Cold and wintry conditions on the way

As IWO reported on Monday, Ireland is on course for a period of much colder weather from Sunday through the early days of next week with potential for disruptive snowfall in the eastern half of Ireland in particular.

Cold air will be drawn in from the Eurasian landmass, bringing cold conditions across Ireland with snowfall for Leinster, east and north Ulster and east Munster in particular.  This evening's model output suggests a return to milder conditions from the Atlantic on Thursday which could be preceded by more extensive snowfall for a time before precipitation turns back to rain in all but the far northeast.

Since early January, headline writers across Ireland and the UK have made numerous mentions of the ‘Beast from the East’ and how it could be set to return to our shores for the first time since the epic snowfalls of February 2018.  These predictions came after the Sudden Stratospheric Warming (SSW) event of early January.  However, as iWeather Online indicated on 15th January, a SSW does not always mean we will be shovelling snow off our driveways two weeks later.  The swift jump in temperatures in the stratosphere over polar regions can often take many weeks to impact our weather. In fact, history tells us that less than half of all SSWs lead to an outbreak of severe cold weather here.  

So, is the 'Beast from the East' on the way?
If current computer model output for Sunday into the early days of next week verifies, then we would be looking at subzero temperatures at night and daytime temperatures struggling to get above freezing.   The finer details of this cold spell have yet to be determined but present indications that significant snowfall is possible in Leinster, east and north Ulster and east Munster.  Western counties would be drier with good sunny spells at times but extremely low overnight temperatures.  The trend is your friend in the forecasting world and right now, the output is trending towards a period of significantly cold weather from this weekend.

Will it snow in my back garden?
Forecasting snow totals at this range would be a fool’s errand but in a north-easterly to easterly setup east and north Ulster, Leinster, and east Munster would be favoured. Due to a strong easterly breeze some shower activity may result in snowfall further inland, including in eastern parts of Connacht. Snowfall down to sea level is expected from Monday with a sleety mix likely at lower levels on Sunday.  Tonight's model output would give rise to streamer activity which that brought heavy snow to the eastern half of Ireland in particular during 2010. Streamers are lines of showers that form over a body of water and align themselves with the wind-flow, bringing a constant "stream" of showers over a certain area. They are also known as Sea or Lake Effect showers, as they are a common wintertime occurrence near the Great Lakes region of the USA. In Ireland they generally  form over the Irish Sea and affect north and east-facing coastal regions of Leinster and eastern Ulster.  Snowfall totals can vary greatly from one location to another even in a relatively small geographical area, as was witnessed in 2010 and again in 2018.

How long will the cold spell last?
Current indications are that colder conditions will extend from the northwest on Thursday night into Friday.  Conditions will get progressively colder during the weekend as the coldest air reaches the east coast later on Sunday bringing heavy and frequent snow showers.  A transition to milder weather is currently earmarked for Thursday but we will keep an eye on this over the coming days.

What Met √Čireann Says

Met √Čireann's
Gerry Murphy  says, "We will have very cold weather for Sunday, Monday, Tuesday and Wednesday. The winds will feed in showers over the eastern half of the country and those showers will be of sleet and snow.  As the cold weather persists, each day and each night will be colder. The showers will become wintery. A fair few of those are likely to be of snow from Sunday into Wednesday.”

Speaking to The Irish Times, the forecaster cautioned that it was too early to “pin down a number” as to how many centimetres of snow will fall.

“That’s why we have said there will be significant accumulations, but it will be more than a few centimetres,” he stated. “I don’t want to put amounts because it is only going to frighten people at this stage. I can’t give an exact figure."

The UK Met Office says, “Although amounts of snow across England are likely to be less than seen across Scotland, the potential is there for some heavy snow across eastern England later in the weekend, and perhaps elsewhere in southern Britain as we head into next week, with very cold easterly winds.”

iWeather Online's daily long range weather forecast contains further details. Click here to view.

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