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Rhybuddion

Sul 20 Awst Cyhoeddwyd am 00:00

Rhybuddion DU

Rhybudd Tywydd

Cyhoeddwyd gan y Swyddfa Dywydd

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

Sunday 20 August

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 20 August

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 21 Awst Cyhoeddwyd am 10:00

Rhagolwg Misol

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

Crynodeb
An uncertain start to climatological autumn!

Last week brought yet another bout of showery, breezy weather for all parts of the UK. Although there were some pleasant sunny intervals, temperatures struggled a little too across many districts, the exception being the southern and eastern counties of England, where temperatures occasionally peaked into the mid-twenties.

Whilst the last full week of the climatological summer does offer some warmth across southern parts of the UK at first, the general theme of showers, breezy spells and temperatures staying at or just below the seasonal average stays firmly in place. As we move into early September, the weight of evidence from the available forecasting tools and computer models leans in favour of a continuation of the cool and showery theme, particularly across the northern half of the UK.

It should be noted that confidence in the forecast themes for the coming weeks is particularly low at present, even for a monthly outlook. The source of this uncertainty is the potential for significant tropical storm activity across the warm waters of the Caribbean and western Atlantic over the coming weeks. Such tropical disturbances can inject a good deal of moisture and energy into the prevailing Atlantic synoptic pattern. The knock-on effect is that small perturbations can form in the Atlantic jet stream that are often missed by the forecasting models. These perturbations can have a large effect on the track of any Atlantic lows that pass close to or over the UK.

Read on to find out our latest thoughts...

Llun 21 Awst—Sul 27 Awst
Some warmth in the south, but wetter in the north

This week begins with a low pressure system centred just to the northwest of the UK. Across the southwestern half of the UK, outbreaks of patchy rain will be accompanied by extensive low cloud and a muggy feel, whereas northeastern regions will begin on a fresher and brighter note. The rest of Monday will see the humid, cloudy and damp conditions move northeastwards towards southern Scotland, Northern Ireland and northern England, where rain could turn quite heavy later in the day.

By Tuesday, the rain will be confined to Scotland and Northern Ireland, where it could again turn heavy at times. Further south, skies will often be cloudy, but any brighter spells in the south could permit highs into the mid-twenties. Through Wednesday, a cold front will sweep from west to east across the UK, bringing further spells of rain, to be followed by much brighter conditions later, though still with showers, particularly in the north. A noticeable drop in humidity will accompany the clearer conditions, making for a pleasant feel. Given that the cold front will likely take much of the day to reach the far southeast of England, temperatures here could peak in the high twenties.

For the remainder of the week, and into weekend, at time of writing, the majority of computer models suggest that pressure will remain low towards the north and northwest of the UK. As a result, our best estimate at this stage is that many northern and central parts of the UK will remain breezy with the risk of showers and a cooler feel, though still with the chance of some pleasant sunny intervals. The best chance of drier, brighter and warmer weather will across southern, and particularly southwestern parts of the UK. However, as noted above, there is a considerable amount of uncertainty in the detail for this period, which largely relates to how the jet stream is influenced by tropical developments in the Atlantic. So stay up to date with the latest forecasts throughout the week to make the most of the Bank Holiday weekend.

Llun 28 Awst—Sul 3 Medi
A mixed bag for the start of autumn!

As we move into September, the relatively high level of uncertainty in forecast detail continues to be a feature of the weather forecast. At the moment though, indications from forecast model data do tend to suggest that the Atlantic jet stream will be positioned such that pressure will remain low to the north and northwest of the UK much of the time. This scenario will permit a continuation of the cool and showery theme to the northwest, with the greatest chance of lengthier drier and warmer spells occurring across southeastern parts of the UK. That said, a significant minority of forecasting models do allow pressure to build over a greater proportion of the UK. Should this scenario unfold, much of the UK could enjoy finer weather, with showery conditions limited to the far north. All will depend on how a significant bend in the jet stream way to the south of the UK develops, and at present there is no model consensus on how this feature evolves through the period. As always, we will keep abreast of the latest developments and keep you updated!

Llun 4 Medi—Sul 17 Medi
Still no real agreement!

At time of writing, forecasts from the different computer models for the middle part of September were decidedly divergent! That said, on weight of evidence, it is thought the most likely scenario is for wet and windy conditions to affect most parts of the UK at times, with the possibility of occasional gales, and a generally cooler feel. Conditions will certainly not be continuously poor though, with some drier and brighter spells expected, particularly further south. We await further forecast model data with interest!

Wythnos nesaf

Will next week bring any greater degree of confidence in the longer term forecast!? Will any sign of some early autumnal warmth appear!? Find out the answers to both these questions in next week's issue...

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 28 Awst

Crynodeb

Llun 21 Awst Cyhoeddwyd am 15:40

Crynodeb

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

Rain in the north, cloudy and humid in the south.
This Evening and Tonight

Rain in the north of England and western Scotland will slowly move further north and east. Some heavy bursts are likely in the Highlands. Further south, it will be mostly cloudy and humid with widespread hill and coastal fog.

Tuesday

Rain across Scotland will fizzle out, before more heavy rain spreads into Northern Ireland and then western Scotland. Further south will be brighter and significantly warmer with a few showers.

Outlook for Wednesday to Friday

Wednesday and Thursday will be fresher but mainly dry in England and Wales. Showers are likely further north. Friday's showers will be heavier across northern England and Wales.

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