Beast from the East – Extreme weather in the UK
The causes, effects and responses to the Beast from the East
Under normal circumstances, winters in the UK are mild compared to some places on the same latitude. This is because of the jet stream, a warm air mass that travels across the Atlantic Ocean from Mexico to the UK. However, a meteorological event called stratospheric warming disturbed the jet stream – allowing cold winds from Russia to travel as far as Great Britain. At this time of year, there is normally a polar vortex – a large mass of cold air – in the upper atmosphere, also known as the stratosphere. This vortex is what causes air to usually move from west to east. However, there was a huge rise in air temperature of around 50C in an area around 18 miles above the Earth in the North Pole. Sudden stratospheric warming caused a weakening of the jet stream. This led to a change in direction of the winds approaching the UK from west to east to east to west, allowing a cold air mass (polar continental air mass) from Russia to cover The UK.
Air masses affecting the UK – source: Met Office
When the air left Siberia, Russia, it was around -50°C. By the time it reached the UK it was just below freezing, though this was still cold for the time of year. The air mass picked up water over the North Sea which resulted in heavy snowfall when it reached The UK.
Storm Emma was a weather system which originated from the Azores and travelled north to the UK. On 1st March 2018, the weather front brought blizzards, gales and sleet as it hit the cold air brought down by the Beast from the East. The Met Office issued a series of red warnings for southern England. Without the cold air, and if there were normal or average UK temperatures, Storm Emma would instead have caused wet and windy conditions.
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