Are we expecting a Sudden Stratospheric Warming?

Following a minor Sudden Stratospheric Warming (SSW) event in January, the Stratospheric Polar Vortex (SPV) has now recovered. Our forecasts for the coming week also suggest that conditions will become milder. So why does there continue to be speculation that cold weather is on the way for the UK with snow and ice for many?

The latest forecasts are showing that a major SSW is now likely to take place. The recent minor SSW weakened the SPV and it’s now likely to collapse and reverse in the middle of February.

A major SSW often makes the jet stream meander more, which can lead to a large area of blocking high pressure over northern Europe, including the UK. This blocking high pressure can lead to cold, dry weather in the north of Europe, including the UK, with mild, wet and windy conditions more likely for southern areas of the continent. However, this is not always the case and impacts on UK weather can also be benign when an SSW occurs. 

SSW 2023

Prof Adam Scaife, Head of Long-Range Forecasting at the Met Office, said: “There is now over 80% chance of a major SSW occurring. Although the impact will become clearer nearer the time, any effect on UK weather is most likely to occur in late February and March.”

Other factors can also impact the UKs weather in winter such as the Madden Julian Oscillation which is now also tracking towards a state that favours a cooler spell in late February.     

In the meantime, it is important to remember that the occurrence of an SSW does not always equate to a ‘Beast from the East’ type scenario even though this happened in 2018. For example, in 2019, there was an SSW but little impact on the weather for the UK and NW Europe.    

The current extended range forecast for mid-February suggests that the most likely scenario is for broadly changeable weather with westerly conditions and influxes of wind and rain at times, particularly in the northwest. Temperatures are likely to be around average through mid-February.  We will be updating forecasts with a close view on late February and early March as the SSW unfolds.

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