High for becoming cloudy with rain at times on Wednesday but becoming lower from Thursday regarding details and timing of precipitation due to uncertainties regarding development and movement of a low over the western UK.
Dry and clear. Fresh northwesterly winds.
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.
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.
Gale force winds (gusts over 50mph) make walking difficult and strenuous with a potential to be blown over by gusts. There is often a marked increase in winds through cols or on exposed ridges and summits. Distances can take longer to cover and compass bearings become harder to follow accurately.
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.
Dry start but increasing cloud brings outbreaks of rain and snow. Strengthening westerly winds.
|Chance of precipitation|
|900m||W 13 15||W 17 20||W 16 20||W 20 26||W 20 27||W 23 30||SW 25 31||SW 23 29|
|600m||SW 8 11||SW 11 14||SW 10 13||W 14 18||W 16 22||SW 17 23||SW 16 22||SW 14 21|
|300m||S 3 6||SW 6 11||SW 5 9||W 8 15||W 10 19||SW 10 19||SW 10 19||SW 8 18|
|Valley||S 4 7||SW 7 12||SW 5 10||W 8 15||W 11 20||SW 11 20||SW 11 21||SW 10 21|
Remaining dry but cloud increasing through the early hours, although clear spells may lead to some low level fog patches developing across the east of the area towards dawn. Then a bright morning, especially across the south and east but cloud continues to increase bringing outbreaks of snow from mid afternoon. During the late afternoon the snow turns increasingly to rain at all levels, the precipitation most persistent across northwestern hills. The evening remains cloudy with rain generally necoming patchier.
Around 80% through the morning with occasional cloud above about 750m but falling to near zero in the northwest and around 25% over southern and eastern hills as cloud becomes periods or persistent above 600m and lowers to 450m at times across northern and western hills.
Good or very good through the morning, although several hundred metres in early low level fog patches and cloud, becoming several kilometres in rain and snow.
Overnight temperatures in eastern valleys likely to fall below freezing. Thaw of lying snow expected through the evening.
Area - Snowdon Date - 20 March 2018 Time - 11.00am Snow Above - 850m Report By - Snowdon Warden Route Taken Llanberis Path Conditions Wet surfaces are coated in ice. Heavy frost cover on rocks and vegitation. Depth of snow increases with altitude. Snow drifts in areas. Slopes and paths paths covered in hard snow and ice. Kit Advice The following is a list of additional kit required based on the current conditions. Ice axe and crampons recommended. Wear crampon compatible boots. Wear sturdy walking boots. Take waterproofs, hat, gloves and spare warm layers.
Outbreaks of rain largely dying out overnight but remaining cloudy with, especially for western and southern fells, patchy drizzle through the rest of the morning. More persistent and occasionally heavy rain, with some sleet or wet snow for a time on summits, arrives during the afternoon and evening.
Westerly 20mph backing more southwesterly through the morning and increasing 35mph, with gusts around 50mph over ridges and summits through the afternoon and evenin.
Best chances, around 60% for a time, across eastern hills and, especially through the afternoon, northeastern hills with cloud becoming occasional above 750m, but little chance over western hills with periods or persistent cloud above about 450m for the most part.
Very poor in cloud otherwise, especially across eastern hills, good or very good falling to several kilometres in rain and perhaps a kilometre in summit snow.