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Friday, 13 December 2013: dawn to dusk
Printable view Forecast issued: 1702 on Friday, 13 December 2013
A dry start, but becoming very windy with heavy rain pushing in around late morning and continuing throughout the afternoon, before clearing by late evening. Storm force winds likely across the summits and exposed ridges.
|Heavy snow||No Risk|
|Storm force winds||Medium||Gusts of 80-90mph are possible for a time during the afternoon.|
|Gales||High||Widespread gales developing during morning and continuing throughout the afternoon, easing later.|
|Severe chill effect||Medium||Feeling more like -3 to -5C across the summits.|
|Persistent and extensive hill fog||High||Isolated patches of hill fog during night. Extensive hill fog developing during the afternoon.|
|Heavy persistent rain||High||Persistent, and often heavy, rain setting by late morning and continuing throughout the afternoon.|
|Strong Sunlight||No Risk|
|Dawn to 0900||0900 to 1200||1200 to 1500||1500 to dusk|
Becoming mostly dry overnight as the showers gradually ease. Under the influence of clears skies, turning rather chilly in sheltered valleys for a time. However, thickening cloud will spread into the area through the morning with widespread upland gales. The winds will increase further with the onset of rain during the afternoon. A combination of the heavy rain and severe gales will lead to atrocious conditions throughout the afternoon. The gales will ease during the evening with the rain gradually clearing to the east.
Generally good, but becoming poor in the rain and very poor in the hill fog.
Summits generally clear overnight, but patches will form down to 700m around showers. Cloud bases will thicken and lower through the morning, with scattered bases developing down to 700m. The cloud bases will become extensive with the onset of the rain during the afternoon, with bases around 400-600m with patches down to 200-300m across western hills. The cloud will become less extensive later in the evening with some northern summits becoming clear of cloud.
Southwesterly 30-40mph, becoming southerly 50-70mph with gusts up to 80-90mph possible for a time across summits and ridges during the afternoon. Easing to southwesterly 20-30mph by late evening.
|Valleys||Plus 3 becoming 11 Celsius|
|900 m||Plus 2 becoming 5 Celsius|
|Freezing level||Above the summits.|
A drier and brighter morning and early afternoon across the park with some good spells of sunshine. However, the winds will increase once again during the late morning and afternoon period with upland gales developing. Cloud will thicken from the south as the afternoon progresses with some showery outbreaks of rain developing by evening.
Generally very good or excellent, but becoming moderate to poor in the showery rain later, and very poor in the hill fog.
Patches of hill fog may shroud some western hills overnight. However, hills becoming cloud-free during the morning. However, thicker cloud will push up from the south during the latter part of the afternoon and into the evening with broken layers developing above around 600-700m.
Southwesterly 30mph, becoming southwesterly 40-50mph during afternoon.
|Valleys||Plus 1 becoming 12 Celsius|
|900 m||Plus 3 becoming 5 Celsius|
|Freezing level||Above the summits.|
Outbreaks of showery rain will affect the park at times, but this will clear later in the day with a few showers following. These showers will fall as sleet and wet snow across the summits. Freezing level around 900m. Although the winds will remain fresh to strong, they will not be as strong as recent days.
Scattered showers overnight, wintry across summits, but then it should turn dry for much of the day with some sunny spells. Later on in the evening it should cloud over as a band of rain and strong winds spread in from the northwest. Freezing level around 900-1000m.
A wet and very windy day with outbreaks of rain, heavy at times, during the morning. This will clear to blustery showers during the afternoon. These Freezing level above the summits, but dropping to 900m later in the day.
Latest: 11/12/2013 16:39 Yr Wyddfa - Snowdon; No adverse ground conditions.
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