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Rhybuddion

Sul 21 Medi Cyhoeddwyd am 00:30

Rhybuddion DU

Rhybudd Tywydd

Cyhoeddwyd gan y Swyddfa Dywydd

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

Sunday 21 September

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.

Sunday 21 September

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

Ynglŷn â Rhybuddion Tywydd y Swyddfa Dywydd

Mae BBC Tywydd yn darparu dau fath o rybudd tywydd gan y Swyddfa Dywydd: Rhybuddion a Rhybuddion Cynnar.

Bydd Rhybuddion yn cael eu cyhoeddi pan disgwylir tywydd garw o fewn y 24 awr nesaf.

Bydd Rhybuddion Cynnar yn cael eu cyhoeddi mwy na 24 awr cyn tywydd garw.

Mae yna dri chategori o ddigwyddiad: Coch, Ambr a Melyn – y mwyaf difrifol yw Coch.

Mae Rhybudd a Rhybudd Cynnar yr un lliw yr un mor ddifrifol â’i gilydd ond eu bod wedi eu darogan i gyrraedd ar adegau gwahanol. Felly, y gwahaniaeth rhwng Rhybudd Coch a Rhybudd Coch Cynnar yw amseriad y digwyddiad.

Pan mae rhybudd mewn grym, ceir gwybodaeth lawn yn Rhybuddion Tywydd y Swyddfa Dywydd (dolen allanol 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 15 Medi Cyhoeddwyd am 10:00

Rhagolwg Misol

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

Crynodeb
Feeling more like summer!

September so far has been warm and dry, quite a contrast to August which was the coldest since 1993 and the wettest since 2004. That did skew our summer's statistics away from the overall warm and dry theme characterised by June and July, so some may think it quite considerate of September doing August's work. Meteorologically speaking however we're into autumn now and the nights are getting longer and cooler, as we saw last week; the warm afternoons have followed cool and at times misty mornings.

So where might this week take us? Well, perhaps even closer to summer than we've already been enjoying. The reason for the settled weather is a blocking anticyclone which has been sitting over the UK and keeping Atlantic weather fronts at bay. In the last few days it's slipped over to Scandinavia, but continues to dominate our weather and will introduce a continental southeasterly flow across the country. This means temperatures could rise by more than five degrees above average where the sun shines. As we're only in September it's too early to call it an Indian one, but how long will this extension to summer last?

Llun 15 Medi—Sul 21 Medi
Temperatures on the rise

Despite this week's overall dry theme for the UK, rain greeted central and eastern parts on Monday morning. This will become increasingly confined to eastern Scotland through today. Otherwise it's mainly fine with sunny spells, but some showers will possible in central and eastern areas. For the rest of the week it will be dry with sunny spells for most, and thanks to that southeasterly flow it will become very warm by Thursday in parts of the south and west. Areas of cloud are expected to continue affecting northeastern parts of the country at times, with some occasional spots of rain or drizzle. There is a chance of some showers in the southwest at times, but these will be isolated, and the fine weather should persist through the weekend.

Llun 22 Medi—Sul 28 Medi
The anticyclone's dominance diminishes

Areas of high pressure are known for being stubborn and difficult to shift. Sometimes weather forecast models can be too quick to move on these blocking highs, so such situations can be characterised by noticeable disagreement between different computer models. The presence of a tropical weather system, Edouard, in the Atlantic this week is also likely to add uncertainty into next week's forecast, even though most weather models seem to suggest currently that it will remain in the Atlantic and be steered towards the Azores. All this considered it seems likely at the time of writing that the settled, anticyclonic weather will continue into the first part of next week. It may turn windy and more changeable in the northwest towards the end of next week, with an increasing risk of showers or spells of rain, but the southeast should mostly remain fine.

Llun 29 Medi—Sul 12 Hydref
Change of month, change of weather?

It seems fairly common to be writing about a change in weather type as we approach a change in month, and it seems that this forecast will not present an exception to that rule. However, having noted above the tendency for weather models to trend towards a more Atlantic-influenced weather pattern rather more soon than a blocking area of high pressure would wish to allow, confidence is lower for such a change. Nevertheless, model consensus favours somewhat changeable conditions for the end of September and early October, with settled weather interspersed with occasional unsettled spells. The drier periods with some warm sunshine are expected to be most prolonged across the south and east, whilst outbreaks of rain may tend to be most frequent across the north and west. During the more settled conditions daytime temperatures are likely to be around and often above average, although chilly overnight with a risk of fog patches. During any unsettled spells daytime temperatures are likely to be below or close to average.

Wythnos nesaf

Will we see a genuine Indian summer?

Rhagolygu Misol
Mae'r tywydd y tu hwnt i'r wythnos i ddod yn herio hyd yn oed yr arbenigwr tywydd mwyaf profiadol. Mae modelau rhagolwg rhifiadol y tywydd o'r 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 creu darlun o'r tebygoliaeth o'r gwahanol fathau o dywydd fydd yn effeithio'r DU.

Diweddariad nesaf am 10:00, Llun 22 Medi

Crynodeb

Sadwrn 20 Medi Cyhoeddwyd am 12:38

Crynodeb

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

Isolated showers in the south tonight. Dry and sunny tomorrow,
This Evening and Tonight

Cold, dry and largely clear in the north. Staying mild further south, with cloudy skies and isolated showers, although the fresher, clearer conditions in the north will continue to push south through the course of the night.

Sunday

Any lingering cloud in the far south will soon clear, leaving a fine day with sunny spells. A chilly start, but feeling warm by the afternoon, especially in the south.

Outlook for Monday to Wednesday

Fine and often sunny across the south and east. However cloudier with rain at times across northern and western parts. Light winds, but turning windy in the northwest by Wednesday.

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UK Fideo Rhagolwg

Rhagolwg UK Diweddarwyd 17:40, Sadwrn 20 Med Mae’r fideo yma ar gael yn Saesneg yn unig.