Saturday, February 16, 2013

Turning Colder And More Settled Later Next Week


February has been a pretty wet and windy month so far with the jetstream positioned over the country for much of the past 16 days.  However, model consensus continues to indicate much colder weather arriving near the end of next week. There will be a good deal of dry, bright weather away from the west and southwest where Atlantic frontal systems could bring some rain or drizzle at times. 

The chances of such a scenario materialising are realistically greater than 60% but models can be wrong, even when they all show a similar outcome at 5-7 days. So we're into a watch situation rather than an alert at this distance. In the meantime, the weather will be changing very gradually as this currently mild air mass loses its upper support and this may lead to an increase in fog and mist especially over central and inland eastern, northern counties.

The below collage features output from four of the main computer models, namely the UKMO (UK), ECM (European), GFS (USA) and GEM (Canada).  The GEM (top left) and UKMO (bottom right) are both suggesting a slack east-north-east airflow over Ireland bringing largely dry conditions with some scattered wintry showers for eastern counties. The ECM (top right) and GFS (bottom left) meanwhile, indicate moderate southeasterly winds but a less cold airmass over Ireland. 
Click to enlarge. Images c/o meteociel.fr
According to TMT Senior Forecaster Peter O'Donnell: "Wednesday to Sunday of next week  is indicated to be colder than normal, in east to southeast winds. The depth of cold air (which appeared rather shallow at this time on yesterday's model runs) appears somewhat more substantial especially across Leinster and Ulster, so that temperatures may fall to 2-5 C in the west and south, but somewhat further towards 0-3 C in the east and north. This may bring a risk of mixed wintry precipitation at times in those regions."

Peter added: "Some models are still hinting at an even colder, snowy outcome during the period, but I would like to see that trend become better established before venturing to rate it as a very likely outcome. I would set the probability of some accumulating snow (away from milder west coast) at about 50-60 per cent on the current guidance (most likely to happen Friday to Sunday). I would rate the chance of a more severe outbreak with heavy snow or severe cold more like 20-30 per cent for eastern Ireland although if you read the forecasts for Britain, you'll see that it appears very likely there."

What others are saying:

WEDNESDAY: Gradually turning colder during the day, especially in the east, with strengthening southeast winds. It will stay mainly dry though with sunny spells, though some rain is still likely in the southwest. On Wednesday night, temperatures will drop close to or just below freezing in many areas. A few wintry showers are possible in eastern coastal areas.  THURSDAY: is expected to be a very cold day everywhere with afternoon temperatures in low single figures. The stiff easterly winds will make it feel extra cold, despite the sunshine. There is a small risk of wintry showers in the east, and rain will continue to threat the southwest, but most areas will continue dry.  FURTHER OUTLOOK: Current indications are that the mainly dry and very cold weather will continue for the next days.

UK Met Office (forecast for Northern Ireland):

UK Outlook for Thursday 21 Feb 2013 to Saturday 2 Mar 2013: Conditions during the second half of next week and at the weekend are expected to be cold, mostly dry but rather cloudy and breezy, with the best of any brighter weather across the west and northwest of the UK. The cloud in the east may be thick enough at times to produce some wintry showers, with some thicker cloud also spreading into the southwest at times giving some outbreaks of rain and hill snow. This may then possibly spread east to affect some other parts of the south during the weekend. Looking ahead to the last week of February, conditions likely to be largely dry but on the cold side at first but there is a low risk of some unsettled weather reaching the southwest and perhaps slowly spreading northwards.
Simon Keeling, Weather School:


The Meteo Times daily long range weather forecast contains further details in relation to the coming week’s weather in Ireland. Click here to view.

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TMT article written by Mark Dunphy