Wales Cymru Regional Discussion - January 18th 2013, 06z onwards

[Gorky101]

SE Wales, atm, looking good again for a significant fall of snow on the 12z Gfs, too.

Any chance of a westwards correction on this one, similar to Friday just gone?

I would worry too much yet as you know over the last few years they almost always get corrected westwards

[J10]

SE Wales, atm, looking good again for a significant fall of snow on the 12z Gfs, too.

Any chance of a westwards correction on this one, similar to Friday just gone?

To me the 12Hz is already a westward correction on the 06Hz. Further north as well, so better chance of precipitation generally compared to 06HZ.

Are further corrections likely, yes, as to whether the corrections are in the "right" direction is another matter.

[benb]

Strange because it seems to be beefing up all the way worth keeping an eye on I think but I guess the easterly wind will keep it away from us

It seems a pretty complex/messy set-up across the country, atm; who knows exactly how these different systems (snow in the NE of Wales arriving from the south east and front appraoaching from the south west) are going to interact with each other?

It'd be great if it did push on up because most of S. Wales currently has 850 uppers of -8/-9c, temps of around 0c and dew points below freezing!

[snowy36]

SE Wales, atm, looking good again for a significant fall of snow on the 12z Gfs, too.

Any chance of a westwards correction on this one, similar to Friday just gone?

Benb anything is possible, it will be this time tomm when we know where it's going to go. I know it looks good for us in se but it could end up anywhere.

[bradymk]

GFS 0.5 HR http://www.meteociel.fr/modeles/gfs/precipitations/3h.htm shows a different scenario to NAE. Snow/rain moves in from the west overnight before moving back west through the day. Im not reading much into Tuesday at the moment, it really is a difficult forecast and its going to be another one of those where we wont know until right before the event but the potential is there for more snow, where and how much, who knows at the moment.

Edited January 20, 2013 by bradythemole

[snowy36]

GFS 0.5 HR http://www.meteociel...itations/3h.htm shows a different scenario to NAE. Snow/rain moves in from the west overnight before moving back west through the day. Im not reading much into Tuesday at the moment, it really is a difficult forecast and its going to be another one of those where we wont know until right before the event but the potential is there for more snow, where and how much, who knows at the moment.

Brady do u trust the GfS, i think it dogs do. I never take any notice in it, for me i look at the ecw then the ukmo then the Nae and then lastly the dogs do.

[bradymk]

Brady do u trust the GfS, i think it dogs do. I never take any notice in it, for me i look at the ecw then the ukmo then the Nae and then lastly the dogs do.

Every model has its strengths/weaknesses. GFS has also been good at northerly setups whereas it tends to overdo the atlantic in easterly situations where i prefer the euros. So its really about the type of setup. GFS precip charts are normally pretty useless also however until you have agreement between models, its hard to make a forecast. The GFS is having a tough time at the moment and has been pretty poor recently alongside ECM in some extent at times. UKMO and GEM have been the best in the last week for sure.

[Jackfrost]

The 15:56 BBC forecast showed snow moving across South Wales in the early hours of Tuesday.

As much I enjoy following each chart run and as overly-simplistic and unadventurous as it sounds, I only begin to accept that an event is highly likely when the Met Office and BBC TV forecasts take note. They've been extremely accurate during this cold spell.

Edited January 20, 2013 by Jackfrost

[Wales123098]

Already -2.7c here after max temp of -0.9c. Not so cloudy so could see coldest night of the winter tonight

[mikeocarroll]

As much I enjoy following each chart run and as overly-simplistic and unadventurous as it sounds, I only begin to accept that an event is highly likely when the Met Office and BBC TV forecasts take note. They've been extremely accurate during this cold spell.

And really, that's the best approach to take. It's fun to look at the models and see the range of possiblities that might happen, but if we try and forecast events before the Meto (i.e. telling friends & family "looks like we will have some snow next week") then we often end up with egg on our faces. Weirdly, the expert forecasters at the Met Office seem to be better at forecasting than we are.

Snow has been slightly more here today than I expected but still not amounting to anything much, less than a cm. Makes for a picture perfect wintry scene though, shame about some people cancelling their bookings for next weekend, I did tell them there's a good chance conditions will be better by then, but they weren't having any of it.

[in the vale]

a further couple of inches of snow could fall in the next couple of hours. So long holiday, hello oil tank refill!

It's possible - the snow seems to still be coming across from the East for a while yet - looks better than it did earlier. Your area should be getting a bit of a pasting now? I've ordered oil for Tues - 61p!! Glad ours does DD!

[Ginkrots]

Derek rightly maintaining an open view on twitter regarding next weekend. It's a long time away in terms of weather and modelling so I find it bizarre how many posters on the forum are sure it'll be mild.

@DerekTheWeather: Blimey, the Canadian model has a big low over the English Channel next Sunday - would bring heavy snow to the south! http://t.co/dlLw19tM

[in the vale]

Derek rightly maintaining an open view on twitter regarding next weekend. It's a long time away in terms of weather and modelling so I find it bizarre how many posters on the forum are sure it'll be mild.

@DerekTheWeather: Blimey, the Canadian model has a big low over the English Channel next Sunday - would bring heavy snow to the south! http://t.co/dlLw19tM

Derek Brockway rolling out the GEM at D7 is about as near to ramping as I've ever seen from anyone BBC-related! Edited January 20, 2013 by in the vale

[keithlucky]

Derek rightly maintaining an open view on twitter regarding next weekend. It's a long time away in terms of weather and modelling so I find it bizarre how many posters on the forum are sure it'll be mild.

@DerekTheWeather: Blimey, the Canadian model has a big low over the English Channel next Sunday - would bring heavy snow to the south! http://t.co/dlLw19tM

Yes a big sliding low next weekend dragging bitter easterlies seen that forecast for next weekend,Watch towards middle of next week pressure build from the N East ,this is a very stubborn block shaping up to a 1982 scenario slowly but surely getting colder .

[Marcus_surfer]

There was some light snow this morning but it has been brighter, colder than yesterday with a max of just 0.4C. Temp now is at -1.0C.

[Panayiotis]

Yes a big sliding low next weekend dragging bitter easterlies seen that forecast for next weekend,Watch towards middle of next week pressure build from the N East ,this is a very stubborn block shaping up to a 1982 scenario slowly but surely getting colder .

Sure hope so! The 12z has made small improvements on the NE block, and hope the 18z follows, people must remember its 6 days away and in terms of weather a lot can change in that time.

[SnowStorm(Jamie)]

Certainly very interesting times looking through the charts id agree snow chances can really come from largely any direction when the cold air is present over us.

Tuesday seems to be the one to keep an eye on as we could possibly be effected by small areas of low pressure bringing the increasing risk of precipitation.

GFS 12z:

http://cdn.nwstatic....2/42/ukprec.png < Tuesday Precipitation

http://cdn.nwstatic....degisotherm.png < 0C isotherm quite low and falling lower as colder air gets pulled back over from the east.

The result is we see a period of sleet and snow moving in to South Wales/Mid Wales:

http://cdn.nwstatic....ctypeuktopo.png

UKMO 12z:

Simular sort of idea to the GFS for around the same time increasing risk of precipitation moving in from the south:

http://www.meteociel...2-594.GIF?20-16 < 42hrs

http://www.meteociel...8-594.GIF?20-16 < 48hrs

With upper air temperatures around -4c or below:

http://www.meteociel...U42-7.GIF?20-16 < 42hrs

http://www.meteociel...U48-7.GIF?20-16 < 48hrs

So again period of sleet and snow moving into South Wales.

NAE 12z:

The NAE model also has this feature and did show it on its 06z run, increasing precipitation swinging up on Tuesday:

http://expert-images...012206_2012.gif < 42hrs

http://expert-images...012209_2012.gif < 45hrs

http://expert-images...012212_2012.gif < 48hrs

Upper air temperatures around this time are around -4C down to around -6C:

http://expert-images...012209_2012.gif

Dew points below freezing apart from maybe the far SW:

http://expert-images...012209_2012.gif

Also SUB 528 DAM air is entrenched in:

http://expert-images...012209_2012.gif

Again the result is a period of sleet and snow intensifying as it moves very slowly (Slack flow) NE. If your caught under that band of snow and live away from the coast there's the potential for some good accumulations as looking at the charts i don't see where any fast progression of the front would come from.

Of course caution must be taken as these features will be placed in different places as runs go by.

Ice warnings also in force across Southern UK for Monday and Tuesday.

For some reading Met Office forecast snow accumulations across the UK Sunday/Monday:

http://www.metoffice..._snow_continues

[Panayiotis]

Very good post @SnowStorm(Jamie)

Edited January 20, 2013 by Panayiotis

[Panayiotis]

Why do the BBC still have heavy snow for Cardiff, when nothing on the precipitation chart lower down on the page shows nothing?!

http://www.bbc.co.uk/weather/2653822

this may have something to do with it!

Edited January 20, 2013 by Panayiotis

[keithlucky]

Excellent post Jamie the word entrenched! is perfect way to describe this cold pool of air .

[gareth moo]

Thanks Jamie! Excellent analysis and reasoning as always..

[Penderyn]

Lluwchwynt!

Its blowing a blizzard!

Edited January 20, 2013 by Penderyn

[ourson]

Why do the BBC still have heavy snow for Cardiff, when nothing on the precipitation chart lower down on the page shows nothing?!

http://www.bbc.co.uk/weather/2653822

this may have something to do with it!

BBC forecasts are probably generated automatically, so no real human input. Still hopeful to see some more snow in the coming days!

[snefnug]

It's possible - the snow seems to still be coming across from the East for a while yet - looks better than it did earlier. Your area should be getting a bit of a pasting now? I've ordered oil for Tues - 61p!! Glad ours does DD!

Yikes! Think I'll add new oven to my wave goodbye list!

Right, that's it for tonight - last lampost watch shows snow still snowin', soo glad I stocked the freezer last Wednesday! Working from home has its upsides, but downsides are - wacking through the oil, and no not being able to get to work.....

[Cymro]

Mae'r oerfel yn dal i afael ar Gymru fach, mwy o gyfleoedd eira i ddod gyda'r wythnos unwaith yn rhagor, yn wir unwaith y cewch chi'r aer oer wedi'i wreiddio mae'r posibiliadau o eira o bob cyfeiriad yn rhai real iawn.

The cold weather is still holding it's crip over Wales, more snow oppertunities to come in the next week once again, once the cold air is with us and entrenched as such, the posibilities of snow from every direction are endless.

Edited January 20, 2013 by Cymro