Wales Cymru Regional Discussion - January 15th 2013>

[soupsurfer7]

BBC online 5 day forecast for Cardiff has a heavy snow symbol for Friday and light snow symbol for Saturday, savour the moment!

Edited January 15, 2013 by soupsurfer7

[Daniel Miller]

heres to wishing for cold and snow all weekend. gfs 12z showed snow all weekend for nwales what about swales?

Also showed a fair bit for us down south, though, not as good as the UKMO (and not as trustworthy IMO)

I suggest to not ignore this GFS run, but view it with scepticism. Overnight runs V.Important!

Angle of the low is not so SW, not a good thing - A little more marginal for the far West perhaps.

Further on at 84hr (Saturday morning) we have colder uppers over us (whole country in at least -4, with -8 uppers fast approaching)

Edited January 15, 2013 by Daniel Miller

[TonyH]

Just one chart I want to post this evening which is GFS 12z ensembles (these are for Powys):

There are two key points to be drawn from this I think:

1) Look at the huge divergence for 18 Jan (Friday), a rare degree of divergence for just over 48hours away, with upper air temps ranging from +3c according to some peturbations, to -9c with others. Neither of those would be great for a snow event as the one would be too mild (leading to rain) while the other suggests the absence of any mild incursion, in which case it would be dry. Therefore there is low confidence in Friday's snow event with around 1/3 of members going for snow to rain (relatively rapidly), the majority going for more or less all snow for Powys, and a small possibility (around 10%) of the front not really reaching Powys at all. It should be said that this is an extremely rough and ready analysis as there is only so much can be gained from looking at solely 850hPA temps and in a single location at that.

2) The other notable is the high confidence in this set of ensembles for continuing cold, the mean upper temp stays around -5c throughout which is well below the seasonal average with no peturbations at all go for sustained average temperatures let alone mild. So we may have more opportunities for cold and snow over the coming few weeks, which would tie in with speculations about the effect of the sudden stratospheric warming that began last week. Something worth bearing in mind for those of us who end up disappointed with the weather over the next few days (and it is the nature of these events that someone, somewhere is going to miss out, at least relatively).

Spot on interpretation Mike!

[dhillcrest]

BBC online 5 day forecast for Cardiff has a heavy snow symbol for Friday and light snow symbol for Saturday, savour the moment!

If you click on the days though, it shows sleet on Friday as well, and rain on Saturday. Hope you get an upgrade!

[benb]

Gfs 18z still keen on widespread, prolonged snowfall for Wales on Friday. By the evening the cold air looks to be digging back westwards, possibly extending the snow risk back into the far South West...

http://cdn.nwstatic..../h850t850eu.png

Another great run, so far, imo!

60hrs and counting...

Edited January 15, 2013 by benb

[bradymk]

Ok so is the 18z the start of the correction south and west? WE HOPE SO!!!!!!!!! praying NAE is having an off day however.

[TonyH]

Potentially a lot of snow to come Friday to Saturday, at the moment mid and north Wales and Midlands look snowiest, turns to rain SW Wales (copy of my latest tweet).

Edited January 15, 2013 by TonyH

[welshwizard]

hi all I have noticed from derricks forcast and ians in south west that they are saying 2 to 5 cm for low areas, if that does happen and it be good if it did. that's not that great as snow events go is it? 1 or 2 inches would not take that much snow to come out of the sky, i heard them say on tv this morn that for every cm of rain = 10cm of snow so that atlantic storm coming in(fingers crossed) cant be that good if you know what I mean, or have they got the amount of snow/rain wrong on the forcasts? I know nothing is set in stone and anything could happen but I would have thought if it snows heavy for that many hrs it has to be far more than 1 to 2 inches.whats your thoughts if it did hit wales as snow.

[J10]

GFS 18hz next stop

Upgrade Central.

Seriously though it is slightly slower moving everything east, there is a slight better angle of attack, and a a result more of the precipitation will be of snow.

Of course, this doesn't guarantee anything, but very much game on for a potential significant snow event on Friday.

Note the above covers up till around Saturday - the Medium term not included .

[TonyH]

They always tend to go conservative while they dont really know whats about to happen, in truth it will be highly variable as usual, some parts missing out others getting many inches (possibly).

[benb]

18z Gfs looks like sending more shortwaves down the same route... repeat performance for the start of next week, perhaps?

Ok, let's get the first one out of the way, but potentially a very snowy pattern...

[bradymk]

this is a big upgrade from GFS for snow potential, we need the 00z to help back this up however. Very cold saturday and saturday night. BANK THIS RUN NOW!

[Snowmadsam]

Potentially a lot of snow to come Friday to Saturday, at the moment mid and north Wales and Midlands look snowiest, turns to rain SW Wales (copy of my latest tweet).

As long as I see some snow settling,which I think is looking likely then I'm happy

Edited January 15, 2013 by Snowmadsam

[butters]

just checked out the bbc 5 day froecast for here in cwmbran it it shows heavy snow for friday but when you click on friday to expand it it shows light snow from 15:00 until 06:00 saturday morning so why is the overall forecast heavy snow.mind you i'd like to see how 15 hours of light snow would add upp on the ground.heres hoping its right

[SnowStorm(Jamie)]

GFS 18z seems similar to earlier if you ask me, i noticed during Friday the Zero degree isotherm is quite low:

http://cdn.nwstatic....degisotherm.png

More than likely this is because the cold SE surface flow off Europe:

http://cdn.nwstatic....8/63/ukwind.png

Very interesting as with some elevation the chances of snow will be higher (as always really)

As the models currently show ECM, UKMO, GFS it appears most of Wales will see a period of snowfall Friday apart for the SW (Probably drawing a line from Swansea NW to Aberystwyth (as the rain/sleet area- snow at elevation 150-200m Perhaps)

Where dew points will be higher:

http://expert-images...1806_2_1518.gif

Of course this is all subject to change and is just a rough idea of how things might go. By this time tomorrow Friday will be coming in to the NAE's range and i suppose there will be more than a few anticipating the mesoscale models guidance!

Thursday night you can start to see the low on its way in from the Atlantic:

http://expert-images...011718_1518.gif

Notice the milder uppers to the S/SW and this is only on thursday night, wouldn't take much northward progression to move that over most of S Wales, vital that the upper flow can turn more SE or you'll see the warmer upper air temps advance to quickly.

Worth noting on the NAE watch this little feature thursday:

http://expert-images...011706_1518.gif < Precipitation

http://expert-images...011706_1518.gif < Dew points

http://expert-images...011706_1518.gif < Upper air temps

Many parts could see a period of light/moderate snowfall if it does indeed swing through in the early morning:

http://expert-images...011706_1518.gif

[Gorky101]

Bridgend council have had advance warning of a potential 24-36 hours of snow from 0500 hours Friday (just on local radio)

[Snowmadsam]

There is such a wide range of solutions and we are no closer to getting a solid answer.

Just gonna have to wait, for west Carmarthenshire and East Pembrokeshire its most likely going to be a snow-snow event, I am basing this on how I see it .

[Marcus_surfer]

What time are we likely to see PPN start falling in S Wales on Friday?

[welshwizard]

There is such a wide range of solutions and we are no closer to getting a solid answer.

Just gonna have to wait, for west Carmarthenshire and East Pembrokeshire its most likely going to be a snow-snow event, I am basing this on how I see it .

I think you will get your snow,they seem very excited in the model thread, talk about snow snow and cold cold all happy in there (for now)

[Snowmadsam]

I think you will get your snow,they seem very excited in the model thread, talk about snow snow and cold cold all happy in there (for now)

You have to admit it, it would be funny if it stalled....more snow hahaha...

I am sure you will as well, ...just got to wait really

[marclt]

The ITV Weather just now was useless. Not sure there was any point in broadcasting it, if i'm honest.

[welshgritter]

This room is 'Snow Mad'.................!!!! My stab in the dark - Rain I need a day off.....

[pyrotech]

BBC main forecast was more in line with NAE, Snow moving in on Thursday then rain over most of Wales with the Snow over the border.

[J10]

GFS 18z seems similar to earlier if you ask me, i noticed during Friday the Zero degree isotherm is quite low:

http://cdn.nwstatic....degisotherm.png

More than likely this is because the cold SE surface flow off Europe:

http://cdn.nwstatic....8/63/ukwind.png

Very interesting as with some elevation the chances of snow will be higher (as always really)

As the models currently show ECM, UKMO, GFS it appears most of Wales will see a period of snowfall Friday apart for the SW (Probably drawing a line from Swansea NW to Aberystwyth (as the rain/sleet area- snow at elevation 150-200m Perhaps)

Where dew points will be higher:

http://expert-images...1806_2_1518.gif

Of course this is all subject to change and is just a rough idea of how things might go. By this time tomorrow Friday will be coming in to the NAE's range and i suppose there will be more than a few anticipating the mesoscale models guidance!

Thursday night you can start to see the low on its way in from the Atlantic:

http://expert-images...011718_1518.gif

Notice the milder uppers to the S/SW and this is only on thursday night, wouldn't take much northward progression to move that over most of S Wales, vital that the upper flow can turn more SE or you'll see the warmer upper air temps advance to quickly.

Worth noting on the NAE watch this little feature thursday:

http://expert-images...011706_1518.gif < Precipitation

http://expert-images...011706_1518.gif < Dew points

http://expert-images...011706_1518.gif < Upper air temps

Many parts could see a period of light/moderate snowfall if it does indeed swing through in the early morning:

http://expert-images...011706_1518.gif

There is a definite improvement here for the situation on Friday, a better wind direction, colder dewpoints and colder uppers and the snow risk is slightly better as well. Of course we all know GFS over doing temps in Coastal areas ( including last night).

If this occurred it would be a mostly snow event, perhaps Pembs missing out.

Things are likely to change of course.

[keithlucky]

What time are we likely to see PPN start falling in S Wales on Friday?

Hard to say Marcus I think the east ward progress of the front is slowing down (at the moment around mid day) also i still see the first front struggling to cross the borders ,also the GFS precipitation charts show the front moving back westwards ,So a 24hr event means a stalled front. Edited January 15, 2013 by keithlucky