Thursday, January 17, 2013

Something Wintry This Way Comes – Ireland Set To Experience Cold Weather With Some Snow


UPDATE, 4PM here


After some brief flirts with cold weather during December and again this month, interspersed by one of the mildest starts to January in recent years, Ireland now seems highly likely to experience a period of much colder weather.

While large swathes of Britain have been in the freezer since last week, the pest from the west is now set to be tamed by the beast from the east, at least for much of the week. Colder east to south-easterly winds will in stages replace a much less cold airmass emanating from the Atlantic. Rather than the Greenland Express which brought an abrupt transition to severe cold in Nov/Dec 2010, it will be more like the slow train from Scotland this time around as colder conditions seep south-westwards over Ireland.

The first signs of this will be visible in parts of northern and eastern parts of Ireland overnight tonight and during Friday as a band of rain readily turns to sleet and snow, particularly on high ground where some accumulations are likely (see below map). Given the projected rainfall totals for Thursday into Friday, some localised flooding is possible as the ground remains saturated in many places.  The UK Met Office has issued an Amber Alert for much of Ulster for Friday and Saturday. It said: "Rain will turn increasingly to sleet and then snow at all levels across Northern Ireland during the course of Friday afternoon and evening, with some placing receiving accumulations of 5-10 cm of snow overnight into Saturday and as much as 15-20 cm above 200 metres, with drifting in the strengthening east to northeasterly winds. The public should be prepared for travel disruption."

Click to enlarge.
By midday Friday the heaviest rain has cleared much of the west and south with snow turning to rain further north and east. It will push back westwards for a time on Friday evening through Saturday morning. Image Ogimet.com
Cold weather will spread across the rest of the country during the course of the weekend and by Sunday night through Monday there is potential for further snow in all but coastal parts of the south and west, which will stay somewhat milder. Tuesday to Friday of next week will see even colder weather becoming established with the threat of snow highest in eastern, eastern and southern counties.

Commenting on the weather for the coming days, The Meteo Times Senior Forecaster Peter O’Donnell said: “Tonight, a frontal system will push slowly across the country bringing rain that could begin to turn to sleet or snow in parts of Ulster on Friday, while ending elsewhere. Colder air in place over Britain will push this front slowly back as low pressure forms near Donegal. By Saturday, colder air at or slightly below freezing will have seeped into most of the counties north of a Dublin to Galway line, then we face the uncertain prospect of stronger low pressure interacting with this front from its position somewhere off to the south or southwest of Kerry. This will tend to pull the frontal boundary slowly south and change any rain to sleet then snow from north to south. Possible outcomes vary from a rather messy mix to an all-out winter storm and the models are still struggling to resolve the Monday and Tuesday outcomes for the Atlantic storm."

UKMO air pressure chart for Monday showing plenty of mixed precipitation (rain/sleet/snow) across Ireland consistent with recent output. Image Meteociel.fr

Peter continued: “Tuesday to Friday of next week now appear to be a very cold interval with a high risk of snow accumulations at times, some periods of strong E to NE winds, and some freezing fog. Roads may be very icy throughout. Temperatures could be as low as -1 C daytime and -7 C overnight next week with local modification where winds cross warmer open water. Higher elevations could see a range from -3 to -9 C. This wintry spell is about 70% likely (in my view) and there is still some chance of a milder outcome than this. There is also a slight chance of a more severe blizzard-like outcome.”

Commenting on the long range outlook, Peter said: “With much uncertainty evident in the output of the main computer weather models in relation to the longer range prospects, the only thing we can add is that some models are signalling a slightly milder turn in the last week of January but with more severe cold building up in Scandinavia getting ready possibly for a more severe assault on Britain and Ireland.”

Meanwhile, Met √Čireann - Ireland’s national meteorological agency - this morning issued a weather warning for next week. It is warning that there is a high probability of a severely cold week with maxima predicted to be in low single figures with severe air and ground frosts at night. The agency added: “Strong easterly winds up to mid-week will produce significant wind chill and make it feel bitterly cold everywhere. Some snow showers are possible especially in the east and south where there may be some accumulations but for most areas it will be mainly dry. Freezing fog may develop over the second half of the week as the winds drop and sub-zero temperatures then may persist during daytime.”


The Meteo Times daily long range weather forecast contains further details in relation to the coming week’s weather in Ireland, as well as details on the ongoing cold spell in Britain. Click here to view.

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Article written by TMT's Mark Dunphy
Graphic by TMT's Ian Carruthers