General Model Output Discussion

[cold snap]

Afraid not, those are the ensembles from tonights 12Z ECM run.

All gone very quiet in here.wished i never looked.still in f1 even so.

Shocked that ECM ensembles back that run,dissapointing stuff.Need a bumper 18Z tonight to see in the new year.

ECM has been giving us the most coldest and best runs of late to see that is heartbreaking.

Edited December 31, 2009 by cold snap

[January Snowstorm]

The trend is there for all to see on the gfs also i.e. sinking high

Maybe some just choose to see only certain things

[Cecil Hogmanay Melchett]

Solid agreement for sustained cold on ecm ens.

Control looks good,bit of a split next weekend as you'd expect at that range.

HNY everyone.

[swilliam]

Looking through the GEFS members at +240 there is some support for the ECM OP evolution - maybe 20-30%.

Looking towards the end of the run probably over half do not support much of a cold continuation (including those with a Sthly wind)

So guaranteed cold for 6/7 days, then maybe 30% chance of losing it around by 10 days followed by something around 60% at far FI. Pretty good odds I would suggest. If we were in mild sw winds at the moment we would be talking about the possibilities for cold solutions in FI - not the opposite.

[Evening thunder]

I think the colours for the control and operational on that link is swapped round so the control was colder for London, just like the Netherlands

If the red line is the operational then we would be doing pretty well to get max's of 3c and mins of 0c under the set up shown by then!

The ECM does look a bit over progressive and quick at replacing the Greenland high with a deep low in 2-3 days!, but I wouldnt completely dismiss any output without good evidence to do so..

[PB22]

I think the colours for the control and operational on that link is swapped round so the control was colder for London, just like the Netherlands

Good spot that man!

The operational ECM was one of the mildest solutions based on that.

[Michael Fishermans Friend]

GEM had a very diamond shaped HP(similar to the ECM)moving south into mid-Atlantic, where as at the same time period GFS HP was more pebble shaped with a more bias ENE flow as opposed to the direct North or NNE that the ECM/GEM shows and hence the collapse - if that makes any sense?

Those ECM ensembles look a bit worrying - could be effecting these shores by Thursday, let's hope its a blip.

Edited December 31, 2009 by Timmy H

[SMU]

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

These have now updated- the crucial thing for me- ( apart from the fact that its one of the mildest) is that at day 8 when we all said it would be wrong the 12z operational temperature profile is going against nearly every other member-

the Operational has it warming up- whilst nearly all the ensemble suite has it dropping off a cliff again-0

S

Edited December 31, 2009 by Steve Murr

[Cecil Hogmanay Melchett]

Good spot that man!

The operational ECM was one of the mildest solutions based on that.

Certainly was Paul.

I would guess there is a Northerly day 5 to 6 as we see the north sea modification for de bilt.

Thereafter majority inc control go cold while the op goes very mild.

Lets hope the op isn't the trendsetter.

[nick sussex]

ECM ensembles for Reading:

http://www.ecmwf.int/samples/d/banner/page.html

Operational was not without support, the control was milder...has ECM picked up on something new tonight?

I think you might be reading it the wrong way round, the control run was actually colder for days 9 and 10, the operational does have some support but there is still a good amount of runs staying colder.

For further east over the Netherlands its a similar story, the control run staying cold with the operational run at the top end of members, of course we do have to bear in mind that any new trend is always likely to be an outlier when it's first shown. In these situations if its a new trend in relation to the trough over the eastern USA then the others would pick up on this quickly, if theres to be a switch it will likely happen by tomorrows 00hrs runs, alternatively it may overreact to the upstream signal in which case a middle ground solution may happen.

Although the ecm might not be as good as we had all hoped, upto 168hrs its still very cold, any less cold air wouldn't even get in most probably till around 192hrs. Personally i think we might find at worse a middle ground solution with high sitting over the uk, although at this stage I'd still go for a high just to the north with a colder surface continental flow remaining for southern and se areas. I went with this last night and still think its a plausible scenario.

Edited December 31, 2009 by nick sussex

[swilliam]

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

These have now updated- the crucial thing for me- ( apart from the fact that its one of the mildest) is that at day 8 when we all said it would be wrong the 12z operational temperature profile is going against nearly every other member-

the Operational has it warming up- whilst nearly all the ensemble suite has it dropping off a cliff again-0

S

The odds looks about the same for the ECM ensembles as for the GEFS ones I posted previously.

[Geordiesnow]

ECM ensembles for Reading:

http://www.ecmwf.int/samples/d/banner/page.html

Operational was not without support, the control was milder...has ECM picked up on something new tonight?

Actually, it would be the GFS who picked it up first, remember all those posts dismissing previous 06Z runs because its being "over progressive" and we should bin it.

I wonder why we not binning the ecm run for?

I still don't see what the worry is all about, even if that does occur, there is plenty of cold weather to get through and even at times snowy weather.

[weather eater]

ECM ensembles for Reading:

http://www.ecmwf.int/samples/d/banner/page.html

Operational was not without support, the control was milder...has ECM picked up on something new tonight?

I think there are plenty of occasions when a run appears to have a degree of support from its ensembles, but turns out wrong. No doubt tomorrows ECM will be different and also have support from its ensembles.

[cold snap]

How good is ECM usually in the f1 range?

Im not sure

[PB22]

I think you might be reading it the wrong way round, the control run was actually colder for days 9 and 10, the operational does have some support but there is still a good amount of runs staying colder.

Yes, I got them mixed up! Its confusing having the colours like that, especially trying to read them when its New Year's Eve!

All in all, great output tonight, with a nailed on cold spell lasting for at least another week. Happy New Year everyone!

[Frosty.]

The operational ECM was one of the mildest solutions based on that.

Can we breathe a sigh of relief then paul?

Anyhoo there is good agreement from the models for it becoming very cold for at least the next 144 hours with snow at times and frosty nights, if it turns milder after that we can't really complain too much.

[Uncle_Barty]

How good is ECM usually in the f1 range?

Im not sure

I'd say Messrs. Hamilton, Button and Schumacher are better

Anyway - it is 'only one run', and FI is probably t+120 max given the highly unusual situation.

[PB22]

Can we breathe a sigh of relief then paul?

Anyhoo there is good agreement from the models for it becoming very cold for at least the next 144 hours with snow at times and frosty nights, if it turns milder after that we can't really complain too much.

Hi Karl,

I wouldn't be too worried about any model output beyond T+144 to be honest, whatever its showing...there will be plenty of twists and turns over the coming days as the cold becomes established.

[nick sussex]

Actually, it would be the GFS who picked it up first, remember all those posts dismissing previous 06Z runs because its being "over progressive" and we should bin it.

I wonder why we not binning the ecm run for?

I still don't see what the worry is all about, even if that does occur, there is plenty of cold weather to get through and even at times snowy weather.

Please don't goad me like this! Model verification stats only go upto 144hrs in which case the ecm called the whole pattern correct upto that point, the reason we had to bin the gfs 06hrs run the other day was for two reasons ,firstly it took the high too far west when actually the pattern was edged east and had the sw low for early next week running too far ne, on both counts it was totally wrong!

Anyway happy New Year all, will be back later, of course earlier than most seeing as we're an hour ahead here.

Edited December 31, 2009 by nick sussex

[Frosty.]

Hi Karl,

I wouldn't be too worried about any model output beyond T+144 to be honest, whatever its showing...there will be plenty of twists and turns over the coming days as the cold becomes established.

Thanks paul and happy new year to you and everyone else

Fingers crossed we have a better 18z than last night and then a nice surprise on the 00z later, we still have a bitterly cold N'ly to NE'ly to enjoy for most of next week at the very least.

[PB22]

Thanks paul and happy new year to you and everyone else

Fingers crossed we have a better 18z than last night and then a nice surprise on the 00z later, we still have a bitterly cold N'ly to NE'ly to enjoy for most of next week at the very least.

Cheers Karl, Happy New Year!

I think its easy to forget some of the charts we actually have in the more reliable timeframe, i.e.

http://www.wzkarten.de/pics/Rtavn1201.html

http://www.wzkarten.de/pics/Recm1201.html

http://www.wzkarten.de/pics/Rukm1201.html

Yet for much of the evening we have mostly been discussing the ECM beyond T+168! Makes a welcome change really!

[Glacier Point]

GFS and GEM H5 ensemble means day 11-15:

http://raleighwx.easternuswx.com/models/cmcensemble/12zCMCENS11-15day500mbHeightAnomalyNH.gif

http://raleighwx.easternuswx.com/models/gfsensemble/12zENS11-15day500mbHeightAnomalyNH.gif

CPC day 8-14 anomaly:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

There is more flow going northward, as evidenced by tendency in relative angular momentum,

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltend.sig.90day.gif

(look 40-50N - westerl wind increase)

... but the response should be for a mid latitude high at worst. Therefore, ECM 12z is an outlier.

[Southender]

Thanks GP for that great analysis. Thats put my mind at ease somewhat.

[Ben_Cambs]

GFS 18z out starting to come out soon. Great analysis from GP there thank you. So using this basis, should we expect GFS 18z to keep its distance from ECM 12z?

[Cloud 10]

Perhaps these gfs ensemble mean charts might provide better guidance for 168hrs+ ?

Will see how this one verifies,as it seems to be following the script of a mid lattitude high.