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Rhybuddion

Sadwrn 3 Rhagfyr Cyhoeddwyd am 00:15

Rhybuddion DU

Rhybudd Tywydd

Cyhoeddwyd gan y Swyddfa Dywydd

Mae'r cynnwys hwn ar gael yn Saesneg yn unig.

Saturday 3 December

There are no weather warnings in force anywhere in the United Kingdom.

Rhybudd Llifogydd

Rhybudd gan Asiantaeth yr Amgylchedd neu gan SEPA yn yr Alban a Chyfoeth Naturiol Cymru yng Nghymru

Mae'r cynnwys hwn ar gael yn Saesneg yn unig.

Saturday 3 December

There are no flood warnings in force anywhere in the United Kingdom.

Ynglŷn â Rhybuddion Tywydd y Swyddfa Dywydd

Mae’r Swyddfa Dywydd yn rhybuddio’r cyhoedd a’r rhai sy’n ymateb i argyfyngau o dywydd garw ac enbyd a allai fod yn beryglus i fywyd neu a allai gael effaith eang, drwy’r Gwasanaeth Rhybudd Tywydd Garw Cenedlaethol (NSWWS).

Mae’r Swyddfa Dywydd yn darparu rhybuddion am law, eira, gwynt, niwl a rhew. Bydd lliw yn cael ei roi i bob rhybudd, yn dibynnu ar gyfuniad o debygrwydd hyn yn digwydd a’r effaith gallai ei gael.

Am fwy o wybodaeth, darllenwch Ganllaw Rhybuddion Tywydd y Swyddfa Dywydd (dolen Saesneg).

Ynglŷn â Rhybuddion Llifogydd

Mae’r rhybuddion llifogydd yn cael eu cyhoeddi gan Asiantaeth yr Amgylchedd, Scottish Environment Protection Agency a Chyfoeth Naturiol Cymru, a’u hanfon at Ganolfan Dywydd y BBC. Yna rydyn ni'n cyhoeddi crynodeb o rybuddion wedi eu seilio ar y wybodaeth ddiweddaraf sydd ar gael. Pan mae rhybuddion llifogydd difrifol yn cael eu rhyddhau, bydd rhain yn cael pwyslais ar ddarllediadau teledu.

Dysgwch mwy am Rybuddion Llifogydd

Mae yna nifer o ffyrdd y gallwch chi ddarganfod os yw eich ardal chi mewn perygl o lifogydd. Mae Asiantaeth yr Amgylchedd, Scottish Environment Protection Agency a Chyfoeth Naturiol Cymru yn diweddaru eu rhybuddion 24 awr y dydd trwy rif Floodline.

Floodline - 0345 988 1188

Rhagolwg Misol

Llun 28 Tachwedd Cyhoeddwyd am 10:00

Rhagolwg Misol

Mae'r cynnwys hwn ar gael yn Saesneg yn unig.

Crynodeb
Autumn but not as we've known it.

Autumn 2016 has been very different from recent years. The three month period has been characterised by very slowly changing weather patterns. This has been as a result of the jet stream being weak close to the British Isles resulting in a blocking weather pattern. Normally in autumn, cold air from the polar regions comes southwards across Canada, meeting warm air feeding up from the tropics. This tends to strengthen the jet stream, a fast moving ribbon of air high up in the atmosphere. This is the driving force for deep areas of low pressure to be quickly transported across the Atlantic in our direction bringing frequent spells of very wet and very windy weather and also mild conditions. This autumn has been noticeably absent of such weather patterns, Instead we have seen high pressure in charge of our weather a lot of the time with drier but colder easterly winds. Our first wet and windy spell came at the beginning of last week when Storm Angus affected more southern parts of England. Even then, high pressure returned to quieten our weather down again as last week went on.

Llun 28 Tachwedd—Sul 4 Rhagfyr
December to begin on a high

This week will get off to a quiet start, quite different from the very wet and windy weather we saw last Monday. High pressure will dominate our weather throughout this week keeping a lot of dry and settled conditions. The early part of the week will be characterised by cold, sunny weather in many places with a widespread severe frost on Monday night, the coldest night of this autumn across England and Wales. Further north, the frost will be more patchy with cloudier skies edging in across Northern Ireland and western Scotland. Some rain here during Tuesday and Wednesday. This less cold weather with grey skies will edge across England and Wales during Wednesday and Thursday. The rest of the week and over the weekend will continue mostly dry and rather cloudy with just a little light rain in the west. The best of any brighter skies by day and patchy frosts at nights will be over more sheltered eastern parts of Scotland and England.

Llun 5 Rhagfyr—Sul 11 Rhagfyr
Keep an umbrella handy

As we move further into December, it does look as though we will all experience a more unsettled spell of weather. High pressure will give way to an area of low pressure which will bring rain and stronger winds across the country from the west. There is a possibility of the rain being preceded by snow over hills in the north. Rain in western parts will be heavy at times and will be accompanied by stronger winds but the rain will be lighter and patchy in eastern areas. The more unsettled interlude is expected to be short lived with drier, brighter weather expected to follow later in the week and into the weekend. This will mean a return to drier weather with some sunshine but also sharp overnight frosts and freezing fog patches.

Llun 12 Rhagfyr—Sul 25 Rhagfyr
Will Christmas be white?

The weather into the second half of December and the lead up to Christmas is looking very different to what we saw last year. December 2015 saw severe flooding in many parts of the country with generally mild conditions. This was as a result of a series of active weather systems coming in from the Atlantic and crossing the British Isles. This blocking weather pattern and weaker jet stream discussed earlier looks set to still be in place during the second half of December with only slow changes in our weather. There are signs that high pressure will build close to the British Isles with some settled conditions. This will again bring sharp overnight frosts and freezing fog patches which will be slow to clear by day. There will be some unsettled interludes but they will be fairly limited and not as severe as we saw last December. However with below average temperatures, there is a chance of snow during any unsettled spells, more especially over high ground in the north. So in summary, the consensus from the various weather models is for the unusual autumn weather to carry on into early winter with colder and drier weather expected compared with normal December conditions.

Wythnos nesaf

Will the year end on a chilly note?

Rhagolygu Misol
Mae rhagolygu’r tywydd hirach nag wythnos ymlaen llaw yn her i hyd yn oed yr arbenigwr tywydd mwyaf profiadol. Mae modelau rhagolwg rhifiadol y tywydd gan y Swyddfa Dywydd a'r Ganolfan Ewropeaidd ar gyfer Rhagolygon Tywydd Ystod-Canolig (ECMWF) yn cael eu rhedeg nifer o weithiau'r mis (a'r tymor) i ddod, er mwyn dyfalu sut dywydd fydd yn effeithio ar y DU.

Diweddariad nesaf am 10:00, Llun 5 Rhagfyr

Crynodeb

Sul 4 Rhagfyr Cyhoeddwyd am 14:42

Crynodeb

Mae'r cynnwys hwn ar gael yn Saesneg yn unig.

Foggy night for many, with widespread frost in the north.
This Evening and Tonight

Largely clear skies across northern and central areas mean widespread frost and some freezing fog patches are going to develop here. Low cloud and hill fog will develop across the south and south-west, where it will turn less cold.

Monday

Another rather cold day for most. Sunny spells towards the north and east. Cloudier with hill fog in the south and west, and milder in the far south and west.

Outlook for Tuesday to Thursday

Milder than of late with rain and strong winds at times, particularly in the north and west. Towards the south-east it should remain drier, but some rain is still possible.

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