07 March 2024 , 13:06
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A freak weather event that only happens "once in every 250 years", known as a Sudden Stratospheric Warming, may potentially appear over Britain.
The SSW has the potential to send temperatures plunging far below zero. The weather front is taking place high in the earth's atmosphere for the third time since November last year. SSWs are so rare that it's the first time three have happened during a winter since records began.
The SSW phenomenon usually leads to periods of cold weather and snow on the ground. It is caused due to the increasing of temperatures in the stratosphere which funnels cold air down in a polar vortex. This causes a change in the jet stream, which can in turn create "areas of blocking pressure", in which cold conditions remain over the UK for prolonged periods. This process is what led to the infamous 'Beast from the East' in 2018.
Although snow like we saw in 2018 isn't expected in the coming days, some parts of the country (particularly in the north) could see some over hills at the start of next week. Temperatures are expected to fall at the same time. Boffins at the Met Office have calculated just how rare it is to get three SSW events like we have had in recent months.
Professor Adam Scaife, Head of Long-Range Forecasting at the Met Office, said: "Although we have not seen it before, we recently documented the chances of an unprecedented three SSW events happening in one winter. Our research work, using multiple computer simulations, showed that this could occur about once in every 250 winters. Although this is very rare, we also found that the chance of multiple SSW events is increased during El Niño and so the chance of multiple events this winter is raised."
Gales, snow and rain to batter country today with 80mph wind gusts
While temperatures are warmed in the atmosphere, they can plunge on the ground (NurPhoto via Getty Images)AN SSW event led to the ‘Beast from East’ which froze the nation in 2018. Similarly, whilst an SSW did cause the Beast from the East in 2018, a year later in 2019, it didn’t lead to any such big freeze - it all depends where the high pressure system lands. It can cause a dip in temperatures because when the high altitude, westerly winds reverse, the easterly winds that take their place progress southwards through the atmosphere.
After a week in which the country was battered by wind and rain it perhaps does not feel like meteorological spring has arrived. Weather maps have shown yet more rain moving in from southern England up until next weekend, with the heaviest downpours expected on Sunday, March 17. A 450-mile rain bomb will continue the following week, with low temperatures and fast winds likely.
However things could be worse as a forecaster showed how it is more likely to snow at Easter than people getting the white Christmas they cherish. Nick Finnis, from netweather, said: “While it turns increasingly mild or warm across SE Europe. But given it will be late March that the blocking looks more likely to develop, the chances for wintry weather will be diminishing.
“Though it can still snow in early April in southern Britain, more especially at night. It is ironically more likely to snow in Easter than Christmas if Easter falls in late March. But snow tends not to hang around as it quickly melts during the day away from higher ground in the north.”