Wales - Regional Weather Discussion

[Bobby]

I can see Pen Y Fan from here and can't see any snow. I'd be surprised if we saw anything more than snow on the mountain tops with some wet sleety stuff down to lower levels next week, I'm not excited anyway. Would love some snow though.

Edited December 3, 2011 by Barb-

[SnowStorm(Jamie)]

NAE now out

Dewpoints sub zero across Wales Monday 6am

http://expertcharts....120506_0306.gif

850Hpa at -6 Mid and N Wales, -5 S Wales

http://expertcharts....120506_0306.gif

Rain/ Snow Charts, mix of rain and snow

http://expertcharts....120506_0306.gif

In a nutshell, NAE synoptically very similar to GFS but going for lower ground temps esepcailly round coasts , which in turn reduces the surface dewpoint.

Indeed if the GFS & NAE dewpoints are to be believed then those showers shown on the NAE will gradually turn to snow over Ceredigion away from the immediate coast.

Edited December 3, 2011 by SnowStorm(Jamie)

[welshgritter]

So reading between the lines....looking like Sunday/Monday possibly Tuesday I will be getting minus ground surface temps for S Wales in my commercial reports?

[TonyH]

I would say that inland areas getting frost Monday and Tuesday mornings, and a threat again later in the week.

[andymusic]

Definitely gonna be cold this week that's for sure - the odd flake of sleet or snow could well turn up anywhere - but nothing like our deep freeze scenario we had last year - not yet anyway!

Scotland will take the brunt of the cold weather this week - already filling in nicely at The Lecht

Chance of a few wintry flurries into central Wales Sunday into Monday

Edited December 3, 2011 by andymusic

[Scarlet_Snow]

Can't complain with a bit of wintry weather thats likely to happen this week, even if it just means a few flakes or hail showers or whatever, anything's better than what we've had recently. I enjoy looking at the pictures from Scotland etc. like above! May even get something similar down here this winter if we are lucky, fingers crossed

[SnowStorm(Jamie)]

Again the NAE shows the potential for snow showers during Monday in parts of North and West Wales.

Upper air temperatures over Wales generally around -5C lowering further to -6C in Northern Wales as we go further in to Monday:

http://expertcharts....120500_0312.gif

http://expertcharts....120506_0312.gif

Dew points below 0C although higher around those coastal fringes:

http://expertcharts....120500_0312.gif

http://expertcharts....120503_0312.gif

http://expertcharts....120506_0312.gif

GFS has dewpoints around about 0C in the west lower towards North and East.

sub 528DAM line is shown to be covering Wales during this period:

http://expertcharts....120500_0312.gif

http://expertcharts....120506_0312.gif

And now we can look at the precipitation charts from the NAE:

http://expertcharts....120500_0312.gif

http://expertcharts....120503_0312.gif

Just to point something out ill post the precipitation accumulation @ 48hrs:

http://expertcharts....120512_0312.gif

You can see these amounts are highest over the north Wales coast, Gwynedd & Ceredigion.

Going by all that Gwynedd & Ceredigion may see a "streamer" set up (line of showers pusing in from Irish sea) which will be of rain/hail on the coastline but further inland i tend to favour some snow even towards lower levels there, especially as this is happening during the early hours of Monday Morning:

http://expertcharts....120500_0312.gif

Due to the moderating effect of the warm Irish sea i dont think anything will stick to lower levels, adding to this the strong contrast between the warmer irish sea and the colder upper air flowing over it will promote quite allot of convection and the showers on Monday in North Wales could well be accompanied by some Thunder.

http://hw.nwstatic.c...ukstormrisk.png

http://hw.nwstatic.c...ukstormrisk.png

[TonyH]

One factor that may negate snow in Ceredigion below about 300masl is sea temperatures that are still above 10c, and so the WNW wind will need a lot of cooling by the uppers, and so any snow likely to have melted below this level.

Edited December 3, 2011 by TonyH

[soupsurfer7]

I have a feeling Monday will be a day of snow falling, but probably not sticking in Ceredigion.

Edited December 3, 2011 by soupsurfer7

[TonyH]

Guide to the weeks weather Sunday 4th to Saturday 10th December (west Wales and Midlands specific)

Headline: Rain or showers at times, quite cold early and late in the week, some snow for high ground

Autumn 2011 was the second warmest in the central England temperature series that goes all the way back to 1659, with only 2006 being warmer. Rainfall wise for November, it was rather dry, with 93mm falling on Llanwnnen, 45mm on Coventry and just 31mm on Rugby (only half the average here). Maximum temperatures below 5c early and again late this coming week will be a shock to the system with a bit of a taste of Winter!

Sunday to Tuesday southern Britain is in a rather cold west to NW flow of air, this originating over the Canadian Arctic, although greatly warmed by its long passage across the Atlantic, and nowhere near as cold (or snowy) as Scotland will be. Quite windy with showers at times for most of us, these most frequent for west Wales and during Monday, with fewer reaching the Midlands, unless the 'Cheshire gap' allows them through, and more in the way of dry bright weather here. Showers will be heavy at times, with hail quite a feature for west Wales, and snow for the hills, more especially Snowdonia and the tops of the Cambrians, although it is unlikely that Lampeter will see more than a few wet flakes. Frosts could well be a feature given clear enough skies and lighter winds during the Sunday and Monday nights.

It turns milder Tuesday night through to Thursday but still quite windy, with some more rain at times, but dry brighter intervals too.

A great deal of uncertainty in the model outputs for the end of the week, but it looks as though another short lived colder snap arrives with more wintry showers of rain, hail, sleet, and snow for the hills again, with overnight frosts returning too.

ECM

maintains the procession of cool lows from the WNW next weekend, while

GFS

moves high pressure towards western Britain, however the

GFS

runs have been fluctuating wildly recently, so the more unsettled theme could be back by the pub run!

Edited December 3, 2011 by TonyH

[J10]

Good Analysis there Tony ,we have better analysis here than the MOD thread.

One thing to consider when looks at showers early next week is that the wind direction is more of a NW than a NNW, as a result showers may well push further east than would normally be the case.

[Jayfromcardiff]

Hi all, glad to be back for winter - lets hope we all get tons of snow!

[Daniel Miller]

Hi all, glad to be back for winter - lets hope we all get tons of snow!

Hey Hoping it's similar to last years snow watching on here! Have a feeling we won't see much this side of New Years, after though, maybe something of a mix of last years cold/snow and Jan 2010's length, or longer! (hopes )

[J10]

http://www.metoffice...st/?tab=fiveDay is a very handy resource as well.

Any sign of Adam so far this winter.

Nearly forgot today's update

Latest Update

This is Sunday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Monday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Tuesday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Wednesday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Thursday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Friday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Saturday's 850Hpa for 6am Next Mon http://hw.nwstatic.c.../h850t850eu.png

This is Sunday thickness chart for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Monday thickness chart for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Tuesday's thickness chart for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Wednesday's thickness chart for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Thursday's thickness chart for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Friday's 850Hpa for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

This is Saturday's 850Hpa for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

Very similar to recent days, a very slight downgrade though. No real change in my thoughts.

[SnowStorm(Jamie)]

http://www.metoffice...st/?tab=fiveDay is a very handy resource as well.

Yup just been checking that link now, i certainly like the features on the map menu.

I have found this website for Irish sea surface temperatures: http://cobs.pol.ac.u...plot=t&type=034

Some of those temperatures are over 12C if not more, it also has the NAE model for the Irish sea area but only goes out to t-36hrs.

Just going over the latest run of the NAE now, much the same as earlier, although the colder air starting to lift out from the south by the end of the run. Precipitation amounts will vary from run to run but using the accumilation again @ 48hrs still shows the same general idea of where the showers will be focused: http://expertcharts....120518_0318.gif

This run actually brings the colder thickness values further south over north Wales for a time, around sub 522DAM i believe which would make snow more likely to lower levels if other factors such as Upper air & Dewpoints remain supportive: http://expertcharts....120500_0318.gif

[Marcus_surfer]

Nice to be back in here folks, looks great up in scotland at the moment, looks like Snowdonia and the beacons may have some snowfall tonight and monday.

[DeepSnow]

Yeah and Meto say Showers in North and West Wales, away from immediate coast falling as snow! So some lucky people could get their first snow of the winter, though I think us in the south, esp people like me who are below 100M might have to wait a fair while before we see any snow! Im sure it will happen in Jan/Feb if it doesn't this month though!

[J10]

What has surprised me is how well this has held up and I expected it to downgrade to a non event.

Northern parts of Wales can expect to see a little snow, while southern areas might see a little, but I think hail and sleet is possible for those areas missing out on any snow.Settling snow though is likely to be reserved for high ground in the north and possible the Beacons in the south.

Given the current synoptic setup though, this is a bonus.

All my opinion of course,

[soupsurfer7]

I'm hoping to see a white Plynlimon in the morning

[SnowStorm(Jamie)]

The NAE still showing showers driving into the Gwynedd & Ceredigion area later tonight and through the early hours of Monday morning:

http://expertcharts....120500_0406.gif

http://expertcharts....120506_0406.gif

Upper air temperatures around -6/-5C with dewpoints below freezing in that area, taking into account the freezing level and the possibility of heavy showers id say during the early hours wet snow down to about 150M with just rain and hail on the coast however. Accumilating snow will not be a feature away from the Brecon Beacons & Cambrian mountains

[DeepSnow]

Just out of curiosity, next year I hope to go to Aberystwyth Uni, how does that area normally do for snow over winter?

[keithlucky]

A dissapointing start to winter considering how spoilt we were last year,unless we can get a HP to alter the flow of the gulf stream what we see is what we got .A westerly flow with rain or showers at times,this weather pattern could easily last all the way to xmas .ideal weather for N Scotland but not for us in the south UK .

[SnowStorm(Jamie)]

Just out of curiosity, next year I hope to go to Aberystwyth Uni, how does that area normally do for snow over winter?

In Aberystwyth you will be exposed to showers/streamers coming in off the Irish sea on NNW/NW flows more so than Bridgend is, provided it is cold enough these can produce a fair amount of snow.

[soupsurfer7]

Just out of curiosity, next year I hope to go to Aberystwyth Uni, how does that area normally do for snow over winter?

Aberystwyth does well for snow when we have northerlies and northwesterlies due to the irish sea, as snowstormjamie has said. However, we do very badly from snow coming from the east, because the cambrian mountains block weather coming from the east. In an easterly set up, sunny and cold conditions is what we normally get. I grew up near and around Aber and from the late 90s to about 2007/08 ish there was very little snow, but in recent years we have been very lucky Also the coastal position means we miss out on a lot of marginal situations. It is very common in winter to have snow about 10 miles east of Aber in the hills and nothing at all in the town itself.

[andymusic]

Beautiful big rainbows as the showers bang through here - amazing - like some alien has turned on a light - and the -5 upper air comes ever closer!

EDIT - Snowing in Carlisle! and Scotland looks fairly white too!

Edited December 4, 2011 by andymusic