Surges in Arctic air caused by wobbling polar vortex, Sean Batty explains

It might feel like winter has suddenly remembered it’s winter – but what we’re seeing just now isn’t just a local story.

The cold gripping parts of Scotland is part of a much wider, and more complex, weather pattern.

We’re not alone

Yes, it’s winter. But spells of very cold and snowy weather like some parts of the country are currently experiencing are becoming increasingly rare. And it’s not just Scotland feeling the chill. Much colder-than-average conditions are affecting Alaska, Canada, Scandinavia, central Europe, Turkey – and even Iraq and Syria.

Middle East cools as Greenland warms up

Before this starts to sound like the Northern Hemisphere is sliding into a new ice age, it’s important to stress that balance – or equilibrium – is at play. While some regions are exceptionally cold, others are experiencing temperatures that are far milder than usual.

Greece, Bulgaria, Romania, central Russia, much of the US, eastern Canada and even Greenland are all warmer than average right now.

In fact, parts of Greenland and Baffin Island in Canada are an extraordinary 20 – 25C above normal. Baffin Island is seeing daytime highs of around -4C – which sounds bitterly cold to us, but should be closer to -25C at this time of year. Nuuk, the capital of Greenland, is expected to reach 4C on Tuesday – temperatures more typical of May here.

At the other extreme is Alaska, which has just recorded its snowiest December on record. Some of the coldest areas are now seeing highs of around -45C – conditions that are almost impossible for us to imagine.

The writing was on the wall weeks ago

During winter, as the Arctic falls into 24-hour darkness, extreme cold builds over the Pole. This helps to create a fast-flowing ribbon of air high above the Arctic known as the polar vortex. It acts like a ring of ice, keeping the cold air locked over the Pole.

When the winds within the polar vortex weaken, that cold air can escape southwards into parts of Europe and the US.

And this is the key point: this winter, the polar vortex has never really got going properly. Instead of being a tightly spinning system, it has been wobbling – allowing repeated surges of Arctic air to spill south in recent weeks.

While the polar vortex will attempt to strengthen again in the coming days and pull some of the cold back north, it looks set to weaken once more next week. That raises the risk of another cold outbreak later in January and into February.

What does this mean for the rest of winter?

A persistently weaker-than-average polar vortex increases the likelihood of further cold and wintry spells. Other climate drivers are harder to pin down and may become more influential as the season progresses – but for now, a sustained return to much milder weather looks unlikely.

Shorter-term risks

Tuesday will be less cold as rain and hill snow spread across the country. This should lead to a temporary thaw of lying snow at lower levels in the north, while adding further snow to the Grampians.
Shetland is likely to stay in the cold air, with a risk of heavy snow Tuesday night.
Wednesday turns colder again, with snow returning to northern areas, though this may become sleetier near coasts and islands by Thursday.

The next feature to watch closely is Thursday night into Friday morning, when a spell of wet and windy weather will move across England. How far north this system reaches will be crucial — if it pushes further north, it could bring heavy snow to southern Scotland.

Definitely one to keep a close eye on later this week.