Cold snap predicted as sudden stratospheric warming hits jet stream
Chilly winds from Eastern Europe will cause the mercury to plummet by the weekend, the Met Office has said.
Britain will be gripped by a potentially lengthy cold snap as sudden stratospheric warming looks poised to cause temperatures to tumble.
Forecasters have warned that the meteorological event has disturbed the jet stream – allowing chilly winds from Eastern Europe to blast the UK – and could last well into March.
Met Office spokesman Oli Claydon said that the highs of 14C expected on Monday will be short lived and that temperatures will “slowly ramp down through the week”.
As the jet stream moves to the north, largely dry and settled conditions will develop, but colder air will also come in from the east pic.twitter.com/Yjlj7UmaPB— Met Office (@metoffice) February 19, 2018
Describing sudden stratospheric warming, he said it was caused by a huge rise in air temperature in an area around 18 miles (30 km) above the North Pole.
“There is a very big, very cold pool of air that circulates around the North Pole – sudden stratospheric warming, as it says on the tin, is when the stratosphere suddenly warms,” he said.
“Last week we saw that take place – a sudden jump of around 50C – so that can disturb the way that cold pool of air moves around the North Pole very high up.
“That can lead in around 70% of instances to it impacting the drivers that affect our weather in northern Europe as well.
“So what we are seeing in this case is it disturbing the jet stream and weakening the jet stream.”
This, he said, will see the usual wet and windy conditions ushered out, and will allow high pressure to “build and dominate” over northern Europe.
From the middle of the week Mr Claydon said this shift will allow an easterly breeze to establish and bring cold air towards Britain, with it feeling close to freezing in some parts.
“As that high pressure builds an easterly flow will start to develop and we will start getting an easterly wind and cold air moving in from Eastern Europe by the time we get to the weekend,” he said.
Mr Claydon said sudden stratospheric warming and its impact on British weather is “not a yearly occurrence but is not unheard of”, and last impacted the UK in 2013 and 2009.
“These colder conditions are expected to last into next week and could be fairly prolonged, and could still be with us into the beginning of March,” he said.
The Met Office also said there could be some frosty nights, and warned that into next week even colder air from Russia could move across the country.
But the forecasters said that although the risk of snow is very low this week, due to the dry nature of the air, this could change after the weekend.
Dr Thomas Waite, of Public Health England’s extreme events team, urged people to check on friends, family and neighbours during the cold snap, and to make sure their homes are heated to at least 18C.
He said: “With the days feeling a little longer and lighter it can be easy to forget that cold weather can still kill.
“Over 65s, those with conditions like heart and lung diseases and young children, are all at particular risk in cold weather as their bodies struggle to cope when temperatures fall.”