Winter Model Discussion 12Z 15/1/13 onwards.

[ForeverPomeroysnow]

Please be true Gavin or we will have to sneak over and steal your snow:)

[Mark Neal.]

So an interesting potential snowy spell of weather for parts of our shores, perhaps even all of us could get some snowy scenes in the next few days.. Thereafter GP's views seem good news indeed, we could be about to see a noteworthy spell of weather, interesting times ahead.. P.S I found this video animation earlier about the GFS Model earlier, very funny! http://www.youtu.be/JmH56ypfFeA

Edited January 16, 2013 by Mark Neal.

[Troubleatmill]

Just seen full GFS London ensembles (sorry cant post as on phone) - one word, sensational. The mean 850 stays -5 or below for 10 DAYS. And though snow predictions by raw GFS not to be treated as gospel, a high snow chance is given for those 10 days with no let up whatsoever.

indeed, no end in sight, forget the gradual rise long term

[Richie V]

So an interesting potential snowy spell of weather for parts of our shores, perhaps even all of us could get some snowy scenes in the next few days.. Thereafter GP's views seem good news indeed, we could be about to see a noteworthy spell of weather, interesting times ahead.. P.S I found this video animation earlier about the GFS Model earlier, very funny! http://www.youtu.be/JmH56ypfFeA

superb vid lolol

[Troubleatmill]

reminds me of feb 1996 this set up, FWIW here is the bbc forcast for that day, although models are yet to firm anything up this could well turn out to be the same as far as Fridays event goes

[Frosty.]

The latest meto update goes for a very wintry outlook for the north and east of the uk, a little less cold at times in the south and west with heavy rain but also colder spells with more widespread snow and frosty weather, I think the message is the further north and east (ne) you are, the more wintry it will become and that the far west and southwest will largely miss the coldest weather. Friday looks very severe, the weekend also cold in the n and e with more snow, the southwest less cold with rain, so at least the complete breakdown to the freeze shown on the 6z from the middle of next week has little or no chance of verifying, after reading GP's post, it looks like we will all be in the freezer for long periods in the next few weeks.

[Methuselah]

I know how tempting it is, but could we please try to stick to what today's models are saying? Pretty please?

[Potent Gust]

The latest meto update goes for a very wintry outlook for the north and east of the uk, a little less cold at times in the south and west with heavy rain but also colder spells with more widespread snow and frosty weather, I think the message is the further north and east (ne) you are, the more wintry it will become and that the far west and southwest will largely miss the coldest weather. Friday looks very severe, the weekend also cold in the n and e with more snow, the southwest less cold with rain, so at least the complete breakdown to the freeze shown on the 6z from the middle of next week has little or no chance of verifying, after reading GP's post, it looks like we will all be in the freezer for long periods in the next few weeks.

Sounds great Frosty. I always wonder where I fit in with these updates. Living in Tamworth I am right in the middle of the country. Will I be more likely colder or milder?

[patrickshere]

Waiting tentatively for the 12z now from both NAE and GFS as Friday moves into the reliable time frame. I'm weary of any output much past the weekend. With lying snow over much of the country it'll be that much harder to shift the cold, and we could get some very low maxima's/minima's on Sunday with -15 -> -20 likely sunday night in places and maxima of -5 not being unlikely during the day.

edit: Metcheck is a good laugh for my region:

http://www.metcheck.com/UK/dayforecast.asp?zipcode=aylesbury&day=2

http://www.metcheck.com/UK/dayforecast.asp?zipcode=aylesbury&day=3

http://www.metcheck.com/UK/dayforecast.asp?zipcode=aylesbury&day=5

http://www.metcheck.com/UK/dayforecast.asp?zipcode=aylesbury&day=6

http://www.metcheck.com/UK/dayforecast.asp?zipcode=aylesbury&day=7

Wow.

Edited January 16, 2013 by mituozo

[V for Very Cold]

Wonder what the models are sying re: Saturday... we have Friday pegged as a snow event, but does bacttleground Britain finsih Friday...or are there residual events on Saturday?

[Frosty.]

Sounds great Frosty. I always wonder where I fit in with these updates. Living in Tamworth I am right in the middle of the country. Will I be more likely colder or milder?

Well I would favour what the ecm and ukmo are showing, so on balance I think you should stay cold with snow at times, I think the gfs outlook shown on the 00z and 06z op runs is totally out of sync with the ens mean. GP's post has reinforced my confidence in a prolonged and very wintry outlook.

Edited January 16, 2013 by Frosty039

[IanM]

Gavin

Don't get too hung up on GFS snow depth charts, they are experimental and well known for being a little over enthusiastic....

This weekend has the potential to be very wintry for all but the far south west and Ireland

[Rollo]

superb vid lolol

Thanks for that Mark-its f-----g hilarious. Edited January 16, 2013 by Rollo

[Ali1977]

Mon could be another snow storm looking at charts...if Fri snow does not melt some big depths, and transport problems could occur

[Waterspout]

Gavin

Don't get too hung up on GFS snow depth charts, they are experimental and well known for being a little over enthusiastic....

Just a technical note about these! It's based on the GFS WEASD (Water Equivalent Accumulation Snow Depth) field. As we all know (!) The Melted water accumulated equates to a snow density which can vary from 3 times that (compacted snow) to may be 10 times ( freshly fallen) . So, as you say, it's only a best estimate of real Snow Depth assuming the density is a constant(!) Which it won't strictly be.

John Ward of the GFS team explains it thus:

<< In the model a simple algorithm is used to determine if falling precipitation is rain or snow. If it's determined to be snow, both total precip & WEASD will be incremented by the precip amount. So, for any period the accumulation of water equivalent must be less than or equal to the total precip.

At each forecast interval (6 hrs for example) the total precip is set to zero and precip is accumulated for the next period. Since WEASD is the water equivalent of snow depth, it is not reset to zero so it can represent the water equivalent accumulating at the surface. It continues to be incremented if the temperature is low enough to support snow may become larger than the total precip for any given forecast interval. >>

Edited January 16, 2013 by Waterspout

[john mac]

I think we need to start to plan contingencies for a potentially sustained and very severe spell of wintry weather, of which Friday could just be the start.

NWP is presenting a number of potential snow events next week, which could well provide substantive accumulations.

The longwave trough migrating eastwards off the eastern coast of North America is consistently being modelled by ensemble means as cutting through a developing mid Atlantic ridge mid to late next week. That provides an eddy in the flow which is likely to enhance the easterly flow off an already frigid land mass to our east and north-east.

Thereafter, the ridge could retrogress towards the NE Atlantic and Greenland bring in another surge of Arctic air from the NE. That would give us a sustained period (with snowcover for much of the UK) of below normal temperatures.

I've grabbed the 06z GEFS at day 13 which depicts the synoptic pattern with a trough firmly ensconsed over Europe and high pressure to the north.

Thats a bit worrying GP, i have a business on a high street so obviously concerning, by contingencies what are we talking? sorry for being a bot off topic mods but i need to ask this to stuart.

[No Balls Like Snow Balls]

Thats a bit worrying GP, i have a business on a high street so obviously concerning, by contingencies what are we talking? sorry for being a bot off topic mods but i need to ask this to stuart.

I don't think you should buy fingerless gloves but full blown wooly mits.That's my contingency advice

Edited January 16, 2013 by No balls like Snow Balls

[KTtom]

Could someone please tell me if this T+60 chart is the latest one issued? If it is then its much further west than the models are showing?

http://www.wetterzentrale.de/pics/brack1a.gif

[Paul T]

Interestingly, the position of the PPN over the UK at 12:30pm is already where the NAE positioned it for 6pm today.

The NAE at 12pm today had the PPN clearly over Ireland, and not over the Irish sea. (below)

Whilst the current radar grab and 6pm NAE look very similar (below)

Is the PPN being more progressive? Will it push further inland than expected tonight? Will the band on 'friday' arrive sooner, is this a sign it may drive through the UK further than currently programmed?

So many questions!

[snowking]

Just a little caution to be had with regards to friday

When we have snow falling into dew points several degrees below 0c, its always very difficult to predict just how much of it will make it to the surface.

That 10cms figure at the moment is very very loose - could be 5cm less....could be 5-10 more.....very difficult to say until the higher res models get into range, and even then, take any figures seen with a pinch of salt

SK

[Sunny Leith]

I remember once seeing someone posting the daily met forecasts from 62/63 (I'm not ramping to that extent believe me).

Point is, even then there was always talk about mild incursions, little less cold at times etc ... in fact, and in general, the cold just sustained despite daily forecasts that suggested this that or the other.

Like I say, I'm NOT ramping to that extent, but not surprised to see these kind of possibilities being mentioned. We'll soon see the reality either way.

The latest meto update goes for a very wintry outlook for the north and east of the uk, a little less cold at times in the south and west with heavy rain but also colder spells with more widespread snow and frosty weather, I think the message is the further north and east (ne) you are, the more wintry it will become and that the far west and southwest will largely miss the coldest weather. Friday looks very severe, the weekend also cold in the n and e with more snow, the southwest less cold with rain, so at least the complete breakdown to the freeze shown on the 6z from the middle of next week has little or no chance of verifying, after reading GP's post, it looks like we will all be in the freezer for long periods in the next few weeks.

[Mac_SE]

Thats a bit worrying GP, i have a business on a high street so obviously concerning, by contingencies what are we talking? sorry for being a bot off topic mods but i need to ask this to stuart.

You could always message him to help keep the thread clear...

[No Balls Like Snow Balls]

Latest from Twitter and MH

High RESO models really signaling a well organised front with some significant vorticity associated with it on Fri = risk of mod/hvy snow

[hammerb32]

Mon could be another snow storm looking at charts...if Fri snow does not melt some big depths, and transport problems could occur

Indeed, to my relativly untrained eye additional snow fall on Monday looks like affected similar areas to those in the firing line on Friday, looks like it will be a quite significant fall as well.

[MisfitDog3]

I don't know! The longer I look at the Fax charts the more my past experience of these sorts of events tells me that the snowfall south of the M4 is at serious risk of being toned down at the 11th hour. I don't like the proximity of the 528 line or the anticipated angle of the front. It just looks v. marginal and southern counties seem to have a tendency to come out on the wrong side of any odds on these type of west to east events. Probably just my cynical middle age speaking....