Wales - Regional Weather Discussion

[summer blizzard]

I was really expecting to see some snow over the summits of Snowdon today, but as per the webcam, it just looks wet.

-4C uppers with freezing level below the summits is a recipe for snow over mountains. Strange!

Uppers are quite mild at the front of the front so you need to be getting to the back edge before seeing snow.

[Backtrack]

Uppers are quite mild at the front of the front so you need to be getting to the back edge before seeing snow.

The front has passed through though, and there are some colder uppers around the area. Should be some snow.

[TonyH]

Quite a decent cold front earlier, very heavy rain and a near gale. 10mm rain in 3 hours and a 5c drop in an hour from 12c to 7c by 1400.

[Snowmadsam]

I am a bit confused about Monday, can anyone help

[soupsurfer7]

Hello guys! Nice to be back on the Welsh thread

Here's hoping that the high ground of mid Wales might see some wintry precipitation early Monday morning...

[andymusic]

I am a bit confused about Monday, can anyone help

looking generally colder next week with a possible early taste of winter - the odd snow shower around and cold winds from a north westerly direction

[Isolated Frost]

I am a bit confused about Monday, can anyone help

All I can say based SOLELY upon the 12Z GFS:

Cold and wintry with -5c uppers, strong nw'ly in the morning (-5c uppers covering all of Wales!)

Even cooler and quite snowy with -6c uppers reaching the north coast, -5c for the most part with a strong nw'ly

Becoming less cool with -2c/-3c uppers for the night and on Tuesday (still below average)

And then on Wednesday another almighty nw'ly blast with -5c uppers...

Very cool and wintry, above 500m you could see snow lying for a good week, above 100m then you probably will see snow! Very good signs for the first widespread snowfall, lets hope for no downgrades, ey!

[Scarlet_Snow]

Looks interesting nonetheless, always had a feeling that the colder weather would turn up out of the blue this year after the recent mildness, hopefully some of us will see something wintry! Just got to keep an eye on the models now

[Snowmadsam]

All I can say based SOLELY upon the 12Z GFS:

Cold and wintry with -5c uppers, strong nw'ly in the morning (-5c uppers covering all of Wales!)

Even cooler and quite snowy with -6c uppers reaching the north coast, -5c for the most part with a strong nw'ly

Becoming less cool with -2c/-3c uppers for the night and on Tuesday (still below average)

And then on Wednesday another almighty nw'ly blast with -5c uppers...

Very cool and wintry, above 500m you could see snow lying for a good week, above 100m then you probably will see snow! Very good signs for the first widespread snowfall, lets hope for no downgrades, ey!

Have you replaced andymsuic! :o (another optimist YAY!)

[Scarlet_Snow]

Have you replaced andymsuic! :o (another optimist YAY!)

You cannot replace andymusic for optimism

[Isolated Frost]

Have you replaced andymsuic! :o (another optimist YAY!)

Oh but it looks very well, this Andymusic seems like a top bloke !

[swales]

Very cool and wintry, above 500m you could see snow lying for a good week, above 100m then you probably will see snow! Very good signs for the first widespread snowfall, lets hope for no downgrades, ey!

For Scotland maybe....

[J10]

The problem with the event next week is that it is 6-7 days away and events like this tend to disappear/downgrade within that timeframe.

We are only tapping into the remnants of the cold, and it is not a full on blast, thicknesses are around 528 which is marginal at best, and that's before a downgrade.

If the charts are very similar in terms of 850HPa and thicknesses by say Wednesday/Thursday, then it might be worth looking at again.

But on a positive side, at least at those looking for cold, it is promising and it should give snow to other parts of Europe (Scandinavia and perhaps the Alps) , which have been mild so far this Autumn period.

The general theme of my comments from yesterday stands, it seems likely that Wales will received some sort of Polar Maritime airflow early next week. But this event is likely to downgrade slightly by then making snow not that likely for most. My suspicion is that by next Monday the -5c 850Hpa line will not reach Wales.

If people wish to keep trends to see how things transpire.

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

[TonyH]

Strange that Derek Brockway would mention snow for north and west Wales next Monday this far out, when as you say Julian, the cold enough uppers may not even touch Wales.

Edited November 29, 2011 by TonyH

[keithlucky]

Strange that Derek Brockway would mention snow for north and west Wales next Monday this far out, when as you say Julian, the cold enough uppers may not even touch Wales.

Yes Derek is not a snow ramper has been having a beer with Andy?

[andymusic]

Strange that Derek Brockway would mention snow for north and west Wales next Monday this far out, when as you say Julian, the cold enough uppers may not even touch Wales.

probably only mentioned the possibility because it's such a contrast from what we've been having through the autumn!

me a snow - ramper?????????? - mind you I have had a few words with old Derek on twitter now and again!

Edited November 29, 2011 by andymusic

[TonyH]

True Andy!

[keithlucky]

probably only mentioned the possibility because it's such a contrast from what we've been having through the autumn!

me a snow - ramper?????????? - mind you I have had a few words with old Derek on twitter now and again!

See Andy you a bad influence lol.

[SnowStorm(Jamie)]

I think the flow from the NW is likely models have been showing this for sometime now, how cold that flow will be though remains uncertain at this point. We need that thrust of cold air more directly from the North, the models do show this albeit briefly (around the 120-144hrs mark).

But the most likely location for snow is still around the higher ground of N. Wales perhaps extending southwards if we pick up that colder flow. So we need to keep an eye on how the models show this pattern developing over the next few days.

[andymusic]

18z on it's way out - let's see if the GFS gets a little more serious about the potential cold weather

[keithlucky]

I think the flow from the NW is likely models have been showing this for sometime now, how cold that flow will be though remains uncertain at this point. We need that thrust of cold air more directly from the North, the models do show this albeit briefly (around the 120-144hrs mark).

But the most likely location for snow is still around the higher ground of N. Wales perhaps extending southwards if we pick up that colder flow. So we need to keep an eye on how the models show this pattern developing over the next few days.

Yes still looks good for our first sight of some wintry precipation Saturday night Sunday -Monday,N ireland Scotland should get a good covering.

[SnowStorm(Jamie)]

Its looking increasingly likely that we will see a thrust of cold Polar Maritime air from the NW with upper air 850hpa temperatures of -5C flooding SE over Wales. However how potent this cold shot will be is undecided yet, and ive noticed today that the sub 528DAM line is shown slightly further northwards on the GFS model at least when considering the period of Monday going into Tuesday next week. - That being said that line does still lie across Mid & North Wales:

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

To add keep in mind the sea surface temperatures over the Irish sea, currently these are above average with temperatures of just over 12C this is important because the strong NW surface flow will be comming right over the Irish Sea and this will keep temperatures higher especially for areas closer to the coastline.

As it stands higher parts of N/NW Wales will be the most likely location for snow showers.

Met Office Outlook for the Brecon Beacons on Monday is shown here: http://www.metoffice...t_pressure.html

The sleet/snow showers around the peaks theme fits in with the 0C Isotherm chart from the GFS on Monday which shows the freezing level around 700-800M:

Still worth keeping an eye on though since its still 5 days out yet. I wonder if the GFS 18z will again show that frontal wave running SE on Sunday developing more rapidly and becoming more intense it has done this since Sunday, if that happens we will more likely see the cold air flooding southwards more rapdily on the rear of it i think.

[J10]

Continuing the previous theme.

If people wish to keep trends to see how things transpire.

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 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 Today's thickness chart for 6am Next Mon http://hw.nwstatic.co.uk/gfsimages/gfs.20111130/12/114/hgt500-1000.png

The progression seems clear, both in terms of the wind direction being a NW rather than a NNW, and the 850Hpa -5 line and 528 dam thickness edging ever so slightly north.

At the current rate, some wintriness possible for quite a few, hail, sleet and perhaps wet snow, more especially if not restricted to hills and mountains.

But lying snow for the mountain tops if even there.

[Blackjack]

i know nothing except what i can gleen on the forums and weatheronline charts.

Is it me or is the 528 dam line and 850hPa -5 line shooting back up north in the latest models. I profess to know nothing but i bet Madden and Corbyn are feeling less and less confident and more and more stupid. Euro high moving but nothing like a Scandi or Greeny high developing any time soon.

I can't see any significant cold digging in anytime before Christmas.

Edited December 1, 2011 by Blackjack

[DeepSnow]

It doesn't look likely atm of much in the way of any real cold and snow this side of christmas does it? Doubt anyone in low lying areas south of Mid-Wales will see much if any snow! (though one can hope). Just hope January will give us some good cold and snow!