Model Output Discussion

[ChartViewer]

The charts are good but the cold air is like treacle and doesn't want to come our way. Must be Mr Brown putting it off. Excluding the ECM where the cold uppers do arrive big style.

I refer EVERYONE back to OON post this morning. Go for a walk, Im taking my Bulldog and

going to test hIm in the Thames ...Only joking but please relax as Weathereater

said today, models evolve NOT downgrade or upgrade and please try to enjoy this.

Its going to get colder. FACT.

Me Im walking my Bulldog and see how quickly he wants to go home

Also I stll love that 1060mB GH

[The watcher]

First of all, the trend is still the same, the only change has been in the detail and that is to be expected whilst the models are still fine tuning within the 96hr range.

I feel very intimidated from putting up my thoughts on what the last few runs (ECM, GFS, UKMO) suggest because I'd get shot down by the overwhelming amount of people who may well be dissapointed (expecting severe cold and snow).

I don't know about anyone else, but this is the first time I have ever felt unhappy about forecasting and model watching....far too much unneccesary posts and remarks in what was once quite an interesting read.

I will point out that because the models are still chopping and changing and our main cold advection and Northerly are forecast later next week, that those seeking snow need to take a rest and wait for the models come Monday/Tuesday, by then they will start firming up on PPN and Frontal details. Believe me it is the smartest thing to do.

The nearest wintry mix to occur is of course Monday night but this is very localised (The East) and is still firming up on exactly where the risk will occur, but its only a risk as of now.

My confidence is high on a minimum 24hr Easterly switching Northerly with the cold to last a minimum of 5 days. Risk of scattered Sleet/Snow showers (possibly a more localised streamer) for E/SE England (maybe E Scotland and E Ireland if the low 850hpa' advect enough West) come Thursday next week, then as the flow turns more Northerly the risk transfers to NE/N/NW areas. Then (should frontal systems pass through) we could see a widespread Moderate snow event followed by heavy snow showers for a good portion of the UK (next weekend).

BUT, Big But at that....even though we are in quite a reliable time range, we can all still see that much is changing, thus NOTHING is set in stone in regards to wintry precipitation nor length and potency of cold. The chance of something prolonged is considerable and good IMO, but what isn't 100% is not guaranteed.

[Cheese Rice]

The easterly has downgraded, and i can see why posters would be upset as the easterly looked amazing. The models showed amazing consistency for over a week, then it all downgraded, which is pretty poor considering it was showing the same blow for days in day out. Unfortunately the easterly isn't going to be anything special but good none the less, we have to remember this is December, mid December. How many times have we seen an easterly so early? Not that often at all, and after the easterly it is becoming apparent a northerly may come into place, after that we could see more reloads.

The best thing to do is wait till Tuesday to get the full picture, expect more downgrades and upgrades as the models are still uncertain about this easterly.

If i compare the progged easterly on Wednesday 2nd run:

Then compare todays progged easterly:

Well a pretty poor easterly For England but an Upgrade for Eastern Europe in terms of cold air.

Edited December 12, 2009 by 10123

[johnholmes]

Last post of the night, then you can all get on with it as its a waste of time trying to have a constructive discussion with some people who have little grasp of reality.

The Parallel run is promising:

http://91.121.94.83/...gfs-0-96.png?18

In a way, I hope double figure temperatures return soon, its no more than some people deserve.

I can understand your exasperation Paul-hence why most of my posting is now reserved for a blog unless I try and answer any queries on here.

Its all far too fast for me and I have to say often not very well thought out by some posters, but then we all have to learn and this is a good spot. If only people would stop being personal and making rather silly and unkind remarks at times-its unfair and causes grief for the already hard pressed admin/mod folk.

Like I said many many pages ago -its Christmas-show some goodwill to one another-after all its only the weather and I doubt more than 4 maybe a few more on here, actually rely on the weather for their livelyhood?

[Frosty.]

In a way, I hope double figure temperatures return soon, its no more than some people deserve.

According to the 18z they will just in time for christmas, lol

But, before that, the 18z is another wintry run, not as wintry as the gfs 12z and nowhere near the level of the ecm 12z but the possible return of mild weather is still well over 200 hours away but it's ominous that the gfs is now showing the end of the cold spell before it's really properly even begun..gulp

[Paul]

For those who haven't noticed - we have a technical model thread now available for a slower paced more in depth discussion:

[johnholmes]

According to the 18z they will just in time for christmas, lol

But, before that, the 18z is another wintry run, not as wintry as the gfs 12z and nowhere near the level of the ecm 12z but the possible return of mild weather is still well over 200 hours away but it's ominous that the gfs is now showing the end of the cold spell before it's really properly even begun..gulp

come on Frosty-GFS goes out to 16 days-how long do you expect a cold spell to last?

Have a look in the stats and tell me how many Decembers have had 16 days cold weather that you can remember?

[Freezing-Point]

I don't know the answer to this, but am am going to make a logical assumption, so this is more of a question.....

Its been said by many on here the the models are only as accurate as the data which is fed in. Fair enough, an obvious statement. But surely irrespective of the accuracy of the input data, the models accuracy is dependant on the quality of the program which is processing the data.

Now in the case of our usual UK winter weather - atlantic dominated, there must have been a significant amount of learning put into the programming code to enable more accurate data processing. Hence we have more accurate mid range forcasting for this type of event. But in the case we have in hand at the moment - a rare easterly, the models do not have same quality of processing to provide accuracy over the mid range because there has been so little learning. This is why there has been such disagreement between them and also why we see constant upgrades and downgrades.

[Bartlett Low]

My point will only add to the huge amount of frankly rubbish clogging up this thread.

The synoptics are good, the outcome maybe good or great or ok but the quality of posting here is little better than the Bill Farkin Grebe days on Snowatch. At least there was a laugh to be had (initially) then.

For the people who like to read through the model thread to get a quick gist of what a run shows without scrolling through the charts, please, please DO NOT POST LOOKS GOOD AT T+60 LOOKS BAD AT T+WHATEVER, commenting on every single chart as it rolls out.

If you read back through the last five days worth of model discussion posts, well, they could easily be condensed down to half a dozen pages of worthy posts.

Please don't think I'm discouraging interest in the upcoming cold spell, far from it. But just think. Sorry and thank you

[The PIT]

to be fair Pit they were pushing their own canoe out so to speak.

John Hammond for instance on ITV always has the Met O logo showing the charts are based on Met input. As I've posted they all have a link into the techie discussion I've explained but what the other companies do with it and how is up to them.

I can only post their comments when they were asked about this during there talk at Hallam although the question was really about the weather girls. However they were quite clear on saying the BBC was the best for the forecasts. Perhaps you ought to ask Mr Fish if he's changed his mind since then.

Question about rubbish. I suspect this is the same problem as model swapping to show the desired result which happens a large amount in winter more than in summer. Rubbish posts I suspect refer too posts that say the next ice age isn't coming. Since most of speculation is in FI land the rubbish posts maybe right. Alternative views arn't rubbish just a different view point perhaps it maybe better to discuss rather than then shred it.

Edited December 12, 2009 by The PIT

[TEITS]

Last post of the evening.

I want to show you some charts to illustrate how the models continue to predict a colder E,ly arriving late next week.

GEFS Mean

18Z GFS

GFS Parallel

ECM

Like I say the extent, duration, severity is up for question not whether it will occur or not at this stage.

Don't forget like I said earlier the latest fax charts DO NOT back the UKMO model.

[johnholmes]

a rare easterly, the models do not have same quality of processing to provide accuracy over the mid range because there has been so little learning. This is why there has been such disagreement between them and also why we see constant upgrades and downgrades.

with respect this comment is not correct.

At T+00 the models are fed all the available data for that time-it then goes away and plays the tune its been given, the SAME ONE EVERY TIME-based on the laws of thermodynamics solved by complex mathematical equations; and its stops at the time its told to stop; T+24, T+ whatever.

The only differences in models is the distance apart, not in time scale, but horizontal and vertical dimensions, some are every 60km some are every 5km, some have 10 levels some have 100 levels between the surface and the Tropopause.

hope that helps.

[The Eagle]

IMO the ECM is the model that should be taken most seriously by every poster here. This nonsense of disregarding it and all that is just that - nonsense. It is Europes main model. Simple as that. Perhaps every National Meteorlogical Center in Europe pays into it and it is an excellent model. Instead what we have is people getting all upset at one run of a US model which like I said before is free to us because no reputable National agency in Europe would pay to use it. So that is what they think of the GFS. That is why we have the ECM. Im actually supprised that people like John Holmes - who worked for the MO - sit back and allow such commentary about the ECM daily without responding. Some of the comments about it are completely daft. I just don't get it.

[Bristawl Si]

I have very little knowledge compared to some of the main 'players' on here, but i have seen many cold and eventually snowy situations develop in years gone by.

They normally take a while to develop/evolve and by now i would have expected most posters to realise that the models chop and change until much nearer the timeframe. Sometimes i wish the GFS wasn't 4 times/day!

I think on numerous occasions some of the more experienced contributors have commented that easterlies are some of the most difficult to predict too far ahead. Just be patient all. It can be frustrating sometimes, but we're only viewing computer models after all.

I'm a trends person and nothing has really changed that much in the last few days, except in the detail. It will be cold and then maybe v.cold by next weekend, but as for snow, well, the best advice i can give is just wait and see.

I enjoy reading the posts from Nick Sussex, Steve Murr, TEITS and GP to name but a few. What i don't want to see is constant sniping and one liners that add nothing, otherwise it will just become like that forum that used to be on the BBC a few years ago.

[Frosty.]

come on Frosty-GFS goes out to 16 days-how long do you expect a cold spell to last?

Have a look in the stats and tell me how many Decembers have had 16 days cold weather that you can remember?

Some of the recent runs have shown the cold spell lasting throughout with stronger blocking, mostly the parallel version but it now looks like ending before christmas day which would be unfortunate to say the least. Every run is different but you can only go by the most recent data available I would say, correct me if i'm wrong john.

[Snowyowl9]

It`s like watching a soap opera tonight.

It`s only a different variation on the greenland high theme.

http://91.121.93.17/pics/Rtavn961.png

http://91.121.93.17/pics/Rtavn962.png

http://91.121.93.17/pics/Rtavn1681.png

http://91.121.93.17/pics/Recm1201.gif

http://91.121.93.17/pics/Recm1921.gif

Fax chart for midweek.

http://91.121.93.17/pics/brack3.gif

Re the cold air, not surprised the air is less cold coming on the latest 2 GFS runs with

the wind flow is slacker unlike ECM.

[Paul]

The number of posts being removed / edited this evening is getting ridiculous - those who are posting off topic comments or are breaking the forum guidelines in other ways, you're ruining these threads for those who want to actually discuss the models.

So please, consider what you're posting - if you post is off topic, doesn't add to the discussion or breaks the forum guidelines then do not post it by doing so you're being totally unfair to the other members and the team who then have to spend time removing your posts - we'll be going through the trash can later / tomorrow and all those members who are having a large number of their posts removed will find themselves stopped from posting for a period of time.

Just wanted to repost the above - it's been quite an eye opener in the last 20 mins or so since I posted it as several posters have had a handful of posts removed so clearly don't bother to read/take note of anything that's posted in here, have no respect for the other members of the forum or indeed the team. Pathetic really.

[Bartlett Low]

Question about rubbish. I suspect this is the same problem as model swapping to show the desired result which happens a large amount in winter more than in summer. Rubbish posts I suspect refer too posts that say the next ice age isn't coming. Since most of speculation is in FI land the rubbish posts maybe right. Alternative views arn't rubbish just a different view point perhaps it maybe better to discuss rather than then shred it.

Not at all Pit - I'd like to think we all like a well argued stance, whatever the viewpoint.

[johnholmes]

Im actually supprised that people like John Holmes - who worked for the MO - sit back and allow such commentary about the ECM daily without responding. Some of the comments about it are completely daft. I just don't get it.

I do try mate-but have another life besides Net Weather-please read my blogs and lrf to see that ECMW is used as and when I think it should be used as is GFS and UK Met.

I have, somewhere in the bowels of Net Weather posted on several occasions about ECMWF in some detail, if you read my lrf you will almost always see some comment that it is, as it almost always does, outperforms GFS on the northern hemisphere scale.

hope that helps.

I'm off to bed.

[damianslaw]

Mmm this time yesterday I was saying that come this time today all the major models would be consistent in similiar thinking, alas GFS, Meto and ECM are showing slightly different synoptical outputs for Wednesday onwards, but all based on the concept of low pressure tracking through the North Sea.

At this range because the low pressure is still not progged for 72 hours, perhaps in hindsight it isn't too surprising to see slightly different outputs as to its track. Low pressure systems tracking down the North Sea are very difficult to predict in terms of which course they take and it probably won't be until later on Sunday or even Monday morning that their will be model agreement on its path. Consequently siding with what the models are showing thereafter I feel at this stage is a bit of a futile act.

My belief is that an easterly or sorts is more or less a dead cert for Wednesday onwards, whether it will have a long draw of cold air attached remains to be seen. Another difficuly models always have with is picking out any troughs that may appear in a cold flow, with the relatively warm waters of the North Sea sudden development of such features seem very likely and will not be spotted until close range, again this will make forecasting where any snow showers develop or longer spells of snow difficult until short range.

Best thing to do at the moment is give the models a bit of time to sort themselves out, and not get too concerned when the GFS shows a different run in the space of a couple of hours, there is no point really.

Longer term - teleconnections = deep negative NAO and AO with greenland high - the flow for the foreseeable future therefore will be a north-easterly quadrant.

[Freezing-Point]

with respect this comment is not correct.

At T+00 the models are fed all the available data for that time-it then goes away and plays the tune its been given, the SAME ONE EVERY TIME-based on the laws of thermodynamics solved by complex mathematical equations; and its stops at the time its told to stop; T+24, T+ whatever.

The only differences in models is the distance apart, not in time scale, but horizontal and vertical dimensions, some are every 60km some are every 5km, some have 10 levels some have 100 levels between the surface and the Tropopause.

hope that helps.

Nothing else, no GW or AGW before SC starts on his hobby horse or anything else of such ilk.

Ok, but the equations used must be adjusted at intervals to improve accuracy. This can only be based on learning. If there is no learning then how can forcasts improve?

[The Eagle]

I do try mate-but have another life besides Net Weather-please read my blogs and lrf to see that ECMW is used as and when I think it should be used as is GFS and UK Met.

I have, somewhere in the bowels of Net Weather posted on several occasions about ECMWF in some detail, if you read my lrf you will almost always see some comment that it is, as it almost always does, outperforms GFS on the northern hemisphere scale.

hope that helps.

I'm off to bed.

Thanks John. I just am trying to get across the point to others that the ECM is the model we should most pay attention to. We all pay for it after all.

Edited December 12, 2009 by The Eagle

[Michael Fishermans Friend]

Some of the recent runs have shown the cold spell lasting throughout with stronger blocking, mostly the parallel version but it now looks like ending before christmas day which would be unfortunate to say the least. Every run is different but you can only go by the most recent data available I would say, correct me if i'm wrong john.

Have to say every run I've seen from the GFS in FI is the same! and thats ending the 'colder spell' of weather before Xmas, if we take 240+ hrs as the lo-resolution end of the GFS howcomes it is predicting more or less the same scenario run after run and not coming up with altenatives to the synoptic pattern?

Still up in the air about the forthcoming easterly IMO to the extent and severity but I believe we will experience at least a couple of days followed by a less cold Northerly which looks fairly certain, but then to continue for the rest of the run more or less on the same tact seems strange?

[nick sussex]

Oh dear the mood in here has really suffered this evening! in circumstances where the models diverge all output past this point in terms of detail can be placed in the bin, the way forward then is to stick to just the general pattern, what seems to have been missed in here with all the mass hysteria breaking out after every single model run is a consistent pattern, easterly, block near greenland edging westwards and troughing over scandi with low moving south in the further outlook.

Alot has been said about the high sinking, this is not the case, the block edges west, the easterly disappears because low pressure is heading south, you don't get long lasting easterlies initially with this pattern because the block is over greenland,in recent winters easterlies have normally ended with the jet running over the top and sinking the block southwards with a return to sw'erlies.But this time the jet will not sink the block.

In terms of the current pattern this could turn into a decent length cold spell if the block doesn't edge too far west, as you can see this happens right at the end of the ecm but this is well into FI and probably likely to change again. Given the recent chopping and changing and trying not to state the obvious and something that seems to have been missed by some members is that more changes are likely so whats the point of taking the model output as fact.

The ecm ensembles show the uncertainty with scatter past next Thursday, although the trend at least for the Netherlands remains cold.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Edited December 12, 2009 by nick sussex

[ChartViewer]

As for the Models you know as well as I do that what we are seeing

in the next 10 days is fantastic synoptics....1060mb GH, -10 air, reloads ENE then N winds

Once we get the cold we wll experience some fantastic colder temps towards Xmas.

Could someone post nexts THURSDAY chart up againt that of lasts years exact chart?

Think that will stop some of the negativity?

Edited December 12, 2009 by ChartViewer