Long Range Weather Forecast For Ireland (14 January 2021)


TRENDS for the week of 14 to 20 Jan 2021

-- Temperatures will average 1 to 2 deg below normal values.
-- Rainfall will average 50% to 75% of normal values.
-- Sunshine will average near or slightly above normal.


TODAY will be rather cloudy with some brighter intervals developing. Most if not all areas will have dry conditions or at worst, brief intervals of drizzle or light rain in parts of the southeast. Winds will gradually become northwesterly at about 40-60 km/hr. It will be cooler than yesterday but not particularly cold at 7 to 9 C.

TONIGHT will be chilly as skies clear to allow for frost and some dense fog patches, especially in the inland lowland areas of the southeast and central regions. Lows -3 to +2 C.

FRIDAY will start out with some sunshine through increasing high cloud. You may spot a solar halo around mid-day as clouds thicken, then by evening it will be raining on the west coast but remaining dry to about midnight further east. Rather cold most of the day and getting milder in the evening to midnight/0300h period, temperatures rising slowly to around 7 C in the afternoon and 10-12 C overnight. Not very windy but somewhat stronger winds developing in the evening and overnight (southwest 50-70 km/hr).

SATURDAY the cold front of this system will sweep through around 0300-0600h and partial clearing will follow as the rain ends quickly (10-15 mm expected by Saturday morning). The partly cloudy, breezy and cooler conditions will continue in the afternoon with temperatures slowly falling from morning highs of 10-12 C to afternoon readings near 7 C.

SUNDAY will be partly cloudy with some good sunny spells in places, and moderate temperatures, a slight frost to start in some inland areas, lows -2 to +3 C then afternoon highs near 7 C.

MONDAY will be overcast with rain becoming heavy at times by end of the day, strong south to southwest winds developing, lows near 4 C and highs near 10 C.

TUESDAY ... the outlook has changed somewhat as this Monday low is now moving east somewhat slower than earlier expected, and won't be past the Irish Sea until about mid-day Tuesday. Therefore Tuesday will start out still rather mild and wet, with cooler air arriving in two waves, one around mid-day dropping temperatures to about 6 C then a second cold front in the evening pushing readings down to freezing or -1 C. Showers and strong westerly winds of 70-100 km/hr will evolve into wintry showers and snow on hills with northwest winds 80-110 km/hr with strong wind chill values by Tuesday night.

The OUTLOOK remains a bit uncertain although various models seem to be converging on a shared solution -- cold air will build in for several days, it may not be quite the coldest possible air mass but it will feel very cold in brisk winds, daytime temperatures 2-4 C and overnight lows -4 to -2 C, passing wintry showers in northwest winds sometimes backing to southwest as troughs rotate around the now-stalled low (from Mon-Tues) parked near the coast of Denmark with a trough to another weaker low near the Orkneys north of Scotland. The big question is, how long will this cold air remain in place before the Atlantic, showing signs of re-energizing around Friday 22nd, pushes back with mild air and rain? Some models say the cold air will hold it back for several more days and yield around the 27th for a time, but with the cold air not pushed very far north and looking like it could make another surge to the south by early February. Other guidance suggests the milder flow will win out around the weekend of the 23rd-24th but it could come in with bands of snow, sleet and rain in succession as the cold air will be reluctant to leave such wonderful surroundings.

-- Peter O'Donnell for IWO