What is a Beast from the East and why does it bring heavy snow? Here is Met Office explanation

Snowfall has been forecast for the weekend, with up to 15cm being predicted in the south-east.

Parts of Portsmouth, Havant and Waterlooville are covered by the yellow weather warnings – which last from noon on Saturday until 11.59pm on Sunday.

The up-coming wintry weather is said to be the result of a ‘Beast from the East’.

But what exactly does that mean?

Here is the Met Office explanation:

What is a ‘Beast from the East’

On the Met Office website, it says: ‘A phrase used to describe cold and wintry conditions in the UK as a result of easterly winds from the near continent.

‘When pressure is high over Scandinavia, the UK tends to experience a polar continental air mass.

SEE ALSO: Snow forecast for Portsmouth, Gosport, Fareham, Havant and Waterlooville next week by BBC weather

‘When this happens in winter, cold air is drawn in from the Eurasian landmass, bringing the cold and wintry conditions that give rise to the 'Beast from the East' moniker.’

Why does it cause heavy snowfall?

The Met Office explains on its website: ‘The characteristics of the air depend on the length of sea track during its passage from Europe to the British Isles. The air is inherently very cold and dry and if it reaches southern Britain, with a short sea track over the English Channel, the weather is characterised by clear skies and severe frost.

‘With a longer sea track over the North Sea, the air becomes unstable and moisture is added, giving rise to showers of rain or snow, especially near the east coast of Britain. The UK’s lowest temperatures usually occur in this air mass, lower than minus 10 °C at night, and sometimes remaining below freezing all day.’

Continuing: ‘Polar continental air only reaches Britain between November and April. At other times of the year, the source region is neither cold nor snow-covered and winds from northeastern Europe bring a form of tropical continental air.’

A message from the Editor, Mark Waldron

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