Snowdonia mountain area forecast
Forecast issued: 0435 on Saturday, 4 February 2012
Overview for Saturday
A cloudy start, with rain, sleet and snow spreading in from the west, coupled with lowering hill fog and strengthening winds.
Hazards
High risk of Severe chill effect: Low temperatures coupled with rain, snow and brisk winds will lead to a high risk of windchill.
Medium risk of Heavy snow: Spells of snow will become increasingly heavy and persistent during the afternoon.
Medium risk of Gales: Winds will reach southwesterly gale later on.
Medium risk of Persistent extensive hill fog: Hill fog will steadily thicken and lower to valley floors by dusk, particularly in snowfall.
Medium risk of Heavy persistent rain: Snow will progressively turn to rain later in the afternoon.
Low risk of Blizzards: Snowfall will be coupled with wind speeds of around 45mph later on.
No risk of Storm force winds; Thunderstorms; Strong sunlight;
Weather summary and probability of precipitation for Saturday
| Dawn to 0900 |  |
Cloudy | 20% chance of precipitation |
|---|---|---|---|
| 0900 to 1200 |  |
Heavy snow | 60% chance of precipitation |
| 1200 to 1500 |  |
Sleet | 70-90% chance of precipitation |
| 1500 to dusk |  |
Heavy Rain | 70-90% chance of precipitation |
Detailed mountain weather forecast
Saturday
Weather
A cold and cloudy start, with spells of rain sleet and snow making their way in from the west soon after dawn. Conditions will deteriorate as the day progresses, with hill fog lowering from 800m to 300m by mid-afternoon, lowering further still in any more prolonged snowfall, more likely over the east in the afternoon. Wind chill will become increasingly marked as the day progresses, eventually reaching gale-force by dusk.
Visibility
Generally moderate, occasionally poor in snowfall. Very poor in hill fog.
Hill fog
800m and lowering to 300m by mid-afternoon, occasionally valley floors in snowfall.
Maximum winds above 500m
Increasing to southwesterly 45mph.
Temperature
Valleys: Minus 8 Celsius locally, becoming plus 4 later.
900 m: Minus 3 becoming plus 2 Celsius.
Freezing level: Generally ground level, rising above the summits by dusk.
Ground Conditions
Latest: 03/02/2012 10:29 Frozen ground at all levels. Light snow above 400 metres. 20cm of snow at 400 metres. Areas of old light snow above 400metres.
Sunday
Weather
A cold start with patchy valley fog, particularly over remaining areas of lying snow. This will clear to a dry and bright morning, although rather cloudy. Cloud will lower later in the morning to affect the higher reaches of the range during the afternoon, coupled with further spells of mostly light rain and sleet. Winds will start brisk northwesterly but ease during the day.
Visibility
Very poor in early valley fog. Otherwise good.
Hill fog
Early valley fog should clear during the morning. Patches around the higher summits possible later.
Maximum winds above 500m
Northwesterly 30mph, easing.
Temperature
Valleys: Minus 2 becoming 5 Celsius.
900 m: Minus 1 Celsius.
Freezing level: 700m.
Outlook
Monday
A milder start than of late, although still with frost. Rather cloudy for much of the day with spells of rain and sleet likely. Light southwesterly winds. Freezing levels rising clear of the summits.
Tuesday
Again a rather cloudy day, with rain easing in-situ to leave a drier afternoon. Moderate southerly winds. Freezing levels above the summits.
Wednesday
A dry and bright start, perhaps with some sunny spells, but becoming increasingly cloudy with spells of heavy rain later. Brisk and increasing southwesterly winds.
