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Snowdonia

Confidence

High for much milder conditions than of late but becoming medium in details especially regarding timing of rain around the middle of the week.

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  • Tuesday
  • Further outlook

Sunday 17 December 2017

Sunrise: 08:25   Sunset: 15:59
Moon phase: New

Dry with clear spells and strong northwesterly winds.

Monday 18 December 2017

Weather hazards

Severe chill effect Low likelihood Hide detail

Wind significantly lowers the ‘feels-like’ temperature relative to the actual temperature, with even moderate winds significantly adding to the chilling effect. Strong winds can result in a severe and debilitating wind chill many degrees below the actual temperature. This effect will be enhanced in rain or wet snow. Without protection, prolonged exposure could result in frost nip or frostbite on exposed parts of the body and/or hypothermia.

Poor visibility Low likelihood Show detail

Poor visibility presents challenging route finding conditions. Visibility could be significantly less than 50 metres in all directions with few or no visual references, especially on featureless moors or plateaux. Distances become hard to judge and cliff or cornice edges can be difficult to recognise. These conditions require good navigational skills. There is a risk of white-out conditions when mist or fog is combined with extensive snow cover.

Headline

Dry with sunny spells. Strong winds at first and again later

Weather at 800m

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Partly cloudy night Partly cloudy night Partly cloudy night Sunny intervals Sunny intervals Sunny intervals Partly cloudy night Partly cloudy night
<05% <05% <05% <05% <05% <05% <05% 10%
Chance of precipitation
1,000 1,000 900 1,000 1,000 1,800 2,100 2,100
Freezing level (m)
The level above which snow is expected to settle or the ground is expected to be frozen

Wind speed and direction (mph) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m NW 22 27 NW 18 23 NW 12 15 W 7 9 SW 8 10 SW 10 12 SW 12 15 SW 13 16
600m NW 12 17 NW 10 13 SW 7 9 S 6 8 SW 6 9 S 10 12 S 12 16 S 14 18
300m NW 6 14 NW 4 11 S 3 5 SE 3 5 S 3 6 S 4 8 S 6 12 S 7 15
Valley NW 6 14 NW 5 12 S 3 5 S 3 5 S 3 7 S 5 8 S 7 12 S 8 15

Temperature (°C) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m 1 1 1 1 2 3 4 4
600m 3 3 3 3 4 4 5 5
300m 5 4 4 4 6 5 5 5
Valley 6 6 5 5 7 6 6 6

Feels like temperature (°C) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m -5 -5 -4 -3 -2 -1 0 0
600m -1 -1 0 0 1 1 1 1
300m 2 3 3 3 5 4 3 3
Valley 4 4 4 4 6 5 4 4
Sunrise: 08:26   Sunset: 16:00
Moon phase: New

Weather

Dry with some long clear or sunny spells. Low level fog in eastern valley's will be slow to clear perhaps lingering through the day in some spots.. A thaw of lying snow and frozen ground is likely to develop at all levels.

Chance of cloud-free mountain/hill tops at 800m

Around 75% with occasional of cloud above about 750m. Chances fall during the evening as cloud begins to increase.

Visibility

Very good or excellent with some good panoramic views of surrounding hills and mountains. However visibility may be a few hundred metres or less in valley fog.

Meteorologist's view

Strong winds and near zero temperatures on the summits produce a significant chill effect, especially through the early hours. Where fog persist in the valley's temperatures will struggle to make much more than 2 or 3 Celsius.

Ground conditions

Area - Snowdon Date - 16 December 2017 Time - 11.45am Snow Above - 500m Report By - Warden Yr Wyddfa Route Taken PyG Track Conditions • Heavy frost cover on rocks and vegitation. • Depth of snow increases with altitude. • Paths difficult to follow. • There is a steep bank of snow below the Fingerstone Kit Advice The following is a list of additional kit required based on the current conditions. • Ice axe and crampons essential. • Wear crampon compatible boots. • Ski goggles for strong winds and blowing snow. • Take waterproofs, hat, gloves and spare warm layers.

Tuesday 19 December 2017

Sunrise: 08:27   Sunset: 16:00
Moon phase: New

Weather

A generally cloudy day with outbreaks of mainly light rain or drizzle. Best of any brighter spells expected across the more sheltered eastern hills.

Maximum wind speed expected

Southerly or southwesterly winds around 20mph with gusts around 35mph over ridges and summits

Chance of cloud-free mountain/hill tops at 800m

Little chance for many hills with periods or persistent cloud above about 450m, with patches below, but rising to around 30% over eastern hills as cloud becomes occasional above 600m at times

Temperature

  • At 800m Around plus 4 Celsius
  • Valley Around plus 4 or 5 Celsius, but nearer 1 or 2 Celsius in the east, rising to plus 10 Celsius
  • Freezing level Well above the summits

Visibility

Good falling to just a few kilometres in rain and drizzle.

Wednesday 20 December 2017

Sunrise: 08:27   Sunset: 16:00
Moon phase: New

A mainly cloudy day with outbreaks of rain, perhaps drier, brighter later in the north. Occasionally strong southwesterly winds turning more northwesterly and easing. Freezing level falling to around 1000m later.

Thursday 21 December 2017

Sunrise: 08:28   Sunset: 16:01
Moon phase: Waxing crescent

Rather cloudy start but mainly dry with sunny spells developing, especially in the east. Mainly light winds. Freezing level around 1000m

Friday 22 December 2017

Sunrise: 08:28   Sunset: 16:01
Moon phase: Waxing crescent

Mostly cloudy with patchy rain, drizzle and, for a time, summit snow, with eastern hills and mountains likely to see the best of any brightness. Fresh southwesterly winds. Freezing level rising above the summits..

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