UK snow travel chaos
© Trinity Mirror
Snow chaos is predicted for Scotland after the arrival of a rare polar weather system
The UK faces a three-week freeze with temperatures plunging as cold as -15C because of a rare North Pole phenomenon that triggered the 2010 big freeze and nationwide white-out. The worst cold spell of winter, with widespread snow, ice and travel chaos, threatens from February 11.

The North Pole's high-altitude air has suddenly warmed up and is set to shunt cold low-level Arctic air south to Scotland. However, the whole of the UK is set for a bitter spell of freezing temperatures.

The event, known as a Sudden Stratospheric Warming (SSW) usually chills Scotland for two weeks or longer and sees widespread snow. It has not occurred for four years, official records show. The warning points to the Arctic phenomenon in its February to April forecast being briefed to the Cabinet Office, transport bosses, councils and emergency services.

An SSW often allows cold air to flood Britain from the east and is forecasting "colder and drier conditions" from the end of the week for up to three weeks, lasting into March. The last SSW event to hit Scotland was in early 2013, which saw the coldest March for 51 years, with snow and -12.5C lows as late as March 31 in Braemar, Aberdeenshire.

SSW events also triggered -16.1C lows in Altnaharra, Highland, in November 2010 - starting December 2010's month-long Big Freeze. Britain's record coldest ever February temperature is -27.2C, set on February 11, 1895, at Braemar, Aberdeenshire.

A Met Office forecaster said: "It is likely to become rather cold in the East, and from mid-February until the beginning of March, high pressure over the continent will gradually build. "Our weather is likely to stay on the cold side, with a lot of dry days. "Nights will bring further frost. The start of March may turn more unsettled."

The government February to April contingency forecast said: "The probability of Sudden Stratospheric Warming is higher-than-normal in February. "These events disrupt the stratospheric polar vortex and, more often than not, bring cold weather to the UK." Professor Adam Scaife added: "A Sudden Stratospheric Warming involves a complete reversal of the high altitude polar jet stream.

"This can burrow into the lower stratosphere. "The Atlantic jet stream often weakens and moves south. This allows cold air from the east into northern Europe and the UK." If easterly air reaches the UK and becomes established, temperatures could fall as low as -15C.