Winter Model Discussion - The Hunt For Cold - 12th Dec

[Paul T]

Struggling to see the mild Swesterly's if I'm honest;

141hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/141/h850t850eu.png =11oC in the south west

168hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/168/h850t850eu.png = 10oC in the south west

228hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/228/h850t850eu.png = 11-12oC in the south west

I actually tought i was being rather sceptical as some regulars question my judgement, but on balance I think I have a more balanced and honest view of the situation.

[Gavin Hannah]

And the ridging arrives at t.384.

Cold pooling over Canada

Edited December 13, 2012 by IBringTheHammer

[Snowman.]

Still got that Arctic high not as strong but still their!

[OldMetMan]

Hmm, 18Z GFS looks reasonable up until about T180, then it goes kind of demented. The Nova Scotia LP is more slow moving in this run but at around T180, it would be logical to see a triple-point get caught in the jet and rush E. Instead, the GFS moves the whole works bodily E - not logical at all!

Note too the appearance of a new HP nearer to Scandinavia, which the GFS, as you would expect, quickly dispatches.

However, the small signs continue. Should make for some fascinating model watching the coming days.

[Geordiesnow]

I actually tought i was being rather sceptical as some regulars question my judgement, but on balance I think I have a more balanced and honest view of the situation.

Yeah, there may be some mild SW'lies but infact, the cold spells from the East do tend to start with a southerly flow as low pressure from the Atlantic tries to head into Europe, sometimes these Southerlies change to an Easterly if any blocking heads far enough Westwards and the trigger low heads for enough Eastwards.

There is only small signs that the output may turn colder again but at this range, the trend is not strong enough to get stressful about and the foreseeable will be Atlantic based weather. The output is not that bad really, it has some potential in it for sure but you do tend to think have we wasted a great opportunity here with that blocking high, it can't stay around forever unfortunately.

[nick sussex]

I think what we need to see tomorrow is that shortwave developing in the eastern USA, if you notice on the 18hrs we saw a weak feature, we need a developing shortwave to run east into the base of the trough,as this phases this will pull the northern end nw and help stretch the troughing.

With risk comes reward, this could then take energy into Iberia drain some of the energy away from the northern section and hopefully split this.

As I said earlier its complex because of timing issues, shortwaves and how far east the pattern gets, each incremental step west adds more margin for error which is what we need.

I expect this place to busy in the morning, our Xmas hopes are finely balanced, it could go either way but none of us want to hear those hideous words that suggest that everyone in the UK loves mild weather. The infamous At Least It Will Be Mild comments banded about by some in the weather media, no no no we want those scenes on Xmas Cards not mild, drizzly dirge!

Edited December 13, 2012 by nick sussex

[Kentish Snowman in Yorks]

141hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/141/h850t850eu.png =11oC in the south west

168hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/168/h850t850eu.png = 10oC in the south west

228hrs: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121213/18/228/h850t850eu.png = 11-12oC in the south west

I actually tought i was being rather sceptical as some regulars question my judgement, but on balance I think I have a more balanced and honest view of the situation.

You are correct in what you say taking those charts in isolation at face value but I think its the overall trend and the bigger picture we should be concentrating on. For example the lowering of heights to our south and the reorganisation of the blocking to our north and east.

I certainly think a new trend is emerging in this regard and tomorrow's 0z suite should make the picture a little clearer.

[MKN]

From reading this thread there's so many if this does that n if this heads south east etc etc. At the minute without even looking properly at the charts I can see there's more hope casting than forecasting taking place. We need a big change in the models with proper heights in the right place for anything noticeable of the cold variety to take place. For the next 7 days id pretty much rule any cold out. Hopefully after this period we get favourable changes but id say that mild is well and truly the favourite going forward as things stand.

[LomondSnowstorm]

141hrs: http://cdn.nwstatic..../h850t850eu.png =11oC in the south west

168hrs: http://cdn.nwstatic..../h850t850eu.png = 10oC in the south west

228hrs: http://cdn.nwstatic..../h850t850eu.png = 11-12oC in the south west

I actually tought i was being rather sceptical as some regulars question my judgement, but on balance I think I have a more balanced and honest view of the situation.

Equally, at +141 maxima are around 4-5C across the spine of the country (2-3C) in the highlands. At +168, maxima still only 4-5C across the central belt, around average elsewhere, at +228 around 3-5C widely.

I'd say the bigger picture is one where we might get a decent opportunity for a cold shot, if only temporarily, from the east of northeast, which has been a possibility for the last few days but has finally started to appear on some of the operationals. Whether we see it verify or not is another matter.

[ribster]

From reading this thread there's so many if this does that n if this heads south east etc etc. At the minute without even looking properly at the charts I can see there's more hope casting than forecasting taking place. We need a big change in the models with proper heights in the right place for anything noticeable of the cold variety to take place. For the next 7 days id pretty much rule any cold out. Hopefully after this period we get favourable changes but id say that mild is well and truly the favourite going forward as things stand.

Then surely you're in the wrong place, as I thought the idea was to look at the charts, as many of the previous posters have and given their views on.

[fergieweather]

For anyone interested in the wet and windy weather tomorrow I've made a post about it here

As for what the models are currently showing I've checked all their runs from the previous days still seeing small upgrades in the reliable time frame like high pressure systems being upgraded and lows being downgraded just time will tell as we get closer.

Probably aware but we've upped emphasis on winds tomorrow for much of S England. Decidedly wild for some, especially to SE later PM with troubling hook-like development of ppn and associated swathe of gusts potentially 50-60kts based on high-res products (e.g. Kent & possibly parts around London)

[nick sussex]

From reading this thread there's so many if this does that n if this heads south east etc etc. At the minute without even looking properly at the charts I can see there's more hope casting than forecasting taking place. We need a big change in the models with proper heights in the right place for anything noticeable of the cold variety to take place. For the next 7 days id pretty much rule any cold out. Hopefully after this period we get favourable changes but id say that mild is well and truly the favourite going forward as things stand.

Lol! I think most would agree with you regarding the next 7 days but if you looked at the charts properly you might see theres a chance of something turning up.

If people just commented on what the charts showed and didn't explore the range of possibilities then what exactly are we supposed to be discussing in a model discussion thread?

You can make a case for a continuation of mild and a change to colder conditions this evening. It could go either way given that all the models agree on a jet tracking quite far south, we don't need some big pattern change just a bit of luck, we'll see over the next few runs which way it will go.

[swfc]

Tentative signs of a short term change but its so complex to get there it seems as likely as the last episode! Not a great deal of blocking to the north ete but things do seem volatile so anyone's guess.we do now seem not to be overwelmed with nao'c+s,b+q m+s ete ete ete which seem to add more confusion with minimal result!lol

[Catacol]

Someone said earlier a week is a long time in weather forecasting. Never mind a week... 3 days can seem like an eternity.

However as the doom and gloom posts turn a bit more hopeful tonight let's get a bit of perspective. Here in the SW the cold stayed all day - that's 4 days of hard cold. The ground is so solid that all my sports stuff was cancelled throughout the week: no snow, but pretty damn bitter.

We now have a day or two of mild, before becoming average/cool again in NW air, and then a cold fightback, with the energy over Canada sucked out of the area by the vortex transfer that started properly yesterday. This was always going to be the key moment. See this chart for Thursday - vortex over in Siberia and very little on our side to keep the atlantic pumped up. The result will be more of a slider scenario... I suspect GP's slider scenario would have been right on the button this week had the modelling of the vortex tail not been underestimated.

Therefore is this undercut scenario that is just beginning to pop into the output realistic? Yes. For the first time this winter we have a slight deviation from the NetW forecast which pointed potentially to a northerly in the run up to Xmas, but the heights this week did not win back far enough west this week, so easterly from undercutting lows must be favourite from here.

Most encouraging for me is the sense that we have constant pressure from the east, and right on cue we have a major predicted final assault on the vortex in the next couple of weeks which will help rob the vortex of any sustained energy for a good while. Others more knowledgeable than me have stated in the strat thread today that the damaged vortex is most likely to stay on the Siberian side after that attack - this should allow the Siberian high to back west once again through January, if correct.

I dont buy the MetO forecast and I think it just proves that they put very little energy into serious seasonal forecasting at present.

Edited December 13, 2012 by Catacol_Highlander

[snowking]

Very quick update for you on the ECM32 control

Mid range, in the run up to and over the xmas period, weak ridge to our west cutting off and forcing the mean trough to head SE, introducing weak varying E/NE/SE flow, then into the first 10 days of the new year back to some atlantic mobility. Towards the 10th HP ridges from the azores up to the UK and joins HP to our NE, and this then gets pulled NEwards...a little December 1962-esque

Nothing especially mild though, and sub -5c 850's around the aforementioned xmas period and into the new year in association with that variable Ely flow.

I must say actually very consistent with monday's update, though as per todays NWP output, a general southerly shift from the previous output

SK

[Weathizard]

What are the 18z ens like so far? Can't look at them because on phone!

[AWD]

Very quick update for you on the ECM32 control

Mid range, in the run up to and over the xmas period, weak ridge to our west cutting off and forcing the mean trough to head SE, introducing weak varying E/NE/SE flow, then into the first 10 days of the new year back to some atlantic mobility. Towards the 10th HP ridges from the azores up to the UK and joins HP to our NE, and this then gets pulled NEwards...a little December 1962-esque

Nothing especially mild though, and sub -5c 850's around the aforementioned xmas period and into the new year in association with that variable Ely flow.

I must say actually very consistent with monday's update, though as per todays NWP output, a general southerly shift from the previous output

SK

So basically we look to be spending the next 4 weeks chasing "Easterly" flows?

If we keep trying & repeating the pattern, we might get there one day.

[snowking]

I should possibly also add as a little tease - a huge uptick in the formation of high-mid lattitude blocking in the final few frames - first response signs to the progged stratospheric warming? Who knows....

SK

[Dean E]

GFS is really holding on to the Russian High, right through the run... incredible! Seems like another default GFS after +120 with numerous Lows spinning off the Coast of NE America, I think that is most likely to change in the short term.

But as SK said, very dramatic shift towards a SSW just in the last few frames. Very interesting to see if this becomes a common theme

SM

[Cloud 10]

Probably aware but we've upped emphasis on winds tomorrow for much of S England. Decidedly wild for some, especially to SE later PM with troubling hook-like development of ppn and associated swathe of gusts potentially 50-60kts based on high-res products (e.g. Kent & possibly parts around London)

NAE has tomorrow's low center further south than the gfs and also has more rainfall projected.

Looks like a very messy day tomorrow.

[Iceni]

I dont buy the MetO forecast and I think it just proves that they put very little energy into serious seasonal forecasting at present.

But we already did! That super computer was bought with taxpayers' money. Agree about the rest.

[Hedgehog]

Rather premature if you ask me.

Absolutely no chance the interaction between the LP and the block to our NE is going to be resolved yet. Clearly a change is occuring in todays output but the trouble is nobody including the models knows what it is!

Agree, unusual to say the least

It looks like the cold and the block may win, but i think patience may be needed on!!!!!!!!!!!

[Cheshire Freeze]

This is where it would be handy to have Ian active on the thread so we could gain an insight into what the MOGREPS is showing in terms of trends. It spotted this milder Atlantic incursion before the ECM, GFS or UKMO.

EDIT just seen he's posting in here again

Edited December 14, 2012 by CreweCold

[Duane S.]

To my mind, it was today / tomorrow at the latest that we neeed to see a new trend emerging if we are to have any chance of a cold Xmas. And i'd say the models have obliged. The vortex is for once doing us a favour as it looks to exert pressure on the block and there is a growing tendancy for it to edge west again. I don;t see any sort of mad retrograde to Greenland or the like but watch out for signs of weak but possibly effective +ve heights to the north of us, possibly part in response to the jet driving more on a more southerly track.

ECM stunning relative to some of the dross we have had to look at over the past few days. I always thought the Atlantic profile past 4-5 days just didn't look right on recent chart showings. I think we will see a continued trend of a less active Atlantic over the coming days.

And all this could be a nice little appitiser to what could occur second half of the winter. With a potentially massive warming on the cards, this throws up all sorts of possibilites. 62/63 comparisons are not far fetched IMO. I'm not saying we will have a repeat of that winter! but certainly there are many similarities to be drawn.

[osmposm]

I dont buy the MetO forecast and I think it just proves that they put very little energy into serious seasonal forecasting at present.

Um, sorry - what proves that the MetO 'put very little energy into serious seasonal forecasting at present'? The fact that you disagree with it?

Edited December 14, 2012 by osmposm