Wales Cymru Cold Spell Discussion

[Marcus_surfer]

i got a horrible feeling that this event could be rain for quite a few, as the temp outside does seem to be a few degrees above freezing now and if this arrives at 12 or 2 tomor it going to be even warmer.

my car is showing +2 so must be even warmer at lower levels, what temps are others getting as i am not sure if my car is correct.

Your car is very wrong.

At mumbles its 1.4 °C / 34.5°F(@18:00) with a 14mph wind from the East. This is normally the warmest place in Wales. (In Winter)

Edited January 11, 2010 by Marcus_surfer

[Ukwoody]

I just hope we're not too far west and close to the sea!

Oh, Pyro, thanks for the appology but I think I can safely from all of us, don't worry mate. I dont think theres hardly anybody who got it right even Ian Fergusson admitted they were way of the mark, though no one was quite sure why. We still love you ;-)

woody

woody

[ourson]

i got a horrible feeling that this event could be rain for quite a few, as the temp outside does seem to be a few degrees above freezing now and if this arrives at 12 or 2 tomor it going to be even warmer.

my car is showing +2 so must be even warmer at lower levels, what temps are others getting as i am not sure if my car is correct.

Its been 1c or 2c at the most all day here. Feels a lot colder tonight compared to last night.

[CardiffStorm]

Great forecast Pyrotech. So has the front moved South or stalled then as originally (a few days ago) I believe it was expected to be pretty much all rain or sleet? Or am I wrong?

Edited January 11, 2010 by jamo_s

[J10]

Evening all,

Firstly can i apologise for such a poor forecast for Sunday / Monday

I predicted 3 cm for coastal areas and up to 15cm for favoured areas in Wales.

Well percipitation was poor, Wind was much less than forecast and cardiff had a snowfall that resembled dandruff at best.

Mid wales did fair a little better with signifigant Snow at Newtown.

So this week now.

The whole event for Tuesday is marginal but the right side of Marginal.

850s temp and 2m temp are just right for snow , Thickness is not but its not so critical in this set up.

Dew points look fine

West Wales will quickly whiten up following south west England, Cardiff may see sleet before it too sees heavy persistant Snow.

Winds again are set to increase and i have more confidence in both wind speed and percipitation amounts.

Coastal areas most likely to be effected by modified air from Bristol channel, Tommorrow evening this could increaese snowfall amounts but later on it will take it beyond marginal from the west.

Snow Amounts depend how quickly north this moves but here is my thoughts for the situation as it looks tonight

Swansea and swansea Valleys 4 - 6 inches possible sleet near coast later

cardiff 4-8 inches possible sleet to start then snow till Wednesday day time.

Merthyr 6-8inches with drifting snow and high routes closed due to conditions, A470 brecon Beacons could close for a time from blowing snow.

This is same for eastern parts of high ground including gwent valleys.

The actual track of the low is imperative and so changes are likely, it can not be ruled out for a sleet event for coastal areas throughout but latest NAE is not showing this at the time of forecast.

This is the way that w normally get our heavy but short lived snowfalls and i am not convinced that an upgrade will yet occur, this is more likely than a rain event so i would not be surprised to see 30cm somewhere over the next 36 hrs

I hope you are right. the SE wind is coming from a frozen France, and the impact of the sea should be minimised by its fairly short track. Much better than a SW for this respect, but this impact cannot be ignored.

[nomad098]

Cardiff barage @ 19:10

temp 0.9

dp -0.5

wind from due east @ 4mph

if it stays like this should be snow for cardiff shouldn't it?

Edited January 11, 2010 by nomad098

[CardiffStorm]

Cardiff barage @ 19:10

temp 0.9

dp -0.5

if it stays like this should be snow for cardiff shouldn't it?

Depends what the temperature is like in the day, today it reached about 1.6 DgC which I think is ok for snow but could be on the sleety side.

[Marcus_surfer]

Cardiff barage @ 19:10

temp 0.9

dp -0.5

if it stays like this should be snow for cardiff shouldn't it?

yes a significant risk at the moment

[nomad098]

yes a significant risk at the moment

strange thing is the high temp was recorded at 10 past midnight

[pyrotech]

Great forecast Pyrotech. So has the front moved South or stalled then as originally (a few days ago) I believe it was expected to be pretty much all rain or sleet? Or am I wrong?

Thanks for nice comments on the forum.

Its more to do with track of the low it needs to stay where it is forecast to be to the west of Ireland.

Secondly the fronts by the time they reach us become occluded rather than a warm front.

Every little helps

As Jackone said colder better tonight, More so to the East of us and over Devon and Cornwall but again the cold here will help too.

Heavy percipitation will help cool temps as it approaches also, Evaporative cooling can help greatly in marginal events.

[keithlucky]

Thanks for nice comments on the forum.

Its more to do with track of the low it needs to stay where it is forecast to be to the west of Ireland.

Secondly the fronts by the time they reach us become occluded rather than a warm front.

Every little helps

As Jackone said colder better tonight, More so to the East of us and over Devon and Cornwall but again the cold here will help too.

Heavy percipitation will help cool temps as it approaches also, Evaporative cooling can help greatly in marginal events.

Are we still looking at around miday or later hopefully.

[Marcus_surfer]

strange thing is the high temp was recorded at 10 past midnight

could have been a increase in wind or maybe the odd flurry?

[CardiffStorm]

Ahh right, thanks for clearing that up pyrotech. It probably would have helped if I had looked at the FAX chart first.

Edited January 11, 2010 by jamo_s

[Jackfrost]

hope the forcasts are right for once and we have snow! :unsure:

[J10]

Are we still looking at around miday or later hopefully.

Looking at NMM , quite light to start off at around 2pm, and it gets heavier later from around 5pm.

[Marcus_surfer]

Looking at NMM , quite light to start off at around 2pm, and it gets heavier later from around 5pm.

When is it likely to slow down? It's coming in fairly quickly looking at the Satellite

[J10]

When is it likely to slow down? It's coming in fairly quickly looking at the Satellite

Not sure, very much a case of nowcasting.

This is from the South West Discussion thread.

I think the thread is just a little too pessimistic regarding tomorrows events. We have seen over recent winters the odd Channel Low which has failed to deliver however the ingredients for a major winter storm are there. The cold surface pool which has been around for weeks, lots of precip, strong winds and the flow ahead of the low is crucially from the se to east which brings low dew points and drier air. The actual main low is likely to stick in the sw approaches near southern Ireland with the shortwave running east this will slow the precip which means you get prolonged snowfall.

The key thing to look at is temps over northern and eastern France as this is the sourcing of air ahead of the low,there is still some uncertainty with the extent of the heaviest precip but we should know more after the latest NAE model comes out.

[baggielad]

Your car is very wrong.

At mumbles its 1.4 °C / 34.5°F(@18:00) with a 14mph wind from the East. This is normally the warmest place in Wales. (In Winter)

I'm measuring a temp of 0.9c on the hill between Mumbles and Langland. However I'm not hopeful for tomorrow as I'll think we'll just get wet snow at best.

Having said that anywhere just a little bit further inland should be OK for snow.

I remember that 1996 event well as I was living in Cwmavon about a mile up from Port Talbot and we had several inches of snow but just down the road in the town there was nothing.

[benb]

Thar she blows...

I think we want the centre to (eventually) track up the west coast of Ireland? Somethiong of a clearance before the cloud arrives.

I'm down to 0.1c here.

Edited January 11, 2010 by benb

[SnowStorm(Jamie)]

Upper air over France on the NAE:

http://expert.weathe...011118_1112.gif

and the 2m Temperature @ 18GMT:

http://expert.weathe...011118_1112.gif

Cold there and thats good because the flow as we have seen in the last few days is forecast to be from the SE:

http://expert.weathe...011215_1112.gif

Dont want to see to much flow directly from the South or it will pull up the warmer upper air temperatures with it. Looking good so far though.

[benb]

This link should take you to the weather info for France

http://www.wunderground.com/global/FR.html

Many of the channel ports below freezing. Must be more so inland, best get the Michelin map out for the rest,eh?!

[bennytes]

http://www.bbc.co.uk/blogs/weather/ianfergusson/

Ian Fergusson's latest update about the snow risk

South Wales, IS the mask of Zorro!

just a thought, if the arrival of the low is delayed, as he says, isn't that good for snow? doesn't it mean the block is putting up a better fight than first thought?

Edited January 11, 2010 by bennytes

[benb]

Upper air over France on the NAE:

http://expert.weathe...011118_1112.gif

and the 2m Temperature @ 18GMT:

http://expert.weathe...011118_1112.gif

Cold there and thats good because the flow as we have seen in the last few days is forecast to be from the SE:

http://expert.weathe...011215_1112.gif

Dont want to see to much flow directly from the South or it will pull up the warmer upper air temperatures with it. Looking good so far though.

Looking at those charts brings home exactly how important the SEasterly wind is to this set up! Every km of frozen France those winds do or don't travel over is going to have an impact on what happens here...

[keithlucky]

IAM furgerssun http://www.bbc.co.uk/blogs/weather/ianfergusson/

Edited January 11, 2010 by keithlucky

[benb]

Is Zoro chasing a baby crocodile away to the east, as fast as his little legs will take him?

Edited January 11, 2010 by benb