Model Output Discussion - moving into Winter

[bluearmy]

7 minutes ago, Eastern Scotland WX said:

Jesus Christ, look at GEM!

Not good for coldies across most of the country but could develop again from day 8  

Edited December 1, 2022 by bluearmy

[MATTWOLVES 3]

9 minutes ago, Geordiesnow said:

This afternoon runs are showing why I don't believe in a true Greenland high set up as we are getting into the time frame where spoilers pop up and we do see that on the UKMO in particular. 

The GFS spoiler seems to be the Iberian low once again, still room for upgrades though but not quite the output that will get this place celebrating.

Mate this place would be looking for a downgrade and not celebrating if the Day after tomorrow sypnotics were about to play out.

No dramas here..let's wait for the ens too play out and see where ECM and the ens from that take us.

In the meantime sitback chill and have a lovely cup of Yorkshire tea.

[Skullzrulerz]

2 minutes ago, Tim Bland said:

Draw me a better winter chart?! 

Still a bit of a long way to go, would like to see these charts getting to just a few days away, not around Day 10.

[Ali1977]

It’s hard to see a breakdown anytime soon with this pattern, Ice days and colder and colder nights in any clear skies, especially with a snow covering. 

[TSNWK]

1 minute ago, Tim Bland said:

Draw me a better winter chart?! 

Easy to do +6 instead of +222 bottom left

[Tamara]

On 29/11/2022 at 15:45, Tamara said:

a tumble in mountain torque is signposted as means of the extra tropical wind-flow budget playing its part in the overall correction of relative and total angular momentum.

And here it is. The retrogressing block signal that is now fully advertised by numerical models.  Very robust -ve East Asian Mountain Torque (shaded blue above 30N and the red line on the torque graph) essentially creating an extra tropical wind-flow vacuum in the Pacific as the starting pistol to a powerful downstream retrograde signal. As suggested yesterday it's a biggie, and there are ramifications from this signal for quite some time to come which is the fascination for me.

The question remains long term how far the retrograde evolves and how the -ve NAO behaves accordingly. The intuitive reasoning remains that attritional battle ground towards NW Europe culminates in an attempted breakdown - which tries to re-set to another Atlantic trough and amplifying downstream ridge. Does the Eurasian feedback reload this as another Scandinavian block, or, does the polar jet then prevail and create a more traditional zonal pattern with heights across mainland Europe?   

Finely balanced in my neutrally objective opinion as much more work will be required from the tropics next time round to assist, with angular momentum at a lower base level than it has been up to this -VE EAMT. Reasoning behind that has been given fully already this week.  I don't personally, at this time, believe the Eurasian feedback signal on its own is enough.

However, all of that is some way ahead. From my own point of view though, the evolution of the diagnostic remains the focal interest.

 

[Ice Day]

Yep, GEM is heading in a different direction by day 8.  Really not sure what to make of this?!

[BLAST FROM THE PAST]

 

this imo is far better than this

 

 

cold elongation is just so much longer…and will get deeper.  Love the 12z….awesome run.  Don’t always look for the ‘flood’ as it suddenly goes as quick as it gets here

 

BFTP

Edited December 1, 2022 by BLAST FROM THE PAST

[northwestsnow]

Just now, Ice Day said:

Yep, GEM is heading in a different direction by day 8.  Really not sure what to make of this?!

Yuk.

No thanks.

[halny]

50 minutes ago, Singularity said:

I don't usually give ICON the time of day but it is interesting to see where it sits relative to the 00z ECM and GEM runs as of +180 hours.

I do recall that ICON was the most consistent and surprisingly accurate with the Beast from the East in 2018. Whereas other models flip-flopped, it had it nailed on and didn't budge.

Edited December 1, 2022 by halny

[Eastern Scotland WX]

GEM at 240h

[Rain All Night]

Just now, Eastern Scotland WX said:

GEM at 240h

May we see?!

[Singularity]

Took me several minutes to identify what sent GEM down its own path (it's not like the ECM 00z - markedly different across N. Asia).

Look at the low south of Iceland on the 12z GEM run (left) at +120 hours. It's considerably further west than on the 12z ICON (middle) and UKM (right) runs.

This causes the high between Iceland and Greenland to become fully cut-off, changing its orientation toward west-east rather than southwest-northeast.

The GFS 12z has also moved the low further west compared to its previous run, but not so quickly, which means cold air reaches the UK before the high re-orientates. Then it has the re-amplification which tweaks things again - we'd otherwise have been looking east as of day ten, like with the 12z GEM.

Still, that low heading so far west in a hurry is a feasible way in which things could turn out chilly rather than cold for the UK later next week. Can't say I'd back GEM over UKM at this lead time, but stranger things have happened and that low has been giving the models a hard time.

Edited December 1, 2022 by Singularity
GFS Connection

[Ali1977]

BFTE setting up with the GEM , day 10 thought so unlikely !! That’s some easterly though

[Lampostwatcher]

GfS 12z is a bank from next friday onwards 

❄🌨🌨

Superb run 

[Vikos]

Gfs puts the continent into the freezer. Fine for me, but it’s GFS…

[Robbie Garrett]

UKMO FAX Chart for today

UKMO FAX Chart to +120hrs

 

I suspect the reason confidence is low and it's difficult to prog is because there's probably not much data for a big HP cell over Greenland and a North Atlantic stream, as weak as it is or has been.   The Jetstream is heading south.   Whilst we might not get deep cold alas 2010 (Jan/Nov/Dec) - we might get something else, and that's snowfall, and shed loads of it.

A lobe of PV into Canada, sending WAA into Greenland at 120hrs+

 

I was just reading the NOAA outlook; and this is there thoughts.

"Various aspects of the forecast have been in flux over recent runs."

"Operational models have been fairly chaotic with some of the specifics"

"The ensemble means providing somewhat more stability."

In terms of the pattern that will eventually effect us downstream.

Quote

Meanwhile the past 24-36 hours of guidance has trended toward a much slower progression of what troughing remains over the eastern Pacific/western U.S. as a portion of the system's energy shears out into the progressive flow downstream.

"Today's model solutions are in good agreement in predicting an amplified 500-hPa flow pattern during the 6-10 day period. Amplified positive 500-hPa height anomalies persist over the North Pacific and Greenland in dynamical model forecasts. Daily 500-hPa height forecasts show that an amplified ridge over Alaska on day 6 is forecast to de-amplify and reform over western Alaska during the period. A positively-tilted trough is predicted over the southwestern CONUS at the start of the period, and a negatively tilted amplified trough is predicted over the north-central CONUS early in the period. The trough over the West de-amplifies and reforms over the Pacific Coast later in the period in today’s ensemble means, while the trough over the north-central CONUS is predicted to progress eastward over the Northeast. The ECMWF ensemble mean predicts a more amplified trough over the Pacific Coast relative to the GEFS ensemble mean."

 

[danm]

More variations on a theme coming out from the models, which you'd expect at this range. The big picture continues to look excellent, with our best chance of a December cold spell since 2010. Nothing guaranteed at this stage, which is to be expected when the main action isn't projected to kick off until the end of next week. 

[Tim Bland]

What a run! I’ll take the delay if it leads to what is shown from day 7!

[Midlander]

1 minute ago, Tim Bland said:

What a run! I’ll take the delay if it leads to what is shown from day 7!

Same, happy to suffer a delay if it turns out like the GFS 12Z

[TSNWK]

9 minutes ago, RainAllNight said:

May we see?!

Careful what you wish for.. 

[feb1991blizzard]

GFS ex-parallel 12z ends up a stonker, but goes a really long winded way its hard to have any faith in it.

 

Edited December 1, 2022 by feb1991blizzard

[Valleyboy]

16 minutes ago, northwestsnow said:

Yuk.

No thanks.

Might be ok, that low would correct south, so would end up a snow event for some.

[mb018538]

10 minutes ago, Tim Bland said:

What a run! I’ll take the delay if it leads to what is shown from day 7!

That's what you want to see. None of this marginal -4c rubbish.....-8c line clear of the south of the UK in mid December. Snow snow snow.

[Skullzrulerz]

14 minutes ago, Tim Bland said:

What a run! I’ll take the delay if it leads to what is shown from day 7!

Back to Day 10 + kicking the can down the road.

Don't get me wrong, it looks awesome but with the GFS recent performance, I would take the chance of winning the lottery.

Personally we need to get the cold in quickly then the rewards will hopefully follow.

A very important Ecm coming up...