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Snowdonia

Confidence

High for generally warm weather, but medium to low for the extent of the lower cloud affecting the eastern ranges throughout and for the detail of the showers.

  • Monday
  • Tuesday
  • Further outlook

Monday 28 May 2018

Weather hazards

Strong sunlight High likelihood Hide detail

Harmful UV levels from sunlight increase with altitude giving a greater risk of sunburn and eye damage, even on some overcast days. On breezy days, the cooling effect of wind on exposed skin may disguise any feeling of sunburn until it is too late. If there is snow cover, glare increases the effect of UV rays especially on the eyes. It is advisable to wear sun block, protective clothing such as a long-sleeved top and hat and have good quality eye protection.

Poor visibility Medium 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.

Thunderstorms Medium likelihood Show detail

Lightning is a significant mountain hazard which can result in serious injury or death. Mountain terrain often leaves one highly exposed to lightning strikes. Hail may give unpleasant conditions with torrential rain and localised flash flooding also possible, mainly in Summer months.

Headline

Early mist and low cloud soon clear, with warm sunshine developing. This may trigger some heavy, locally thundery showers during the afternoon.

Weather at 800m

06:00 09:00 12:00 15:00 18:00 21:00
Sunny day Sunny intervals Heavy shower day Thunder shower day Heavy shower day Partly cloudy night
00% 00% 20% 30% 20% 00%
Chance of precipitation
2,700 2,700 2,800 3,000 2,900 2,800
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

06:00 09:00 12:00 15:00 18:00 21:00
900m N 4 5 NE 4 6 E 8 11 N 10 13 NE 13 16 E 18 22
600m SE 2 3 N 5 8 NW 8 12 NW 7 11 NE 8 11 E 10 14
300m NE 1 3 N 5 7 N 7 10 NW 6 9 NE 4 8 E 6 11
Valley NE 1 3 NW 5 7 N 7 11 NW 7 11 N 3 8 E 5 10

Temperature (°C) By altitude above mean sea level

06:00 09:00 12:00 15:00 18:00 21:00
900m 13 14 15 16 16 15
600m 14 15 17 17 18 16
300m 16 18 19 18 19 18
Valley 16 18 20 18 19 18

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

06:00 09:00 12:00 15:00 18:00 21:00
900m 13 14 14 14 14 11
600m 15 15 16 16 17 15
300m 17 18 19 18 20 17
Valley 17 19 19 18 20 18
Sunrise: 05:01   Sunset: 21:27
Moon phase: Waxing gibbous

Weather

It will be a misty start in places, with some low cloud. This will soon clear to allow warm spells of sunshine to develop. Many ranges will stay dry through the day, however some scattered afternoon showers are likely to develop. These will be locally heavy, and bring a chance of isolated slow moving thunderstorms. These will ease through the evening, then low cloud and mist will once again return to eastern ranges overnight.

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

80-90% with bases lowering 700-850m in showers.

Visibility

Poor, perhaps very poor at first and again during the evening across eastern ranges. Otherwise good or very good, becoming moderate or poor in showers.

Meteorologist's view

Strong afternoon sunshine bringing a risk of sunburn.

Ground conditions

No recent ground conditions report available. For archived reports see - http://www.snowdonia.gov.wales/visiting/walking/ground-conditions

Tuesday 29 May 2018

Sunrise: 05:00   Sunset: 21:28
Moon phase: Full

Weather

Early low cloud will be slow to clear, especially across eastern ranges. The best of the brightness will be in the west, with plenty of sunny spells developing. Most ranges will remain dry, with only the odd light shower possible during the afternoon, especially in the east.

Maximum wind speed expected

East 15mph with gusts 25mph across exposed ridges and summits

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

90% and 70% for the west and east respectively.

Temperature

  • At 800m Plus 8C rising 16C for a time during the afternoon
  • Valley Plus 8C rising 22C for a time during the afternoon
  • Freezing level 2500-3000m

Visibility

Poor, perhaps very poor at first and again during the evening across far eastern ranges. Otherwise good or very good, becoming moderate in any showers.

Wednesday 30 May 2018

Sunrise: 04:59   Sunset: 21:30
Moon phase: Full

Similar to Tuesday with most stays dry with plenty of sunshine, but cloudier in the east, particularly early and late in the day. However risk of heavy showers spreading from the east during the evening. Summit winds light to moderate from the east. Freezing level above all summits.

Thursday 31 May 2018

Sunrise: 04:58   Sunset: 21:31
Moon phase: Full

Showery at first, with a risk of thunderstorms, particularly during the afternoon and into the evening. Winds will remain light, with freezing level well above all summits.

Friday 1 June 2018

Sunrise: 04:57   Sunset: 21:32
Moon phase: Waning gibbous

A similar day to Thursday, with sunshine and showers, these mainly developing for the afternoon and likely heavy and thundery at times. Light winds and freezing level well above all summits.

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