Model Output Discussion - 28th November

[Dampdorset82]

^^^^^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!

I agree, we could talk about the minor to major situations that can affect even a small area of the UK that has been forecast a specifc let alone the island as a whole.

There needs to be a high degree of perspective when talking weather models and the science behind them. Thats not to say dont enjoy a good debate and the odd ramp afterall its our passion of weather that brings us here.

Back to the models a few of the big guns are pointing to colder conditions @ 144hrs JMA ECMWF and UKMO. GFS is stand alone to a certain degree with its placement of the vortex.

Im very intrigued as to how tomorrows GFS compares to the above 3.

[pyrotech]

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

I think to some extent that issue has been addressed, its been ECM in my opinion making the overcooking this year, a few times now GFS was lower intensity than ECM and ECM had overcooked them. One such storm system had a lot of interest on here but became a damp squib. It was definitely an issue with GFS previously thou. Thats not to say it will not make an error that way in future, but i seemed to notice some kind of adjustment appeared to have been made this year.

[Dunstable Snow]

^^^^^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!

I fully understand where you are coming from CC but your earlier post refers to a 14 day timescale. What I do see during that period is the potential for snow for many, frequent frosts and temperatures well below average. Perhaps the issue here is the definition of widespread snow - The far south may well miss out but from the South Midlands northwards I think there is a real opportunity for snow, frost and temperatures well below average. The potential is also there for a trigger low setting up an easterly - this could happen and then the far south becomes a player, maybe a major player. I just feel that you have dimissed the chances out of hand based on the current model output without considering the picture picture, which to be honest is most unlike you. If we had a flat zonal pattern and a firing up northern jet then yes. I dont quite see that at the moment and I think that is the point Z is making also. If the northern jet does fire up then yes it is probably good night for 2/3 weeks but we are not there yet in my view. Lets see whwere we are come the middle of December !

[Cheshire Freeze]

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.

Yeah pretty exciting model outputs from a NH perspective if you happen to be over on the Pacific side! The vortex can paint as many pretty pictures as it wants but IF and whilst we have those low heights & vortex energy around Greenland & high pressure attempting to reside over parts of Europe and UK & the jet going over the top we will not be joining in the party!

Edited November 29, 2012 by CreweCold

[Snowy Easterlies]

http://modeles.meteo...-2-1-336.png?18

look at that wonderful greenie high, but then look at our island, nothing special, people need to stop obsessing about the state of the vortex because too many things need to go right for us, if this happens we could not be more unlucky, its not actually bad for the north ,if you run through the rest of the run, but there is no proper cold really, and there is no strong easterly or northerly blast, just slack cold conditions a bit like now

Edited November 30, 2012 by Snowy Easterlies

[AutumnMists]

Yeah pretty exciting model outputs from a NH perspective if you happen to be over on the Pacific side! The vortex can paint as many pretty pictures as it wants but IF and whilst we have those low heights & vortex energy around Greenland & high pressure attempting to reside over parts of Europe and UK & the jet going over the top we will not be joining in the party!

At the end of the day, it's all about if this and if that ... it's pretty understandable not too make a decision at this time and therefore there is no point telling us to drown our hopes out, likewise it would be stupid for someone to tell us we're in for deep cold for the next few weeks.

Some of it is common sense ... but everyone understands where you are coming from and digging out information is always useful.

[Cheshire Freeze]

At the end of the day, it's all about if this and if that ... it's pretty understandable not too make a decision at this time and therefore there is no point telling us to drown our hopes out, likewise it would be stupid for someone to tell us we're in for deep cold for the next few weeks.

Some of it is common sense ... but everyone understands where you are coming from and digging out information is always useful.

TBH realistically there's too much evidence/information to post in any plausible fashion. In previous posts I've referred to output and posted charts so trawl back to see where I'm coming from. I asked for someone to post me some evidence (more than the odd ensemble or the UKMO run) to counter my argument but I've had no replies as of yet. In my eyes there's more evidence to reinforce my argument than disprove it. Am I wrong?

[Dunstable Snow]

At the end of the day, it's all about if this and if that ... it's pretty understandable not too make a decision at this time and therefore there is no point telling us to drown our hopes out, likewise it would be stupid for someone to tell us we're in for deep cold for the next few weeks.

Some of it is common sense ... but everyone understands where you are coming from and digging out information is always useful.

CC has made his decision - no significant cold and snow for the next 14 days - see above !! Myself and a couple of others are saying that its not so clear cut and we would not want to call it yet - I have read through the post and that is my understanding ! Fully respect peoples views but some have already called it - CC being one !

[Buzz]

For those that want to have a moan about the winter, there's a thread just for you right here:

Anyone who wishes to ramp, there's also a thread for you here:

[Cheshire Freeze]

CC has made his decision - no significant cold and snow for the next 14 days - see above !! Myself and a couple of others are saying that its not so clear cut and we would not want to call it yet - I have read through the post and that is my understanding ! Fully respect peoples views but some have already called it - CC being one !

Things can and probably will change quite quickly but I'd say the turnaround time from what is already projected is around the 14 day timeframe so 11th-14th Dec may be a time when we see things change. Remember, I'm not writing off December as a whole month.....but the next 10-14 days look fairly set to me. Obviously better charts may begin to be churned out over the next week or so as we enter the time where charts further into December are being churned out.

The pattern will eventually change (more than likely as a result of that vortex segment moving away from the Greenland area), this perhaps owing to further disruption of the vortex through warming of the strat which will continue to distort and distend. Patience required (as ever) though.

Edited November 30, 2012 by CreweCold

[Dunstable Snow]

Things can and probably will change quite quickly but I'd say the turnaround time from what is already projected is around the 14 day timeframe so 11th-14th Dec may be a time when we see things change. Remember, I'm not writing off December as a whole month.....but the next 10-14 days look fairly set to me. Obviously better charts may begin to be churned out over the next week or so as we enter the time where charts further into December are being churned out.

I know that you are not and you are a poster who I respect and enjoy reading. I remember well your battle with Ian last January and respected you quality of input. You were right then , but so was he to a fashion but it took 17/18 days for what you were saying to materialise and it certainly did in the SE midlands. That may well be the case this time round for cold as we know that cold more often than not takes a protracted route to these shores. I just get a feeling this time round that there is the potential for things to change at short notice to cold and stay there. Its not the preferred option but it could happen and that is the point I was trying to make - 14 days is a long time in poltics and meteorology !

[Cheshire Freeze]

I know that you are not and you are a poster who I respect and enjoy reading. I remember well your battle with Ian last January and respected you quality of input. You were right then , but so was he to a fashion but it took 17/18 days for what you were saying to materialise and it certainly did in the SE midlands. That may well be the case this time round for cold as we know that cold more often than not takes a protracted route to these shores. I just get a feeling this time round that there is the potential for things to change at short notice to cold and stay there. Its not the preferred option but it could happen and that is the point I was trying to make - 14 days is a long time in poltics and meteorology !

I'm not going to be right every time......it doesn't work like that in the world of meteorology but that's what keeps us engrossed! I hope I'm wrong and we see some movemement towards more wintry charts in the near future rather than in the 10-14 day time frame stipulated!

Can we start this process with the 0z charts, pretty please?!

Edited November 30, 2012 by CreweCold

[nick sussex]

In the higher resolution the GFS 18hrs although probably totally wrong! is really not so bad, I think people may well have had a different view if the run would have produced some snow as the low cleared followed by some lovely sunny days and frosty nights. Indeed under that slack flow its certainly possible to get a strong inversion with also some freezing fog and sub zero maxima.

And thats really not out of the question with just a little tweek here and there, indeed if you look at the UKMO under that slack flow with low pressure that could also be a bit more interesting at 144hrs, and before that a chance for some snow in northern areas and a little further south with just a little more amplification.

Indeed if you look at what the outputs suggested a few days back they've actually improved over the last few runs in terms of the track of the low.

As I said earlier the NH pattern is condusive to colder synoptics in Europe, its not like we need a fiction writer to plot a way to get them to deliver as was the case for most of last winter.

There are several opportunities in the next ten days to tap into some more wintry conditions, if the models have overdone the northern arm of the jet then we'll surely take one of those, if not then as long as the PV remains disrupted there will be more and if we see that piece of the PV in ne Canada pull further west then things could change quite markedly.

So as much as I can imagine people are feeling impatient which is understandable lets give it another ten days and see what the situation is then.

[ZONE 51]

GFS-18z(500-1000hpa)

This warm sector with mondays low is the only yellow i can find over the next 12days

The gfs run through the next 2 weeks is cold, and at times wintry with heavy falls of snow over northern hills.

There is a few whips at cold being stronger, and it won't take to much of a change in the right direction(for cold)to get snow in the south to low levels, i don't see any sign in the forecast models of a mild Dec, only flirts into the sw/s at times, the north is on for quite alot of hill snow over the days ahead with some getting to low levels.

Cold and wintry!

Edited November 30, 2012 by ElectricSnowStorm

[Weathizard]

In the higher resolution the GFS 18hrs although probably totally wrong! is really not so bad, I think people may well have had a different view if the run would have produced some snow as the low cleared followed by some lovely sunny days and frosty nights. Indeed under that slack flow its certainly possible to get a strong inversion with also some freezing fog and sub zero maxima.

And thats really not out of the question with just a little tweek here and there, indeed if you look at the UKMO under that slack flow with low pressure that could also be a bit more interesting at 144hrs, and before that a chance for some snow in northern areas and a little further south with just a little more amplification.

Indeed if you look at what the outputs suggested a few days back they've actually improved over the last few runs in terms of the track of the low.

As I said earlier the NH pattern is condusive to colder synoptics in Europe, its not like we need a fiction writer to plot a way to get them to deliver as was the case for most of last winter.

There are several opportunities in the next ten days to tap into some more wintry conditions, if the models have overdone the northern arm of the jet then we'll surely take one of those, if not then as long as the PV remains disrupted there will be more and if we see that piece of the PV in ne Canada pull further west then things could change quite markedly.

So as much as I can imagine people are feeling impatient which is understandable lets give it another ten days and see what the situation is then.

Absolutely spot on Nick, a well informed, balanced post. There will be opourtunities in the coming 10 days we'll just need that little bit of luck as we always do here, more patience is needed from some as some more experienced members/forecasters have said, we must be patient. ECM & GFS mean both around -2/3 up to 240 hours, how people are so negative i simply do not fathom

[Isolated Frost]

http://modeles.meteo...-2-1-336.png?18

look at that wonderful greenie high, but then look at our island, nothing special, people need to stop obsessing about the state of the vortex because too many things need to go right for us, if this happens we could not be more unlucky, its not actually bad for the north ,if you run through the rest of the run, but there is no proper cold really, and there is no strong easterly or northerly blast, just slack cold conditions a bit like now

So, let me get this straight, you look at one of the 20 ensemble members, at 336- and show me a chart where this a low nearby the nation, which is under below average upper air temperatures, but you decline to show the more closer term solutions that the same member shows beforehand- which show very cold easterlies and a Greenland high at D10, not D13 as your chart shows.

Why are we judging this on 'significant cold'? No 'significant cold in 14 days'. Tomorrow and this weekend look like having sharp frosts, and very low maxima, especially in the north. Afterwards, there is a tendency for a battleground, a 2-3 day 'milder' (less cold) interlude- before a slider low through the UK on a NW-SE tint; there is afterwards a good likelyhood of cold and wintry weather, especially in the north.

The stratospheric conditions are becoming more conductive, the vortex is notoriously weak, the H5 anomalies are positive, the ensemble means show colder than average weather for the next 2 weeks- and there is no signs of this stopping soon.

And yet people are complaining because we are not managing to get 'significant cold' on this small island on the edge of the atlantic...

It is going to get cold, colder than usual, and the atmosphere is conductive to something more substantial, but people complain because the NWP aren't providing December 2010 synoptics...

[summer blizzard]

it has developed way south SB. btw, ecm developed another one of these in its 00z run and BOM does the same on its 12z. is this normal for this time of year ?

It's not normal buts it's origins do not make it a technical sub-tropical depression as it is fully barllonic, not bartropic.

It was a tropical wave.

Irrelevant, tropical waves are nothing more than collections of thunderstorms and do not have warm bar-tropic cores.

[Mark Neal.]

Two very good posts from both Nick and I.F. The models I think are still struggling and hopefully in future runs will be start showing even more promising signs. As for now, UKMO earlier had plenty of potential and from both ECM/GFS last output nothing remotely mild, infact staying cold generally with snowfall for northern areas an increasing possibility. I think some people don't look at the bigger picture, I think we are well placed. Cold air is starting to build to our NE in my view we are just waiting to tap into it. Roll on today's model runs, I shall be looking for more interesting trends and wider picture!

[Snowy Easterlies]

So, let me get this straight, you look at one of the 20 ensemble members, at 336- and show me a chart where this a low nearby the nation, which is under below average upper air temperatures, but you decline to show the more closer term solutions that the same member shows beforehand- which show very cold easterlies and a Greenland high at D10, not D13 as your chart shows.

Why are we judging this on 'significant cold'? No 'significant cold in 14 days'. Tomorrow and this weekend look like having sharp frosts, and very low maxima, especially in the north. Afterwards, there is a tendency for a battleground, a 2-3 day 'milder' (less cold) interlude- before a slider low through the UK on a NW-SE tint; there is afterwards a good likelyhood of cold and wintry weather, especially in the north.

The stratospheric conditions are becoming more conductive, the vortex is notoriously weak, the H5 anomalies are positive, the ensemble means show colder than average weather for the next 2 weeks- and there is no signs of this stopping soon.

And yet people are complaining because we are not managing to get 'significant cold' on this small island on the edge of the atlantic...

It is going to get cold, colder than usual, and the atmosphere is conductive to something more substantial, but people complain because the NWP aren't providing December 2010 synoptics...

the timeframe from that chart i posted is irrelevant because im saying that kind of chart can happen, i have seen quite a few ensembles members like that this week and last, my point is we could see a fat greenland high and still be in average or just below average temps, if you have a look at the uppers on that run they are not that cold apart from the north, if we get a pressure rise to the south who cares if there is a lot of northern blocking about still because it won't benefit us that much, like the chart i posted showed, anyway im not saying thats gonna happen im just saying it could happen, if we got a west based NAO or blocking that is too far north, then the teleconnections will still be technically correct because there is blocking, just sadly other things don't fall into place for our island and we might get nothing

just to clarify my point, that whole run on that ensembles member i posted is not very cold and tell me where is the raging easterly,despite a nice greenie high, the flow looks very slack with uppers at about -4 its all conjuncture anyway

plus i agree with polar warsaw and Crewe, people on here want snow, not a few chilly days of dry cold, people make out that this current spell is unheard of in December when its actually not, if we had dry ice days then at least that would be good for now

Edited November 30, 2012 by Snowy Easterlies

[Isolated Frost]

if we had dry ice days then at least that would be good for now

It all boils down to this. We live in the UK. Our weather by default should be dominated by atlantic weather, however, Rossby waves cause a meridional flow. Add to this to the various other stratospheric and tropospheric factors that contribute to changing the pattern that should be default to the Northern Hemisphere.

I don't think some people understand just how hard it is for us to actually change the default pattern and achieve cold weather, never mind saying 'ice days' are 'good for now'...

[chionomaniac]

I have just had to delete a large number of posts from the same suspects who spend most of every night on here moaning. If they are replaced in the morning by more of the same then I suspect that that will be their last for a while.

Please stick to the model thread for model discussion and use the moaning thread for the moans.

And if you don't think that the weather that you like isn't going to appear for around two weeks then great, take a break from model watching for this time and come back after then - just don't clutter this thread moaning about the fact in the meantime if you choose not to have that break.

Thanks.

Edited November 30, 2012 by chionomaniac

[Jupiters Winter]

GFS 00z looking much better at T135 with the jet around the low towards the SW further south. Much in a way a different run; Every run seems to be on a different run....

Blocked towards the north and energy towards the south with -10's towards the east ready to enter the UK... JET only issue out toT160+

low resolution and back to default for GFS as per usual. Overall Better.

Edited November 30, 2012 by Jupiters Winter

[Jupiters Winter]

Everything ----- Vortex, Uk Block, scandi block. euro block ,,, southerly block., northerly block,,,, blizzards,,,, -10;s,,,, Lows.....End of the world.

What the hell is going on in FI?!?

[Jupiters Winter]

Note of interest: The whole GFS 00Z run from now until 384 is below the 0c upper line except this sunday and monday coming. First for me.

[Zakos]

Wow, what a run from the GFS, a major, major turnaround.

As early as 72 hours, we have an upgrade to the strength of the Arctic high (yawn) how many times does it need to be said that the GFS underestimates the block.

18z

00z

At 120 hours, the hemispheric pattern is virtually the same as yesterdays, However there is a shift west in the pattern over the UK, plunging the UK back into cold uppers after the mild blip. westward correction - Another flaw the GFS is infamous for.

Towards the end of the high res output, the Atlantic high merges with the Russian high. Pressure begins to rise over Scandinavia. The rise in pressure is very rapid indeed. look how much it rises in 48 hours-

Eventually producing this epic chart.

note how earlier on the run the Arctic high sank over Siberia, and then merged with the Russian high. This combined with the Atlantic high provides a very substantive block. That block is going nowhere fast, easterly winds for at least a week from that.

If you look at the next 72 hours, the Arctic high tries to build into Greenland. It fails to do this due to the residual energy over Canada. My view is, the Arctic high will instead sink into Siberia, and then rapidly head west to merge with the Russian high and the Atlantic high, to form a very powerful block over Scandinavia. This is exactly what the GFS shows this morning.

This is all very far out and subject to change. In the shorter term, a fairly insignificant shift west results in a very significant upgrade for the UK. This small change illustrates why those who wrote off the next 14 days were wrong plain and simple. With a cold pool just to our east,it was quite obvious that any westward shift would result in the UK in cold uppers.

A positive run in all aspects. Let us hope the trend continues today.

Edited November 30, 2012 by IanM