Long Range Weather Forecast For Ireland (16 December 2020)

TRENDS for the week of 16 to 22 Dec 2020

-- Temperatures will average 1 to 2 deg above normal but it will be turning colder at the end.
-- Rainfalls will average near normal amounts (now that we've had most of the current system's rainfall).
-- Sunshine will average near normal amounts.


TODAY will continue quite breezy and locally windy, as the storm blows itself out over west Ulster and later over the Hebrides. Winds generally southwest to west in most parts, 50 to 80 km/hr, some higher gusts currently around north Kildare and parts of Meath, Dublin should settle back into that range too. Less windy (currently) Mayo and west Galway will see a gradual increase to westerly 50 to 80 km/hr as a stronger gradient reaches those areas. Some areas of showery light rain continue, especially close to the decaying centre of the low (now near south coast of Donegal Bay), and in parts of west Munster. Later on, there will be a few brighter intervals especially near the southeast coast and into the north midlands. Highs near 11 C.

TONIGHT will be partly cloudy to overcast with a few showers, lows near 7 C.

THURSDAY will be overcast, breezy and mild with 10-20 mm rainfalls setting in after mid-day, highs near 11 C.

FRIDAY will see intervals of heavier rain in parts of the east during the first half of the day, then a general cooling trend as winds veer more southwesterly in the 50-80 km/hr range, lows near 9 C and highs 10 to 12 C.

SATURDAY will be breezy and rather cold with passing showers, winds southwest 50 to 80 km/hr, lows near 4 C and highs 7 to 9 C.

SUNDAY will be breezy and cool with fewer showers, some longer dry intervals, and bits of sunshine possibly, lows near 4 C and highs near 8 C.

MONDAY a final Atlantic storm in the series will arrive over the south with rain and moderate south to southwest winds, temperatures 8 to 10 C. Further north, an east wind will be fairly cold with a potential for sleety mixtures to develop, temperatures 3 to 7 C.

TUESDAY a secondary wave may form behind the Monday system and that one could track into the southeast pulling the colder air further south, so that many places could see a sleety mix of rain, wet snow and frozen mixed precipitation. The main question about that will be intensity, just light falls with a dusting, or more significant coatings possible? We will be keeping an eye on how this develops (for the 22nd).

WEDNESDAY colder with passing wintry showers, winds north to northwest 40 to 70 km/hr, lows near 1 C and highs near 5 C.

THURSDAY (24th) will be a cold, fairly bright day with isolated wintry showers, likely some small accumulations of snow on higher terrain, lows near -1 C and highs 4 to 6 C.

FRIDAY (Christmas Day) will also be cold and there are hints in some guidance of an interval of sleet or snow developing. One scenario is that a weak front moving in from the Atlantic could run into the embedded colder air and rain might turn to wet snow. Another scenario is that the flow turns more northeast then easterly, with snow possible.

OUTLOOK is for whatever colder air masses are then available to deepen their grip for a few days, with high pressure likely to prevail, so cold and dry is the likely outcome after Christmas. It looks about five degrees below normal rather than any brutally cold 2010-type scenario but still cold enough for snow in any east wind streamers.
- Peter O'Donnell for Irish Weather Online.