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Rhybuddion

Llun 23 Ionawr Cyhoeddwyd am 15:43

Rhybuddion DU

Rhybudd Tywydd

Cyhoeddwyd gan y Swyddfa Dywydd

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

Monday 23 January 2017

YELLOW WARNING for FOG for much of ENGLAND AND WALES

Valid from: 1700 on Monday 23 January

Valid until: 1100 on Tuesday 24 January

Areas of freezing fog, some dense, are expected to form again during Monday night and into Tuesday morning. The fog will become widespread in places, most likely in the southwest of the warning area early in the night and then in other areas later in the night and early on Tuesday morning.

Driving conditions will be difficult with journeys likely to take longer than usual and delays to air travel are possible.

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.

Friday 20 January

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 23 Ionawr Cyhoeddwyd am 10:00

Rhagolwg Misol

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

Crynodeb
High pressure loses its grip, but for how long?

Just a fortnight ago, a series of relatively intense weather systems brought a wintry spell of weather for all parts of the UK, with snow for many areas, accompanied by gales at times. Conditions settled down somewhat into last week though as an anticyclone built over our shores, making for a rather quiet week in general terms. That said, the cold and dry air that filtered across southern and eastern England from the intensely cold continent brought some interesting temperature contrasts across the UK. On Tuesday, the daytime maximum temperature struggled to reach just 2 Celsius at Langdon Bay in Kent, in stark contrast to a very mild 13 Celsius at Aboyne in Aberdeenshire. As the week progressed, the cold, clear, sunny conditions in the south gradually moved north to give all parts a pretty chilly end to the week.

The week ahead will begin with high pressure still firmly in control of the weather across large parts of the country, but as we head towards the coming weekend, weather systems will likely bring the return of a slightly milder feel.

February also looks like starting on a relatively unsettled note, but there are signs that pressure may start to build from the southeast again towards the middle of the month.

Read on to find out the details...
.

Llun 23 Ionawr—Sul 29 Ionawr
Gradually becoming milder for most, but not all!

After a particularly frosty start on Sunday morning (with patchy snow for mid-Wales, the West Midlands and Scotland), and temperatures of -8 Celsius recorded across southeast England, Monday isn't beginning on quite as cold a note. That said, the cold continental air which is hanging on means some harsh frosts still. The fog that will likely affect many parts of the country, particularly across southern and eastern parts of England, may linger in places, but elsewhere a relatively fine and dry day is expected.

Tuesday will begin with a frost again, with further foggy patches for southern areas, but a mostly fine and dry day is expected again for many although northwestern areas will turn wetter, windier and milder as that dominating high pressure starts to give way to Atlantic weather systems.

By Wednesday, drier air filtering in from the south and southwest will end the risk of early morning fog patches, with another largely fine and dry day expected for most, but again, conditions will be wetter and windier to the northwest. Thursday is expected to be broadly similar to Wednesday,

Through Friday and into the weekend, the high pressure system that has been keeping the Atlantic weather systems and the onset of milder air at bay for so long will finally slide away to the southeast. Consequently, most parts of the country will experience some wet and windy weather at times, with all areas become less cold.

Llun 30 Ionawr—Sul 5 Chwefror
February to start on a wet and windy note.

The final month of winter looks as if it will get off to a breezy and relatively mild start across most parts of the UK. At time of writing, the overwhelming majority of forecast computer models suggest that the jet stream will push a series of Atlantic weather systems from west to east across our shores. The heaviest and most frequent rain and the strongest winds are currently expected to be most prevalent across northwestern parts of the UK, with southeastern areas staying driest for longest. Although winds will likely often be strong, a slight frost is still anticipated for sheltered rural areas in the east at times.

Llun 6 Chwefror—Sul 19 Chwefror
High pressure to return across the southeast?

As is always the case, confidence in details of longer range forecasts tends to tether off significantly as we project further and further into the future. Even taking this factor into account, trends for the weather during the middle of February are proving difficult to determine. At this stage, analysis of the available forecast computer model data suggest that the relatively mild, wet and windy theme from the previous period will continue on into the middle of February. There are however some indications that pressure may start to build again across southeastern areas of the UK, which could mean the return of harsh frosts and cold sunny days for this part of the UK.

Wythnos nesaf

After what will most likely be a relatively mild start to February, are there any signs of a return of prolonged cold weather? Find out 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 30 Ionawr

Crynodeb

Mawrth 24 Ionawr Cyhoeddwyd am 02:40

Crynodeb

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

Dense fog in the south, damp and breezy further north.
Today

Dense freezing fog will be slow to clear across parts of southern England and Wales, but away from this it'll be cold with sunny spells. Scotland and Northern Ireland will be cloudier, breezier and milder with light rain at times.

Tonight

Locally dense fog will re-form across eastern and southern England. Elsewhere, variable cloud will give patchy frost for some, whilst northern England and north Wales may see some light rain.

Wednesday

Staying cold and dry across England and Wales with fog slowly clearing southern parts to give some sunshine. Milder and windier in the north-west with rain affecting the Hebrides later.

Outlook for Thursday to Saturday

Colder and windier for all on Thursday and Friday, with sunny spells by day and frosty nights. Winds easing into Saturday with showery rain, mainly in the north and west.

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