Model Output Discussion - The final stretch to Christmas

[tinybill]

i know  it  wont happen  but if it did it would  be  nice!!!

[snowking]

Yes but the GEFS have:

 

NASA: geos-0-114.png  Germans: gme-0-108.png

 

Brazilians: cptec-0-102.png  Indianians: ncmrwf-0-120.png

 

Russians (last night): wmc-0-120.png 

 

Looking at the ECM height bias you can see why their T168 chart(+) is unlikely to verify:

 

ECM1-168 (1).gif NOAA_NWS_NCEP_WPC_MODEL_DIAGNOSTIC_-_INTERACTIVE_MODEL_BIAS_PAGE 3.png NOAA_NWS_NCEP_WPC_MODEL_DIAGNOSTIC_-_INTERACTIVE_MODEL_BIAS_PAGE 4.png

Not really sure I understand your final point there IDO...

Sure the positive height bias to our west may result in stronger cyclogenesis....but more pertinently the height bias over the UK is a negative one, which would make the assertion of higher heights (in association with an MLB) from the ECMWF seem even more likely, especially at day 6.

That is not to say this will be the outcome by any means, but the height bias charts shown there do not suggest to me any less tendency for the ECMWF to be correct here.

SK

[frosty ground]

the problem i have with that nick is that the souteastward track of the low doesnt to me look mas plausible as the gfs's... but maybe thats the point, the gfs might be playing safe when the more unusual ecm (etc) track is closer to the mark.

Except the the models don't play anything safe they simply follow the rules they are programmed with........ 

[Nick F]

the problem i have with that nick is that the souteastward track of the low doesnt to me look mas plausible as the gfs's... but maybe thats the point, the gfs might be playing safe when the more unusual ecm (etc) track is closer to the mark.

 

GFS's operational track over last few runs has little support from the 51 00z ECM/EPS members, the majority and ens mean take the low SSE or SE across mainland UK something akin to 00z UKMO. Mind you little support from 06z GEFS for the ECM op or even UKMO, with most taking the low SE down the North Sea. Be interesting to see if there's still a stand off on the 12Zs and if there is, what the t+96 and t+120 faxes coming out later this evening make of the low.

 

I do think the GFS, like others, is too quick to flatten the high that builds once the weekend low clears, I would expect the next Atlantic S/W upper trough to slow and amplify mid-Atlantic more towards the Euro solutions, though it's hard say at this juncture how long the resultant MLB will hold on. Really need to see some energy undercutting such a high centred over NW Europe for it stay in place.

Edited December 23, 2014 by Nick F

[nick sussex]

Yes but the GEFS have:

 

NASA: geos-0-114.png  Germans: gme-0-108.png

 

Brazilians: cptec-0-102.png  Indianians: ncmrwf-0-120.png

 

Russians (last night): wmc-0-120.png

 

Looking at the ECM height bias you can see why their T168 chart(+) is unlikely to verify:

 

ECM1-168 (1).gif NOAA_NWS_NCEP_WPC_MODEL_DIAGNOSTIC_-_INTERACTIVE_MODEL_BIAS_PAGE 3.png NOAA_NWS_NCEP_WPC_MODEL_DIAGNOSTIC_-_INTERACTIVE_MODEL_BIAS_PAGE 4.png

We're not talking of T168hrs, the key timeframe is T120hrs and the models you put as support for the GEFS don't even have verification stats or none that I've managed to find so far and are not seen as major models.

 

If the situation was reversed and the GFS was showing the coldest solution and all the other major models disagreed would you still think the GFS was correct?

[Whether Idle]

GFS's operational track over last few runs has little support from the 51 00z ECM/EPS members, the majority and ens mean take the low SSE or SE across mainland UK something akin to 00z UKMO. Mind you little support from 06z GEFS for the ECM op or even UKMO, with most taking the low SE down the North Sea. Be interesting to see if there's still a stand off on the 12Zs and if there is, what the t+96 and t+120 faxes coming out later this evening make of the low.

 

I do think the GFS, like others, is too quick to flatten the high that builds once the weekend low clears, I would expect the next Atlantic S/W upper trough to slow and amplify mid-Atlantic more towards the Euro solutions, though it's hard say at this juncture how long the resultant MLB will hold on. Really need to see some energy undercutting such a high centred over NW Europe for it stay in place.

Agree with this analysis - along the lines that  I posted this morning.  The 12zs will be revealing, one way or the other.

[IDO]

Not really sure I understand your final point there IDO...

Sure the positive height bias to our west may result in stronger cyclogenesis....but more pertinently the height bias over the UK is a negative one, which would make the assertion of higher heights (in association with an MLB) from the ECMWF seem even more likely, especially at day 6.

That is not to say this will be the outcome by any means, but the height bias charts shown there do not suggest to me any less tendency for the ECMWF to be correct here.

SK

 

The problem I see it is that the D6 to D7 height bias is maintained and is even stronger and edges east with the flow of the pattern. So assuming this bias is maintained and no reason to doubt this, as the ECM op was again clearly another outlier: 

 

 

Then we have to assume D8-D10 op charts are going to over do the block's amplification. So really T168 is unlikely to verify and D8-10 even less. I was not referring to the LP track or it's cyclogenesis as I believe the height bias over rides any effect with respect to track of the LP system viz a viz the subsequent MLB, and it is that height bias that leads to the D7-10 charts over doing the amplification. The GEM sends the LP south as well but with its weaker height bias it looks a lot more like GFS at D9+:

 

 

 

Its only my take on it and of course that bias may no longer apply if this is a genuine signal (though I doubt it).

[Frosty.]

Maybe I was OTT negative earlier, at least next week looks on the cold side of average with plenty of frost and perhaps freezing fog as we catch a welcome break from the Atlantic zonal train..but like many on here..I want snow dammit:-) ukmo model seems to have done pretty well compared to the rest and January is awaited with interest as we seek the cold heart of winter!

[Penrith Snow]

If the models and MetO are correct for January then the OPI is dead in the water!

Back to the drawing board lads.

Andy

[Downpour]

We're not talking of T168hrs, the key timeframe is T120hrs and the models you put as support for the GEFS don't even have verification stats or none that I've managed to find so far and are not seen as major models.

 

If the situation was reversed and the GFS was showing the coldest solution and all the other major models disagreed would you still think the GFS was correct?

That was very similar to the question I posed him earlier Nick, which remained unanswered by IDO. I said last night that I remained reasonably satisfied with the seasonal picture that the models are showing in the reliable timeframe, regardless of the enthusiasm by some members for highlighting mild charts at T12th-of-Never hrs.

 

As I see it the mild air will be pushed away come Christmas Eve followed by a system that as yet we do not know the track of.

 

Another member mentioned Jan 2013, which was an absolute snowfest in my part of London. 

 

That is clearly a very optimistic solution but I see no reason why people are looking too far beyond the weekend system at this stage, unless it is in a "search for mild", which I suppose is a valid, if personally unwelcome, motive. 

[bobbydog]

The problem I see it is that the D6 to D7 height bias is maintained and is even stronger and edges east with the flow of the pattern. So assuming this bias is maintained and no reason to doubt this, as the ECM op was again clearly another outlier: 

 

ensemble-tt6-london (2).gif

 

Then we have to assume D8-D10 op charts are going to over do the block's amplification. So really T168 is unlikely to verify and D8-10 even less. I was not referring to the LP track or it's cyclogenesis as I believe the height bias over rides any effect with respect to track of the LP system viz a viz the subsequent MLB, and it is that height bias that leads to the D7-10 charts over doing the amplification. The GEM sends the LP south as well but with its weaker height bias it looks a lot more like GFS at D9+:

 

gem-0-132.png  gem-0-204.png

 

Its only my take on it and of course that bias may no longer apply if this is a genuine signal (though I doubt it).

IDO, how is the ECM "clearly an outlier"?

apart from the sharp downward spike on the 1st, it appears to me to follow the main clustering on the chart you posted

[IDO]

IDO, how is the ECM "clearly an outlier"?

apart from the sharp downward spike on the 1st, it appears to me to follow the main clustering on the chart you posted

 

At D9 and D10 it is the coldest member within the ensemble. Even though it has a small cluster support it does this so many times and they never verify you have to make a judgement call and on past performances it is most likely an outlier. For the same reason when it was showing 13c for the 28th December a couple of days ago I called it an outlier even though it was within a small cluster:

 

 Current forecast for 29th is now 9c lower

Edited December 23, 2014 by i'm dreaming of...

[Yarmy]

If the models and MetO are correct for January then the OPI is dead in the water!

Back to the drawing board lads.

Andy

 

The SAI would be too (or at least the correlation would weaken), but we're still only 23 days into Winter so plenty of time to prove themselves yet. Only just looked today, but the ECM and UKMO seem to support each other in the "reliable" range, but it could just be coincidence given the inter-run volatility. I can't take the GFS seriously at the moment, especially after the parallel 06z yesterday took an outlandish jaunt to Narnia. Nonetheless, I wouldn't discount IDO's thoughts: he certainly deserves a lot more respect than he seems to have been getting in recent days. 

[Dr. Astro]

The SAI would be too (or at least the correlation would weaken), but we're still only 23 days into Winter so plenty of time to prove themselves yet. Only just looked today, but the ECM and UKMO seem to support each other in the "reliable" range, but it could just be coincidence given the inter-run volatility. I can't take the GFS seriously at the moment, especially after the parallel 06z yesterday took an outlandish jaunt to Narnia. Nonetheless, I wouldn't discount IDO's thoughts: he certainly deserves a lot more respect than he seems to have been getting in recent days. 

 

Add the CMA to that too, it does not get much of a mention being a Chinese model, but it's in agreement, and brings in a stronger Easterly.

 

Perhaps the 12Z's will go down this route...

[Smiler1709]

If the models and MetO are correct for January then the OPI is dead in the water!

Back to the drawing board lads.

Andy

If you take a look back through many great winters for snow and cold your find that these situations normally start from absolutely nothing and can surprise even the most professional forecasters.

Don't get hung up on the here and now, things will change and it could go either way.

The opi is just one ingredient for a cold winter and nothing was set in stone when the final value was negative. Plus the opi forecast was for January to turn cold, so still plenty of time for change.

[John Badrick]

If the models and MetO are correct for January then the OPI is dead in the water!

Back to the drawing board lads.

Andy

So if the OPI is correct for Jan then are the Met office dead in the water?? Game on I say!!!

[shotski]

Sorry but what's OPI mean ?

Also SAI. Thanks.

[Nick L]

Can we keep OPI discussion in the relevant thread please:

 

https://forum.netweather.tv/topic/81494-october-pattern-index-opi-monitoring-winter-season-2014-2015/

 

Thanks.

[Cloud 10]

Sorry but what's OPI mean ?

Also SAI. Thanks.

 

OPI = October Pattern Index

 

SAI = Snow Advance Index

[karlos1983]

That's an unexpected development.. doesn't appear to be phasing as previously modelled?

 

Or I could be a tad premature. I'll hush for a few frames me thinks 

Edited December 23, 2014 by karlos1983

[MisfitDog3]

A year ago today we were feeling the full impact of one of the worst storms of last Winter. There was no chance of anything stopping that conveyor of misery. What we have is a very different and currently unpredictable outlook. Might go cold. As others have said, it's all changing day on day. Nothing to be miserable about. ...especially given where we were this time last year...

[Cloud 10]

1st 12z model out of the blocks is the GME with the beginnings of an Easterly.

 

[Matty M]

The different phasing shown on the GFS Op results in much less cold air advection across the UK.

[ItNeverSnowsInWindsor]

No backtracking from the GFS op 12Z with the track of the Low this weekend...

 

Edited December 23, 2014 by prolongedSnowLover

[karlos1983]

The different phasing shown on the GFS Op results in much less cold air advection across the UK.

 

It's bigger sister appears to be following the same route

 

 

UKMO sticks to it's guns

 

 

Also shows better heights to the North of the UK, I know who my money is on..

Edited December 23, 2014 by karlos1983