Ireland could see heavy snow and cold in coming weeks due to ‘sudden stratospheric warming’

SSW, which brought on the Beast from the East in 2018, does not guarantee freezing cold conditions

Ireland could see heavy snow and extremely cold temperatures later this month or in early March, as a weather pattern that brought on the Beast from the East storm in 2018 “is highly likely” to develop over the next week.

Forecasters have said there is a major Sudden Stratospheric Warming (SSW) event forecast to occur over the next week.

An SSW is a weather phenomenon where the temperatures in the stratosphere over polar regions rise significantly in just a few days.

This rapid warming in the stratosphere is so high it is not felt on the ground. Major SSW events increase the likelihood for colder than average weather over northern and north-western Europe for several weeks to a few months after the event, but do not guarantee it.

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Paul Moore, a climatologist at Met Éireann, said it usually takes between two and three weeks for a major SSW event to have an effect on the tropospheric circulation, meaning the atmosphere closest to Earth.

“Every SSW event is different and not all of them disrupt the tropospheric patterns below. For example, the SSW event in January 2019 did not significantly disrupt the tropospheric patterns below and had no effect on the weather patterns over north-western Europe,” he said.

“The SSW event in February 2018 caused major disruption to the tropospheric patterns below and led directly to the colder than average temperatures in Ireland during February and March 2018, including the very cold outbreak from the east culminating with storm Emma at the end of February and beginning of March 2018.”

Mr Moore said global weather models can usually accurately forecast what is going to happen in the polar stratosphere one or two weeks in advance, making the upcoming SSW event “highly likely”.

“Forecasting how a SSW event imprints on the tropospheric weather patterns below is much more difficult to resolve, especially prior to the SSW event itself,” he said.

“Therefore, for now, it is unresolved how the upcoming SSW event will affect the weather patterns over north-western Europe. The timing for any impacts, if they do occur, will likely be towards the end of February or the beginning of March.”

Shauna Bowers

Shauna Bowers

Shauna Bowers is Health Correspondent of The Irish Times