Met Éireann has forecast several days of scattered snow showers this week, along with a ‘Sudden Stratospheric Warming’ (SSW) for early January.
The weather event described as a SSW led to the 2018 snow storm known as the Beast from the East.
However, the forecaster has said it is currently uncertain how January's SSW will affect Ireland’s weather in the coming weeks, because it is already in a “very blocked” pressure set-up.
Each SSW is different, with less than half leading to colder conditions in Ireland, according to the forecaster.
While the weather event in February 2018 led to that winter’s infamous snow fall and Storm Emma, another SSW in January of 2019 had “no significant impact” in Ireland.
A Sudden Stratospheric Warming (SSW) is forecast for early January 2021.
It is uncertain how this will affect our weather in the coming weeks as Ireland is already in a very blocked pressure setup.
Read more on this in our New Meteorologist's Commentary https://t.co/8m3ZjBI7hk pic.twitter.com/EIOOteGus6Advertisement— Met Éireann (@MetEireann) January 4, 2021
A SSW event refers to the reversal of the zonal winds in the stratosphere from westerly to easterly, along with a rapid jump in temperatures in the winter polar stratosphere.
Following the event, an “equatorward shift of the tropospheric jetstream” can cause cold conditions over northern Europe, and these impacts can be long-lasting.
Snowfall
Ahead of the SSW weather event, Met Éireann has forecast several days of "bitterly cold" and snowy conditions across the island.
Most areas will be dry throughout Monday, though showers of rain, hail, sleet or snow will affect parts of Leinster and Munster.
Severe frost with ice will return in many areas on Monday night, as temperatures fall to between -3 and +1 degrees.
On Tuesday, frost and ice will clear very slowly and persist in some areas, while wintry showers of rain, hail, sleet and snow will continue to affect parts of Leinster and east Munster.
Bitterly cold
Tuesday night will be “bitterly cold” with widespread severe frost and ice, while scattered wintry showers of hail, sleet or snow will affect the eastern half of Leinster.
Wednesday will continue very cold. During the evening rain will develop in the northwest and will spread southeastwards throughout the night, falling as sleet or snow in some areas.
On Thursday morning, rain, sleet and snow will continue to move southwards and will clear in the afternoon, with sunny spells and some wintry showers in Ulster and Connacht. Thursday night will be cold and mainly dry, with widespread severe frost and icy patches.
Friday will be cold and mainly dry with sunny spells, with widespread and severe frost arriving again during the night.
By the weekend, daytime temperatures will rise to between three and seven degrees on Saturday and five to eight degrees on Sunday. Frost will be less widespread and less severe.
