Model Output Discussion

[snowking]

I think it's worth mentioning again that the GFS charts you see was from a major warm outlier.. The majority of the runs showed a good -5 degrees on the 850 temps

Sorry to sound like a broken record guys but can we firm up on the use of the terminology please

The GFS is not a warm OUTLIER. Granted its one of the warmer runs on the ensembles but this doesnt make it an outlier, it simply makes it one of the warmer runs

An outlier would have the operational all on its own - where as here it has some (granted, its limited) support

Kind Regards

SK

[West is Best]

The 0Z GFS has certainly upgraded the E,ly for early next week

Sorry Dave but that is manifestly not the case.

Doesn't mean we won't have a fantastic cold spell in the long run, but early next week is now much more transitional on all the overnight runs for the 3 reasons I cited above. Let's not get hung up over the term 'downgrade' which might appear to worry some people. What we can refer to is that:

1. The high pressure is further east

2. The high is less strong

3. The high does not link as successfully nor as sustainably with the Greenland high

In the long run it might not make the blindest bit of difference, and besides ultimately a north-easterly is heaps more interesting than a straight easterly.

[WhiteFox]

A few different solutions being thrown up this morning, no need for any panic. Those of us old enough will recall that you got the cold first and then the snow later, and whichever way we look at this mornings output a cold spell of decent length is on the cards.

Wise words indeed Ian. Some seem too impatient and want the cold and snow to arrive at once. Classic cold outbreaks from the past always started with a period of cold and dry weather before any snow events came onto the horizon. I can remember several events in the 1980s where the forecasts showed very cold temperatures but finished with "No snow in sight". Once the cold became embedded however the snow arrived. Patience all round; if cold manages to become established with this pattern then snow will surely follow. Recent experience suggests that if we have snow at the start of the outbreak then it tends to warm up fairly quickly thereafter.

[liltbrockie]

Sorry to sound like a broken record guys but can we firm up on the use of the terminology please

The GFS is not a warm OUTLIER. Granted its one of the warmer runs on the ensembles but this doesnt make it an outlier, it simply makes it one of the warmer runs

An outlier would have the operational all on its own - where as here it has some (granted, its limited) support

Kind Regards

SK

From:

"What's an outlier?

An outlier is when the control run is different to the vast majority of the ensemble runs. A cold outlier is when the control run shows a colder outcome than majority of the others, and a warm outlier is when the control run shows a warmer scenario.

I hope that helps :o "

I'd say my terminology was correct but... whatever!

Edited December 10, 2009 by liltbrockie

[West is Best]

Slight upgrade by GFS with the depth of the cold in the initial easterly

Ah, ok, I can see why you and TEITS are seeing it as not a downgrade. You are looking at upper air temps. I'm not, I'm looking at the intensity of the flow and the accompanying pattern. Colder uppers are less useful if there's a much slacker flow, which there is. We have basically lost a lot of the bite of the easterly ... at this stage.

[WhiteFox]

Sorry to sound like a broken record guys but can we firm up on the use of the terminology please

The GFS is not a warm OUTLIER. Granted its one of the warmer runs on the ensembles but this doesnt make it an outlier, it simply makes it one of the warmer runs

An outlier would have the operational all on its own - where as here it has some (granted, its limited) support

Kind Regards

SK

Good point and one well worth emphasising. An outlier would be a run which in probablility terms was outside a confidence interval of about 95%; being one of four runs which are fairly close to each other does not make it an outlier, but rather one of the warmer resolutions. Probability may favour the colder solutions, but the control is not an outlier.

[Neilsouth]

Checking the ecm this morning it doesn't look too bad to start with but not exactly a strong ne wind , which turns into a light northerly. So much for that dissapointing :o consistant my ar-e!. A slight risk of snow for east and south east monday to late on gfs but the real deep cold doesn't even get beyond the north while the atlantic attacks from the south. So much for consistance in the parallel aswell , again it's a downgrade. Ukmo doesn't look too bad but even that keeps changing , we may even end up with no snow on this one.

So if you live in the east,south east a low risk of snow and cold while up north it's still looking good.

Very poor , sometimes i wonder if its worth checking the charts in the morning

Edited December 10, 2009 by neilsouth

[nick sussex]

I can`t see how anyone who likes cold can complain about these charts from00z at T96hrs.

GFS http://www.wetterzentrale.de/pics/Rtavn961.png

UKMO http://www.wetterzentrale.de/pics/Rukm961.gif

ECM http://www.wetterzentrale.de/pics/Rtavn961.png

GEM http://www.wetterzentrale.de/pics/Rgem961.gif

Solid agreement there.Cold uppers arriving Sun/Mon from the East.A solid block right up to Greenland.

A good pool of cold air to the NE.

Sypnotic details beyond still to be firmed up but these are wonderfull charts for a good Cold spell which we rarely see in the UK.

I totally agree Phil

2 weeks ago any of those charts would have been met with frenzied excitement! the ecm is perfectly fine, the main thing is we look to be over the first hurdle, the cold looks like it's on it's way, any specific detail isn't possible for a few more days.

[cyclonic happiness]

But surely with a slacker easterly flow going over a still above average North Sea, we would have a lot better chance of propagating troughs? So all is not lost, still an amazing setup and we are only 11 days into winter.

[snowking]

From:

"What's an outlier?

An outlier is when the control run is different to the vast majority of the ensemble runs. A cold outlier is when the control run shows a colder outcome than majority of the others, and a warm outlier is when the control run shows a warmer scenario.

I hope that helps :o "

I'd say my terminology was correct but... whatever!

Hello my friend,

I see your point but unfortunately here it has got some credible amount of support (around 4 runs from what I can see). Bearing in mind this is in graph format and the strong links between meteorology and mathematics, in mathematics an outlier is when certain data on a given graph is anomalous from the trend

heres an example:

http://mathworld.wolfram.com/images/eps-gif/OutlierScatterplot_1000.gif

In the instance of the GFS the operational has at least some support, and so it cannot, IMO, be labeled an outlier

But i realise its a bit of a subjective topic given the definition on the forum

Kind Regards

SK

[VillagePlank]

0z really not that bad, chaps. Perhaps in comparison to recent charts, maybe ...

Here's the 500/1000 TT chart for Monday (ie sub T+100)

Into FI and we see the cold retreat from the South and East, and a new batch approach from the North and East.

[Terminal Moraine]

I'll be interested to see if the GFS 06z run keeps a similar prognosis to the 00z run for next Saturday ( 19th ).

A major snow event for the Midlands northward if those charts were to come to fruition with blizzard conditions over high ground at least.

No support whatsoever from ECM though and at a range of 220 odd hours it's just something to be aware of.

Overall some sort of cold spell seems almost a certainty and the current charts are about the best I've seen since I started with the BBC's snow watch about 9 years ago, particularly so early in the season.

It's all very remeniscent of the build up to some of the classic winters of the 50s, 60s 70s and 80s but then again analogues are a dangerous thing.

[Snowly does it]

To anyone who is worried about the upper temps etc showing for the 0z GFS, I would not be too concerned away from the south coast itself - the LP system that barrels along underneath the UK would deliver an absolute pasting of snow for parts of the UK were things to come off like that and its passing reloads the cold air back into the whole UK in any case.

GFS 0z is a thing of beauty.

ECM 0z is not as impressive as yesterday but look at consistency here - the ECM is changing run to run, I'd wait until the ECM medium term settles on a pattern for 2/3 runs before worrying overly about it.

[Nick F]

Ah, ok, I can see why you and TEITS are seeing it as not a downgrade. You are looking at upper air temps. I'm not, I'm looking at the intensity of the flow and the accompanying pattern. Colder uppers are less useful if there's a much slacker flow, which there is. We have basically lost a lot of the bite of the easterly ... at this stage.

I think though that many are only interested to whether it'll snow or not, rather than strength of flow and depth or cold. Certainly as it stands on the GFS - could be some snow to lower levels across some parts early next week. Though of course it's too far off at the moment to say more than that there'll be the possibility of some wintry showers early next week towards the E and SE as the cold increases.

[Snowyowl9]

Sorry Dave but that is manifestly not the case.

Doesn't mean we won't have a fantastic cold spell in the long run, but early next week is now much more transitional on all the overnight runs for the 3 reasons I cited above. Let's not get hung up over the term 'downgrade' which might appear to worry some people. What we can refer to is that:

1. The high pressure is further east

2. The high is less strong

3. The high does not link as successfully nor as sustainably with the Greenland high

In the long run it might not make the blindest bit of difference, and besides ultimately a north-easterly is heaps more interesting than a straight easterly.

You would`ve ramped these charts big time last year with your name La nina.

This means our cold spell will last longer.

UKMO and ECM.

http://91.121.93.17/pics/Rukm1201.gif

ECM still showing a NE-ly

http://91.121.93.17/pics/Recm1681.gif

See the states are having had a severe snowstorm already

GFS is better as there is a snowstorm showing later on but that was a mild outliner at that point,and high goes further north.

http://91.121.93.17/pics/Rtavn2401.png

[West is Best]

I think though that many are only interested to whether it'll snow or not, rather than strength of flow and depth or cold. Certainly as it stands on the GFS - could be some snow to lower levels across some parts early next week. Though of course it's too far off at the moment to say more than that there'll be the possibility of some wintry showers early next week towards the E and SE as the cold increases.

You're right. What concerns me there Nick is that if that trend continues there won't be as much convection out of it. High pressure generally = less precipitation. We need to see if the intensity is maintained with proper low pressures forming off the north sea.

Lol re. La Nina. I was still ramping away last year as 'West is Best'. These are indeed still fabulous synoptics, just a shade less glossy than yesterday in the short term, that's all. And only to my eye. Still superb.

Edited December 10, 2009 by West is Best

[Nick F]

You're right. What concerns me there Nick is that if that trend continues there won't be as much convection out of it. High pressure generally = less precipitation. We need to see if the intensity is maintained with proper low pressures forming off the north sea.

Lol re. La Nina. I was still ramping away last year as 'West is Best'. These are indeed still fabulous synoptics, just a shade less glossy than yesterday in the short term, that's all. And only to my eye. Still superb.

You're right to say about the lack of bite from the ECM concerning the easterly early next week, certainly it has a slacker flow across the south compared to GFS and pressure higher with a 1030mb high parked over NW UK, so not so great unless you live in the far SE.

[Yeti]

Hello my friend,

I see your point but unfortunately here it has got some credible amount of support (around 4 runs from what I can see). Bearing in mind this is in graph format and the strong links between meteorology and mathematics, in mathematics an outlier is when certain data on a given graph is anomalous from the trend

heres an example:

http://mathworld.wolfram.com/images/eps-gif/OutlierScatterplot_1000.gif

In the instance of the GFS the operational has at least some support, and so it cannot, IMO, be labeled an outlier

But i realise its a bit of a subjective topic given the definition on the forum

Kind Regards

SK

There are quite a few different definitions for identifying outliers (e.g. greater than 1.5x SD away from mean, etc.) but I agree with you; there is too much support from other members to call it an outlier.

[VillagePlank]

Lol re. La Nina. I was still ramping away last year as 'West is Best'. These are indeed still fabulous synoptics, just a shade less glossy than yesterday in the short term, that's all. And only to my eye. Still superb.

... oh, I don't know, rather like thunderstorms and such like: one thing out of place, and, well, disappointment all round. Still have to add, though, I don't recall seeing synoptics like this since I started on being a web-weather-nerd (WWN) some years back.

[Cecil Hogmanay Melchett]

UKMO is nice

GFS is very nice

GEM I haven't seen

I'm not sure what to make of ecm,its not as good as the other two i dont think there is much doubt about that.

Still,nice block around Greenland in the reliable.I think the evolution from 144h is still to be firmed up on

so no need to panic about an operational.

Lets see how the ecm ensembles look,the 0z has been in the milder pack for the last few days.

edit GEM is very nice to.

ECM looking a bit lonely with its evolution to my eyes.

Edited December 10, 2009 by happy days

[MR EXTREMES]

cold and snow away from the south great news for poor old badboy now im going to double dose on my prozac:wallbash:.

but then when is anything straight forward on the model runs.

ecm looks slack gfs looks better with a reload but overall things changing fast but the omega block is there but not looking like it can take to much.

[Frosty.]

Stunning GEM 00z, especially in the FI part of the run, deep scandi trough, hp retrogression to greenland with a bitter NNE'ly blast, the gfs 00z is another stunner and we have intense cold lasting until beyond christmas, quite amazing cold becoming entrenched on the gfs 00z run with snow showers and severe frosts and no sign of mild weather in sight. This is why i'm hoping the ecm 00z was a blip as there were no more than a few wintry showers to look forward to on that particular run. From what I can decipher, fine with frost and some fog in most areas until and including next tuesday, then an increasing risk of snow, colder air and sharper frosts from midweek onwards.

[Eugene]

The simple truth is that model watching fatigue has set in, this chart at just T+72 hrs would of set pulses going just a week or two ago now most are acting like its a bartlett high scenario showing on the models

http://www.wetterzentrale.de/pics/Rtavn721.png

http://www.wzkarten.de/pics/MT8_Manchester_ens.png

I doubt if anybody is really unhappy with these ensembles if they told the truth.

[Cecil Hogmanay Melchett]

So,after viewing all the models.

ALL of them EXCEPT ecm show a peolonged cold spell for the UK.

Let's hope the fly in the ointment isn't the winner here.

I say this because on all the models all you can see is a long cold spell,ecm seems to transfer the energy

away from scandy and the flow becomes slack and we dont get the 'trigger' we need to advect the cold air west from

the NE.

I really dont like the ecm op on closer inspection,yes it looks cold and mainly dry next week but by the end of

it the jets coming over the top.

mild outlier please weather gods.

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

says 10 Dec.

Is this the new set?

[Rollo]

Sometimes I think that seeing so many charts a day gives us worries that years ago would not have existed, we all know that 00 will differ from 06 and so on -we should just be pleased that overall the promised spell has at this stage stayed very much as it was 2-3 days ago and fine tuning may well occur until maybe 12 hours prior to the main event. As TM said in a post earlier " in the 9 years of chart watching he cannot remember such synoptics", I fully concur.