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Snowdonia National Park forecast

Rhagolygon Parc Cenedlaethol Eryri
Issued 2116 Friday, 03 July 2009 / Cyhoeddwyd 2116 Dydd Gwener, 03 Gorffennaf 2009
Sunrise and sunset timesSunrise / Codiad Haul : 0357 , Sunset / Machlud Haul : 2044

Hazards / Peryglon

Hazard

Thunderstorms.

Forecast for daylight hours for Saturday / Rhagolwg ar gyfer oriau'r dydd Dydd Sadwrn

General situation / Sefyllfa cyffredinol Patchy low cloud clearing, then sunshine and showers, some heavy. Breezy.
Weather / Tywydd Broken low cloud at first, down to 300 metres, mainly across the west of the Park and on west and southwest slopes. However, this will quickly thin and break. Otherwise a day of sunshine and showers, some of these heavy with the risk of thunder. Showers are expected to last into the evening. Strong sunshine between the showers. Windy on higher peaks and ridges.
Visibility / Gwelededd Moderate or poor at first and very poor in hill fog. However, the visibility will improve very good during the morning, only to fall temporarily moderate with the heavier showers.
Cloud base / Gwaelod y cymylau Broken low cloud at first, mainly across western parts of the Park and especially on western slopes, down to 300 metres. However, this lifting and clearing by mid morning. The further broken low cloud is possible down to 600 metres in and after heavier showers.
  Wind / Gwynt Temperature / Thymheredd
300m South or southwesterly 10 to 15mph. 14 Celsius, increasing to 20 Celsius by afternoon.
500m South or southwesterly 15 to 20mph with gusts to 35mph. 12 Celsius, increasing to 16 Celsius by afternoon.
900m South or southwesterly 25 to 30mph with gusts 40 to 45mph. 10 Celsius, increasing to 14 Celsius by afternoon.
Freezing level / Lefel rhewi Above the tops.

Forecast for daylight hours for Sunday / Rhagolwg ar gyfer oriau'r dydd Dydd Sul

Weather / Tywydd Any patchy low cloud clearing, then sunny spells. However, showers will again break out. Many of these should be light during the morning and early afternoon, but there is a risk of heavy and perhaps thundery showers developing from mid afternoon onwards. It will be rather windy, especially over higher peaks and ridges.
Visibility and cloud base / Gwelededd a gwaelod y cymylau Very poor in hill fog at first, otherwise good or very good, except falling moderate in any heavier showers later.. Well broken low cloud down to 300 metres at first, mainly across the west of the Park, this quickly lifting and breaking. Then further well broken low cloud is possible down to 700 metres in association with heavier showers.
Wind, temperature and freezing level / Gwynt, thymheredd a lefel rhewi Southwesterly 30 to 35mph with gusts 45mph. / 10 Celsius, increasing to 13 Celsius by afternoon. / Above the tops.

Outlook for Monday / Rhagolygon ar gyfer Dydd Llun

Sunshine and showers. Some of the showers are likely to be heavy with a small risk of thunder. Patchy hill fog is possible down to 600 metres during and after heavy showers. Good visibility falling temporarily moderate in heavier showers. Breezy at higher levels.

Outlook for Tuesday / Rhagolygon ar gyfer Dydd Mawrth

A windy day with sunshine and showers, some showers heavy with a risk of hail and thunder. Low risk of west or northwesterly gales over higher peaks and ridges. Good visibility falling temporarily moderate in heavier showers.

Outlook for Wednesday / Rhagolygon ar gyfer Dydd Mercher

Sunny spells and scattered, mainly light, showers. Good visibility with cloud bases mainly above the tops. Windy, especially over higher peaks and ridges.

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