Llansadwrn (Anglesey) Weather: Snowdonia Snowline Report

Snowdonia Mountains Winter 2012 - 13

 Snowline histogram

October

November

Light snow was lying on Snowdon on the first as low as 2750 ft and Carnedd Dafydd and C. Llewelyn 3100 ft . Snow showers across the summits during the day. Slight snow and ice precipitation deposits also on the Carnedd Dafydd and C. Llewelyn, sprinklings on Tryfan and above Cwm Idwal as low as 2750 ft in the afternoon. A little more snow fell on the 2nd and 3rd when evident as low as 1800 ft in places when showers of ice precipitation were frequent in the afternoon. On the 4th snow was lying mainly on Carnedd Llewelyn and C Dafydd, Cwm Idwal (2000 ft) and westward, there was little or non on the range eastward of C. Llewelyn. Frequent ice precipitation showers on the 5th with snow as low as 2500 ft with snow on the summits 7/8th. Ice precipitation and slight snow fell on the 17th and was lying on the summits on the 18th with powderings as low as 2400 ft mostly on the NW-facing slopes of western mountains. On the morning of the 21st there was light snow on C. Llewelyn and a sprinkle on Yr Wyddfa at 0900 GMT. Cumulus cloud formed over the snow on Llewelyn for a while and when cleared most snow had thawed and disappeared before noon. Following ice precipitation late on the 22nd there was slight snow lying on summits over 3000 ft on the 23rd this persisting with the addition of small amounts of ice precipitation over the following days. Overnight 26/27th rain at lower levels fell as snow above 2000 ft and on the 27th there was slight snow on NW-facing Drum and light to moderate cover mainly west of Carnedd Gwenllian, including below Ysgolion Duon at 2000 ft, and Snowdon at 2500 ft and above. On the 28/29th snow was persisting on N-facing slopes and cliffs with good cover on Garnedd Ugain and Crib y Ddysgyl with slight snow/ ice on the summits of the Carneddau. Precipitation overnight 29/30th resulted in a little more snow deposited on the tops Carneddau, Y Garn and Snowdon with a sprinkling on Cadair Idris (2930 ft). Fresh snow, seen and further E than previously and around Foel-fras, as low as 2000 ft near Ysgolion Duon.

DP. Snowfall events: Snowdonia. Bulletin: Climatological Observers Link, November 2012 511, 12.

December

Snow was present on the mountains on the 1st and persisted, topped up from time to time with slight falls 1/3rd, during freeze/ thaw conditions. Fresh snow overnight 4/5th left slight snow pellets and snow as low as 1200 ft in places with light snow at 1800 ft, light to moderate in places above 2500 ft. On the 6th with snow showers sweeping across the summits at 0900 GMT in a strong SW'ly wind snow was lying light to moderate cover above 2250 ft (700 m) with sprinklings as low as 1100 ft (325 m) near Ogwen Cottage, and some also on Cadair Idris. Showers continued through the day. On the 7th it was snowing on the tops at first in the morning, light snow cover across the range above 2500 ft including Foel-fras, the Glyderau and Crib-y-ddysgyl. Less snow lying at lower levels (from 2000 ft) on the 8th, but with temperatures below zero overnight on the summits light snow cover remained above 2750 ft. On the 10th levels were little change as in sunshine freezing conditions prevailed across all summits; with frozen snow and ice. The 11th similar levels, snow a little patchier in places on sunny slopes above 2000 ft, some unbroken snow on the tops of the Carneddau, freezing conditions prevalent on the tops and in shade, frost remaining in valleys. Some wet snow fell on the summits on the 14th; broken snow persisting on the central Carneddau, Glyderau including Y Garn, and around Snowdon on the 15/16th. Some ice precipitation late on the 17th left fresh snow on the summits of the Carneddau over 3000 ft with sprinkles on north-facing cliffs and slopes on the 18th. Deep gully snow on Y Garn and Carneddau. Snow mainly broken above the railway on Crib y Ddysgl. By the 21st following rise in temperature and rain only remnant snow was left. There was a little fresh snow on some summits overnight 25/26th. A mixture of ice precipitation late on the 29th left a fresh sprinkling of snow on the summits of the Carneddau, Snowdon and Cadair Idris on the morning of the 30th

DP. Snowfall events: Snowdonia. Bulletin: Climatological Observers Link, December 2012 512, 14.

January

There was a little ice precipitation on the summits on the morning of the 11th. Ice and sprinklings of ice precipitation on summits on the 12th. Intensely cold on the summits (AWS reporting -9C at 09 GMT) with light snow on Yr Wyddfa mostly on NE aspect on the 13th. During the afternoon slight snow at low levels including SE Anglesey (not settling). on the mountains slight wet snow lying at 1000 ft, light snow above 2000 ft. Snow also on summit of Cadair Idris. On the 14th there was lying light snow on the summits and slight snow as low as 2500 ft in places. Further fresh ice precipitation and snow in the afternoon and evening. Light snow was lying generally at 1750 ft and as low as 1000 ft in places and at Ogwen on the morning of the 15th. There was a covering of snow also on Cadair Idris. Light snow remained above 1750 ft on the 16/17th with thawing and rain at 1000 ft on the 17th with snow above 2500 ft with moderate accumulations. On the 18th there was snow falling at sea level settling in Llandegai, Llanfairfechan and Llanberis. There was snow in Dolgellau and Cadair Idris. Light snow accumulations at 1000 ft increasing with light to moderate falls over 2000 ft; blizzard-like conditions in strong E/SE'ly wind the temperature on Snowdon (summit AWS) reported -6C at 09 GMT. Moderate to heavy snow in places including NW Anglesey and A55 to Holyhead with snow on the beach at Rhosneigr, and mountains including Cadair Idris, and around Bala during the day, in SE Anglesey snow settling from 2130 GMT. Snow lying to sea level on the 19th, moderate to heavy accumulations of dry snow on the mountains above 1000 ft. Temperature on Snowdon summit at 09 GMT -7C. Snow at sea level in many places on the 20th, some compaction has taken place, but little thawing taken place, icy. Snow flurries and showers at times around the summits, temperatures continuing sub zero. Similar on the 21st, snow on the foreshore in places and lying snow above 750 ft. Ice precipitation, ice crystals, snow pellets and snow at times. Snow had blown off some slopes of the Carneddau with drifting in places. Moderate accumulations around some summits. Ice precipitation overnight 21/22nd and early on the 22nd; sub zero temperatures reported on Snowdon summit; lying snow generally from 750 ft, remnant snow on the foreshore in places including NW Anglesey. On the 23rd lying snow from 750 ft, snow flurries through the day, ice and remnant snow at all levels and shaded slopes and valleys. Much the same on the 24th, snow and ice generally above 500 ft, remnant snow in places from sea level. By the 25th any snow at sea level had disappeared and heavy rain during the afternoon thawed much of the thinner snow cover; on the summits precipitation was snow. On the 26th snow was much reduced and cover very broken except around the summits. Areas of remnant snow above 2750 ft on the 27/28th. Remnant snow and ice on the 29 - 31st.

February

The month began with some remnant snow and snow flurries around the summits. On the 2nd there was a sprinkling of fresh snow on northern summits of the Carneddau and Yr Wyddfa, and N-facing slopes as low as 2750 ft. Showers of ice precipitation overnight 4/5th with scattered deposits as low as 300 ft. Slight snow particularly on W-facing slopes above 2000 ft; old snow and ice above 2500 ft. Overnight 6/7th fresh snow light to moderate over 2500 ft, slight from as low as 750 ft in places on the morning of the 7th. Fresh snow overnight 7/8th added to moderate accumulations over 2500 ft and left slight wet snow as low as 1500 ft in places. Gully and old areas of old snow in places with light snow variable from 2000 ft persisted until the 12th. Fresh snow early on the 13th, moderate above 2500 ft at first, with sleet and snow as low as 750 ft at 09 GMT. Soon turning to rain with snow rapidly disappearing at all levels especially in places below 2750 ft by noon. Areas of old broken snow persisted mostly above 2350 ft on 14th and 15th with sprinklings of fresh snow around the highest summits. Light snow, old snow and ice persisting on the 19th mainly around Snowdon and Carneddau, most on Carnedd Dafydd with lesser amounts C. Llewelyn and eastward. Little change up to the 22nd: old snow and ice generally above 2500 ft.. Early on the 23rd showers off the Irish Sea brought ice precipitation (snow pellets and snow flurries) leaving sprinklings mainly on to N-facing slopes and summits above 2500 ft, but as low as 1000 ft at Ogwen and in Cwm Idwal. On the 24th there were fresh falls of mixed ice precipitation as low as 750 ft. Snow was lying at 2750 ft in icy conditions with some remnants at 2000 ft on the 25th and 2500 ft in places on the 26th. Light broken snow remained on some summits over 3000 ft on the 27th and 28th, and on cliffs with gully snow and patches as low as 2350 ft in places.

March

The month began with light broken snow in places on the highest summits, some gully snow and snow patches as low as 2350 ft on the Carneddau. Some broken snow was present around summits on the 3rd with snow patches remaining on the morning of the 6th. Early on the 10th fresh snow left a sprinkling as low as 2500 ft, most in the east on Drum, Foel-fras and Carnedd Llewelyn, less so westward on Carnedd Dafydd and Yr Wyddfa. On the 11th it was icy around 1000 ft with slight snow generally above 2750 ft with frequent areas of old snow between. Sub-zero temperatures on the summits persisted with old snow and ice. Fresh scattered light snow 12th, 13th and 14th with snow overnight 15/16th lying 2500 ft on the morning of the 15th, moderate in places, and slight at 2250 ft with thawing deposits as low as 2000 ft in places. Snow overnight 14/15th lying at at 2750 ft on the 15th. Fresh snow overnight 15/16th lying 2500 ft on the 16th. Light to moderate snow 16/17th lying as low as 2000 ft on the morning of the 17th, wet snow at lower levels deposits at 750 ft quickly thawing, wet snow and sleet at 300 ft not settling. Further snowfall overnight 17/18th with deep snow on the mountaintops and as low as 2500 ft in places covering recent snow with some drifting in E'ly winds, light snow as low as 1000 ft. Most snow on more western mountains including Moel Eilio. Little change in levels on the 19th with further snow overnight 19/20th topping up cover at higher levels with light snow as low as 1000 ft at Ogwen. Similar levels on the morning of the 21st; lowest at 1250 ft. Snow overnight 21/22nd and snowing on the morning of 22nd significant falls over 1000 ft, blizzard at higher levels continued all day. Deep snow in places with large drifts and cornices overhanging cliffs; avalanche warnings had been issued. Similar conditions on the 23rd, still snowing, in strong to gale-force winds blizzard at 1000 ft. Snow as low as 400 ft on N-facing slopes of the Carneddau. Snow in NE Wales, snowing also on Cadair Idris. Reports of snow between 10 and 50 cm deep in places with large drifts. The temperature did not get above zero all day in places on the 23rd. Lake Vyrnwy minimum -4.2C and maximum -3.3C. Little change in snowline on the 23rd and 24th with snow as low as 500 ft. Further ice precipitation showers on the 26th, little change in snowline, strong E'ly winds continue to blow snow into deep drifts, fill gullies and scour slopes leaving icy deposits at all levels generally above 250 ft. The variable conditions of snow and ice reported as being 'very difficult' at all levels N Snowdonia and Cadair Idris. Low temperatures and light to moderate E'ly winds persisted; little change in snow levels to the end of the month.

DP. Snowfall events: Snowdonia. Bulletin: Climatological Observers Link, March 2013 515, 14-15.

April

The month began with snow lying above 1000 ft with 30% cover as low as 750 ft on the N-facing slopes of the Carneddau. Snow was thin on some slopes, but deep in places with drifts persisting at all levels. Several lakes remain frozen, or partially frozen. Moderate to deep snow on the tops with cornices on cliffs. Snow also persisting on Cadair Idris and on Yr Eifl, The Rivals, Lleyn. Little change on the 4th except that more bare patches had appeared below 1500 ft on the Carneddau where snow had brown off into drifts. Ice and snow were persisting at all levels generally above 500 ft. More snow-free areas visible on lower slopes on the 5th and 6th, but moderate or deep snow with drifts persisting at higher levels and summits. The early morning sunshine was producing snow-glint off slopes where the surface was icy. On the 7th snow had reduced on the wind-scoured slopes, but large areas of deeper snow remained with remnants as low as 750 ft, possibly lower in some places. Little change in levels on the 8th and 9th, but on the 10/11th larger snow-free areas had appeared on slopes. Snow on the summits with bare ground showing through old drifted snow along with deep gully snow at lower levels with remnants as low as 750 ft, 500 ft in some places. On the 12th bare ground was more evident on slopes, areas of old snow and drifts persist. More broken snow and bare areas along the tops of the Carneddau on the 13th; C. Llewelyn mostly unbroken. Deep gully snow with snow on some cliffs. Remnant ice and snow persisting in places as low as 750 ft, 500 ft in some shaded places. Snow patches and some remnant snow persisting. On the 26th showers of ice precipitation left transient sprinklings of snow on Carneddau and Yr Wyddfa. On the 27th snow patches were frequent on the Carneddau some (now smaller) as low as 1000 ft and larger mostly above 2500 ft.

DP. Snowfall events: Snowdonia. Bulletin: Climatological Observers Link, April 2013 516, 10-11.

May

The month began with frequent snow patches mostly at 2500 ft, or more, but a few remnants were surviving as low as 1000 ft. Ice precipitation as low as 300 ft overnight 15/16th left a sprinkling of fresh snow above 2500 ft on Carnedd Llewelyn and C. Dafydd on the morning of the 16th. A good amount of snow in Y Ffoes Ddyfn (The Deep Cut) 2950 ft at the beginning of the month lasted until after the 17th, but soon melted. Snow patches remained on NW-facing Carnedd Dafydd at 2500 ft near Ysgolion Duon and 2600 ft and 2750 ft above Cwm Bychan near Foel-grach until the end of the month.

DP. Snowfall events: Late snow patches on the Carneddau Mountains. Bulletin: Climatological Observers Link, May 2013 517, 11.

June

Two small snow patches near Ysgolion Duon had survived until June, but could not be seen on the 3rd, along with 3 larger patches near Foel-grach. The 2 patches above Cwm Bychan near Foel-grach seen from Llansadwrn on the 3rd were visited and photographed by Gordon Perkins on the 4th (photo left) from Foel-grach looking towards Carnedd Llewelyn) and (right) from above Cwm Bychan looking towards Bethesda and Anglesey. This patch is arched with a small stream beneath. There was a third patch lying further E under Foel-grach at about 2600 ft. It was a surprise to see Y Ffoes Ddyfn empty of snow on the 4th confirming that it is not filled with late snow every year as indicated by a lack of a typical late snowbed flora. On the 16th the snow arch of the Cwm Bychan patch collapsed splitting into two, either side of the gully. On the 18th one streak of snow remained and the last remnant was observed on the 21st. In 2010, at this location, snow also remained until the 21st June, but the patch at Y Ffoes Ddyfn (The Deep Cut) on the SSE-facing flank of Carnedd Llewelyn survived until the 28th, the latest to survive in recent years in England and Wales.

DP. Snowfall: The last surviving snow patches on the Carneddau Mountains. Bulletin: Climatological Observers Link, May 2013 518, 9.

You can view the snowline histograms for previous years here:

 

 Winter 2011-2012
 Winter 2010-2011
 Winter 2009-2010


 

You can view complete snowline reports for previous years here:

 Winter 2011-2012
 Winter 2010-2011
 Winter 2009-2010


For earlier archived reports refer to the Site Map.

 

Notes

Observations are made as near to 0900 GMT as possible. I have a good view from Llansadwrn, weather permitting, across the Menai Strait towards the Snowdonia Mountains. I can see the northern slopes of the mountain range from Moel Eilio (west of Snowdon), Snowdon summits (Yr Wyddfa and Crib Goch), the Carneddau and to Foel-fras and Drum on the eastern end near the Conwy Valley. With the aid of binoculars I make daily records that include any ice precipitation observed, the lowest altitude of snow lying at >= 50% cover and >= 30% cover, together with any snow patches. I aim to update the diagram during the season at least twice weekly if there is snow.

These pages are designed and written by Donald Perkins, Copyright © 1998 - 2013. All Rights Reserved. Document dated 25 July 2012 and updated during the season http://www.llansadwrn-wx.co.uk




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