Deep Freeze 2? Sudden Stratospheric Warming, snow and Met Office weather forecast explained

Same weather phenomenon caused ‘Beast from the East’ in 2018 and Deep Freeze of 2010

It is the weather system that brought weeks of snow to Britain back in 2010 – and again in 2018. Now, the Met Office has confirmed that a Sudden Stratospheric Warming is likely to occur in the coming weeks.

Despite its name, it could lead to an icy blast across the UK and potentially heavy snowfall, just as thoughts are turning to spring. The SSW could arrive towards the end of February or early in March, forecasters have said.

But what is an Sudden Stratospheric Warming? We’ve put together a brief guide.

Basically speaking, an SSW sees rapid warming occur high up in the stratosphere. This then can lead to snowfall and wintry temperatures, such as when an SSW occurred in February 2018, when it became known as the “Beast from the East”.

The ‘Beast from the East’ in 2018 caused heavy snowfall of up to 22 inches in some areas, and was estimated to have caused up to £1.2bn in damage across the country. Another SSW led to the month-long “Deep Freeze” in 2010, which saw thick snow on the ground for weeks, even in low-lying areas.

However, not all SSW’s lead to severe frosty temperatures, such as in January 2019, when it caused next to no change in the UK’s weather. So although a SSW is likely to occur in the upcoming weeks, it doesn’t mean that we will necessarily have heavy snowfall.

What has the Met Office said?

An SSW is the term used for when jet streams high up in the atmosphere in both hemispheres create large waves that break the stratosphere – ultimately weakening the polar vortex. This means that winds can be reversed from westerly to easterly, allowing cold air that has been bottled up to escape.

A forecaster from the Met Office said: “A major SSW often makes the jetstream meander more, which can lead to a large area of blocking high pressure over northern Europe, including the UK.”

“This blocking high pressure can lead to cold, dry weather in the north of Europe, including the UK, with mild, wet and windy conditions more likely for southern areas of the continent. However, this is not always the case and impacts on UK weather can also be benign when an SSW occurs.”

What is the forecast?

The Met Office long-range forecast for the dates between February 22 and March 8 suggests that there will be “bands of rain and strong winds”, which will also come with a “risk of some wintry showers in the intervening colder brighter interludes between these frontal systems”.

The full statement read: “Some of these frontal systems perhaps spreading further to the south-east, although much of the south and south-east will likely be relatively drier. Confidence in the forecast around the turn of the month becomes much lower, and whilst the more likely scenario is one of a continuation of similar conditions experienced through the latter half of February, there is a low probability of some much colder weather developing.”