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Snowdonia

Weather hazards over 300m on Mon 25 May 2015

High risk

No high risks
none

Medium risk

Persistent extensive hill fog
Relatively warm and humid air will lead to persistent hill fog, especially in the northwest.

Low risk

No low risks
none

No risk

Blizzards
none
Heavy snow
none
Storm force winds
none
Gales
none
Severe chill effect
none
Thunderstorms
none
Heavy persistent rain
none
Strong sunlight
none

Mon 25 May 2015

A predominantly dry but rather cloudy day, with hill fog proving persistent on windward slopes in particular. The cloud may just be thick enough at times to produce the odd spot of drizzle, however the general theme is for dry weather. The cloud will be thinnest in the southeast, but even here it is likely to persist in what should be a reasonable if slightly humid-feeling day in the Park.

Time
0000 to 0300 0300 to 0600 0600 to 0900 0900 to 1200 1200 to 1500 1500 to 1800 1800 to 2100 2100 to 2400
Weather
Partly cloudy night Cloudy Drizzle Cloudy Cloudy Cloudy Cloudy Cloudy
Precipitation probability
0% 20% 40% 20% 10% 10% 20% 20%

Visibility

Very poor in hill fog, otherwise good.

Hill Fog

400m on windward slopes, lifting as high as 700m in the southeast leeward side of the range, but any breaks will be limited.

Max wind above 500m

Northwesterly 20mph.

Temperature

Valleys:
Plus 8 becoming 13 Celsius.
800m:
Plus 2 becoming 5 Celsius.
Freezing level:
Above the summits.

Issued at: 1458 on Sun 24 May 2015

Tue 26 May 2015

Another cloudy morning, with the odd spot of light drizzle possible. The highest summits may just protrude from the low cloud by the start of the afternoon, with the lower level hill fog then beginning to fragment to leave a brighter end to the day more generally across the slopes.

Visibility

Very poor in hill fog, otherwise good. Perhaps very good on the higher tops from afternoon, although significant hill fog must be traversed to reach this height.

Hill Fog

Broken around 400m, becoming well-broken at 700m later. Snowdon and other high peaks may just protrude from the cloud to start the afternoon before the lower cloud fragments, although this is low confidence.

Max wind above 500m

Northwesterly 25mph.

Temperature

Valleys:
Plus 8 becoming 14 Celsius.
800m:
Plus 5 Celsius.
Freezing level:
Above the summits.

Issued at: 1458 on Sun 24 May 2015

Wed 27 May 2015

Fine with sunny spells to start Wednesday, however high cloud will invade from the west into the afternoon, with a strengthening southwesterly breeze developing. Becoming wet and windy by evening, with gales at height.

Issued at: 1458 on Sun 24 May 2015

Thu 28 May 2015

Bright but blustery, with scattered showers possible on strong northwesterly winds. The wind and the threat of showers should abate later, although it should become more generally cloudy.

Issued at: 1458 on Sun 24 May 2015

Fri 29 May 2015

Another mild but rather murky day, with light southwesterly winds, hill fog and eventually perhaps a little light rain.

Issued at: 1458 on Sun 24 May 2015