Wales - Regional Weather Discussion

[keithlucky]

I'm clinging onto Mark Vogans prediction that there will be a brief averaging of temps then a plunge into colder weather from the 15th with widespread snow leading up to Xmas. I know he has his detractors, but i'm very interested to see any changes in the models over the coming few days. Anyone else noticing the beginnings of a high over Greenland in some of the models over the coming week. Will it develop???

If he's right then i take my hat off to him.

If he's wrong i'm holding out for colder weather to arrive after New year

The met office are saying HP over ireland with snow showers mainly NE UK friday cold and dry west UK,on the model forum no HP west of ireland thats what they saying mild and wet.Take your choice who you want to believe.

[J10]

Always was going to be marginal, a few showers this morning, One other problem with the warmish sea temps with the wind direction being more of a WNW, rather than NNW, which not only reduced the shower potential but also pushed the warming effect of the sea further inland than would usually be the case.

Final 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's 850Hpa for 6am Next Mon http://hw.nwstatic.co.uk/gfsimages/gfs.20111204/12/18/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 thickness for 6am Next Mon http://hw.nwstatic.c...hgt500-1000.png

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

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

A slight downgrade but the 9am charts look a little better. There will be showers tonight, and there will be some snow/wintriness, but how wintry and how much penetration there is from the North and Western coasts, is still up for debate.

We'll know by this time tomorrow, retrospective weather forecasting is much easier (and safer)

This was the final outcome

850Hpa http://hw.nwstatic.co.uk/gfsimages/gfs.20111205/06/00/h850t850eu.png

thickness http://hw.nwstatic.co.uk/gfsimages/gfs.20111205/06/00/hgt500-1000.png

[Scarlet_Snow]

Always was going to be marginal, a few showers this morning, One other problem with the warmish sea temps with the wind direction being more of a WNW, rather than NNW, which not only reduced the shower potential but also pushed the warming effect of the sea further inland than would usually be the case.

This was the final outcome

850Hpa http://hw.nwstatic.c.../h850t850eu.png

thickness http://hw.nwstatic.c...hgt500-1000.png

I'm guessing with a NNW the pembrokeshire dangler would of been more likely to form?

[keithlucky]

I'm guessing with a NNW the pembrokeshire dangler would of been more likely to form?

Better chance of seeing some wintry flurries friday -saturday when the wind is more from the N West fingures crossed.

[J10]

I'm guessing with a NNW the pembrokeshire dangler would of been more likely to form?

NNW winds are far better for producing "the Pembrokeshire Dangler", but if you want the white stuff along with it. then you also need a colder airmass.

[DeepSnow]

Been mild here compared to other places during this colder spell, with night time lows not going below 4C and day temps of 6-7C. Just hope something will happen to allow us something on Friday/Saturday!

Would this gives us any chance of some wintery weather, maybe snow?

[welshgritter]

Morning All.....with all the speculation at present on 'will it', 'wont it' and the great North and South divide at present - when do you all feel our Winter will properly kick in? At the moment the mornings are 'a little chilly' but nothing really to get excited about. The commercial reports I get are providing more amber readings (GS temps between 0-3 degrees), but its not hitting zero just yet. All my sites are along the M4 stretch (Swansea-Cardiff).

So............................ everyones views would be much appreciated on when they feel Winter will kick in for sure in the South (obviously I wouldnt ask this question in the Scottish thread!)

[swales]

Looking at the 00z gfs for my location on Friday then the 500-1000 hPa and 850-1000 hPa charts look pretty crap.

Met Office going for hill snow... "wintry from Wales northwards"... So similar to the last couple of days then...

Edited December 6, 2011 by shaunwales

[mikeocarroll]

Been mild here compared to other places during this colder spell, with night time lows not going below 4C and day temps of 6-7C. Just hope something will happen to allow us something on Friday/Saturday!

Would this gives us any chance of some wintery weather, maybe snow?

If that chart were to verify then there would be a chance of wintry weather, similar to the last couple of days but with slightly colder uppers meaning that there may be more chance of any precipitation being snow instead of hail (for example). Hard to predict whether there would be much precip though, I'd guess a few showers on the coasts (= warmer so less chance of snow) but not getting so far inland, but as I said before hard to predict.

Something to keep an eye on but once again its an extremely marginal setup for snow in Wales and even a slight downgrade would wipe any chance of snow. A small upgrade however could bring many of us our first snow of the season.

Edited December 6, 2011 by mikeocarroll

[soupsurfer7]

The MetOffice reckon north Wales is at risk from snow showers late Thursday into Friday:

Yellow Alert of Snow08 Dec 2011, 18:00

Issued at - 06 Dec 2011, 13:44

Valid from - 08 Dec 2011, 18:00

Valid to - 09 Dec 2011, 23:59

Snow showers are expected late on Thursday and through Friday. The public should be aware that these will be heavy at times, and may give significant accumulations that could disrupt travel. Gale or severe gale force northwesterly winds will accompany the snow showers, perhaps leading to drifting over high ground, but these winds will slowly moderate during Friday.

Edited December 6, 2011 by soupsurfer7

[andymusic]

These sorts of set ups tend to favour north and mid wales better than south - snow is generally exhausted by the time it tries to get over the mountains of Wales from North to South - unless there is a particular vigorous low involved - otherwise the south does better out of westerly or south westerly lows bumping up against cold air and then dumping loads of snow on us! - There are exceptions to this rule, but they are very few and far between - one instance being last year where we had an odd front push in from the north west/west which hung around over south Wales for sometime overnight and dumped alot of snow - but then we had extremely low temps, and right now we are still only on the margins of freezing in South Wales - not a penetrating cold or days below freezing (ice days) which would guarantee snow more readily!

Edited December 6, 2011 by andymusic

[DeepSnow]

If things stay the way they are now then I can't see us in south wales getting much snow, if any this side of christmas and probably the new year!? Hope our patience pays off in the new year and we get something good!

[andymusic]

If things stay the way they are now then I can't see us in south wales getting much snow, if any this side of christmas and probably the new year!? Hope our patience pays off in the new year and we get something good!

GFS is playing around with some interesting scenarios - now it's dumped the nasty HIGH - blocking any development - with further heavy pm air incursions approaching the middle of the month - so I think as time goes on - and everything cools down further - these may well get more interesting - even this side of Christmas - we shall watch and wait!

[DeepSnow]

GFS is playing around with some interesting scenarios - now it's dumped the nasty HIGH - blocking any development - with further heavy pm air incursions approaching the middle of the month - so I think as time goes on - and everything cools down further - these may well get more interesting - even this side of Christmas - we shall watch and wait!

Well that sounds a bit more promising What would the warming of the stratosphere do as I see a lot in the model thread that people want that for cold?

[andymusic]

Well that sounds a bit more promising What would the warming of the stratosphere do as I see a lot in the model thread that people want that for cold?

It helps to shift the cold from the artic, towards us like last year when we had the "Deep Freeze" period - there had been a warming of the stratosphere then - it's a delayed effect! Pm incursions aren't normally as good - but they can be and have been in the past - no reason why they can't deliver again either!

[J10]

Met Office Severe Weather Warning for North and North East Wales.

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

Yellow Alert of Snow08 Dec 2011, 18:00Issued at - 06 Dec 2011, 16:45

Valid from - 08 Dec 2011, 18:00

Valid to - 09 Dec 2011, 23:59

Snow showers are expected late on Thursday and through Friday. The public should be aware that these will be heavy at times, and may give significant accumulations that could disrupt travel. Gale or severe gale force northwesterly winds will accompany the snow showers, perhaps leading to drifting over high ground, but these winds will slowly moderate during Friday.

The public are advised to take extra care, further information and advice can be found here: http://www.metoffice...r/uk/links.html

Further south, a widespread frost seems likely for Saturday am. (possible some coastal fringes staying frost free).

[SnowStorm(Jamie)]

A low pressure system is expected to develop just off the NE coast of North America and move eastwards towards the UK rapidly developing as it does so.

Current Modeling on the UKMO, ECM & GFS 12Z all suggest Thursday as the day the low will make impact upon our shores.

For Thursday the GFS is showing a strong SW flow switching to a NW flow across Wales with strong winds likey especially around coastal areas of the western half of Wales:

http://hw.nwstatic.c...2/48/ukwind.png

http://hw.nwstatic.c...2/51/ukwind.png

With heavy rain crossing Wales especially as a cold front runs SE:

http://hw.nwstatic.c...2/48/ukprec.png

http://hw.nwstatic.c...2/51/ukprec.png

As the low pressure that brings strong winds and heavy rain clears eastwards another shot of cold polar maritime air is likely on its rear as the flow switches towards the NW. How far south this colder air gets is unclear yet and im curious whether the models will over exaggerate its southward extent. The Met Office has placed a yellow alert out for snow over Northern parts of Wales for Thurday/Friday.

Heres the latest Fax chart from the Met Office for Friday:

http://www.meteociel.../fax/fax72s.gif

Sub 528 DAM air just over the south coast of Wales with a NW flow, which to me is in line with the Met Office alert mentioned above for north Wales.

Like we have seen during the last cold shot to bring the snow risk further southwards we would need to see less of a westerly flow involved or it would more than likely tip things the wrong side of marginal for snow.

[DeepSnow]

It helps to shift the cold from the artic, towards us like last year when we had the "Deep Freeze" period - there had been a warming of the stratosphere then - it's a delayed effect! Pm incursions aren't normally as good - but they can be and have been in the past - no reason why they can't deliver again either!

Ok thank you! Hope to get that in the new year!! Looks like it will be a windy day for us friday, though most likely just cold rain as have had the last few days in the south!

[Snowmadsam]

Hello Folks,

Just to let you know I am the regional forum host this Winter!

(I am new so don't spam! :smilz38: )

So lets get started......

lets hope for tons of the White stuff!

ECM is coming out soon (or it is!) wonder what the 18Z GFS will offer. Thoughts please...

SnowmadSam

[J10]

The wind direction for the end of the week is better than earlier in the week, it is more of a NW than than a WNW and more importantly the flow origin is generally from the North as opposed to the beginning of the week when it was more from the NW. However the core of the cold goes to the North and East of Wales, as is shown, with the thicknesses being 528 over South Wales on Meto, and even higher on GFS, which also has over 1300m thicknesses as well.

In summary, a more potent cold shot, more akin to a normal winter NW, but with the cold too far to the North East for most of us, but the areas fringing the cold to the North East looking more promising.

These sorts of set ups tend to favour north and mid wales better than south - snow is generally exhausted by the time it tries to get over the mountains of Wales from North to South - unless there is a particular vigorous low involved - otherwise the south does better out of westerly or south westerly lows bumping up against cold air and then dumping loads of snow on us! - There are exceptions to this rule, but they are very few and far between - one instance being last year where we had an odd front push in from the north west/west which hung around over south Wales for sometime overnight and dumped alot of snow - but then we had extremely low temps, and right now we are still only on the margins of freezing in South Wales - not a penetrating cold or days below freezing (ice days) which would guarantee snow more readily!

Potent NNW flows are the most reliable snow source for much of SW Wales, with the temperature differential of the cold airmass and the Irish Sea creating heavy showers funneling in from Pembrohkshire to Bridgend depending on exact wind direction, and if cold enough heavy snow. however I can understand further east this is not the case.

Over the past 10 years this this has very much proved to be the case, and any lows to the south pushing in normally, the warming effect of the sea tends to mean a very poor return locally.

Within Wales there are huge climatic changes, north to south, east to west and coastal to mountains.

[Scarlet_Snow]

The wind direction for the end of the week is better than earlier in the week, it is more of a NW than than a WNW and more importantly the flow origin is generally from the North as opposed to the beginning of the week when it was more from the NW. However the core of the cold goes to the North and East of Wales, as is shown, with the thicknesses being 528 over South Wales on Meto, and even higher on GFS, which also has over 1300m thicknesses as well.

In summary, a more potent cold shot, more akin to a normal winter NW, but with the cold too far to the North East for most of us, but the areas fringing the cold to the North East looking more promising.

Potent NNW flows are the most reliable snow source for much of SW Wales, with the temperature differential of the cold airmass and the Irish Sea creating heavy showers, and if cold enough heavy snow. however I can understand further east this is not the case.

Sometimes I think we must surely be in one of the worst parts for snow in the UK! I can only think of cornwall being worse off

[TonyH]

Not so much as a ground frost from this ending coldish snap. Too much cloud and wind, plus the nearby Irish Sea being quite warm still. Had a few hail showers but mostly plenty of rain showers, although we missed them here yesterday on the whole.

Should be colder Friday with another brief window for wintriness.

[J10]

Sometimes I think we must surely be in one of the worst parts for snow in the UK! I can only think of cornwall being worse off

For much of the early 2000s, we had more snow here than most of southern UK, it may be colder in the winter across much of Central Southern England, but quite often it tends to be dry with very little in the way of precipitation, as is often the case during the year. If you look back to the early days of NetWeather you will see a lot of people in those areas, complaining that there was a lack of appreciable snowfall over many years, especially when you consider that before a few years ago, there was a real lack of potent Easterlies, going back maybe 2 decades.

Over the past 2-3 years though, Southern and Eastern parts of England have done fantastically well, so we haven't done comparatively well against any area, as without fail we do worse than Northern parts of the UK.

One previso though is that we can have decent amounts of snowfall, but it can thaw quickly,

[SnowStorm(Jamie)]

Hello Folks,

Just to let you know I am the regional forum host this Winter!

Happy to be doing the job alongside you to

The wind direction for the end of the week is better than earlier in the week, it is more of a NW than than a WNW and more importantly the flow origin is generally from the North as opposed to the beginning of the week when it was more from the NW. However the core of the cold goes to the North and East of Wales, as is shown, with the thicknesses being 528 over South Wales on Meto, and even higher on GFS, which also has over 1300m thicknesses as well.

Indeed that is true about the flows origin, looking at the charts it is shown to originate from a more northerly point:

http://images.meteoc...CM1-72_vhb0.GIF < ECM

http://hw.nwstatic.c...airpressure.png < GFS

[keithlucky]

If that chart is right plus the met office fax chart which shows quiet a disturb airflow, we bound to see wintry precipation even if its only 24hrs event.