Wales - Regional Weather Discussion

[immortal1969]

Bit of slushy sleet/snow/rain on the Black Mountain Brynamman yesterday,no lying snow.

Edited December 10, 2011 by immortal1969

[keithlucky]

Very stormy week of weather for us in Wales strong winds Tuesday heavy rain followed by squally wintry showers.But Thursdays- Fridays storm if it continues on its present track will be more destructive it will cause extensive damage to Wales with power supplies and property damage right across Wales and southern UK.

Edited December 11, 2011 by keithlucky

[TonyH]

Guide to the weeks weather Monday December 12th to Sunday December 18th (west Wales and central Midlands specific)

Very windy, with damaging gales possible Tuesday, and again late Thursday to Friday. Rain or showers, hill snow, average to rather cold temps

Winds should drop off enough tonight for a slight frost for most.

Dry and bright to start Monday but cloud, wind, and then rain into west Wales though the afternoon, leading to a wet evening here, and then rainy for the Midlands overnight.

A very deep low close to Scotland on Tuesday so a very windy day with gales, and potentially severe gales causing damage during Tuesday for west Wales. Blustery showers and quite a cold day. Rather cold and windy on Wednesday with more showers, these heavy with hail, especially over west Wales, and where hill snow is possible, also perhaps with a longer spell of rain.

A brief ridge of higher pressure permits lighter winds and clearer skies Wednesday night with a slight frost. A frosty start Thursday, but the next storm system is approaching. This one is an explosively deepening low as it rapidly crosses the Atlantic, deepening from 990mbar Wednesday evening to perhaps as low as 930mbar during Thursday night, when it will be somewhere over the UK, and could be our deepest and most severe storms for a few years! It depends on the exact track as its still 4 days off, but should the centre pass through northern England, then Wales and the Midlands would see severe, destructive gales on Thursday night into Friday morning. However, should the low track further north, we would be spared the worst, but still gales for all of us. Areas worst affected will be seeing winds over 100mph, and with a more southerly track even the Midland would get 80mph gusts, so plenty of damage and danger is possible. Needless to say heavy rain for all, along with the gales, this turning to wintry showers on Friday and into the weekend, although any snow should be restricted to the high ground of Wales.

At this stage next Sunday hints at calmer, drier, conditions but frosty.

[J10]

I do hope that the projections for the winds above are overdone.

[SnowStorm(Jamie)]

Lots going on with the weather next week and we are going to have to keep a close eye on that very strong storm system for Thursday/Friday.

But focusing on Monday for the moment and the NAE is showing allot of heavy rain right across Wales as a frontal system moves in from the Atlantic:

http://expertcharts....121221_1112.gif

http://expertcharts....121300_1112.gif

Not only that but some fairly strong winds to go with it:

http://expertcharts....121218_1112.gif

http://expertcharts....121218_1112.gif

After this system clears through by Tuesday we are in a strong westerly flow, with showers/further bands of rain pushing through. Snow is possible on higher ground in Wales, take a look where the flow originates from which is NE Canada/W Greenland:

http://images.meteoc...N42-21_aag4.GIF

http://images.meteoc...UN42-7_ckr6.GIF

Also note the amount of cold being ejected out of that region into the Atlantic which will certainly have a role to play later in the development of Thu/Fri’s storm system. Looking at the GFS 12z for Wednesday you can clearly see the strong gradient out in the Atlantic to the north of the low pressure system there’s lots of cold polar air and to the south warmer sub tropical air is present as shown below on the Upper air chart:

This further develops the storm as it runs eastwards towards the UK and coinciding with a strong jet across the Atlantic & potential jet streak, this storm could become very severe indeed. You can see the jet stream chart below- The jet streak is the region of winds entering the South of the UK at 240mph:

Just to show the surface winds on the latest GFS 12z data:

http://hw.nwstatic.c.../105/ukwind.png

http://hw.nwstatic.c.../108/ukwind.png

Strong winds right across Wales not just on the coast with even stronger gusts possible perhaps even over 100mph on the NW tip of Wales. As always details will change and the exact track of the storm is undecided e.g. further north or further south – Although GFS & UKMO 12z’s showing similar ideas on the storm- Will be interesting to see what the ECM shows later.

Edited December 11, 2011 by SnowStorm(Jamie)

[J10]

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20111211;time=12;ext=105;file=ukgust;sess=6a13052f72fc0cff8a8df1cc9d4e9c04;

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20111211;time=12;ext=108;file=ukgust;sess=6a13052f72fc0cff8a8df1cc9d4e9c04;

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20111211;time=12;ext=111;file=ukgust;sess=6a13052f72fc0cff8a8df1cc9d4e9c04;

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20111211;time=12;ext=111;file=ukgust;sess=6a13052f72fc0cff8a8df1cc9d4e9c04;

The above 4 charts shown the current wind gust projection towards the end of the week. I do hope GFS is overplaying this. We all know of the GFS tendency to overdo "Dartboard" lows.

[Scarlet_Snow]

http://expertcharts.weatheronline.co.uk/daten/proficharts/en/nae/2011/12/11/basis18/ukuk/prty/11121318_1118.gif

Interesting NAE chart? If it verifies...not too far out though!

Edited December 11, 2011 by Scarlet_Snow

[swales]

http://expertcharts....121318_1118.gif Interesting NAE chart? If it verifies...not too far out though!

Not bad.

The high res NMM hasn't got that far out yet but here is the 06z for Tuesday. I hope Net Wx don't mind me posting:

(Note precipitation falling as sleet and snow on the very western Irish coast... Hope those cold uppers push as far over to us)

Edited December 11, 2011 by shaunwales

[Gorath]

Guide to the weeks weather Monday December 12th to Sunday December 18th (west Wales and central Midlands specific)

Dry and bright to start Monday but cloud, wind, and then rain into west Wales though the afternoon, leading to a wet evening here, and then rainy for the Midlands overnight.

That certainly didn't hold out for north west Wales!

We had heavy hailstorms, strong winds, and torrential rain this morning, it's now cleared up into a mostly blue sky day, with very little wind, and mild temperatures.

[TonyH]

No I forgot to mention the chance of showers, I underestimated their prevalence!

Exactly right for here though, a frost last night and a dry bright morning, clouding over with the wind picking up now.

It is a guide more biased to Ceredigion and Carmarthenshire as that's my local area of interest and where most of the people I send the forecast to each week reside, as well as Warwickshire.

Feedback is appreciated, as yours is the first to notice a difference in actual and forecast conditions, I take that as a good sign....

PS Gorath: You will be wet by the end of this afternoon!

Edited December 12, 2011 by TonyH

[andymusic]

Looks like we could well be in for some sleet and snow tomorrow - afternoon, overnight and into wednesday morning according to the nae -

http://www.weatheron...OP=0&INFO=0=

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=42&ZOOM=1&ARCHIV=0&WMO=&PERIOD=

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=48&ZOOM=1&ARCHIV=0&WMO=&PERIOD=

Edited December 12, 2011 by andymusic

[Scarlet_Snow]

Met office got a yellow warning out for tues/wed for snow on the hills above 100m, 10cm or more possible, and even slushy accumulations at lower levels!

[Gorath]

No I forgot to mention the chance of showers, I underestimated their prevalence!

Exactly right for here though, a frost last night and a dry bright morning, clouding over with the wind picking up now.

It is a guide more biased to Ceredigion and Carmarthenshire as that's my local area of interest and where most of the people I send the forecast to each week reside, as well as Warwickshire.

Feedback is appreciated, as yours is the first to notice a difference in actual and forecast conditions, I take that as a good sign....

PS Gorath: You will be wet by the end of this afternoon!

Are you threatening me with a supersoaker? hehe!

I wasn't intending to call your forecast into question, more, highlighting the difference in weather just a few miles up the coast (Wales is only small, after all).

Sorry if I came across as being dismissive - that wasn't my intention, but in hindsight, I see how my lack of eloquent-ness-ism could make it appear that way.

Met office got a yellow warning out for tues/wed for snow on the hills above 100m, 10cm or more possible, and even slushy accumulations at lower levels!

Hmm. After being let down by the yellow warning of snow last week, I won't hold my breath (but I will, however, wax my snowboard - just in case!).

Seeing as the wording covers Scotland and Ireland as well, I'm not convinced that the "Heavy showers will fall as snow over hills above about 100 m, and at times to low levels too" necessarily means Wales.

Here's hoping that I'll be a disappointed pessimist. But surely that makes me an optimist.

Oh, whatever, I just hope it does snow, and snow lots!

[andymusic]

Just had this in me inbox from the Meto

Yellow Warning of Snow for Wales

Yellow Warning of Snow for Wales : Blaenau Gwent, Caerphilly, Carmarthenshire, Ceredigion, Conwy, Denbighshire, Flintshire, Gwynedd, Isle of Anglesey, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Pembrokeshire, Powys, Rhonnda Cynon Taff, Swansea, Torfaen & Wrexham valid from 0300 Tue 13 Dec to 0300 Wed 14 Dec

[SnowStorm(Jamie)]

Just a quick update from me. Met Office yellow alerts being issued for a number of weather types across Wales this week, so theres allot going on Heavy rain, Wind & Snow:

http://www.metoffice...t_warnings.html

The NAE does show some very heavy rain crossing Wales tonight as that frontal system swings through:

http://expert-images...121221_1206.gif

Post frontal system we begin to see the cold westerly flow set in Tuesday with wintry showers about as we head into the evening:

http://expert-images...121318_1206.gif

Snow will be possible inland i imagine where the dewpoints are low enough. The surface flow seems to be from the West South West so it will be interesting to see how the dewpoints respond to this:

http://expert-images...121318_1206.gif < Surface wind

http://expert-images...121318_1206.gif < Dew Points

Worth watching over the next few runs.

Regarding the possible storm system Thurs/Fri we have seen the models so far today have somewhat diluted it, still we should keep watching over the coming days to see where the models go with this.

[TonyH]

1 Are you threatening me with a supersoaker? hehe!

2 I wasn't intending to call your forecast into question, more, highlighting the difference in weather just a few miles up the coast

1 Yes I am!

2 Why not! It was wrong for your back garden

Yes we are in a another week with a snow risk more especially for hills. Wondering whether these anonymously warm Irish Sea Temps will prevent snow falling for most again though, with marginal factors in play once more.

Edited December 12, 2011 by TonyH

[mikeocarroll]

Will be interesting to see if there's any snow or not over the next couple of days - I'll join the pessimist club with Gorath I think because the uppers are extremely marginal for snow; -5c uppers don't get over us until Thursday on the latest GFS & ECM runs (not sure about UKMO - NW charts for this only show pressure). Thicknesses are good though with the 528dam line over us for much of the week, and on a personal note being inland and hilly, Powys is about as a likely a place as any for snow in this set-up, so fingers-crossed. [now is that paragraph hedging bets or what?!]

I'm also interested by the GFS 6z which take Thursday-Friday's "storm" up the English channel and with cold uppers could give us some decent snow on the northern edge of the depression. And if the low does take this track then the weekend could be good and cold with a high chance of snow showers across the whole of Wales, especially on Saturday.

[Gorath]

I would love snow so much. But on the other hand, I've just seen the mountain webcams of where I'll be spending a week in January (WHOOOOA!), and realistically, I probably can wait, and keep some semblance of sanity.

Maybe.

I'd really love to get some boarding done in Snowdonia first though.

[soupsurfer7]

We should see some interesting weather tomorrow then? I for one will be glad to see some falling snow, even if it doesn't stick. Cambrian mountains look like they're in the firing line with a westerly breeze.

[Gavla]

Hi guys, dont post often, well last winter was my last time!. Anyway nice to see some warnings over us including snow for tomorrow evening, seems to have appeared out of nowhere, surely its going to be marginal im 107m asl lol, looking forward to this week possible storms and snow I couldnt wish for more action bring it on !

[Gorath]

We should see some interesting weather tomorrow then? I for one will be glad to see some falling snow, even if it doesn't stick. Cambrian mountains look like they're in the firing line with a westerly breeze.

What exactly do you mean by "cambrian mountains"? I've never seen a concrete definition, and it appears to cover everything all the way from North to South Wales.

[swales]

What exactly do you mean by "cambrian mountains"? I've never seen a concrete definition, and it appears to cover everything all the way from North to South Wales.

Originally the term "Cambrian Mountains" was applied in a general sense to most of upland Wales. Since the 1950s, its application has become increasingly (and arguably illogically) localised to the geographically homogeneous Mid Wales uplands known in the Welsh language as the Elenydd (which extend from Pumlumon to Mynydd Mallaen).

[Gorath]

Yes, but what does soupsurfer mean by it? It's a very ambiguous term, it seems, so I'm interested in where he was referring to.

[Bobby]

Met Office have forecast up to 4 inches of snow for me tomorrow and Wednesday (accumulations above 100m), bit sceptical about that I have to say. Can anyone else see that happening??

Also there's a potential for a channel low snow event on Friday if the trend continues to weaken the low and push it further South.

Bit of a long shot though...

[Gorath]

Met Office have forecast up to 4 inches of snow for me tomorrow and Wednesday (accumulations above 100m), bit sceptical about that I have to say. Can anyone else see that happening??

I doubt it. The wording on the warning also covers Scotland, so I strongly suspect that it's the Scots that are going to see snow down to that level.