Model Output Discussion - 28th November

[NorthernRab]

Excellent consistency following on from the 12z run of low heights deepening to the northwest throughout FI...

Excellent consistency? Eh? It wasn't two days ago that it was showing high pressure!

[Severe Siberian icy blast]

FAX chart shows quite an unusual set up 128 hours with a cold plunge from the north thanks to trough being forced southeast, however, it is hard to say whay might happen next - with the unusual intense low pressure near the azores, I suspect we would see a classic 'col situation' and when this occurs it is a guessing game where things might go next.

The reliable timeframe is Sunday, I think the models will continue to show various scenarios for next week in the coming runs... but the overall trend will be a cold one with heights staying very strong over the arctic which will be the dominant factor, the building blocks for a substantial cold period are certainly setting up shop....

I completely agree, and this is an evolving situation , the models are flipping every single day.

If we look at the reliable however it's looking very good, and next wk at the moment is looking full of potential, all models showing a very cool northwest wind , with the trough coming south. Anything pAst 120 is just for fund, or trends at best ,

[Weathizard]

WHY does the GFS always pump up the Vortex with NO support from any long range signals? Can someone explain? Does it have an in built bias? I know this wont happen anyway, ignoring the GFS ops for a while, no agreement anyway, we'll see but i cant see the GFS proving right.

[Cheshire Freeze]

Excellent consistency? Eh? It wasn't two days ago that it was showing high pressure!

Yes that's why I said between the 12z &18z runs. I was making an observation which countered the arguments that there's disagreements in modelling. To replicate pretty much the same synoptic at 300+ hrs between runs shows quite a degree of confidence, no? If it was a Greenland high shown in pretty much exactly the same manner between runs, people would be crowing on about there being a trend!

People may not want to hear reality but they're only going to prolong their own misery in the long run.

Besides, I hope I'm wrong and if I am I'll gladly eat humble pie!

[bradymk]

From where I am sitting I can't see anything of note for the next 10 days at least.

I wouldnt say that CC, a very interesting 10 days coming up i feel, more for some than others, further north you are the better but widespread below average temps with chances of some snow depending on the tracking of lows. 120 fax chart is one chart that shows the potential next week. Lets see what the overnight models show, a few surprises for all next week i would say, increasing the further N you are.

[AutumnMists]

Excellent consistency following on from the 12z run of low heights deepening to the northwest throughout FI...

trust me, there is never any consistency for anything beyond day 5.

It's pointless digging out the mild pictures when you are ignoring a greater amount of colder or average pictures as you are simply saying that all models agree with each other.

Anyway, if temperatures are to get to average at best in the next 14 days, you can't ask for much more?

Deep cold doesn't come every year

[SnowObsessor90]

If you love cold frosty weather and fog then this is your run with some very cold nights under that high. So a good run for surface cold but not if you want snow. However huge differences between GFS and the other models. Hints at heights rising to somewhere to our N towards the end of this run aswell but where is favoured for this at the moment? Unsettled or anticyclonic? unsettled for me at the moment, even though the GFS has shown this for the last few runs, i still favour the ECM/UKMO solution. Could be some interesting weather next few weeks, a few surprises i feel. Matthew

Or alternatively benign and mild, in my view that's the possible set up you can get during winter, I'd even a typical flat zonal pattern over that particular scenario as it at least provides something of interest in the form of strong winds which is still better than nothing.

Edited November 29, 2012 by Anonymous21

[Alan Medlock Valley]

As others have said the models we're seeing are still better than most of the mild stormy SW muck we put up with in most of the 90's 00's and it's not December yet or traditionally the coldest time of year, there should be a raging gale outside and 10 degrees but instead at the moment it's a few degrees below freezing. Still model wise things can improve even further with the 00z.

[AutumnMists]

Yes that's why I said between the 12z &18z runs. I was making an observation which countered the arguments that there's disagreements in modelling. To replicate pretty much the same synoptic at 300+ hrs between runs shows quite a degree of confidence, no? If it was a Greenland high shown in pretty much exactly the same manner between runs, people would be crowing on about there being a trend!

People may not want to hear reality but they're only going to prolong their own misery in the long run.

Besides, I hope I'm wrong and if I am I'll gladly eat humble pie!

Another thing I should add, No one has been suggesting deep cold or anything like that before day 14.

[phil nw.]

I sense a little bit of niggling creeping in to some posts.

We don`t like deleting and want to keep the thread flowing but a few comments are close to the mark.

By all means have a different pov but let`s keep it friendly and to what`s in the outputs.

Thanks all.

[Zakos]

That may be so but the 18z shows great consistency following on from the 12z. The ECM has shown a few outcomes from run to run but GFS has shown good intra model agreement today. I stand by what I said earlier and that is I really don't see any prospect of a widespread cold/snowy spell in the next 14 days. After that,who knows?

This thread today has, at times, added a whole new dimension to the phrase 'clutching at straws'. If anyone can point me towards more than the odd ensemble or lone operational run that suggests otherwise to the above, feel free.

so what? how many times have we seen great consistency in the models, only for a rapid backtrack? only a few days ago we had virtual cross model agreement of a cold north easterly, only for the ECM to backtrack at the last minute, with the other models swiftly following.

Again, that is irrelevant. The UKMO was very consistent with the North easterly, but eventually fell in line with the other models. Consistency doesn't equate to accuracy.

What reason do you have to write off the next 14 days of weather? besides 2 runs of the GFS?

Nope. straw clutching is what some did during last December, with the Rampant Polar vortex and strong heights to our south. We currently have a negative Arctic oscillation, with a highly disturbed PV, low heights over europe, etc... so how can anyone possibly be straw clutching?

I find your pessimism most unjustified. the models are constantly spewing out loads of different scenarios beyond 120 hours.

There are plenty of things that point otherwise. Weather experts, such as the met office, GP etc. Oh and dont forget the teleconnections.

The models dont have mystical powers to predict the future, they only mathematically compute their output.In this very complicated setup it is no wonder that they are all over the place. I personally find it rather premature that you are using the consitentcy between 2 GFS runs to write off the next 14 days of weather.

Edited November 29, 2012 by Zakos

[bobbydog]

there may not be anything 'epic' showing on the models but i've just had a quick browse through the bulk of them. i certainly can't see anything resembling mild for the forseeable future.

just take this one, picked at random from the JMA-

fairly promising start to winter i think. considering we're not even in it yet...

[Cheshire Freeze]

I'll just add that undoubtedly this run goes pear shaped once again due to that low in the Atlantic becoming isolated from the main pulse of jet to the north. The UKMO highlights perfectly what happens if this low becomes phased as part of the main trough- the Azores high can move WEST & slightly NORTH instead of being shunted east. The end product is a much more amplified situation rather than the dirge of the 12z & 18z GFS runs where we just end up being affected by a mid lat high and the jet looping up over the top.

[chris55]

As others have said it's the jet streak pushing through past the tip of southern greenland thats our problem tonight,

The chunk of PV over northern Canada is like a breeding ground for bits of energy to be spat out towards us.

If we look at how the PV is modelled on the 18z it's interesting

Plus 48 split vortex, we've gone cold, but it's just a little bad luck we didn't go really cold.

Then at plus 186 the PV is reorganising around northern Canada area (there was talk about where the PV would reform after the split)

Then towards the end of the run the PV looks to be moving off to the Eurasian side of the globe (hopefully to be split again soon)

Basically whilst the chunk of the split vortx and the reforming of the vortex is taking place over Northern Canada we are always going to be up against it a bit trying to get a high lat block to the North West and a Scandi high could form but will probably be squeezed over by the energy to the north.

[Duane S.]

Okay, enough is enough, who are you, what do you want, why are you kicking around in December ???

This feature has got me mighty confused. Just downright odd seeing it there.

I know! I'd go as far as to say it's one of the strangest features I've seen on the charts. When it first appeared I thought it would gone within a run or two but no, there it still is, meandering along seemingly disconnected from the geneal weather going on around it! I'm intrigued to know what part (if any) it will play.

[SnowBallz]

WHY does the GFS always pump up the Vortex with NO support from any long range signals? Can someone explain? Does it have an in built bias? I know this wont happen anyway, ignoring the GFS ops for a while, no agreement anyway, we'll see but i cant see the GFS proving right.

It's because all algorithms have an in-built mathematical bias. Some models will exhibit noticeable tendencies, and it's because those eventual outcomes have been placed there, by design. The 'design' is based on long-term probability, which - as we know - is a reliable reference.

It's all part of the rules and thresholds which have to be within models, in order to control the obvious random nature of chaos theory. In short, if you had no general principles - say for the Northern Hemisphere as a region - then compounded chaos theory could, quite plausibly, imagine the earth spinning on an entirely different axis!

So with this in-mind, I feel it's often wise to resist placing so much reliance on the low-res output of, in particular, the GFS. We have seen, indeed we all recognise, it's propensity to 'blow up' low pressure systems - therefore it's reasonable to infer that there is inbuilt design for this.

Hope that helps to give you an understanding of why you see this patterns/trends/favourable evolutions in some models, especially in low-res?

[Backtrack]

A cold night to come by T177, although milder air is edging closer and closer to the UK in time for next weekend.

Tied in with this milder air is a weird looking Pikachu.

Oh well, at least it's looking dry, we also have the cold pool building nicely for us to tap into over on the continent.

Edited November 29, 2012 by Backtrack

[phil nw.]

Just to underline that it`s certainly looking colder than normal here are the Dutch and London Ens graphs

2Mtrs temps. in low single figures and this for London-probably colder days for many other locations.

Not a bad start to Winter.

Edited November 29, 2012 by phil n.warks.

[Dunstable Snow]

so what? how many times have we seen great consistency in the models, only for a rapid backtrack? only a few days ago we had virtual cross model agreement of a cold north easterly, only for the ECM to backtrack at the last minute, with the other models swiftly following.

Again, that is irrelevant. The UKMO was very consistent with the North easterly, but eventually fell in line with the other models. Consistency doesn't equate to accuracy.

What reason do you have to write off the next 14 days of weather? besides 2 runs of the GFS?

Nope. straw clutching is what some did during last December, with the Rampant Polar vortex and strong heights to our south. We currently have a negative Arctic oscillation, with a highly disturbed PV, low heights over europe, etc... so how can anyone possibly be straw clutching?

I find your pessimism most unjustified. the models are constantly spewing out loads of different scenarios beyond 120 hours.

There are plenty of things that point otherwise. Weather experts, such as the met office, GP etc. Oh and dont forget the teleconnections.

The models dont have mystical powers to predict the future, they only mathematically compute their output.In this very complicated setup it is no wonder that they are all over the place. I personally find it rather premature that you are using the consitentcy between 2 GFS runs to write off the next 14 days of weather.

I agree with this assesment. I fully respect CCs view of the situation but i sense that he is being a little one sided in his assesment of the current sitiation. I would say it is 60/40 that he has accurately assessed the current outcome but the above post clearly outlines the differences we are seeing as we go into this winter season. I suspect he may have met up with Ian for a coffee !

[Zakos]

I agree with this assesment. I fully respect CCs view of the situation but i sense that he is being a little one sided in his assesment of the current sitiation. I would say it is 60/40 that he has accurately assessed the current outcome but the above post clearly outlines the differences we are seeing as we go into this winter season. I suspect he may have met up with Ian for a coffee !

Thankyou. He is partially correct in his assessment. Yes things do look fairly dim in the model output currently, it cannot be denied.

He has however failed to acknowledge the high model variability, or the other pointers such as teleconnective support.

He has put too much faith in the models alone, and im not being critical because he is not alone on here.

haha wouldn't surprise me one bit!

Edited November 29, 2012 by Zakos

[Weathizard]

It's because all algorithms have an in-built mathematical bias. Some models will exhibit noticeable tendencies, and it's because those eventual outcomes have been placed there, by design. The 'design' is based on long-term probability, which - as we know - is a reliable reference.

It's all part of the rules and thresholds which have to be within models, in order to control the obvious random nature of chaos theory. In short, if you had no general principles - say for the Northern Hemisphere as a region - then compounded chaos theory could, quite plausibly, imagine the earth spinning on an entirely different axis!

So with this in-mind, I feel it's often wise to resist placing so much reliance on the low-res output of, in particular, the GFS. We have seen, indeed we all recognise, it's propensity to 'blow up' low pressure systems - therefore it's reasonable to infer that there is inbuilt design for this.

Hope that helps to give you an understanding of why you see this patterns/trends/favourable evolutions in some models, especially in low-res?

Thanks a lot for the answer, i assumed this was the case, as in my few years of model watching it becomes increasingly obvious that the GFS has a serious bias for over doing low pressures.

I was also going to ask people, that tropical low, what is it doing there? However i've just noticed nobody really knows, its one of the strangest things i've seen on the models

[TEITS]

Thanks a lot for the answer, i assumed this was the case, as in my few years of model watching it becomes increasingly obvious that the GFS has a serious bias for over doing low pressures.

Depends on how these models are programmed. All the models use the same data but its how they are programmed that makes one more accurate than the other. The only people who can give you an honest answer is those who programmed these models. Clearly the programming of the ECM is far superior than say the NOGAPS.

[Cheshire Freeze]

^^^^^RE above comments. I can see the situation from a holistic perspective BUT as someone who aims to provide a forecast as to where we may be headed over the next couple of weeks, it's important to come off the fence and plump for what I feel is most likely. Emotion, hopes, wishes, dreams and personal preferences have to be cast aside in this instance to provide an unbiased assessment of the evidence I can see before me.

It just irks me slightly that some members see favourable teleconnections as touted by the experts of the site and automatically assume we 100%, without a doubt, will see a cold snowy spell of weather. Anyone with a semblence of meteorological knowledge & general awareness will realise that even though teleconnections may point towards a favourable set up, in reality the siuation 'on the ground' may not come together due to the decreased margin of error owing to us covering a TINY percentage of the earth's surface!

[SMU]

THe low is just a tropical wave thats developed & recurved North & Deepened - Its become a fish storm & recurved into the gap of weakness between the High pressures.

I look forward to tomorrows EUROS & for the GFS to be catching up.

S

[Catacol]

From where I am sitting I can't see anything of note for the next 10 days at least.

I think you need to go and surf a few archive charts for UK winter synoptics and then return to take a long look at the current NH pattern. Nothing of note? We are sitting watching a huge vortex split, at a Europe devoid of any high pressure to the south, and frequent runs pointing to northerly and/or easterly air currents. There is no raging zonal pattern, and my local weather station tonight has the current temp at -2.5 in Somerset in November. That's pretty good for this time of year too.

I dont think it gets an awful lot better than this... unless you are looking at December 2010 as your comparative analog - and then you need to check the archives again and realise that Dec 10 was the second coldest December in UK on record. That was an extraordinary month.

And next week we have the potential for some frontal snow... there are snow showers NOW over north Wales, there have been a fair few runs showing scandy height rises by the end of the week, and ensemble mean temperatures are set to run well below average.

Realism is what this thread needs.