Snow star crystal 1.5mm diameter grown on an electric needle: Photo Ken Libbrecht.

Llansadwrn (Anglesey) Weather:
Snowdonia Snowline Report

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn.

Snowdonia Mountains Winter 2010 - 11

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Current snowlinr histogram. Snowline histogram

Snow on summits of the Snowdon Horseshoe on 4 January 2010.



Snow fell on Cairngorm 4085 ft on the 25th.

Wet snow fell in Coucouron 3812 ft, in the Rhône-Alpes region of France, on the morning of 26th


Early snow in the Massif Central, France. Fresh snow was reported on the Alpes and in Isola, Italy, 4 to 5 cm deep on the 12th. Snow fell in Coucouron, France, on the 17th and 18th when it was lying nearby up to 10 cm deep on the morning of the 18th. There were fresh snowfalls around the summit of Cairngorm on the 20th. There were showers of ice precipitation on the Snowdonia Mountains overnight on the 19th/20th with slight sprinklings on some summits on the 20th. Ice deposits and, or frost was seen on the 24th. Ice pellets fell in rain showers on the 30th.




Light snow fell overnight 6/7th after heavy rain and was lying about 1500 ft on the north-facing slopes of the Carneddau, lower in places on the morning of the 7th. Snow on Snowdon and sprinklings also as low as 2300 ft on Elidir Fach and sides of Llanberis Pass. More snow in blizzard conditions overnight lying 1350 ft on the slopes of the Carneddau on the 8th , almost 1000 ft in places. Snow showers across the range during the day. There was a little more snow lying on the 8th and almost down to 1000 ft near Ogwen Cottage, but on the northern slopes of the Carneddau the level was about 1500 ft. Snow on Crib y Ddysgll under cumulus cloud. On the 9th snow was at 2250 ft below C Dafydd and to 1500 ft in the Nant Ffrancon Pass with broken cover on Moel Eilio and nearby hills. Snow lay at 2000 ft and in places 1500 ft on the 10th in the W while on the E Carneddau it was very broken. On the 11h snow was more patchy, but still lay >50% above 3000 ft with good cover on Crib y Ddysgyl until the 12th. On the 15th a good covering seen on the summits of Crib y Ddysgl, C Llewelyn and C Dafydd lasted until the 17th. Snow patches persisted at 2750 ft up to the 20th when further overnight snowfall left light snow lying at 2500 ft across the Carneddau with some at 1500 ft near Cwm Idwal on the 21st. Snow showers were frequent on the mountains during the afternoon with a little ice precipitation at 300 ft in SE Anglesey. Snow overnight lying unchanged at 2500 ft on the 22nd and 23rd when fresh wet snow fell. The 24th saw more light deposits as low as 2000 ft with the general snowline on the Carneddau little changed. There were slight deposits on Moel Eilio and hills to the West. Frequent showers of snow pellets and snow at low levels in coastal area of Anglesey, Conwy and Gwynedd overnight and on the 25th left light partial coverings on cold ground. The general snow level of the Carneddau was at 2250 ft, and as low as 2000 ft near the Black Ladders and 1000 ft at Ogwen. Snow and snow pellets showers during the day. Precipitation associated with an eastward moving frontal system brought moderate snowfall above 2500 ft and light snow as low as 1000 ft on the 26th. There was also snow in Llandegai, Llanberis, SE Anglesey and along the A55 at Rhuallt Hill. More showers of snow pellets and/ or snow overnight 26/27th. Snow was lying to low levels on the 27th in sub -zero temperatures. Some drifting was occurring on northern slopes in the strong NE'ly wind. On the 28th in freezing temperatures snow was lying above 750 ft generally with icy deposits remaining in places down to sea level. No further precipitation on the 29th, in hazy sunshine and freezing temperatures snow amounts and levels were little changed. The haze cleared in the afternoon giving excellent views. Snow generally just before dawn and still snowing in the morning settling below 250 ft on northern slopes. Snow showers across the summits later in the afternoon.


Light snow at sea level on the mainland, parts of Anglesey including Rhosneiger Beach and along the A55 at dawn. Snow showers continued through the morning. Frequent snow pellet and snow showers on the 2nd and 3rd with snow lying at 250 ft, or below in places including Rhosneiger beach on the 2nd, with moderate to heavy accumulations (15 - 20 cm) at levels over 1000 ft in Snowdonia. With temperatures remaining below zero through the day several of the lakes in Snowdonia including Llyn Ogwen and Llyn Teyrn were already iced over. On the 4th snow was lying as low as 750 ft and patches and/or ice down to 300 ft. More fell overnight 4/5th with large accumulations taking place over 2000 ft although the snowline had risen generally to 1500 ft on the northern slopes of the Carneddau, but remained as low as 450 ft in some places. Temperatures down to -14C on the summits overnight 5/6th with icy conditions down to low levels on the morning of the 6th. Snow persisted thinly as low as 1000 ft in places up to the 9th with patches at 350 ft. As more normal temperatures returned there was a rapid thaw overnight 9/10th leaving mostly patches, some of these still at 350 ft on the 10th. Frequent snow patches, some large remnants from drifted snow, persisted as low as 750 ft with little change up to the 16th. Larger patches in gullies from 2500 ft upwards with broken snow on some summits. Overnight 16/17th heavy snow fell on Anglesey (12 cm SE Anglesey) and on the beach at Rhosneiger being lapped by the high tide. On the mountains 17 cm fresh snow was reported. Showers of snow grains, snow pellets and snow continuing. By the end of the day the snow depth in Llansadwrn had risen to 19 cm. More snow fell overnight from 03 GMT settling at sea level including Rhosneiger beach, it was lying 21 cm in Llansadwrn and 15 cm in Llanfairfechan. Powdery snow compacting, continuing sub zero temperatures and icy conditions to sea level on the 20th. On the 21st cloud circulating around a slow-moving low tracking across North Wales led to moderate to heavy snowfall on the mountains, and Anglesey and Lleyn from noon until the small hours of the 22nd with 15 cm of fresh dry powder snow on Anglesey and accumulations of 30 cm. Substantially greater amounts were experienced at higher levels in Snowdonia. In a remarkable spell of cold weather lying snow remained at sea level, including Rhosneiger Beach, until Boxing Day the 26th. Later in the day warmer air encroached with precipitation, snow at higher levels at first, turning to rain overnight 26/27th with consequent slow thawing beginning at low levels. Overnight 27/28th the rise in temperatures resulted in thinner areas of snow melting so that on the 29th broken snow, large linear drifts and gully patches remained; some smaller patches as low as 150 ft persisted until the end of the month.


A large amount of broken snow, and patches on the 1st with a few small patches as low as 150 ft. Light precipitation during the evening left a sprinkling of fresh snow as low as 600 ft on the eastern Carneddau and generally above 2000 ft centrally. There was fresh snow at 1250 ft on Y Garn and NE-facing slopes of Crib y Ddysgyl. Little changed on the 3rd, but on early the 4th slight snow fell above 2500 ft and in temperatures below zero settled around the highest summits. There was light fresh snow on the 5th at 2000 ft, as low as 1800 ft in Cwm Idwal and on Y Garn while the lowest large patches were at 1000 ft on the Carneddau and Moel Eilio. Further light snow fell on the 7th lying at Ogwen and along the A5 at 1000 ft. Heavy overnight rain, with temperatures on the summits temporarily above zero at midnight, produced a rapid thaw of any fresh snow leaving old packed snow, large patches and refrozen snow and ice on the 8th. On the 9th there were reports of icy conditions and a little fresh snow on the summits. There was heavy rain on the 10th and overnight 10//11th, but large snow and ice patches remained above 1000 ft. More heavy rain on 15/16th and by the 17th the lowest snow patches were at 2250 ft on the Carneddau and Snowdon these persisting little changed to the 25th. As cold air encroached from the N, behind a rain-bearing front, a little snow fell on the summits (-4C) on the morning of the 26th and this thin cover persisted mainly between Foel-grach and Carnedd Llewelyn until the 30th.


Several snow patches were present on the 1st and several paths at higher levels were covered with ice. Larger patches remained up to the 7th when slight snow fell during the evening and this fresh snow was lying generally about 2500 ft on the morning of the 8th. Snow fell on the summits on the 13th (2 cm fresh) and more overnight 13/14th left light snow above 2000 ft of the northern slopes of C. Llewelyn and as low as 1000 ft near Cwm Idwal. Mostly broken snow persisted above 2750 ft , there was a little fresh snow seen on the 16th and 17th and most snow on the 19th was between Garnedd Uchaf (C. Gwenllian 3038 ft) and C. Llewelyn. Light fresh snow was seen on around the summits on the 23rd, 27th and 28th.


Little snow remained on the summits on the 1st, mostly broken patches with a persistent sprinkling seen on the 3rd and 4th on NE-facing slopes on Carnedd Llewelyn, C. Dafydd and Yr Wyddfa. Snow patches remained around the summits, but no deep gully patches remained. There was ice precipitation (snow pellets- graupel) on the 9th with more precipitation on the 10th. Overnight 12/13th there was light snow (forecast for Scotland (heavy) and Cumbria, but again not forecast for Snowdonia) and this was lying at 1800 ft centrally on the Carneddau Mountains, Mynydd Perfedd, Crib-y-ddysgyl and Moel Eilio at a similar altitude. A sprinkling on SE aspect of Tryfan early in the morning had disappeared by 1000 GMT, but on the NW side and in Cwm Idwal snow persisted above 1200 ft into the afternoon. Further showery precipitation overnight in places with persistent light snow on the very cold summits and as low as 2000 ft in the shaded area below Ysgolion Duon. Eastern Carneddau were more patchy while there was a little more on the Glyders and NE-facing slopes around Snowdon. Snow patches were seen just below the summit of C. Llewelyn at 3050 ft up to late on the 22nd, together with some alongside the Snowdon Railway line and a small patch above on Crib y Ddysgyl about the same altitude. A patch was spotted by Jell Ellis on the 26th 50 m W of the rocky summit of Glyder Fawr (3283 ft re-surveyed in 2010). The patch c. 5m x 3 m was within rocks shaded from the sun. Despite higher temperatures 3 patches, mostly shaded, on C. Llewelyn at about 3150 ft were still surviving at the end of the month, though 1 was very small.


The 3 small patches on Carnedd Llewelyn were last seen on the 2nd and had disappeared by the afternoon of the 3rd. It was confirmed on the 9th that there was no late snow in the 'Deep Cut'.


On the 7th very heavy rain during a thunderstorm, and large hailstones, were reported in Anglesey villages of Llansadwrn and Pentraeth, reported descriptions varied from marble to golfball size. I have had no reports of ice precipitation on the mountains.

On the 13th heavy showers during the late afternoon fell as snow on the summits of Carnedd Llewelyn, C Dafydd and Crib-y-ddysgl on Snowdon 'white caps' being seen during the evening when cloud lifted and the sky began to clear. Last May (2010) there were late snow patches and was a sprinkling of snow on the mountains on the 12th & 13th during similar weather.


On the 10th showers of hail were reported at RAF Valley at 0850 GMT. Dark convective shower clouds crossed Anglesey and the Snowdonia range during the morning and around noon produced hail on the Carneddau Click to view image.) and hail and snow on the summit of Snowdon reported on the BBC Wales website. Brief snow was also reported by John Williams on the top of Carnedd Dafydd, Crib y Ddysgl and Snowdon and that at Llanberis, in a temperature around 9 - 10C, some heavy hail showers occurred throughout the day. Ice precipitation also occurred early on the 24th in a localized heavy shower from 0330 GMT moving eastward from SE Anglesey over Carnedd Llewelyn and left a sprinkling (of snow) on the summit.

Snowdonia snowline current histogram.