The chances of a white Christmas in Ireland are “slim” to “unlikely”, according to weather forecasters.
The current mild spell is expected to last into the weekend with highest daytime temperatures reaching about 10 to 11 degrees, in mostly dry conditions.
From Sunday, the weather is expected to be more “unsettled” with further spells of rain on Monday 22nd, according to Met Éireann meteorologist Andrew Doran-Sherlock.
But Mr Doran-Sherlock said from late Monday onwards, conditions would “turn cooler, drier and more settled through Christmas week”.
Pressed on the chances of a white Christmas, Mr Doran-Sherlock said he considered it “unlikely.”
The science behind the forecast involves an area of high pressure to the north of the island. High-pressure areas give rise to a clockwise airflow, and as such Ireland’s winds will be coming from the east and northeast, Mr Doran-Sherlock said.
While the north and northeast winds could feasibly bring snow, he said the fact of the high pressure would likely ensure that any “precipitation would melt before hitting the ground”.
For snow, water vapour must freeze on to tiny dust or pollen particles at about 3,000 metres above ground, in freezing temperatures of zero degrees, creating ice crystals that grow as more vapour freezes on them, eventually becoming heavy enough to fall as snowflakes.
When snowflakes get heavy enough, gravity pulls them down. They fall as snow if the air below stays cold enough. If it gets too warm, they melt into sleet or rain.
“It would need to be freezing all the way down for snow to form”, said Mr Doran-Sherlock.
“At the moment that is not indicated and the signals have been fairly consistent.”
But he said with a forecast of seven to ten days “there is always some uncertainty.”
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Alan O’Reilly from Carlow Weather said the chance of snow on Christmas Day was “slim”. He said the possibility of snow “depends on where the [area of] high pressure sits, but the chances would be higher after Christmas.”
