Following the occasional colder snap so far this winter, the Met Office says that there are now signs that cold winter weather resulting from a sudden stratospheric warming is on the way for the UK.
A sudden stratospheric warming has happened. The warming started around 22 December 2018 and the winds at around 30km above the North Pole reversed from westerly to easterly around New Year’s Day.
The impacts of the sudden stratospheric warming have now propagated down through the stratosphere, resulting in the main stratospheric polar vortex having split and been displaced into mid-latitudes across the Atlantic and European sector of the northern hemisphere, this is typical of the type of pattern you might expect to see in spring.
There remains uncertainty over how quickly the effects of this recent sudden stratospheric warming might propagate from the stratosphere into the troposphere and thus what the impact of this warming event will be on weather conditions over the UK. Unlike the ‘Beast from the East’ last year, this event is burrowing down through the atmosphere relatively slowly.
Deputy Chief Meteorologist, Martin Young said: “The latest forecast suggests the highest risk of any severe wintry weather is from late January and into February. Whether cold spells will be brought about by Arctic air arriving from the north or easterly flows arriving from the continent remains uncertain.
“However, before this happens we expect a rather changeable and relatively mild spell over the weekend and early next week, with some rain for most of us.
“From the middle of next week, and especially during the last week of January and into early February, there is an increased likelihood of cold weather becoming established across all of the UK. This would bring an enhanced risk of snow and widespread frost almost anywhere across the UK, but particularly across northern parts. However, the cold weather may not affect the whole of the UK and it is still possible that some milder and wetter interludes will intersperse this generally cold period, especially in the south.