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Llansadwrn (Anglesey)
Weather:
Eryri (Snowdonia) Snowline Report
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Eryri (Snowdonia) Mountains Winter Season 2024/25
 Latest
reports
Snowline
histogram
September 2024
There was no snow observed in September.
October
Snow fell and was lying on Caingorm Mountain on the 10th above 3600 ft. Some wintry showers were spotted across some Eryri summits on 10th & 11th.
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November
 Snow fell on the mountains on the 18th and more on the morning of the 19th with whiteout conditions on the summits. Temperatures were -5C, or below and windy giving blizzards at times at 0900 GMT. Slight snow had settled almost at sea level on the lower slopes of the Carneddau and several cms lying at Llyn Ogwen and A5 near Tryfan, Cadair Idris and Llyn Tegid. On the 21st snow was lying generally at 850 ft with 30% cover at 250 ft on the lower slopes of the Carneddau and despite a thaw at lower altitude with continuing snow showers similar levels were maintained at higher altitudes in following days. On the 23rd with snow lying at generally 2000 ft on the Carneddau and Yr Wyddfa mountains incursion of warm subtropical maritime air raised temperatures in a few hours from -5C to 10C lead to a very rapid thaw. Runoff was considerable with swollen streams and waterfalls with flooding occurring on the A5 near Ogwen and the visitor car park at Llyn Tegid completely flooded. On the 24th with summit temperatures about 3.6C remnant melting snow was seen in small patches in places at 2250 ft with a few cornice patches remaining on cliffs around 2950 ft. Ice precipitation occurred around the summits at times on the 25-27th and small patches of snow and remnants survived until the 30th despite summit temperatures well above freezing.
December
The weather was very mild on the 1st then on the 2nd it turned colder with ice precipitation resuming around the summits. Snow fell overnight 2/3rd leaving uniformly thin layer of lying snow above 2500 ft on the morning of the 3rd. Return of mild weather on the 4th led to a rapid thaw leaving a little melting snow on the summits of the Carneddau at 3350 ft, then turning colder again icy pockets remained in places. .
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- Read about ice precipitation; snow and the different types of
hail on this website
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To find out more about snow and ice crystals
visit
Ken Libbrecht's website 
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Ogwen Valley Mountain Rescue Organisation OVMRO
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Current weather AWS
- MWIS Mountain Weather Information Service MWIS
- Cairngorm
- Cairngorm summit weather station Intermittent operation Courtesy of Heriot-Watt University Physics Department
- Information
cairngormmountain.org
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You
can view the snowline histograms for previous years here:
Winter 2023-2024
Winter 2022-2023
Winter 2021-2022
Winter 2020-2021
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You can view complete snowline reports for previous years here:
Winter 2023-2024
Winter 2022-2023
Winter 2021-2022
Winter 2020-2021
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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 Glyderau and Carneddau to Foel-fras and
Drum to the east of the range 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), at ( >= 30% cover) and snow patches. I aim to update the diagram during the season at least twice weekly if there is any snow.
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; "Winter 2022-2023."){kind=small}
; "Winter 2021-2022."){kind=small}
; "Winter 2020-2021."){kind=small}
