General Model Output Discussion

[ribster]

100% agree!

SE shut down??? No chance.. If these charts are showing 36/48hrs before then I will hold my head in shame!

I'm only going on the most likely option and the most likely option is these charts are eye candy and will most likely look different come Sunday!

If any member would like to explain to me why 'this time' is the one...and why I should believe that the se will shut down then please do!

I love ramping and the banter but Christ... It's very unlikely (the most likely option) (historic option)

In the same way that you ask for a member to show why these charts are going to verify, perhaps you could show us why they will not? Since the availability of charts online, I have not seen the like, nor in my limited view the entirely plausible evolution from A to B. Referring to history and suggesting that because of what has happened in the past will happen again is foolhardy indeed.

[weather eater]

Ok firstly i disagree with all above

The lp system to our sw would not have brought a foot off snow to us western areas may have had a shout off something decent but just rain for your and my area. Secondly if you are after cold and snowy weather than its a blessing that the lp system did not approach our shores. And finally you say we are already in the event low temps last night i had a hour off light snow just after the midnight cant be bad can it? All i am saying is to take my advice and listen to the more experienced people who has been there done that and got the shirt and atm they are very exited and so should you be as well. Happy new year to you

Actually what most of the experienced people are doing is saying what could happen if runs were to verify, all the experienced members are aware that model output is subject to much revision. Lets not repeat the mistake of getting carried away with model educated guess work and then having to deal with the fallout, if the country fails to disappear under several feet of snow.

[kold weather]

100% agree!

SE shut down??? No chance.. If these charts are showing 36/48hrs before then I will hold my head in shame!

I'm only going on the most likely option and the most likely option is these charts are eye candy and will most likely look different come Sunday!

If any member would like to explain to me why 'this time' is the one...and why I should believe that the se will shut down then please do!

I love ramping and the banter but Christ... It's very unlikely (the most likely option) (historic option)

Well I don't know about shutting down the SE BUT the N.Hemispheric set-up is one that suggest we have every single chance of getting a very prolonged set-up. The broad evolution is a Greenland high toppling BUT importantly the PV still isn't close to as strong as normal and it sets-up in such a way that high pressure will more then likely form close to the UK, however whether its over the UK or just to the north is the difference between a bitterly cold HP set-up or a real beast from the east.

This is a big set-up for an easterly simply because it evolves in the 2nd coldest manner it could, thats with a upper low diving Southwards, then the cold pool being prevented from going any further south as upper currents turn light, then eventually as higher pressure forms nearby its all shunted right over the UK...if we get an easterly flow make no mistake it will be severe cold and importantly very snowy asd uppers will be bitterly cold at 500hpa, the instablity to be released would be pretty impressive even with cooler north sea temps...

The broad evolution is a very plausable one, indeed I'd say most likely option, the only real differences with the models is exact placements of the surface high.

Edited January 1, 2010 by kold weather

[snow drift]

100% agree!

SE shut down??? No chance.. If these charts are showing 36/48hrs before then I will hold my head in shame!

I'm only going on the most likely option and the most likely option is these charts are eye candy and will most likely look different come Sunday!

If any member would like to explain to me why 'this time' is the one...and why I should believe that the se will shut down then please do!

I love ramping and the banter but Christ... It's very unlikely (the most likely option) (historic option)

People are very quick to say that this and that wont happen. Where is your analysis of what will happen?

Some people are enthusiastic and the best line was SM's " I feel like Del boy at the Auction" but don't knock if you are not going to give your own take on what the models are showing.

[snowingtequila]

Hmm.

Why do people STILL allow themselves to get carried away when models like GFS predict Armageddon type rubbish? So often we've seen the models do this, and yet - when it gets closer and closer to the event - what happens? It's an anti-climax. I wish it wasn't, and I wish we'd get these massive snowfalls that would "cut off" certain parts of the country, but it's just not gonna happen. The models might predict it, but then - give GFS another couple of runs - and, by tomorrow, they'll be predicting something completely different. That's how it seems to have gone this winter.

The latest monumental disaster was the LP which moved up from the South at the beginning of the week. That was supposed to deliver "over a foot of snow!!1!!1" to many areas. Did it? Nope.

Nice to look at, but this will not happen. Happy to eat humble pie, but I just know I won't be.

WISE words ...... The charts will probably look different come Monday!

Beautiful looking charts... Yes! But really........

Last weekend that low was modeled to bring a possible foot of snow to Wales and the Midlands..! The SE and EA, midlands was suppose to be under heavy snow showers all day today -was also backed up by the countryfile forecast as well - niether happened

100% agree!

SE shut down??? No chance.. If these charts are showing 36/48hrs before then I will hold my head in shame!

I'm only going on the most likely option and the most likely option is these charts are eye candy and will most likely look different come Sunday!

If any member would like to explain to me why 'this time' is the one...and why I should believe that the se will shut down then please do!

I love ramping and the banter but Christ... It's very unlikely (the most likely option) (historic option)

I have never seen the models show a scenario like this before, have you? Ok so the charts will change as they do every other day but apart from a little wobble they are consistantly cold, This cold spell is already impressive in my eyes and the models are something to get excited about because they are showing something that they have not shown before whilst we have had access to them. if it doesn't happen then Ok we can ask what went wrong and I agree we should always be cautious and not polish the sled just yet, however, if these charts come close to coming to reality then we are oing toi be in a very snowy cold spell. I have just rewatched the countryfile forecast it showed a wintry mix today from the remnents of the front in the SE at 3C

Edited January 1, 2010 by snowingtequila

[SnowBallz]

Ok firstly i disagree with all above

The lp system to our sw would not have brought a foot off snow to us western areas may have had a shout off something decent but just rain for your and my area. Secondly if you are after cold and snowy weather than its a blessing that the lp system did not approach our shores. And finally you say we are already in the event low temps last night i had a hour off light snow just after the midnight cant be bad can it? All i am saying is to take my advice and listen to the more experienced people who has been there done that and got the shirt and atm they are very exited and so should you be as well. Happy new year to you

Where did I say that LP was going to bring a foot of snow to our area (the SE) ??? That was never forecast. What WAS forecast, was that places like Wales the NW and somewhere across the Midlands area would get absolutely deluged by snow. But it never happened did it? The only 'forecast' for the SE would be if the cold air got down quick enough for us to catch some back-edge snow. But, the chances were very remote and - which DID happen - we were forecast to get a deluge of rain. I'm not IMBY though, I'm talking about what the models forecasted for other areas and what actually happened. The two were massively different, and the GFS couldn't even agree on the track of the low right up until hours before it came "GFS backing down at the last minute". If it can't even model extremely short-term trackings of weather systems, then why hold it in such regard for predicting something 9/10 days away???!!

The whole point is, people really need to stop getting themselves worked up into a frenzy about models which forecast the End of Days. Temper your enthuasium with a healthy dose of realism and you might not find yourself being so disappointed when the country carries on as normal, after a couple of hours of sleet.

[Archie_Lewis]

People are very quick to say that this and that wont happen. Where is your analysis of what will happen?

Some people are enthusiastic and the best line was SM's " I feel like Del boy at the Auction" but don't knock if you are not going to give your own take on what the models are showing.

Why do to think???

Because 80% of the time it all downgrades nearer the time!

I admit I'm just learning and have no analysis why it won't happen!

ECM seems to want to change it's mind on a daily basis!

I guess what I'm trying to say is in the 3 years of model watching never EVER have the models been the same on the actual day when predicting 5 days plus!

I'm just remaining extremely cautious!

[Paul]

Please folks, this thread is for the discussion of the model output, not will it/won't it snow, he said/she said type stuff - that can be done in the model chat thread if it's remotely model related or in one of the other general discussion threads if not..

[nick sussex]

No, it wasn't going to be a UK wide event - but, in the end, it turned into the biggest non-event since, well, the last one which the GFS predicted? You know as well as I do that, when the GFS predicted that LP moving up from about 5/6 days out, there was pandemonium about how much snow it would deliver as it crashed into the cold air feed chasing towards it from our NE. In the days leading up to it, the Welsh and those in the Midlands/North were falling over themselves wanting the LP to remain on a Northern track (as predicted by the GFS) as they believed that would deliver them their Armageddon snow event, while others maintained that it would be better for a sustained cold period, were the LP to follow a more Southerly track. In the end, it kinda went somewhere in the middle - and delivered zilch.

Ask yourself: how often do charts some 9/10 days out "verify" ? You know yourself, that 9th/10th January will probably be absolutely nothing like what's being shown on these charts. That's why I don't get all the hyperbole. Don't mind people getting enthusiastic, but at least be realistic. Shut down parts of the SE? More likely that roadworks would.

I'm not disagreeing with you regarding verification of models at that range, everyone knows i have little time for output past 168hrs and am one of the biggest critics of the gfs. There are certain patterns whereby one synoptic dominoes into another as such if for example A happens then B has to occur unless the earth starts spinning in the opposite direction. If you noticed i posted earlier regarding the importance of the Scandi trough not being too far west and the need for the high to topple se wards to help pull the coldest air westwards along its southern flank, this still stands, however we're not talking about events past 168 hrs here. If the ecm verifies at 96hrs and 120hrs then that at least guarantees some major snowfall and then for arguments sake lets say the whole thing implodes ie the high carries on sinking then as it does so eastern and se areas would still have another day or two of snowfall as the high would have to topple se wards thereby the colder air along its southern flank would still be advected west until the core of the high was too far south. The high will not just vanish into thin air, so this is sort of the domino effect i was talking about.

Also bear in mind either way whatever happens i'm not in the UK so theres no bias in terms of my location, i just say it as i see it. If the ecm verifies you may get a few days off work.

[Nick.F]

Although the language, attitude and approach of some of the recent posters is questionable, I think a little space for their opinions are warranted.

Few posters on the forum remember the cold spells in the late 70s and early 80s. Let alone the extreme winters of 47 and 63, so in fairness they have no reason to really believe that it could happen or will happen, especially with the last 20 years (ish) of "modern winters" being all that most remember. There is just no frame of reference for them; generally these days, only personal experience counts and not the "anecdotal" evidence of others.

Modern media output, nay, hysterical hype, and terrible "media" forecasts and presentation does not help. Unfulfilled expectation is a terrible thing.

Maybe with a little more knowledge they may see that the events being discussed are actually possible, some are within the reliable timeframe.

However, as always, the proof will be in the pudding. Maybe, just maybe, they will have the excitement about this winter in their memories some day.

[Frosty.]

What interests me most is where the high will go once it becomes established in FI, I would say from the latest 12z charts that northern britain will have to make the most of the snow showers between mon-wed because by thursday the airflow will become very slack and the snow will have moved away south but as the hp builds in across the north it will remain very cold with severe frosts over the deep and crisp snowfields. For southern britain, especially eastern counties, the snow showers look like running in off the north sea all next week with places like kent being in the firing line for major disruption which will make the last lot of snow they had down there seem insignificant. Most importantly, it's a very cold outlook nationwide as far as the models can see at the moment and there is potential for N'ly and E'ly reloads depending on where the high eventually migrates.

[TEITS]

If it can't even model extremely short-term trackings of weather systems, then why hold it in such regard for predicting something 9/10 days away???!!

I've seen you mention this a few times but where are you getting 9-10 days away?

First of all we have the potential for snow tomorrow night via the troughs. Next the possible NE/E,lys isn't 9-10 days away but being suggested for Tues.

Finally the snow event last week had upper temps around -3C. For next week we could be looking at -12/-14C. Like I said what happened last week has no significance for next week.

Frankly if nobody can get at least a little excited at the current model output then to be honest they need to find a new hobby.

[tinybill]

In the same way that you ask for a member to show why these charts are going to verify, perhaps you could show us why they will not? Since the availability of charts online, I have not seen the like, nor in my limited view the entirely plausible evolution from A to B. Referring to history and suggesting that because of what has happened in the past will happen again is foolhardy indeed.

all i say if this comes off for sunday-monday the east /south east will stop!!

[danm]

Where did I say that LP was going to bring a foot of snow to our area (the SE) ??? That was never forecast. What WAS forecast, was that places like Wales the NW and somewhere across the Midlands area would get absolutely deluged by snow. But it never happened did it? The only 'forecast' for the SE would be if the cold air got down quick enough for us to catch some back-edge snow. But, the chances were very remote and - which DID happen - we were forecast to get a deluge of rain. I'm not IMBY though, I'm talking about what the models forecasted for other areas and what actually happened. The two were massively different, and the GFS couldn't even agree on the track of the low right up until hours before it came "GFS backing down at the last minute". If it can't even model extremely short-term trackings of weather systems, then why hold it in such regard for predicting something 9/10 days away???!!

The whole point is, people really need to stop getting themselves worked up into a frenzy about models which forecast the End of Days. Temper your enthuasium with a healthy dose of realism and you might not find yourself being so disappointed when the country carries on as normal, after a couple of hours of sleet.

To be honest, very few ppl were talking about a "deluge" of snow for the midlands, wales, nw england from that low. There wasnt a significant pool of cold air over us at that point, upper temps were generally too high for pure snow and therefore it always looked marginal. And it was. Some higher parts of Wales got a lot of snow, and some low-lying parts of the Midlands did get quite a bit of falling snow, although not much settled. Now all the models are showing a very cold weather pattern over the next week, and the POTENTIAL for heavy snow. We dont just have one model showing this, but all are showing a somewhat similar pattern that hasnt been seen before in the internet era. I think everyone is fully aware that we should only really get excited when the charts appear within 48 hours, but the fact that a significant trend is being picked up by all models should make all of us sit up and take notice. These charts havent materialised to this extent before since we have had access to them in this way.

[Uncle_Barty]

What sort of temperatures at 500hpa are indicative of deep cold air?

[kold weather]

What interests me most is where the high will go once it becomes established in FI, I would say from the latest 12z charts that northern britain will have to make the most of the snow showers between mon-wed because by thursday the airflow will become very slack and the snow will have moved away south but as the hp builds in across the north it will remain very cold with severe frosts over the deep and crisp snowfields. For southern britain, especially eastern counties, the snow showers look like running in off the north sea all next week with places like kent being in the firing line for major disruption which will make the last lot of snow they had down there seem insignificant. Most importantly, it's a very cold outlook nationwide as far as the models can see at the moment and there is potential for N'ly and E'ly reloads depending on where the high eventually migrates.

I'll be honest this looks even colder then I thought it would be a week ago...I remember suggesting watching out for another -ve NAO after the high sinks but I never ever expected that the toppling phase would possibly bring in a potent easterly spell, no doubt this has been upgraded in a big way recently. I suspect what will happen is the upper high will slowly transfer towards Iceland, less cold perhaps for the 12-15th before a possible northerly/easterly shot again, that would be my punt, eventually followed by the upper high finally slipping SE and a LP attack...but looking at the current trends that could be a long time away...

Also as I said before as long as we get the upper cold low come down with those -40C at 500hpa then we are very likely going to get some severe cold for a time, and given there is a reasonably large margin for error in this set-up, thats why there is such good agreement...

Jim, -35 would be very good for our location...-40 as the models indicate ios the type of temps olar lows tend to be able to form at, so if you want real bitter cold (sub 0c) then -40C is usually a good indicator...

Edited January 1, 2010 by kold weather

[Liam J]

Where did I say that LP was going to bring a foot of snow to our area (the SE) ??? That was never forecast. What WAS forecast, was that places like Wales the NW and somewhere across the Midlands area would get absolutely deluged by snow. But it never happened did it? The only 'forecast' for the SE would be if the cold air got down quick enough for us to catch some back-edge snow. But, the chances were very remote and - which DID happen - we were forecast to get a deluge of rain. I'm not IMBY though, I'm talking about what the models forecasted for other areas and what actually happened. The two were massively different, and the GFS couldn't even agree on the track of the low right up until hours before it came "GFS backing down at the last minute". If it can't even model extremely short-term trackings of weather systems, then why hold it in such regard for predicting something 9/10 days away???!!

The whole point is, people really need to stop getting themselves worked up into a frenzy about models which forecast the End of Days. Temper your enthuasium with a healthy dose of realism and you might not find yourself being so disappointed when the country carries on as normal, after a couple of hours of sleet.

i think the excitment is because the synoptics being shown by the models...yes 'models' as in not just the gfs is that of which alot of younger people will never have seen, we all know the gfs can show major eye candy out in FI and that is usually out past 216 to 384 hrs and never come any closer hence fantasy charts and eye candy, which the gfs loves to throw at us. and yes other models can do this and wobble around even at short notice.

but when all the models are in fair agreement with synoptics, with stunning ensembles to boot you and many others cannot simply dissmiss them as rubbish and say it wont happen, these are very powerful computers and models collecting data on a massive scale, yes they can get it wrong and will but for now enjoy what you are veiwing as you may not see this again for a very long time, and we have plenty to keep us all busy in the short term let alone worrying about next week which is looking extremely cold, plus its not just one model on its own, this is real and experienced forecasters are using the model outputs to put together forecasts which help the public and fascintate all of us here at NW

Edited January 1, 2010 by james12

[SnowBallz]

I've seen you mention this a few times but where are you getting 9-10 days away?

First of all we have the potential for snow tomorrow night via the troughs. Next the possible NE/E,lys isn't 9-10 days away but being suggested for Tues.

Finally the snow event last week had upper temps around -3C. For next week we could be looking at -12/-14C. Like I said what happened last week has no significance for next week.

Frankly if nobody can get at least a little excited at the current model output then to be honest they need to find a new hobby.

Well, people have posted charts for +192. Roughly in my head I thought that was about 9/10 days away. It's actually 8 days. Sorry. But anyway, these charts are supposed to show synoptics which will herald End of Days scenarios with huge snow levels and cut off the SE (etc etc...) Okay, they might, but my point is that all this hyperbole seems to be based on a model which is notoriously prone to error, so much so that - for the last 'main event' (the LP on Monday-ish) it couldn't even work out the track of the system, until the very final moments. Personally, I'd treat such an error (and consistent error-proneness) as pretty serious, and enough of a reason for me to discount it's output, for the time being anyway.

By the way, I'm judging the models (GFS, UKMET, EMC, etc...) on their performance - this isn't about me being sceptical because I'm not old enough to remember that it's happened before. Granted, we're in a very cold period/winter but we've seen on a couple of occasions where the models have predicted 'event' type solutions, only for them never to materialise. For me, this is another event type scenario and - based on the models poor performance prior to this - I'm treating it with due scepticism. As far as I'm concerned though, it's a good enough chance for the models to regain their credibility though.

The good thing though is that, all we have to do is wait until +192 hours to see whether my cynicism is warranted or not I'd GLADLY eat plate after plate of humble pie though, as a major snow event for the UK (I'm not IMBY) is long over-due.

[bluearmy]

to the tune of 'never seen anything like it in my life'

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

note the precip spikes, even in holland. and the op looks a bit on the warm side !!

[Geordiesnow]

I can see where snowballz is coming from but on this occasion the easterly is not at 144 hours but much closer(96 hours) and the set up actually starts much earlier with the slack northerly flow for Sunday/Monday.

I think the easterly is about nailed on now however how long it lasts for is still in alot of doubt(and which areas are in line for the most PPN) imo. And this is where Snowballz try to make the point about the overramping of some posts and we know these over ramping posts can be mis-leading end up in wrist slashing and toys out of the pram posts because the projected snowfall has been downgraded.

The ecm would bring alot of snowfall to eastern and in particular south eastern areas areas but we all know the ecm in the longer range will look different in the morning, whether for better or worst we shall have too wait and see.

[PB22]

to the tune of 'never seen anything like it in my life'

http://www.knmi.nl/e...M_06260_NWT.png

note the precip spikes, even in holland. and the op looks a bit on the warm side !!

Staggering ensembles!

To see the op at the top end is almost beyond belief! I look forward to seeing the London ensembles later.

[weather eater]

I've seen you mention this a few times but where are you getting 9-10 days away?

First of all we have the potential for snow tomorrow night via the troughs. Next the possible NE/E,lys isn't 9-10 days away but being suggested for Tues.

Finally the snow event last week had upper temps around -3C. For next week we could be looking at -12/-14C. Like I said what happened last week has no significance for next week.

Frankly if nobody can get at least a little excited at the current model output then to be honest they need to find a new hobby.

Hi Dave I do agree with what you say in regards the short term, however much of the buzz earlier was in regards the ECM and its later output, now without doubt that was a brilliant run, an easterly of old. But lets be honest this is not the first time this winter that a model run has shown an extended easterly blast, and as yet these have not come off, short blasts, a couple of days yes, but not one of any duration. I think its important to keep in mind that post 120-144hrs model outputs are very variable, I will be very surprised if this extended easterly features on tomorrows ECM 00z (hope I'm wrong). However lets not forget that sometimes in these situations things work out better than predicted, we have snow here at the moment yet there is nothing for this side of the Pennines on the radar.

[nick sussex]

How do i put this! the ECM operational run was not the coldest solution on offer this evening, the De Bilt ensembles for the Netherlands which of course given the pattern are a good indicator are sensational.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

Take into account there are 50 ensemble members, this means that even when each members starting conditions are tweaked the warmest temp any member finds in 10 days is barely above freezing.

Given the support here for very cold conditions and the support for the ecm operational run I would be surprised if the UKMO don't modify their raw data towards the ecm operational run when they update their fax charts later on.

Edited January 1, 2010 by nick sussex

[Uncle_Barty]

Thanks Kold.

ECM indicating sub -35c air over us between 120 and 168h or so then.

[Mikel Nimbus]

How do i put this! the ECM operational run was not the coldest solution on offer this evening, the De Bilt ensembles for the Netherlands which of course given the pattern are a good indicator are sensational.

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

Take into account there are 50 ensemble members, this means that even when each members starting conditions are tweaked the warmest temp any member finds in 10 days is barely above freezing.

ECM was a slight mild outlier? My goodness that is unbelievable!

However, since we are only looking at De Bilt, could it be that the coldest uppers have been advected too far west on the operational run (i.e. over us), whereas the other ECM members would like the colder temps over the Netherlands?

Edited January 1, 2010 by Mikel Nimbus