Wales Cymru Cold Spell Discussion.

[BranMan]

Wales: 60%Blaenau Gwent60%Caerphilly60%Merthyr Tydfil60%Monmouthshire60%Powys60%Rhondda Cynon Taff60%TorfaenHeavy Snow0600 Tue 291800 Wed 30There is a high risk of severe weather affecting parts of Wales and central England. Periods of sleet and snow will spread from the south during Tuesday and are likely to persist well into Wednesday. The snow will be heavy at times with drifting likely in strong easterly winds, leading to blizzard conditions over hills.

10-15cm of snow is likely widely with 25cm or more possible over high ground of Wales.

Disruption to transport and power supplies is likely.

This warning will be updated on Tuesday morning unless superseded by Flash Messages.

Issued at: 1105 Mon 28 Dec

[Ukwoody]

Just spare a thought for us here in Milford Haven then. We hardly ever get ANY snow. Gutted - again.

woody

[DeepSnow]

So at the moment does it look like we will see rain or sleet instead of snow now down here in the south?

[J10]

So at the moment does it look like we will see rain or sleet instead of snow now down here in the south?

You msy see some snow, but possibly not settling, but a range from heavy snow to heavy rain is possible.

[bennytes]

Absolutely no idea. I suspect the timing of the front is good. Temps will be low by 11. Depends on how cold the air is I guess. This is a nowcasting event. No-one's gonna know till it happens. What I do suspect is we might get hit but a difference of miles (Maesteg even Sarn) is gonna make a huge difference.

agreed

i think even you lot down there are gonna get an hammering from this though. This COULD be memorable, (or a damp squib! )

[DeepSnow]

You msy see some snow, but possibly not settling, but a range from heavy snow to heavy rain is possible.

ok thanks, is there still enough time for things to change and get better for us, or is it getting to close now?

[J10]

ok thanks, is there still enough time for things to change and get better for us, or is it getting to close now?

Still time to change, but it may change for the worse as well. Latest BBC forecast showed snow inland, and a wintry mix around the coast.

[bennytes]

ok thanks, is there still enough time for things to change and get better for us, or is it getting to close now?

often, in situations like this in the past, the low will struggle to make progress, and dive south and give France a dumping. this time though, if it goes more southward, WE are the ones who will get a dumping. It may even stall, and dump all it's moisture over us.

who knows, eh?

it'll be interesting, whichever way it goes.

[Blackjack]

Can't wait. I'm between Abergavenny and Hereford so i should be right in the firing line until Wed afternoon

Edited December 28, 2009 by Blackjack

[alijoe]

Can't wait. I'm between Abergavenny and Hereford so i should be right in the firing line until Wed afternoon:yahoo:

You lucky devil... In Magor here so nothing as usual

[bennytes]

just saw this on the South West thread...

Afternoon folks.

Well, an interesting morning and doubtless tomorrow (and Wed, and Thurs) will prove equally challenging. There's a lot at stake, forecasting wise, because for some areas - some - this next bout of wintry weather could prove highly newsworthy as well as downright dangerous / disruptive.

You've doubtless seen how this morning, after further consultation through the PWS, the UKMO issued an early warning for severe (snowy) weather, applying, at present, to parts of Wales and adjoining English counties. A broader swathe of advisories (and note, these a different to warnings in the strict sense) apply to other areas - including the westcountry - albeit for differing but well-reasoned potential consequences.

Since I started work at 0355 today, I've seen and been briefed on two separate NAE runs, alongside some detailed high-res prognoses for rainfall / snowfall totals. An earlier snapshot of such UKMO Chief Forecaster briefing output is viewable on my blog today (http://bbc.co.uk/ianfergusson) for those interested - it offers a flavour of how we tweak our TV and local radio forecasts to cater for the sort of sub-regional outcome expected in the next 48hrs.

Here's the latest thinking, in summary:

RAINFALL - some heavy and in itself likely to be disruptive for some areas - is the core story for most of the westcountry overnight and into tomorrow. Localised flooding quite possible for some. The very tight WBFL gradient developing overnight on the northern flank of PPN will mean an equally tight areal discrimination from transition of rain to snow, with the WBFL typically around 200-400m but as you might expect, this will be readily dropping in heavier PPN to offer a wintry flavour. Equally, into tomorrow the surface temp variance will be extremely marked; e.g., Plymouth and much of Cornwall positively basking (despite the inclement skies and wind!) at >10C whilst up in the likes of Bristol and Glos, ambient will be closer to 3C. Either way, a drab and pretty ghastly day wherever you happen to venture.

The prospect of anything other than rain for all of lowland SW Peninsula and lowland Somerset / Dorset / Wilts is effectively tiny. High-res modelling gives around a 30% risk of snow further north over high ground of Somerset (Mendips Plateau) and upland mid-Wilts, but this risk is elastic and low confidence.

SNOWFALL - the only (westcountry) area with fairly high confidence for possibly quite potent snowfall developing tomorrow is Gloucestershire. We've been at pains to signal this on TV and in much more detail in forecasts today on BBC Glos. Specifically, the Forest of Dean looks like an area where the situation could quickly deteriorate during tomorrow (as you might have guessed, with it nestled alongside the area of most concern delineated on the UKMO Warning page). Cotswolds also look likely to take a wallop, and we've equally been at pains to warn residents there how smaller roads could become impassable and remain so for quite a time.

Snow risk elsewhere - e.g., Bristol, Bath, B&NES, S Glos - remains every bit as marginal as before (see yesterday's forum posts) but clearly, the UKMO has to play the pragmatic card and retain the existing advisories, now extended into other districts, e.g., of Wilts. Effectively, for these regions we'll be forced into a nowcast / short-range forecast and warning scenario through tomorrow, given the low confidence bounds that separate mere 'snow' from snow befitting an actual warning, versus mere advisory. Trust me, it's not plucked out of thin air - these upgrades only happen after detailed analysis and debate via PWS expertise. ]

For our (BBC) part, we've elected (rightly, I think most would agree) to highlight the snow potential for these marginal arreas rather than downplay it, because history amply demonstrates to us how the backlash of forecasting rain but not correctly forecasting disruptive snow is massive and potentially deadly; conversely, forecasting rain that never becomes promised snow largely bothers / upsets schoolkids, skiers and varied snow aficianados, but is otherwise speedily forgotten (and often a major relief for travellers).

SNOWFALL TOTALS: This might shock some other forums here (Midlands / Wales), but our new NAE run is eager to talk-up some 50cm of snow by the end of Wednesday for parts of central/SE upland Wales (and that's even without the drifting, which will be a major factor everywhere). Our best estimate for neighbouring areas such as Forest of Dean could total 20-30cm (same caveat re drifting) and more widely >10cm. Whatever the end result, a recipe for some very, very nasty conditions and some areas such as the Brecon Beacons, parts of Herefordshire etc., will be wholly impassable.

REST OF THE WEEK: Sees the frontal zone effectively stall over the same areas into Wednesday and then sink southwards and yield a moore expansive area of (perhaps disruptive) snow across much of southern England, perhaps ultimately all the way down to the south coast. Some of our modelling of the New Year's Eve events are deeply troubling, with a risk of severe weather (blizzards) into southern-central / SE England and London, which would clearly have major ramifications at a time whhen many people are either travelling or otherwise planning New Year's Eve events, etc. But that's miles away and obviously confidence is low.

If time allows, I will post on updates from the next NAE run.

Best

Ian

[keithlucky]

Still looks maginal on s wales coast the snowrisk chart wales will get a battering 50cms travel caos.Still though as its cold air will dig in given us a few cms in coastal regions before clearing.

Edited December 28, 2009 by keithlucky

[derrylynne]

Still looks maginal on s wales coast the snowrisk chart wales will get a battering 50cms travel caos.Still though as its cold air will dig in given us a few cms in coastal regions before clearing.

Looking at the latest it seems us here in upper Valleys are going to get buried. This could be the worse snowfall here for very many years with none going anywhere for days after this starts falling. Must admit we went out and done a full shop today so we are prepared. But a hell of a shocker to see that we may get up to 50cm - that is over 19 inches - without the drifting. This could be an interesting ride...

[bennytes]

i'm sitting here in my living room in Maesteg, fire on, heating on, and my toes are bloody freezing!

gonna turn them both up to full now, and put my thermal socks on. :lol:

i think this might well be a memorable couple of days, in the country, and on this forum.

don't forget to WARN people, friends and neighbours. I just phoned my brother and my mate, and they both had no clue of the POTENTIAL here.

better safe than sorry. they are talking about possible power disruptions. tell whoever you inform about this to make sure they have candles in the house JUST IN CASE. Food shouldn't be as much of an issue because everyone's fridges should still be quite full from Christmas.

apparantley, Tesco's here in Maesteg is chock a block today with people panic buying.

[dogs32]

i'm sitting here in my living room in Maesteg, fire on, heating on, and my toes are bloody freezing!

gonna turn them both up to full now, and put my thermal socks on.

i think this might well be a memorable couple of days, in the country, and on this forum.

don't forget to WARN people, friends and neighbours. I just phoned my brother and my mate, and they both had no clue of the POTENTIAL here.

better safe than sorry. they are talking about possible power disruptions. tell whoever you inform about this to make sure they have candles in the house JUST IN CASE. Food shouldn't be as much of an issue because everyone's fridges should still be quite full from Christmas.

apparantley, Tesco's here in Maesteg is chock a block today with people panic buying.

yea same here!!!

Going to make sure my dad's OK JUST IN CASE as he is disabled through a stroke.

Might not get much here,but t hen again we might see incredible amount's...

Best to check people I reckon to see if they are OK...

This might get nasty in some places,best be safe than sorry

[Jackfrost]

50cm... That has to be some sort of joke! Certainly something I haven't seen in my lifetime.

[willitbsunny]

Is it safe to tell the children they will be building snowmen tomorrow then? Heaven knows they've been disappointed enough in the past!! (I'm in Brynna btw)

[bennytes]

50cm... That has to be some sort of joke! Certainly something I haven't seen in my lifetime.

yeah, and you are RIGHT in the firing line too!

http://www.metoffice.gov.uk/weather/uk/radar/

precipitation just now hitting the extreme south west tip of Ireland.

[Jackfrost]

yeah, and you are RIGHT in the firing line too!

A huge smile just spread across my face.

Hopefully I'm about to re-live the legendary snowfalls of 8 years before I was born!

[derrylynne]

I have often been told about the snowfalls that left the valleys cut off for weeks. Before I moved here. Always wondered what it must have been like. Looking like we are about to find out. laughs.....

[andy_leics22]

Guys in Wales... I would not be expecting too much just yet. All the models are disagreeing with each other on what will happen. A few models are suggesting that anywhere below 300m in Wales will get rain or sleet. So don't think that it is a garaunteed snowfest yet. Tomorrow will be much a case of nowcasting and radar watching to see where the band will end up and how far North the mild air will be. I would say though people in South Wales don't get your hopes up just yet... Because it is very borderline if you are lower than 300m.

i'm sitting here in my living room in Maesteg, fire on, heating on, and my toes are bloody freezing!

gonna turn them both up to full now, and put my thermal socks on.

i think this might well be a memorable couple of days, in the country, and on this forum.

don't forget to WARN people, friends and neighbours. I just phoned my brother and my mate, and they both had no clue of the POTENTIAL here.

better safe than sorry. they are talking about possible power disruptions. tell whoever you inform about this to make sure they have candles in the house JUST IN CASE. Food shouldn't be as much of an issue because everyone's fridges should still be quite full from Christmas.

apparantley, Tesco's here in Maesteg is chock a block today with people panic buying.

Hmmm lol, you may well be slated by friends and neighbours if this goes belly up.

[Cymro]

Guys in Wales... I would not be expecting too much just yet. All the models are disagreeing with each other on what will happen. A few models are suggesting that anywhere below 300m in Wales will get rain or sleet. So don't think that it is a garaunteed snowfest yet. Tomorrow will be much a case of nowcasting and radar watching to see where the band will end up and how far North the mild air will be. I would say though people in South Wales don't get your hopes up just yet... Because it is very borderline if you are lower than 300m.

Quite agree its very close dont think ive ever felt so much tension over the weather.

[Supercell]

I imagine many of you will be excited by Ian Fergusson's analysis of the situation. I very much enjoyed the talk of some incredible depths, in excess of a foot (without drifting) in certain areas. I hope that those of you who have the snow make the most of it tomorrow and the days ahead. Take pics / videos etc. This could be the sort of event that many of you have been waiting for ! Enjoy.

[Jackfrost]

If I'm honest I can remember a few situations like this in recent years, the last being the "winter storm" that was forecast for February 10th (I think) this year which brought only gales, rain and wet snow, so I shall return to my usual cynicism.

Out of interest, does anybody know if the snowfall of 1982 was this marginal?

Edited December 28, 2009 by jackfrost

[DeepSnow]

I just hope now it goes right for once and we get snow down at my level, im not to hopfull anymore but i it would be really nice to get a good snowfall, i know we won't get anything like what the valleys and higher ground will get but still, a few inches would be good as this winter i haven't really had anything snow wise. Glad to see the temp is dropping now at 4.1C.