Model output discussion - deep cold inbound?

[summer blizzard]

16 minutes ago, Vadoseflame said:

Pretty sure that’s not necessarily a bad thing

So as per NOAA the GFS ensemble mean agrees with the Euro mean until at least day 8.

Wetterzentrale - Top Karten - GFS Europe 06Z

WWW.WETTERZENTRALE.DE

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Wetterkarten GFS Europe 06Z

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=ecm&var=1&run=0&time=168&lid=AVG&h=0&mv=0&tr=24#mapref

 

 

 

[Mr.B]

31 minutes ago, Cold Winter Night said:

It seems so, but not quite.

When we attempt to evaluate how reliable the output really is, it's best to look at a number of things (not exhaustive):

- Is an operational (high resolution) run more or less in line with its own ensemble mean or ensemble clusters?
- Is it in line with other models' operational and/or ensembles?
- Is it consistent with previous runs, or does it jump from one solution to another?
- Is it in line with background signals?
- At what timeframe does a specific model usually perform best?
- Are we talking about more reliable short term forecasts or is it the more fickle FI?
- Does the model have known biases that might be an issue?

ECM had many issues at the end of last week and early weekend, it jumped around quite a bit, was not in line with its ensembles, not in line with the other models and it was mostly FI.
That's why ECM was dismissed. GFS was more steady and in line with other output.

Now the situation is different. ECM is steady and in line with its ensemble and in line with UKMO and others. Those are usually very good at short range (up to day 5,6). GFS is suddenly jumping around, its ensemble is messy and it blows up lows, which is a known bias.
That's why this time GFS is, still cautiously, dismissed by many.

It would not be different if GFS/GEFS were the only ones forecasting cold, with EC/UKMO forecasting mild, so it's not about what we want to see.

For all newbies, please read this brilliant post! 
 

We don’t just discard a suit because it’s not showing what we want to see. That would be a layman’s response. We are, to a lesser extent, scientists and deal mostly in logic. 

[Djdazzle]

9 minutes ago, sheikhy said:

I think we should all forget about the icon and just skip straight to the gfs?!!

As if you will not be looking at it . . .

[sheikhy]

1 minute ago, Djdazzle said:

As if you will not be looking at it . . .

I swear i wont!!!im gona be keeping up with updates though!!the one run i might take a look at is the gfs though

[Badgers01]

4 minutes ago, Mr.B said:

For all newbies, please read this brilliant post! 
 

We don’t just discard a suit because it’s not showing what we want to see. That would be a layman’s response. We are, to a lesser extent, scientists and deal mostly in logic. 

Lovely sentiment but this place sometimes feels where science comes to rest ! 

[Updated_Weather]

5 minutes ago, Severe Siberian icy blast said:

When did the ecm start using an 06?

Since a while I believe. I think it’s different to the public available ecm as I believe it may use different parameters

[Singularity]

If you look back over the GFS runs yesterday, something stands out - it always made more of the low to our south. That's not a new development.

The change has been how it handles the low over the UK. This has adjusted to be more like ECM, UKMO, GEM etc, which means we don't get such a quick, clean advance of the cold air across southern UK during Saturday.

Trouble is, it still makes more of the low to our south as well. This places the cold/mild boundary to our east further north, which impedes south-eastward movement of the low over the UK Sun-Mon. It has to travel far enough that it can then ride the boundary eastward as a wave along the front.

GEFS have been on a similar journey when looking at the main clustering of runs. Being related to GFS, this is not surprising. That the control run has often been similar is indicative of this; the control uses the same starting conditions as GFS, with no perturbation. Its used to check whether changes in resolution have much of an impact. If there's little change, it means differences to other models are more about the dynamics and associated biases of the model.

For the Sun-Mon period, the ECM and EPS have been on a less dramatic journey overall. The Euro low has always been made less of, while the UK low slowly trended south(east) for a few days until settling down yesterday. South for Sat-Sun, southeast for Mon.

Of course, these adjustments had big impacts on later next week but that's not the critical period at this time. For that, ECM and EPS have felt a lot less volatile than GFS and GEFS. That really should count for something - so here's hoping because a lot of pro forecasters are going to end up looking daft otherwise!

[Updated_Weather]

Is it just me or does ICON12z look very similar to ECM 00z?

Edited February 2, 2021 by Vadoseflame

[Polar Maritime]

Right, It's very busy obviously.. So let's please keep on topic or posts have and will magically disappear to keep the thread informative and running smoothly.. As requested at the start of the thread.

And please don't quote a post just to say thanks, that's what the like button is for.

Thanks all.

Edited February 2, 2021 by Polar Maritime

[northwestsnow]

Icon delaying the colder uppers ...

Getting a bit fed up of delays now...

[Updated_Weather]

Just now, northwestsnow said:

Icon delaying the colder uppers ...

Getting a bit fed up of delays now...

Only the icon.. 

[frosty ground]

A shunt north from the Icon, still cold just not as cold

[Mark wheeler]

I think I can live with this .

[frosty ground]

As you can see the shunt north (not helped by a weaker block) is allowing the Atlantic system to slide closer

[Mike Poole]

ICON T132 - oh dear!

These two lows are getting too close together for my liking.

Edited February 2, 2021 by Mike Poole

[The Enforcer]

https://www.netweather.tv/forum/topic/95065-model-output-discussion-is-the-beast-awakening/?do=findComment&comment=4412578

06z NAVGEM from the old thread. Note the low blows up and heads north, but crucially this is only after the colder uppers have been allowed to sink south first, so it is then a 'cold' low with cold uppers embedded in it rather than a pocket of mild air circulating around it.

From what I had seen the full line up from 00z/06z was:

ECM 00z (+Ens) + UKMO 00z + GEM 00z + CMA 00z + GFS Para 06z + ICON 06z + NAVGEM 06z

vs

GFS 06z (+Control & Ens)

I haven't seen JMA 00z/06z or BOM (If it still exists) 0z/06z

[Ice Day]

Icon at 132 vs UKMO and ECM at 144 this morning.  

  

Pretty close match over the UK

[IW Met]

1 minute ago, Mike Poole said:

ICON T132 - oh dear!

These two lows are getting too close together for my liking.

Doesn't look terrible to be honest, hints of an undercut with the main low out west stalling.

 

[TSNWK]

36 minutes ago, SteveB said:

What happens if ICON is a snowy nirvana  from Friday onwards!!!

Promotion to top model status.. obviously

[kold weather]

ICON IMO looks a solid middle ground. The easterlies probably just about make it all the way south but there is more than enough cold air wrapping round that it will be cold in the south regardless of whether we end up in a technical col or we do manage to get the end of the easterly airflow.

Very close call on the 12z ICON, that could very well go either way from 120hrs.

 

 

 

[frosty ground]

1 minute ago, Mike Poole said:

ICON T132 - oh dear!

These two lows are getting too close together for my liking.

Not sure the two lows will meet



 

[If Wishes made Weather]

14 minutes ago, Vadoseflame said:

Is it just me or does ICON12z look very similar to ECM 00z?

There is a difference - the angle of the higher pressure zone to the north between Norway and Greenland. On the one chart, the high pressure is elongated sort of towards Iceland.  This allows a linking toward the large mid Atlantic high - and I believe better blocking from systems coming in from the west.

 

[Mike Poole]

1 minute ago, frosty ground said:

Not sure the two lows will meet



 

No probably not now, but I’d be more comfortable with more margin of error like ECM 0z.

[Updated_Weather]

Just now, If Wishes made Weather said:

There is a difference - the angle of the higher pressure zone to the north between Norway and Greenland. On the one chart, the high pressure is elongated sort of towards Iceland.  This allows a linking toward the large mid Atlantic high - and I believe better blocking from systems coming in from the west.

 

I know there is a difference I said they look similar which they do in some ways.. not a bad run icon really.

[Badgers01]

2 minutes ago, Island Visions said:

Doesn't look terrible to be honest, hints of an undercut with the main low out west stalling.

 

A stalling low out west is not what we want !