Long Range Weather Forecast For Ireland (11 February 2021)


 TRENDS for the week of 11 to 17 Feb 2021

-- Temperatures will average near to 1.5 deg above normal values, with the milder readings in the south and west. Considering that today will average about 4 below normal, that indicates a fairly steady rise to above normal values.

-- Rainfall including melted equivalent of any snow or sleet (which may be considerable in some places) will range from twice normal in the south (possibly nearing three times normal over higher terrain) to closer to average in central and northeast counties, and perhaps 50% above normal in parts of Connacht.

-- Sunshine is going to be fairly limited with a lot of low overcast expected.


... Rain is moving into west Munster and will begin to turn over to sleet and snow inland and could become heavy at times over higher terrain in particular. The progress of the snow or sleet will slow down over the rest of the morning and while there may be sporadic outbreaks ahead of the main band from streamers, the onset of the wintry mix or snow will be around mid-day for central to eastern Munster and south Connacht, and afternoon for the rest of Connacht, the east midlands, and most of Leinster. This round of sleet and snow is likely to grind to a halt somewhere just north of Dublin so that some parts of north Leinster and Ulster may be waiting until the overnight hours to see the snowfall arrive, again with the exception of some streamer activity out ahead of that band. Even at this hour, snowfall amounts are rather difficult to estimate, and are likely to be quite variable from place to place. Some potential amounts could be lost to mixing with drizzle or freezing drizzle mixed with the snow in lower elevations near the south coast and perhaps further inland at times. The ballpark estimate where it does snow would be in the range of 3 to 8 cms, but some places could get just traces to 3 cms. Higher terrain may see 10-20 cm falls, in particular the eastern slopes of the Wicklow mountains look to be primed, as there could be sea-effect snow falling on higher slopes there. Coastal areas all around the south and east are going to be subject to some melting or just a change to cold rain at times. There is also fairly wide model support for a dry "shadow" effect to the northwest of the high ground in the inland southeast, but that would fade out if this snowfall overperforms. Winds today will be from the southeast at 40 to 70 km/hr, sometimes increasing to gusts near 80 km/hr, adding quite a raw feel to the temperatures which will be around 2-4 C before wintry mixtures or snow begins, falling back to 0-2 C in that sleet or snow. Parts of west Munster, especially coastal Kerry and southwest Cork, could see readings of 7 to 9 C and a wind shift to south-southeast.

TONIGHT the sleet and snow will continue to push slowly north and will begin to overspread parts of Ulster and north Leinster, while gradually ending further west. Snow may continue intermittently in south Leinster. Further accumulations of 5 to 15 cms are possible in a few places, 2 to 5 cms more widely. Some central counties will see a brief transition to light rain then foggy conditions as slightly milder air moves in over the slowly melting snow. Outbreaks of heavier rain may develop across west Munster and south Connacht at times, with 10-20 mm potential. Rather than specifying "lows" in this rising temperature regime, values will be around 7-10 C in the southwest, around 3-5 C over central counties, and 1-3 C in the east and north.

On FRIDAY the colder air will be confined to east coast counties and most of Ulster, but there will not be much further encroachment of the milder air with some continued outbreaks of snow and sleet in the northeast, drizzle or light rain in central counties, and occasional rain near the south and west coasts. Winds will remain southeast at about 30-50 km/hr in the east, and will turn more southerly elsewhere, increasing again to 60-90 km/hr. Temperatures will remain steady 1 to 4 C in the east, and will slowly rise elsewhere to around 7 C, 10 C in the southwest.

By SATURDAY the final push of milder air will begin, and this may lead to one last outbreak of sleet or snow in parts of Ulster, possibly inland Connacht and north Leinster, depending on where the fronts have settled by the time a new source of precipitation arrives from the south. This will be producing heavy rainfalls further south and with 20 to 40 mm potential, some flooding from snowmelt could begin. Temperatures will be slowly rising in all regions to reach highs late in the day near 8 C. Winds southerly 70 to 100 km/hr.

SUNDAY will then continue windy and milder with rain at times, and higher risks of flooding as the snowmelt will likely be nearly completed from the higher terrain by then. Highs 10 to 12 C and winds southerly 70 to 110 km/hr.

The OUTLOOK for next week is for relatively mild and occasionally wet weather to continue although there may be a few times where temperatures fall back to the 2-5 C range between mild sectors of incoming lows. As the very cold air is only going to be pushed east about as far as Norway and Germany, it won't be that far away to provide the potential for a renewed cold spell; some guidance suggests that the high pressure area associated will in fact push back west but in such a way as to promote a mild southeast flow of drier air later next week, with that the overnight lows could fall back to frosty levels at times but daytime highs would be quite a bit milder than this current spell.

Astronomy note: new moon occurs today at 1906h (7:06 p.m.) IST. This will produce some high tidal levels along the east and south coasts with the onshore winds expected today. We can't currently see the planets Jupiter and Saturn which are now more or less behind the Sun on the opposite side of the solar system from us. Mars on the other hand is easily found in the night sky, and is approaching the constellation Taurus and the Pleiades, when I was out looking at the clear skies here recently I spotted it almost overhead and looking like a twin of the brightest star in Taurus, reddish Aldebaran (on the other side of the sky, Antares is similar in appearance and its name means "rival of Mars.") Now that we've passed Mars and it's considerably further away than last autumn, it is no longer as prominent.