‘Sudden Stratospheric Warming Event’ forecast for Ireland early this month
A similar event caused the infamous ‘Beast from the East’ in Ireland three years ago.
A ‘Sudden Stratospheric Warming (SSW)’ event has been forecast to hit Ireland early this month, the same type of weather event that led to Storm Emma and the infamous ‘Beast from the East’ in Ireland in early 2018.
An SSW event refers to what Met Éireann describes as “the reversal of zonal winds in the Stratosphere from westerly to easterly, along with a rapid jump in temperatures in the winter polar stratosphere that leads to a complete breakdown of the stratospheric polar vortex (SPV)”.
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/EIOOteGus6
— Met Éireann (@MetEireann) January 4, 2021
While the word ‘warming’ is included in the name for such an event, following a SSW, there can be “equatorward shift of the tropospheric jetstream with associated cold conditions over northern Europe and these impacts can be long lasting,” as was the case with the Beast from the East and Storm Emma in 2018.
In a commentary on the SSW forecast, however, meteorologist Paul Moore notes that every SSW is different and that less than half of them lead to colder conditions in Ireland.
Less than a year after the Beast from the East, for example, a SSW in January 2019 had no impact in Ireland “due to the easterly winds not propagating down into the troposphere from the stratosphere”.
Moore says that it is “uncertain” how the SSW will affect the weather in Ireland in the coming weeks, speculating that it could result in “a more typical weather pattern for Ireland” or that it could also lead to “cold polar air masses flooding south into northern Europe”.
A more detailed commentary on the potential impact of the SSW in Ireland is available on the Met Éireann website here.
Should the SSW lead to more intense wintry conditions in Ireland, it will be an extension of what has been a pretty cold start to 2021 to date.
On that note, wintry showers of rain, hail, sleet and snow are expected in many parts of the country this week, with temperatures dropping to as low as -4 at times and expected to rise only slightly come this weekend.