Anyone who has been following the page over the last week will see I have been closely watching the new year period especially across new years eve into new years day where forecasting models are showing strong signals of disruptive weather conditions. There is a number of different factors that need to be factored in with the fast moving jet stream which is set to form deep low pressure systems around the period.

One thing we do know now that there will be some sort of colder spell in the first days of January something I mentioned 5 days ago with models over the last day or 2 verifying this. Some of the main forecasting models prolong this colder spell into the 2nd week of January but again big uncertainty how long at this range so for now we will focus around the new year period as it's much clearer.

The above animation shows a few areas of low pressure between the 30th December to the 2nd of January passing close to Ireland bringing spells of wet and windy weather. One thing to watch out for across the west and northwest between the 30th December to 1st of January is the rainfall amounts expected across western and northwestern counties especially Mayo, Galway, Donegal, Sligo & Leitrim which could see between 40mm to 90mm which could trigger a orange rainfall warning especially for Donegal based on the below ARPEGE model run. Most of that heavy rainfall is forecast to fall between the 30th into the 31st new years eve.

New years day in particular is day of interest as forecasting models have a potential disruptive low pressure system moving across Ireland bringing with it the risk of stormy conditions and potentially heavy snowfall for places also. Some will remember in last week's update I mentioned the risk of low pressure systems running into colder air over the new year period which could bring the chance of heavy snowfall. Weather forecasting models are also now playing with this idea but this will all depend on the track of the low pressure system on new years days.

Below I have attached 3 different weather model runs.

Above is the ECMWF weather model which has the low pressure further north with the main risk of snow across the northern half of Ireland. Snowfall highlighted in purple / pink.

Above is the ICON weather model which has the low pressure further south over the central half of Ireland with the main risk of snow across the west, midlands & East of Ireland. Snowfall highlighted in purple / pink.

Above is the ARPEGE weather model which has the low pressure further south again of the south coast of Ireland with the main risk of snow across the south of Ireland. Snowfall highlighted in purple / pink.

I do think at this stage the ICON model run would be more likely outcome with much of the west, midlands, east and some northern counties most at risk. If this does happen then we would be looking at disruptive snowfall for new years day starting in the morning and falling much of the day. Temperatures from new years day are set to fall to freezing as very cold air is then pulled in behind as the low pressure system clears to the east later new years day into the 2nd which would result in snow sticking around on the ground for a few days. This could also result in very cold night time temperatures over the first few days of 2025.

There will also be a risk of very strong winds on new years day which could result in further disruption and if that heavy snowfall does manage to develop during the day then some places will see blizzard type conditions. On top of this, the risk of power outages would also be high.

As mentioned above very cold temperatures are forecast to stay with us into the second week of January with the main weather models the Ecmwf, Gfs and GEM weather models showing this.

I will have further updates over this weekend as we get closer to the period. We may see Met Eireann issue a weather advisory and some warnings as early as Sunday especially with the risk of rain and flooding in the northwest ahead of the new years day storm .

Kenneth from the Donegal Weather Channel

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