Model output discussion - winter proper underway

[jvenge]

4 minutes ago, I remember Atlantic 252 said:

slug needs to be further north, but potentially cold, frosty foggy in the south, warm in NW, esp Scotland

Eh? That's showing 8-12 degrees in the south coast and 6 a little further north. I don't think anywhere but very high ground would get frosts from that.

Edited December 12, 2017 by jvenge

[warrenb]

No Atlantic train on this run.

[beng]

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=222&mode=0&carte=1

This could just be the first sign of some amplification returning in the atlantic in response to the reforming Canadian West Coast ridge.

 

[comet]

56 minutes ago, TEITS said:

In my opinion we haven't been seeing wild swings in the output in recent days. Actually the models have been consistent in bringing us a return to milder SW,lys.

Personally I think members should forget about the predicted Scandi HP and focus on just what the models are currently predicting. The reason I say this is because even towards the latter stages of the GFS we couldn't be further away from an E,ly via a Scandi HP if we tried. If anything any future cold spells in distant F.I are more likely to come from a NW/N,ly.

Agreed. Nothing what so ever to suggest any sort of cold spell developing from the east northeast in the next 10 days at least. in fact I could not think of a worse winter chart than the one offered up by the 06z at t192.

[stodge]

5 minutes ago, I remember Atlantic 252 said:

slug needs to be further north, but potentially cold, frosty foggy in the south, warm in NW, esp Scotland

Following on from the 00Z OP and Control. Yes, we do need a shade more continental flow admittedly but that looks a good chart for frost and fog in the SE and IF the fog lingers it would be very cold by day - quite possible to have an ice day in London under fog even with very high 850s.

[I remember Atlantic 252]

4 minutes ago, jvenge said:

Eh? That's showing 8-12 degrees in the south coast and 6 a little further north. I don't think anywhere but very high ground would get frosts from that.

high needs to be a bit further north

[warrenb]

What have we got here then

[jvenge]

2 minutes ago, stodge said:

Following on from the 00Z OP and Control. Yes, we do need a shade more continental flow admittedly but that looks a good chart for frost and fog in the SE and IF the fog lingers it would be very cold by day - quite possible to have an ice day in London under fog even with very high 850s.

No it doesn't. That's not a good chart for anything even close to resembling an ice day in London. Unless ice has a new freezing point and I wasn't informed.

 

[Interitus]

12 minutes ago, jvenge said:

Quite, but it isn't actually showing in 2sd, just close to, and briefly, before moving back into a standard deviation.

The updated chart is not even close to 2sd, indeed, not beyond 1sd -

 

[nick sussex]

Operation Save Christmas!

The GFS 06hrs run develops more amplitude upstream and tries to retrogress the high within T240hrs. That's a welcome sign after the early morning runs which were poor for cold prospects.

I wouldn't look further than that when the lower resolution kicks in but we'll take any better news today. Only one run so we'll have to see if this trend continues.

[warrenb]

I think we are going to start getting some interesting ENS from today. Not cut a dry by any means.

[northwestsnow]

7 minutes ago, Interitus said:

The updated chart is not even close to 2sd, indeed, not beyond 1sd -

 

That looks horrendous !

[Tamara]

Had a lovely reversion to childhood afternoon yesterday making the most of the relatively modest product of a very unexpected snowfall (that led rather nicely to the opportunity to change my avatar).

Yet another reminder that so many spend so much time by a computer waiting for the weather they crave and then keep on looking for the next opportunity when its waving at them through the window!

So, a quick inspection this morning shows that it seems that recommendations (for a few) to read, carefully, the posts from 7th November have been ignored and misleading representations continue. Its been continually emphasised that any evolution to Scandinavian heights, or, alternatively an evolution to flatter upstream pattern is based upon, at least, three things (and in that respect I'm not going to repeat the latest post of the other day which *should* have made all this clear enough anyway)

1) The imprint of tropical convection feedbacks which have shifted over recent weeks to a Pacific led pattern rather than traditional La Nina Indian Ocean based one. I see that Catacol has written quite extensively on this theme very recently.  

2) The natural conclusion of the present tropical cycle which will involve loss of atmospheric angular momentum and some de-amplification of the pattern which takes us into the immediate post next weekend period

3) The actual longer term outcome (Christmas but more especially beyond) which is based upon whether the next tropical convection cycle shows intention to replicate another eastward moving pattern back through them Maritimes and West Pacific (and hence emulate the latest cycle in terms of the atmosphere imprinting the very east based nature of this La Nina). This is the cue for a further boost in atmospheric angular momentum tendency and return of the Global Wind Oscillation to Phase 4. It would be this that could very conceivably coincide with seasonal wavelength cycle change (Dec>Jan)and point to height rises to the NE. Tentatively, it could still conceivably happen sooner - irrespective of what NWP *appears* to suggest.

The alternative outcome would be for a weak and indeterminate signal based back in the Indian Ocean which dissolves the downstream rossby wave amplification feedback and sustains any mid month flatter pattern. The Global Wind Oscillation (below) would reflect this with a return to the Phase 1,2 and 3 orbits

This, absolutely no doubt, would be the "lemming" solution and time to abandon the thread before the usual people flood it with pages of curdled extrapolations of "winters over" out to March.

In truth its obvious from reading around the forum a few have even more absurdly already started doing that while we are still trying to seek sensible and well thought answers to where Questions 1, 2 and 3 lead us. - let alone worry about GWO Phases 1,2 and 3...

In the present, the updated Global Wind Oscillation still continues a very slow orbit towards Phase 8. Which is completely in line with expectations.

The upwards laddering 90 day long term trend in AAM is so apparent from the spider graph. So is the associated and witnessed trend for increased amplification over a reflected period. Its not a coincidence, whatever the small parochial and scepticism element may think.

The implications of Phase 8 GWO synoptically were posted the other day, and within a reliable NWP period are well signalled. But its still very wise not to jump the gun in terms of how the upstream pattern behaves the further out one looks. Whilst that interim milder phase is well advertised, and is not unexpected, it continues to be highly unwise to draw conclusions from NWP suites who are themselves still trying to answer Questions 1,2 and 3.

Expectations of Scandinavian height rise this side of Christmas on the basis of repeated analysis may prove premature, but so are assumptions about sustained flat patterns based on re-ascendancy of the traditional La Nina pattern (and to yet further repeat - a cautionary book was written about this in the November posts )

The metaphorical virtual computer model brakes and reverse gear are always applicable at any time..

Signals lead models. Repeat, reflect, acknowledge..and then breathe and relax..... 

Edited December 12, 2017 by Tamara

[Methuselah]

So, after what appears to be a slow and inexorable drift toward a mild blandness, the 06Z ends at this...It could mean nothing, yet it could mean everything?

[Swave Snow]

Just now, northwestsnow said:

That looks horrendous !

Maybe its also part of the earlier models showing different synoptics? If its derived from the 00 GEFS as according to Bleuarmy on the Stratosphere Temps Thread this run breaks recent continuity.  It could be part of the change others have mentioned.

[Man With Beard]

Much the same on the ECM clusters this morning, variations on a westerly theme around Christmas aside the odd outlier - personally I can still see a way to greater amplification once again in the Atlantic but that's more of a reading into what could happen rather than an observation on the models are showing.

Beyond Christmas, suggestions of a stormier period emerging:

those deep purples showing very cold aloft and potential for deep low pressure systems. They do track a little further south than normal, so could be wintry at times in the north if something like the majority of the clusters varifies.

[bluearmy]

Caution re using strat gfs data from the 00z run. The gefs lacked continuity 

new run dribbling out 

[nick sussex]

Interesting MJO update from NOAA which doesn't match the current longer range outputs apart from the GFS 06hrs run which is the first to hint at the MJO possibly bringing in another pattern change.

 The CPC velocity potential-based and RMM-based MJO indices indicate a MJO signal with the enhanced phase approaching the Western Hemisphere. 

 This envelope is forecast to continue eastward over the next two weeks, although the propagation may be masked somewhat in the RMM index by a competing easterly signal in association with a Kelvin wave approaching the Indian Ocean at present. Equatorial Rossby wave activity in the Central Pacific may further muddy this perspective. 

 The MJO is favored to continue propagating eastward over the West Pacific (Phase- 7) for the majority of Week-1, before progressing into Phase-8 during Week-2. 

 An active MJO over the West Pacific suggests a colder solution from the Northern Plains through the East in approximately two weeks. As the MJO envelope shifts into the Western Hemisphere, lagged impacts over the U.S. become less robust.

 

The above suggests the return of troughing to the east/ne USA with a dig of cold there, depending on the amplitude of that we could see high pressure to the sw pulled further west/nw and colder conditions in western Europe.

They're suggesting that the RMM index might be incorrect and the models might be having problems picking up the correct signal.

Its notable that the forecasts had originally wanted to take the MJO into the COD for about a week before strengthening it once again with movement into phase 7 , yesterdays shortened the time in the COD.

Operation Save Christmas given a further lift but a long way to go yet!

Edited December 12, 2017 by nick sussex

[warrenb]

I have been hearing a lot from forecasters in the States saying that the background signals and data does not tie with what the operational runs are producing.

And maybe this is why we are still getting signals from the Meto and UK forecasters that not all is set in stone.

Edited December 12, 2017 by warrenb

[Weather of Mass Disruption]

3 hours ago, robbo88 said:

What are people's thoughts on the chances of this happening tomorrow night? I get it is the Gfs and it overplays snow.

I am not very good at reading charts so I can't tell what the conditions would be on ecm.

But the regional forecast also mentions rain turning to snow? 

Don't buy it myself as the Beebs forecasts have mentioned mainly rain except for the hills. They could be wrong (and I would love it to be) but in my experience when rain is forecast it is usually always accurate! 

[TEITS]

How I would love to be proved wrong because the 06Z certainly does give some hope towards Xmas. As Nick says we need to hope this trend continues on the 12Z and isn't an outlier.

Just add to Tamara I hope some of your comments were not directed at me. My approach to the models in this thread is simple. I comment on what the models are showing and how based on past experience they might be wrong.

[ukpaul]

 

38 minutes ago, Weather of Mass Disruption said:

Don't buy it myself as the Beebs forecasts have mentioned mainly rain except for the hills. They could be wrong (and I would love it to be) but in my experience when rain is forecast it is usually always accurate! 

Dividing line is somewhere around 100-150m asl with it going up to 200m or so west and east sides of the Pennines by dawn. I live at the lower end but work at 160 asl so could be a difficult journey Thursday morning.

Same is clearly shown by the current snowline here.

Edited December 12, 2017 by ukpaul

[johnholmes]

Not good news for coldies re the overall winter patterns, looking at the latest computer output from UK Met. What the discussions will be in their Ops room trying to marry this output with what we have had and the possibilities according to some on the longer range models we see would be interesting to be able to eavesdrop!

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/glob-seas-prob

[Snowy L]

37 minutes ago, johnholmes said:

Not good news for coldies re the overall winter patterns, looking at the latest computer output from UK Met. What the discussions will be in their Ops room trying to marry this output with what we have had and the possibilities according to some on the longer range models we see would be interesting to be able to eavesdrop!

https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/glob-seas-prob

Sorry but how accurate can these charts be. I find it difficult to believe 95% of the North Hemisphere will have a milder than average winter. The thing that sticks out for me is both polar and mid lattitudes being warmer than average. You can't have both.

Edited December 12, 2017 by Snowy L

[Swave Snow]

4 minutes ago, Snowy L said:

Sorry but how accurate can these charts be. I find it difficult to believe 95% of the North Hemisphere will have a milder than average winter. The thing that sticks out for me is both polar and mid lattitude-wise being warmer than average. You can't have both.

Also why are the professionals on this and the other side of the Pond telling us to go with experience and not Model Output at the moment, couldn't this raw dats fall into the Model output from the last few days? or not?