UK weather: Polar vortex threatens bleak and bitter winter as odds slashed for White Christmas across Britain

Pressure systems locking horns astride the UK will, however, put western counties under threat of heavy downpours.

But meteorologists warn to keep winter coats at the ready with high pressure to the north to blow back the cold.

The Met Office’s Annie Shuttleworth said: “After the weekend, there is a change on the way, and we start to see high pressure to the north of the UK, so we are expecting a shift to slightly more settled weather, particularly in the west.

“The general theme is for low pressure to push through the country at the weekend and then perhaps to sit to the east of the UK, with high pressure to the west with some areas seeing a settled period,

“But we are expecting more of a northerly or northeasterly wind direction, so it will probably turn a bit colder again, and there could be some snow showers across northern areas.”

Today is expected to bring the coldest start of the season so far with temperatures in parts dipping to minus 11C.

Lying snow under clear skies threatens bitterly cold nights ahead, although daytime temperatures will be higher than of late.

A shift in the jet stream will steer low-pressure cyclonic weather patterns in from the Atlantic, raising the flood risk in parts of the country already drenched.

Ms Shuttleworth said: “Friday morning is looking like the coldest start of the week so far, and that is because we have higher pressure building in, and as the winds turn lighter, that will allow more widespread frost.

“We have a meandering pattern to the jet stream, and we are on the cold side, but as the week goes on, the jet stream moves more directly across the Atlantic towards the UK.

“That will allow low pressure systems to bring some wetter and windier weather this weekend, and it will turn a little bit milder.”

The risk of flooding will remain in parts of the country, while elsewhere stays largely dry going into the weekend, she added.

She said: “There is a chance that many northern areas could see a dry day on Saturday, but we are seeing slight variations between model runs as to how a low-pressure system develops.

“We are expecting some wet and for some, some windy weather, and although the rain is not looking exceptional, we have had quite a lot of rain already this month.

“If we do see some heavy spells of rain moving across central areas, there could be some impacts from rainfall.”

The threat of further cold weather comes as long-range forecasters warn changes in the polar vortex may foretell a bleak and bitter winter.

Meteorologists warn the vortex – the spinning air circulation over the North Pole – may weaken and collapse over the northern Hemisphere.

The driver would be a warming of the air high over the Arctic, a Sudden Stratospheric Warming (SSW), similar to that behind 2018’s Beast from the East.

While the US would be first in line for the worst of the freeze, the UK often follows suit later in the season.

Weather Channel meteorologist Jonathan Erdman said: “The polar vortex is forecast to change unusually early, and that could impact the weather in December.

“The polar vortex is forecast to weaken unusually early, and that could lead to more persistent cold weather in at least parts of the US in December.”

Jim Dale, meteorologist for British Weather Services and co-author of ‘Surviving Extreme Weather’, added: “In the longer term, there is a chance that a polar vortex collapse over the winter could bring another period of proper northerly conditions.

“There is every prospect of a polar dislocation, and further very cold weather as we go into winter.”

As the mercury plummets, bookies have taken the snippers once again to the odds on Christmas snow.

Ladbrokes’ Nicola McGeady said: "White Christmas speculation has begun following this week’s snowfall and the odds suggest a winter wonderland could be on the cards for some cities.”