Model Output Discussion 26/11/2012 18Z onwards

[Severe Siberian icy blast]

Ok once again glazier points the voice of reason , thankyou gp , also the ECM 32 dayer looks awesome apparently , so the broader picture to me looks in a word . . . Snowy , all the signals, northern blocking , trough to our south east , massive signal for slider low pressures across th uk , not extreme cold like dec 10 but below average temps with sliding low pressure systems , haven't watched the winter forecast yet but I think i already know where it's going. Awesome.

[ITSY]

broad outlook positive. Any Northernes who likes snow, bank this run:

Edited November 27, 2012 by ITSY

[Thundery wintry showers]

Note that many earlier model runs had the -5C 850hPa isotherm struggling to penetrate beyond northern Scotland, so although the east to north-easterlies that they showed may have brought more precipitation, most of it would have been rain at low levels. 850hPa temperatures look set to dip below the -5C mark over most of the country this week, though on the other hand, the winds will be northerly and this will mean a more pronounced "wishbone effect", with sleet and snow showers restricted to windward coasts. If this was March or April we would no doubt get a fair amount of homegrown shower activity in a setup like this, though of course the stronger sun would generally mean daytime thaws in the sunshine in between the showers.

Troughs, however, cannot be ruled out as they do sometimes turn up at short notice in these cyclonic/northerly regimes, and they could bring rather more widespread snowfall.

The UKMO outputs were too progressive at sending the trough in the North Sea southwards which is why they kept showing a north-easterly or easterly flow, but in fairness the model has only done a slight backtrack this morning (today's T+120 output bears a lot of resemblance to yesterday's T+144 output) while the ECMWF has flipped about rather more.

On the basis of this morning's outputs frontal snow could well be quite widespread for a time on Monday, with Scotland and the north and east of England most likely to see the white stuff. Behind the frontal system there will be some quite chilly polar maritime air due to the NW-SE alignment of the jet, so the subsequent Atlantic-driven weather could well feature some marginal snow events in the north, with very little evidence of heights rising at high latitudes anythime soon and the likelihood of further northerly and north-easterly outbreaks.

Edited November 27, 2012 by Thundery wintry showers

[Mucka]

That is the last 2 model runs (timewise) that have gone for a slider BOM and GFS 06z

I could see hints of it in the overnight output but if it does develop I think it is hats off to Steve Murr who signed off last night hinting that is what he fancied.

Hats off to him even if it doesn't come off TBH since the output has reflected the possibility the day after he mentioned it.

[BOMBHEADS]

the latest GFS run is showing LP after LP sliding under the russian HP, this could produce an interesting scene for the UK if it was to come off, seems to be a reasonable run. best model watching for years, ups and down, better than 2010 for enjoyment.

Edited November 27, 2012 by BOMBHEADS

[MKN]

I thought id read this thread to gain an idea of what to expect over the next 5 days however reading the posts on here I thought there was 0% chance of any snow. I look at the models and from weds through till Sunday snowfall could occur over much of the UK with potential of a decent fall if the low attacking the UK Monday is better aligned as Steve showed last night. after that and your way out into FI so im not fussed about what's shown but if your one of the people that do even the further reaches of the model output show lots of reasons to optimistic.

[124alex]

I thought id read this thread to gain an idea of what to expect over the next 5 days however reading the posts on here I thought there was 0% chance of any snow. I look at the models and from weds through till Sunday snowfall could occur over much of the UK with potential of a decent fall if the low attacking the UK Monday is better aligned as Steve showed last night. after that and your way out into FI so im not fussed about what's shown but if your one of the people that do even the further reaches of the model output show lots of reasons to optimistic.

what next wednesday- sunday, if so it will downgrade :/

[MKN]

This week Alex

[Frosty.]

I like the jet profile on the gfs 06z, nw/se with a southerly tracking jet, lots of energy being pumped into the southern arm of the jet and northern blocking remaining strong, some snow events in FI as lows bump into the cold air over the uk with northern uk particularly at risk of the ppn remaining wintry. As for the rest of this week, turning colder and brighter with widespread frosts, then a cold and unsettled weekend with wintry showers around, next week continuing cold and unsettled, there would be a lot of snow on hills in the north, a much colder 6z than yesterday with the jet further south and nothing remotely mild.

[124alex]

This week Alex

Ok just out of interest if it was to pull off, which areas would likely see any snow from this scenario

[Radiating Dendrite]

The fact that the 6Z GFS is still showing good blocking is encouraging as I often see this is the most atlantic bias run.

[jessandjon]

what next wednesday- sunday, if so it will downgrade :/

Would we get any in Devon and Cornwall? As whenever I look at the charts we seem to miss everything! And whenever I look at the blue bits none of them are over us!

[Nick F]

I look at the models and from weds through till Sunday snowfall could occur over much of the UK with potential of a decent fall if the low attacking the UK Monday is better aligned as Steve showed last night.

I don't think there'll be a widespread chance of snow between now and Sunday, any precipitation looks to be limited to eastern coastal counties, the far north of Scotland and perhaps a few north facing coasts in the west. Sunday onwards, yes, though too much uncertainty over how widespread atm, as Atlantic fronts try to attack the cold from the west.

Edited November 27, 2012 by Nick F

[nick sussex]

In case people start worrying over the GEFS ensembles best factor in inherent model bias and lower resolution with undercutting scenarios.

The ensembles will generally want to take more energy east and north and will take longer to resolve this.

This is also a problem for operationals, less so although still an issue with the balancing act of where the energy goes.

And please give the UKMO some slack in this set up its one of the most difficult forecasts to get right and the areas with chances for snow will change frequently if the slider low does verify.

Edited November 27, 2012 by nick sussex

[No Balls Like Snow Balls]

We know that it will be turning colder from tomorrow and last right until Sunday with temps below avearge for time of year and it will feel cold.

Also if the 06z GFS verifies then early next week Monday and Tuesday will still be cold and below average for the bulk of the country even with winds coming from the W/NW.

Therefore even though it may seem like we have lost the chance of a significent cold spell for the time being (maybe just a few days???) in reality it's going to remain cold in any "milder" blip I think??.

And put into context that it is still late November coming into early December then this cold spell isn't going to be really that bad or disappointing at all IMO. You could even say the cold spell never really ends in FI????

Edited November 27, 2012 by No balls like Snow Balls

[MKN]

this week most likely areas would be Scotland and Wales. East facing coasts have a chance until Thursday morning after then itl be those on the western side on the UK with a greater chance. Remember tho anything that occurs only looks like showers at best at this stage. We could do with a more organised area of precip to give something more meaningful.

[offerman]

Shaun, Spot on, This could be very similar for those of us in Southern England. Slider lows are our best option for snow as the last 3 winters before last year proved for us in somerset. Snow from the north normally fizzles before it reaches the south, we can get good snow from the east as some of the 80`s winters proved.

These lows undercut the main cold flow dropping snow then sucking more cold back in as they pass, so hopefully these charts will strengthen this scenario for snow lovers.

Thanks Ian F for taking the time to post here, really didn`t think after working on the t.v that this is the last thing you would want to do. So nice to see some people on T.V don`t mind mixing with us mere mortal peasants. :-)

next run of charts will be interestings if they can continue the theme of moving that North sea low southward followed by sliders.

[Mucka]

Short ensembles (central UK) (link will show long about 20 minutes from this post)

http://modeles.meteo...run=6&runpara=0

The "mild" bump from the 2nd is delayed 24 hours and somewhat flattened from the 00z

Edited November 27, 2012 by Mucka

[Paul]

The ECM32 keeps the UK in pretty cold air for virtually the entire run with just brief milder interludes a couple of times in early Dec, and around the 19th/20th Dec for a few days. Obviously at this range the specifics can't be taken literally but the pattern is for chilly or cold weather virtually throughout.

[Backtrack]

The ECM32 keeps the UK in pretty cold air for virtually the entire run with just brief milder interludes a couple of times in early Dec, and around the 19th/20th Dec for a few days. Obviously at this range the specifics can't be taken literally but the pattern is for chilly or cold weather virtually throughout.

Although the trend is there, how can we trust a 32 day ECM run when the 10 day ECM run can't even nail the T120 chart?

All of the background signals were there, it's not often we see John Holmes in shock about the 500mb charts being wrong. I think right now everything is up in the air. Cold weather is obviously favoured right now due to higher pressure over the Arctic and a trend for northern blocking to prevail for a time, but I'm not willing to trust any model right now after been so disheartened over the last couple of days.

[492]

Correct me if I'm wrong, but once these systems have moved over land, they will drop a fair bit of snow over the European mainland, increasing the size and depth of the cold pool available when winds are steered in from an easterly quarter.

Yes this is often the case.

[Jaffusmaximus]

We really need to see what happens to the blocking high after it gets attacked from the west. Once the dust settles there will be so many different ways this could go, seeing as all the pieces are still in play for the the block could come back quickly and stronger than before. Things are actually going in the right direction if we would prefer a stronger NE feed as we still need time out in Siberia to allow it to build up enough cold to feed us. Has anyone doubting any cold snap looked further than this weekend?

[andymusic]

this week most likely areas would be Scotland and Wales. East facing coasts have a chance until Thursday morning after then itl be those on the western side on the UK with a greater chance. Remember tho anything that occurs only looks like showers at best at this stage. We could do with a more organised area of precip to give something more meaningful.

think that's going to happen anyway with the atlantic front piling in and delivering copious amounts of snow! - just believe - the cold block will have a good influence over the front!

gfs 6z - here ya go - snow on saturday appearing again

westerly shift on the cold - should be more by the weekend - meaning more snow from the atlantic as it pushes in

this for sunday so far - could well improve lots

sunday night into monday looks full of potential for a full on snowfest as far as I can see - don't know what people are worrying about

cold block will probably shift further west by the weekend - we are in the cold zone and loads of snow could well be with us very very shortly - snowmen city is just around the corner folks!

[Frosty.]

The ECM32 keeps the UK in pretty cold air for virtually the entire run with just brief milder interludes a couple of times in early Dec, and around the 19th/20th Dec for a few days. Obviously at this range the specifics can't be taken literally but the pattern is for chilly or cold weather virtually throughout.

I think we could almost use the 6z as a template for the next few weeks, the outcome will probably be similar with a generally cold and unsettled outlook with spells of rain, sleet and snow and brighter frosty spells with wintry showers to exposed areas. A lot of snow for northern hills and mountains, fantastic for the scottish ski industry if we do end up with increased energy being pumped into the southern arm of the jet, northern blocking looks entrenched and the uk will be at risk of a more potent wintry spell through december.

[london-snow]

Morning all,

Despite the doom and gloom from some here this morning i remain optimistic and do feel that there is still a final big twist to come on the 12z this afternoon in terms of keeping us in the cold once it establishes.

I am also not to disappointed with what the models are showing this morning europe gets cold which we may well tap into and benefit down the line. Blocking evident, Below average temps for the uk. The state of the hemispheric pattern currently and the way it is shaping up further afield.

It's all positive.

It may well be that we have been desperately unlucky at the first shot but the second shot is not going to be to far behind by the looks of things.

Would like to give a mention to GP for releasing his winter forecast and taking time to explain his thoughts going forward not only on the video but also helping us 'novices' out who are still learning - You are a credit to this forum & without you n-w will be worse off.