keeping an eye on’ approach at this stage…

If a split or complete collapse of the stratospheric polar vortex was to occur, think 3-4 weeks before we see any true response. So a time frame of late January/early February if indeed an SSW took place early January.

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Tags: AO, arctic oscillation, greenland blocking, high latitude blocking, nao, north atlantic oscillation, SSW, stratospheric polar vortex