UKs belated snow blast mapped as sudden weather event triggers freeze

UK Weather: Temperatures to drop ‘below freezing’

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New maps show how Britain could be caked in snow in March, thanks to sudden stratospheric warming which increases the risk of an Arctic blast moving eastwards. February has so far been mild for many, with temperatures often creeping above freezing. Despite luring people to think spring could well be on the way, March is said to dash those hopes entirely with a sudden snowy plume heading across the UK on the first day of the new month. 

WXCHARTS, an interactive weather model, shows how the action will begin on February 28 – the last day of this month – with snow hitting northern England and Scotland, but falling as rain across Northern Ireland and most of Wales.

Then, overnight the rain will continue to hit southern and central parts of England, but will blanket large swathes of Wales, Scotland and Northern Ireland in snow. Maps currently only go upto March 1 – but they show what appears to be a sudden freeze hitting the country. 

Jim Dale, a senior meteorologist at British Weather Services, told “It’s on the radar as a watching brief. It is a long piece of string into March as to where any Arctic thrust will end up, but yes the sudden stratospheric warming is in motion.”

Sudden stratospheric warming (SSW) is a term used to describe warming high up in the stratosophere, leading to changes in weather at the surface. Extreme winter cold weather, dubbed the Beast from the East in 2018, was linked to surface effects from SSW. 

The Met Office’s guidance on SSW said: “The term sudden stratospheric warming refers to what is observed in the stratosphere – a rapid warming (up to about 50C in just a couple of days), between 10 km and 50 km above the earth’s surface.

“This is so high up that we don’t feel the ‘warming’ ourselves. However, usually a few weeks later, we can start to see knock-on effects on the jet stream, which in turn effects our weather lower down (in the troposphere).”

In some instances, it can cause the jet stream to snake more, blocking high pressure over the North Atlantic and Scandinavia causing the UK and parts of northern Europe to endure cold dry weather – causing cold easterly winds to develop. 

This can often lead to a drop in the mercury, a snow risk and a potential Beast from the East occurring, although it’s important to note that this weather event does not happen every year, and it doesn’t always lead to these extremes.

The after-effects of SSW are not often seen for two to three weeks after it has happened, so, with that timescale in mind, the start of March could be the period under scrutiny from forecasters at the moment. 

Mr Dale elaborated on the Arctic thrust and where it may end up, although there’s a large uncertainty over where it’ll fall at the moment. He added: “It will happen somewhere but it’s the where that’s the big hole – and it’s all down to luck.”

Meanwhile the Met Office has shed some light on what could be seen. Professor Adam Scaife, head of long-range forecasting at the Met Office, said: “There is now over 80 percent 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.”

Another factor which is contributing to a potential cold snap in March is the Madden Julian Oscillation which is “characterised by an eastward spread of large regions of enhanced and suppressed tropical rainfall, mainly observed over the Indian and Pacific Ocean”, the Met Office adds.

“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,” the Met Office said.

In a statement issued last week, it continued: “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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