Wales - Regional Weather Discussion

[J10]

Well- middle of Jan and, to my mind, there's nothing the right side of marginal, snow-wise, for anywhere in Wales (apart from the very highest peaks in Snowdonia) for the foreseeable future, by which I mean 5-7 days.

All the huff and puff in the model thread regarding the ECM/GFS battle of the models remind me what an inexact and underdeveloped science weather forecasting is, even for trends, beyond that range.

The lack of a foreseeable significant pattern change also calls into question some of the long-range forecasts based on stratospheric warming and what-not, which were forecasting the northern blocking that may have brought some wintry weather to Wales by now.

Personally, I tend to go with GFS at 5-7 days- to my mind it picked out the cold spells of Feb 2009, Dec 2009 and Nov/Dec 2010 pretty accurately from that range and I've no reason to think that it won't do again.

Let's hope the synoptics for a cold spell slot into place for us soon...

I am not sure that I am agree re the pattern change, it is very visible that the Polar Vortex is of a much reduced size than it was previously, an it is impacts of this that we are starting to see causing such fluctuation in the model outputs, it is often been mentioned on the Stratosphere thread, that warmings have not necessarily been in right place for Western Europe to benefit.

[SnowStorm(Jamie)]

Indeed looking at the models we do have a toned down North Westerly blast for the end of the week with high pressure just to our west. Will check the updated Met Office fax charts later but id imagine nothing particularly wintry from this NW shot. Pressure is higher over Wales and the coldest air is further east as shown on the ECM 12z @ 96hrs:

http://images.meteoc...CM0-96_aka5.GIF

Cold day here today and the temperature is currently 0.8C.

[keithlucky]

Do you agree with the country file forecast then Jackone?

[J10]

Do you agree with the country file forecast then Jackone?

I didn't see it, Current Metoffice guidance is for Wales on Wednesday - Friday.

Outlook for Wednesday to Friday:

Cloudy with spells of rain on Wednesday. Brighter on Thursday and Friday with showers, which may turn wintry, especially over high ground, and blustery winds.

Unless the models change for the better, neither will the forecast.

A lot of options remain available for the weekend.

[benb]

I am not sure that I am agree re the pattern change, it is very visible that the Polar Vortex is of a much reduced size than it was previously, an it is impacts of this that we are starting to see causing such fluctuation in the model outputs, it is often been mentioned on the Stratosphere thread, that warmings have not necessarily been in right place for Western Europe to benefit.

Accept your point about the Polar Vortex, but seems to me (and this may be a little simplistic!) that the Azores High (or variations of) has been driving our weather pretty much all autumn and for the first half of the winter, allowing only variations of S through to NW winds. (Exception being the deep depression of mid Dec that went further south than initially predicted, giving Wales some frontal snow, at altitude, and a subsequent wintry NWerly).

Supported by the Azores High, the jet stream has consistently blasted through and kept us synoptically pretty much at square-one and, for the next week or so, this Azores High/ Mid-Atlantic Jet combo looks set to continue...

Correct me if I'm reading this the wrong way, but I'm seeing no signs of any significant hight rises to our north and the Russian High appears too far east (and inconsistently modelled) to be likely to influence us in Wales.

When looking at the models, what form might the first signs of a pattern change take?

[J10]

Not pretending to know this in detail, and I may be completely wrong

But I think the Azores High is more a symptom of the pattern, rather than the driver of the pattern The Jet Stream has largely been further north this winter partly due to the strong Polar Vortex, which is finally breaking down.

What I tend to look for is the absence of blues and purples around the Greenland area in particular and the North Pole in General. For Northern blocking the emergence of Green and Yellow colors around Greenland is what we are striving for.

http://cdn.nwstatic.co.uk/ecmimages/20120116/12/npsh500.024.png

http://cdn.nwstatic.co.uk/ecmimages/20120116/12/npsh500.240.png

is the Northern Hemisphere 500HPa chart which tends to be quite good.

But I would recommend asking the question in this thread

http://forum.netweat...2/page__st__980

As their knowledge of the situation is far greater than mine.

[welshwizard]

hi guys and girls,i am correct in saying that 5 days ago the models showed cold to be here now? and now it still shows the real cold to be here in 5 days. what im trying to say is why does the weather always seem to be 120 or 240 hrs away? and if so is there any point in taking any notice at all until it gets to say 72 or even 48 hrs away. i myself dont have a clue but from what i have read this seems to be the case quite a lot. also when the wind and rain are due in they can say on a monday that friday we will have very heavy rain and gales but when it comes to cold or even sun they dont seem to have the same confidence.

[benb]

Not pretending to know this in detail, and I may be completely wrong

But I think the Azores High is more a symptom of the pattern, rather than the driver of the pattern The Jet Stream has largely been further north this winter partly due to the strong Polar Vortex, which is finally breaking down.

What I tend to look for is the absence of blues and purples around the Greenland area in particular and the North Pole in General. For Northern blocking the emergence of Green and Yellow colors around Greenland is what we are striving for.

http://cdn.nwstatic....npsh500.024.png

http://cdn.nwstatic....npsh500.240.png

is the Northern Hemisphere 500HPa chart which tends to be quite good.

But I would recommend asking the question in this thread

http://forum.netweat...2/page__st__980

As their knowledge of the situation is far greater than mine.

Thanks Jackone- really useful.

Yellows and greens it is then!

[benb]

hi guys and girls,i am correct in saying that 5 days ago the models showed cold to be here now? and now it still shows the real cold to be here in 5 days. what im trying to say is why does the weather always seem to be 120 or 240 hrs away? and if so is there any point in taking any notice at all until it gets to say 72 or even 48 hrs away. i myself dont have a clue but from what i have read this seems to be the case quite a lot. also when the wind and rain are due in they can say on a monday that friday we will have very heavy rain and gales but when it comes to cold or even sun they dont seem to have the same confidence.

It does seem like that, doesn't it!

I think it's probably to do with snowy weather being usually so marginal in this part of the world: it needs a lot of factors to come together for it to actually happen, whereas rainy, unsettled weather occurs, usually, with large parameters of error and is therefore easier to predict accurately.

It perhaps is also the case that the forecasting systems are more used to dealing with 'typical' weather i.e. Atlantic flow and are in a data sense more 'experienced' and so accuracy is more likely. In contrast, weather patterns that bring us snow, are less frequent and therefore the models are less 'experienced' and therefore less accurate.

There's probably also an entirely unscientific frustration factor involved, too- typically, cold weather arrives in Wales last and leaves first (generalisation, I know, but there's some truth in it!), especially in the far west. Therefore, at any hint of cold/snow we tend to follow developments very closely and notice any inaccuracies in the forecasts. In contrast, forecasts for rain don't get anything like the same scrutiny...

Well that's what I think, anyway!

[dyl232]

hi guys and girls,i am correct in saying that 5 days ago the models showed cold to be here now? and now it still shows the real cold to be here in 5 days. what im trying to say is why does the weather always seem to be 120 or 240 hrs away? and if so is there any point in taking any notice at all until it gets to say 72 or even 48 hrs away. i myself dont have a clue but from what i have read this seems to be the case quite a lot. also when the wind and rain are due in they can say on a monday that friday we will have very heavy rain and gales but when it comes to cold or even sun they dont seem to have the same confidence.

....... I know what you mean there 100% with you dont see the point wasting time model watching they just change just before the time comes. Edited January 16, 2012 by dyl232

[keithlucky]

Yes the models are all over the place again GFS raises the possibility of wintry showers over North Wales as the HP retreats westwards.I am convinced that the reason the charts are all over the place is that the weather is about to change ,and February will be cold as continental air takes hold.

[J10]

GFS 18Hz really throws another spanner in the works.

From this

To

in 6 hours

Just when you think things were sorted.

and by T+156, massive changes reducing chances of cold solution.

---------------------------------------------------

http://www.wetterzentrale.de/pics/archive/ra/2010/Rrea00120101127.gif

This is the chart for 27 November last yr when we have proper Northern Blocking.

[benb]

Says it all really...

May well be gone again come the morning!

[keithlucky]

The exact same forecast as forecast as countryfile gave Jackone wintry showers weekend.

[welshwizard]

it all does seem very strange well it does to me who knows nothing lol,how can 6 hrs give such a diff? and as benb says all be diff by the morn,probs blizzards in the morn then mild by afternoon,wont be sun as we dont get sun in Wales.

[Buzzit]

Models are pathetic - schizophrenic would be a kind description - If there is no major pattern change shortly then there should be a whole team of scientists working out what the hls gone wrong !

[TonyH]

Excepting my beloved GFS!!

Edited January 16, 2012 by TonyH

[Cymro]

Excepting my beloved GFS!!

I've got to love this comment made my night

[keithlucky]

Just as was mentioned a couple of days ago been waiting for the met to mention that colder spell of weather was on the way .I quote There is considerable uncertainty regarding the weather during the last few days of January. The slightly more probable scenario at present is that conditions will remain similar to those described above. However there is also a significant risk of much colder weather becoming established right across the UK, with snow in places and widespread overnight frosts.Just to add to the charts confusion lol.

[welshgritter]

So then all. I have been a busy boy....nice bit of cold - so when do I expect to see it come back? Cheers,

[keithlucky]

Should have a frost on Friday possible wintry showers frost Saturday Sunday,Who knows after that still think February looks pretty cold.

[J10]

Pretty much back to where we were before last night's GFS 18Hz.

Does now look a bit cooler over the weekend than Thursday Friday.

[keithlucky]

Jackone the met are more confused than we are ,i am sure they had a late xmas party because the weather forecast for day6 to 15 and 16 to 30 is drivel.

[andymusic]

Well boys and girls the meto think there might be something colder on the way and the GFS 18z also thinks that over the weekend and into next week we could well be seeing cold enough attacks on Wales to actually get some sort of wintry weather - only one run - might be gone tomoz - but the meto also think something's coming so - this could be it - a couple of flakes later and spring arrives - or the snowmageddon and blizzards from hell seizing up the country for the whole of Feb could be on it's way!

[welshwizard]

cant ask this question in mad model thread so i will ask you guys in here,how and why do models have such huge diffrences? and what is the point in them if they are wrong all the time,what i mean is whoever looks at them for future weather prospects cant give any detail out because within hrs they seem to be saying the compleat opposite so why bother going through all the expence when the models act like they are on drugs.maybe im wrong but as a layman it just seems pointless to be honest, is it like this in all countries? America seem to get it right when i see on their weather there is a huge snow storm next week they get what they say, we say no rain and it pours down lol. i dont care what we get as long as its not rain all the time but my kids want snow, but what i would like is a forcast that gives out correct detail. is our weather details rubbish compared to other countries or are they all on a par?