A cold snap is starting to hit the UK, and people in Scotland and the north of England have woken up to snow.
Parts of northern Scotland experienced more than 10cm of snow on Monday (7 March), and another 20cm is possible later this week as a cold front brings snow, ice, wind, and rain, with Brits being warned about "polar vortex" winds that could emerge from the North Pole, according to some forecasters.
The “polar vortex” is a mass of extremely cold air that is located above the North and South Poles of the planet. It is normally restricted to the Arctic, where a huge area of low pressure governs keeps it localised over the region.
But this delicate weather system can be disrupted by a “sudden stratospheric warming” or “SSW”, sending frigid air further south. In 2018, such an event was behind the infamous “Beast from the East” cold snap.
So what can we expect from March’s temperatures, and how likely is it that the country will see another newsworthy weather event? Here is everything you need to know.
What causes polar vortex conditions over Europe?
Polar vortex winds have been visiting lower latitudes more frequently and staying longer than expected in recent years, and scientists say human-caused climate change is partially to blame for their extended southerly escapes.
The polar vortex’s strength naturally changes from year to year. When it is strong, it stays over the Arctic region. However, a phenomenon known as a "sudden stratospheric warming” or “SSW” can cause it to weaken.
When this happens, the high-altitude air over the North Pole warms up. The vortex can then split into two or more freezing vortices, which have a wider geographic range and can head southward towards Canada, the US and Europe.
It is known that the “Beast from the East” of 2018 was influenced by a substantially weaker polar vortex.
Will there be snow disruption in March 2023?
The last truly severe winter cold wave to hit the nation was the aforementioned "Beast from the East," more formally known as Anticyclone Hartmut
It was caused by a disorganised polar vortex that broke out of the Arctic and into Central Europe, and brought icy conditions, heavy snowfall and strong, freezing winds from Siberia. At least 17 people lost their lives in Britain alone as a result.
Meterologists have had their eye on a SSW event in the past few weeks, which has weakened the polar vortex once more, and could send colder temperatures our way.
Though an SSW was responsible for triggering the Beast from the East, whether this one will result in similar conditions remains to be seen. Forecasters will be watching how it all unfolds very closely, with some already saying snow could now hit the country.
According to Met Office meteorologist Aidan McGivern, air currents could "lead to some disruptive snow in places next week", with the worst affected regions likely to be in the north and east.
The forecaster predicts that snow could begin to fall in Scotland on Saturday (4 March), before moving down into some areas of England later, though he said because of "very fine margins," it was "difficult to put further details" on this.
Met Office meteorologist Tom Morgan said: “It does look like the month will begin on the cold side. There is quite a chilly week to come. The first week is likely to see temperatures below average but not exceptionally so.
“But from next weekend onwards there are some small indications we will see winds switch to a northerly direction and that will bring much colder conditions southwards. It is going to be Scotland and the north eastern parts of the UK that are likely to see any snow from that spell.”
What is the Met Office’s forecast?
Tuesday (7 March) could be the coldest night of the year so far with the mercury plunging to minus 15C in some isolated Scottish glens.
People in southern England and South Wales can expect to wake up to snow on Wednesday but it is unclear whether it will settle, the Met Office has said. Snow is more likely to settle when it moves across much of northern England, Northern Ireland and much of Scotland on Thursday.
Met Office meteorologist Alex Burkill said people should “expect to wake up to snow” on Wednesday if they live in the South. He said: “I think over higher grounds such as Exmoor, the Chilterns and the Cotswolds there will be a fair amount of snow.
“Elsewhere it is going to be quite difficult, especially after today’s wet weather, to say how much snow will settle.” He added snow which is expected to fall in the north of England, southern Scotland and Northern Ireland on Thursday and Friday is likely to be “much more impactful”.
Where are there weather warnings?
A yellow weather warning for snow and ice is in place in much of northern and eastern Scotland and north-east England until 10am on Wednesday 8 March.
London, the south of England and South Wales will be covered by a yellow warning for snow all day on Wednesday and until 9am on Thursday and a few centimetres could fall in those areas.
Northern England, North Wales, most of Scotland and Northern Ireland will be covered by a yellow warning for snow between 3am on Thursday and 6pm on Friday 10 March.
The UK Health Security Agency has issued a level-three cold weather alert for the whole of England which is likely to be reviewed in the coming days.
The agency’s head of extreme events and health protection Dr Agostinho Sousa said people should check on vulnerable relatives and told pensioners and anyone with an underlying health condition to heat their home to at least 18C.