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Rhybuddion

Sul 25 Ionawr Cyhoeddwyd am 11:47

Rhybuddion DU

Rhybudd Tywydd

Cyhoeddwyd gan y Swyddfa Dywydd

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

YELLOW EARLY WARNING OF SNOW for northern England, Scotland and Northern Ireland.

Updated 11:45 on Sunday 25th January.

Valid from: 1500 on Wednesday 28th January.

To: 2355 on Thursday 29th January.

A cold and increasingly showery northwesterly flow is expected to develop during Wednesday and last through Thursday. Accumulating snow is likely away from windward coastal districts, especially overnight, with 2-5 cm locally at low levels. Higher ground, above about 150 m, could see in excess of 10 cm. Strong and gusty winds will likely accompany snow showers, and lead to significantly reduced visibility at times.

The public should be aware of the potential for disruption to travel.

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 24 January

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 19 Ionawr Cyhoeddwyd am 10:00

Rhagolwg Misol

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

Crynodeb
Some proper winter weather! But for how long?

January started very mild and very wet but more recently a colder theme has returned to UK shores with a fairly frequent occurrence of frost, below average temperatures and even some snow.

Official overnight temperatures (which run from 1800 - 0600 the following morning) from Sunday night into Monday fell to -12.5 C at Loch Glascarnach and Tullouch Bridge. Thereafter temperatures continued to slide away and reached -13.1 C at Tulloch Bridge. We did not quite reach the record of the most recent coldest night of -13.6 C in 2013 in Janruary.

The next question is how long the cold air will stay around and in what way the milder air from the Atlantic will reach us. How will the weather be affected as we make a transition from colder air towards more normal temperatures? Well, let's take a look.

Llun 19 Ionawr—Llun 26 Ionawr
Brrrrrrr keep the winter woolies to hand.

As we plod through January, we are drawn even further into the throws of our coldest season and a wintry chill will hang in the air right the way through the week.
Monday will be dry, cold and frosty with many areas only slowly recovering to above freezing during daylight hours. A few wintry showers are likely to affect some coastal fringes but for most of us it will be dry and cold despite any sunshine on offer.
Another cold night will follow on Monday night and frosty conditions will prevail. However, across Northern Ireland a cloudier night is expected as a weakening front slowly arrives in from the west. This will fall as a wintry mixture of rain, sleet and snow, decaying as it moves eastwards.
The front will continue to progress slowly eastwards into Britain on Tuesday, introducing areas of cloud and a weakening wintry mix of rain, sleet and snow. The front is not expected to clear eastern areas until Wednesday. This should lead on to a mostly dry end to the week. Regardless of the weather type this week, our overnight temperatures will drop away below freezing and daytime temperatures will work terribly hard to get back up above freezing!
As we approach the weekend, we start to see the various computer models diverge as to what is expected to happen next. Saturday and Sunday herald the slow change from our very cold conditions as the Atlantic shows hints of becoming more gently mobile, allowing frontal system to seep in from the west.

Llun 26 Ionawr—Llun 2 Chwefror
Would you bet on what the weather will be?

Computer models continue to differ in their detail for their solutions for next week, but in general they are signalling a more mobile weather pattern. Temperatures will start to recover towards normal for the time of year and we are likely to see longer spells of rain, with snow being confined to hills and mountains. North western areas are expected to receive the bulk of the rain, while drier conditions are expected to occur more frequently in the south-east.

Llun 2 Chwefror—Llun 16 Chwefror
Pick a card, any card - sun, rain, snow or ice?

As with any long term forecast, the various model solutions create a challenge to identify the weather pattern type that we can expect. Whilst there is divergence in what the models say, the general trend is for a 'zonal pattern'. A zonal pattern is where we see west to east movement of weather systems. This implies that rain will move through relatively quickly, as will quieter drier and colder interludes and there will be greater day to day variation in wind, temperature, sunshine and rainfall.

Wythnos nesaf

Find out how well the various computer models handled the change for the coming weekend towards less cold conditions. As this outlook takes us to the middle of February, it will be of much interest to see what signals the start of spring will bring.

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 26 Ionawr

Crynodeb

Sul 25 Ionawr Cyhoeddwyd am 02:37

Crynodeb

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

Generally cloudy. Some outbreaks of rain, mainly north and west.
Today

Cloudy for most, but cold with clear spells in southeast England at first. Cloud then spreading to all parts, with outbreaks of rain across northern and western parts. A heavy band of rain arriving into the far northwest by evening.

Tonight

Cloudy and mild with a band of rain moving southeast across the UK, reaching the southeast shortly before dawn. Colder, breezier conditions with scattered wintry showers following from the northwest.

Monday

Cloud and rain clearing the far southeast around lunchtime. Scattered wintry showers across Scotland and Northern Ireland easing through the morning to become less frequent. Dry with sunny spells elsewhere.

Outlook for Tuesday to Thursday

Cloud and rain in the north, spreading south Tuesday. Remaining unsettled Wednesday and Thursday, with outbreaks of rain and blustery showers turning increasingly wintry, and with strong winds. Becoming cold.

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Rhagolwg UK Diweddarwyd 12:19, Sul 25 Ion Mae’r fideo yma ar gael yn Saesneg yn unig.