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chionomaniac

Model Output Discussion 25/11/2012 12Z onwards

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When are the ECM ensembles out?

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let’s look at it this way, if the ECM and the others are right and they may well be, then after brief respite we can all go back to watching the rain teeming down and all that goes with it, wont that be fun.

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Noob question here - As per the GFS, what would cause that Canadian Low to vanish? The block is strong?

Can anyone answer this, please?

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When are the ECM ensembles out?

I think it's around 8:30pm

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Hopefully the 18z gfs will cheer us up.

On another cheery note it has just started to sleet here this evening under very heavy ppn.

Yet if you check the parameters thickness, 850's all say no way!!

Anyway back on topic here's hoping for a fine 18Z

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Via my twitter feed (@markydub) I was talking to Ian fergerson "cold pattern still locked in but what will be will be

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Ian why is ECMWF so right and most of the long term evidence over a 2 week period, and it continues now, wrong?

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The AO/NAO forecasts are only reflective of the general NWP. The models change then so do these.

Yes and the AO/NAO have shown where heading into a deep negative phase for days now without much fluctuation, unlike the ECM for example. Until there is less agreement within the AO/NAO perpetrations or a clear trend towards 'positive' I will stick with them thank you smile.png much better than getting hung up on each run that rolls out.

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see my pdf on page 10 post 189 a pile of 'em in there?

Thanks John, that's exactly what I was referring to smile.png

Hopefully we see the UKMO stick to its guns and by tomorrow this place will seem a much more chilled (pardon the pun) place to be!

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It certainly can, I mean some people only 3 years ago were saying northerly block was impossible during winter.

From what I can see with ECM is that it models a piece of the PV across the North Atlantic into Scandinavia. Will that happen? Well we will have to see.

Touche Kevin rofl.gif

As others have said, it's a minor detail that is determining matters, but one that effectively determines whether we have a cold or mild first half of December.

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Can anyone answer this, please?

It's not going to vanish. It needs to drive up the west side of Greenland bringing warm Atlantic air there. If it or a secondary LP spawned from it gets underneath the Greenland block then that's very bad. That's what the ECM shows. GFS shows the better prospect.

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Yes, if you were asked to predict where it would go at about T72/96 you would go for the ECM route.

Obviously the METO have made their outlook which may be subject to a sudden reversal tomorrow. We need to see the ECM ensembles, but we already have ( I think) all the minor models on their side as well as some GFS ensemble members.

The real shame is that as I said it is an all or nothing, it is not as if it is failed Northerly or failed Easterly, where you can have another go a few days later; once the Arctic High has failed the Azores High has won, it's the nature of the beast.

Objectively, 'Terry', would you say that, in this frame, the Azores high has 'won'?

ECH1-240.GIF?25-0

This is still very far removed from raging mild zonality or Bartlett highs, it's certainly not optimal but we still have heights towards the poles and potential down the line from there. And in what timeframe, if the Azores high 'wins', do we get another shot? The overall hemispheric pattern, even with such a large set back, remains promising for the next few weeks. What occurs within that is up for speculation but it's hardly a total write off by any means.

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ECM and some of the lesser models throw a spanner into the works on the 12zs!!!!!

HOWEVER, the UKMO has been rock solid in it's evolution (the ONLY model to do so on the Det run) and GFS is fine.

We will have to wait until the mornings runs to see how this Canadian Low is dealt with across the board on the 00zs, we can't make a judgement on one conflicting set of 12z operationals.

My advise would be to come back in the morning and we should have a better idea of which evolution is more likely.

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Ian why is ECMWF so right and most of the long term evidence over a 2 week period, and it continues now, wrong?

John, I'm only commenting on the NWP tonight and reflecting how similar experiences in past years have gone - generally to Paraphrase Mr Murr - the way of the pear.

The long term evidence may support a PV split with displacement to mid-latitudes, they may show all manor of reasons as to why there should be a pattern change - many times over recent years the actual has defied these probabilities and the +ve NAO has ruled.

The AO/NAO forecasts are neither here nor there because they are reflective of the general NWP.

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Ian you are plain wrong-the 500mb anomaly charts out to about 15 days have a success rate by my fairly basic checking of close on 70%. That is probably a fair bit better than any synoptic model at that time scale so why, again I ask, should we ditch the predicted cold pattern for the ECMWF recent version(s)?

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Can I just make a basic but I think strong anti ECM point? It has been trending for weeks for a strong blocking and a cold spell for the uk. Suddenly this weekend it does a total reversal and gives a mild trend and an Azores high.

So the question has to be, was it a rubbish model for all those vast numbers of signals it gave out over the last week or so or is it rubbish now? Because one of those must be true! Whichever way you look at it (and whichever actually verifies) it has behaved badly and unreliably.

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It's not going to vanish. It needs to drive up the west side of Greenland bringing warm Atlantic air there. If it or a secondary LP spawned from it gets underneath the Greenland block then that's very bad. That's what the ECM shows. GFS shows the better prospect.

Yes I can see what it says and what it needs to do but my question is what causes the outcome on GFS compared to ECM at 144? What does the block need to have in it or around it to stop this low coming through?

Do I make sense?

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Please stick to discussing the models.

Reading this thread is becoming hard work - moderating it more so.

We don't need chat of crushing disappointments, or needless point scoring.

We have a situation where there are two solutions on the table, by all means discuss what you believe in, but please do so respectfully and with models/ charts to back up your pov.

Thanks

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The AO/NAO forecasts are only reflective of the general NWP. The models change then so do these.

Yes of course that is the case, just an index that measures the pressure differential over an area, It's been mentioned a lot over the last couple of days I am afraid as some sort of reason for the ECM and others to be wrong. Haven't been able to follow this forum for a few days because of the pain I feel reading some of the posts.

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what does this tell you Steve?good.gif

http://www.emc.ncep....aphics/acz6.gif

The fax charts won't follow the ECM tonight. The 0z runs tomorrow will crucial and Exeter will make a judgement tomorrow.

John - we will have to see - but we are talking about the direction of a shortwave that will determine matters - the height anomalies will not be relevant.

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Hopefully the 18z gfs will cheer us up.

On another cheery note it has just started to sleet here this evening under very heavy ppn.

Yet if you check the parameters thickness, 850's all say no way!!

Anyway back on topic here's hoping for a fine 18Z

think the nae had that nailed earlier today! so well done nae!

there ya go

12112600_2512.gif

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Some interesting info on the (excellent) TWO thread, that I'd thought I'd pop in here.

Verification stats are interesting to say the least,

ECM verifying on par with NOGAPS at the moment, with GFS leading and UKMO second.

acz6.gif

Also to note is the 500mb anom charts, big differences between ECM and GFS

http://www.meteo.psu.edu/~fxg1/ECMWF_12z/hgtcomp.html

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I think its important to point out that models are often volatile and unstable when dealing with these sort of developments. They generally deal with zonal weather and developments like these are often not clear cut, and the models can occasionally throw up some fairly horrific charts.

And can I also just speak on a personal level for a moment. A lot of these models throw up brilliant outcomes for those in, say, the North-East of England or Eastern Scotland, and even across the rest of Great Britain and into Eastern Ireland. This is where north-easterlies deliver the best. But in my part of the world, whilst these model outputs are nice to see, they generally don't deliver much in the way of snow or cold, and I tend to look at the models more out of interest because my expectations are lower. I'm not suggesting a pessimistic viewpoint over the models, but I think expectations need to be fairly moderate, remember, what we are seeing is an incredibly rare pattern for November and early December. The ECM may be poor but its simply what we can expect for the time of year, especially in these uncertain times. Lets just observe and enjoy the patterns we are seeing, and see them as an example of how unpredictable and surprising the weather can be.

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http://www.emc.ncep....aphics/acz6.gif

I did say previously that I backed the ECM (basically because it's normally so reliable at t96), but I'm having second thoughts - the above model accuracy at 6 days indicates that it's been really struggling in the last few days. Additionally, thinking about it a bit more, the ECM is best at picking out medium range trends, the differences now are to do with the handing of a low pressure system at fairly close range (between t72 and t96) - which is not necessarily one of its strengths.

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