Issued 0349 GMT Monday, 22 March 2010
/
Cyhoeddwyd 0349 GMT Dydd Llun, 22 Mawrth 2010
 Sunrise / Codiad Haul : 0609 GMT, Sunset / Machlud Haul : 1829
GMT |
Hazards / Peryglon
Storm force winds. Gales. Hill fog. Thunderstorms. Heavy persistent rain. |
Forecast for daylight hours for Monday / Rhagolwg ar gyfer oriau'r dydd Dydd Llun
| General situation / Sefyllfa cyffredinol Starting dry but rain soon spreading from the west, with some heavy bursts by late morning. Hill fog. Rain clearing from the west by midafternoon. Windy, with gales, easing somewhat later. | ||
| Weather / Tywydd Dry at first, with occasional hill fog, but outbreaks of rain will soon spread from the west, with more general hill fog developing. Some of the rain is likely to be heavy and southwesterly winds will be strong to gale force. Clearer, drier conditions will then follow from the west by around the middle of the afternoon, with winds veering more westerly and easing somewhat. | ||
| Visibility / Gwelededd Moderate or good, occasionally poor in rain and very poor in fog. | ||
| Cloud base / Gwaelod y cymylau Patches above 300 metres at first. Becoming more extensive above 300 to 400 metres through the morning, with patches below this level in rain. Clearing from the west later in the day. | ||
| Wind / Gwynt | Temperature / Thymheredd | |
| 300m | South to southwest 15 to 20 mph, veering westerly early afternoon and easing to 10 to 15 mph. | Plus 6, rising to a maximum of Plus 10 Celsius. |
| 500m | Southwest 40 to 50 mph, veering westerly early afternoon and easing to 25 mph. | Plus 5 to 6 Celsius |
| 800m | Southwest 55 to 60 mph, veering westerly early afternoon and easing to around 30 mph. | Plus 4 Celsius |
| Freezing level / Lefel rhewi Above summits. | ||
Forecast for daylight hours for Tuesday / Rhagolwg ar gyfer oriau'r dydd Dydd Mawrth
| Weather / Tywydd Dry with variable amounts of cloud and some valley fog patches. Perhaps some brightness at first but cloud becoming widespread by late morning, with rain developing across the area, along with hill fog. Becoming windy. |
| Visibility and cloud base / Gwelededd a gwaelod y cymylau Mostly good, becoming moderate to poor in rain, and very poor in any hill fog. . Cloud becoming widespread in the south of the area and patchy in the north, mainly above 400 metres but perhaps lowering at times to 200 metres in the south. |
| Wind, temperature and freezing level / Gwynt, thymheredd a lefel rhewi Southerly or southeasterly 45 mph / Plus 4 Celsius / Above summits. |
Outlook for Wednesday / Rhagolygon ar gyfer Dydd Mercher
Detail uncertain but probably a cloudy day generally, with rain at times and with occasional hill fog, perhaps becoming extensive and persistent over the higher ground. Southerly winds moderate, perhaps becoming fresh or strong at times.
Outlook for Thursday / Rhagolygon ar gyfer Dydd Iau
A lot of cloud and some further outbreaks of rain likely but probably less wet than on Wednesday, although still with the risk of extensive and persistent hill fog. There is also a risk of more widespread and heavier rain, with increasing winds, spreading across from the south towards dusk.
Outlook for Friday / Rhagolygon ar gyfer Dydd Gwener
Staying windy with a risk of gales. Occasional showers or longer outbreaks of rain, some of it heavy. Hill fog at times, especially in the south and west of the area.
