Model Output Discussion - moving into Winter

[Ali1977]

Pretty convincing from MOGREPS, full support there on cold 850s.

[bluearmy]

O6z eps are marginally faster with the mean trough at day 6. The op may well correct a little slower but currently looks likely that noaa models will have to catch up somewhat. 
 

the control is a little further west than the 00z op. We’re not seeing the eps control and ec op correcting much slower which usually means that they are more right than wrong and that the other models have further to go than the ec to meet each other. 
 

of course the greeny ridge could still take a shove se to suppress the upper trough further south - would hope to see model alignment by the 00z runs on the trough’s arrival. 

[TSNWK]

14 minutes ago, bluearmy said:

O6z eps are marginally faster with the mean trough at day 6. The op may well correct a little slower but currently looks likely that noaa models will have to catch up somewhat. 
 

the control is a little further west than the 00z op. We’re not seeing the eps control and ec op correcting much slower which usually means that they are more right than wrong and that the other models have further to go than the ec to meet each other. 
 

of course the greeny ridge could still take a shove se to suppress the upper trough further south - would hope to see model alignment by the 00z runs on the trough’s arrival. 

Thanks - a tad disappointing as we would have liked to have seen a move from 06Z ECM away from this mornings run - ECM I find is very accurate around 144 / 168 and that is where the issue with   the cold trough  dropping too far west ) and then we see the impact of the " wash up " to our south west ( 00Z ECM) in stead of to our south at days 8 onwards (06Z GFS)  

12Z GFS and UKM need to hold firm and not trend towards ECM.

 

Edited December 2, 2022 by TSNWK

[Kasim Awan]

Dont stress about uppers guys

The modelled synoptics have low heights, light winds & troughs

Low heights lowers the 850hpa altitude increasing the minimum uppers needed for snow

Light winds helps cool near surface temps narrowing any >0C layer aloft. troughs are ripe for evap cooling

warm sectors, coastal influences etc another story lol

[TSNWK]

Just now, Bats32 said:

Where are the MET office getting that from

00z ECM  would be a good place to start.

[Norrance]

Model discussion please. Not Met O. BBC or xc weather.

[minus10]

Interesting that the op and control are on the same page for gfes 6z in my area.

Remember someone,  think it was @Mike Poole saying that if that is the case then the higher resolution is not the issue and that the ens are more pertinent...in this case although significant spread still a fair few supporting the op and control...

That would be a cold day , especially in the south east.. 

[Singularity]

On reflection, it's hit me that the way the 00z ECM went was not just just about how strong the low by the Azores peaked, but the little breakaway low that I've labelled 'L' on this chart. It peels away from the Euro low and provides a 'positive vorticity path' (not a technical term) toward the UK. This allows the intense low to both sustain for longer and take a track further north.

This little low isn't there on the UKM 00z or GFS 00z and 06z runs, so it's either a key feature being overlooked by them so far, or a spurious feature steering ECM the wrong way.

The 00z EPS control run was similar to the det. although the little low didn't venture quite so far west.

I don't have time to check all the individual EPS members but of the first 14, 5 of them have that low or at least a notable extension of the Euro low in that direction. So it's a substantial contributor to the overall EPS direction of travel... whether rightly or wrongly, we can only wait and see.

[phil nw.]

Just for information folks any posts regarding met o/bbc forecasts please use this thread

Just so we keep this thread on topic.

Thanks all.

[sheikhy]

Ecm mean 06z fantastic at 144 hours!lets hope for a slight eastward adjustment on 12z!!control similar to the 00z!!!!

[Robbie Garrett]

One thing I've not seen in this thread IMHO is the background signals to this weather;

• So the question will be what background signals are causing the -NAO (Greenland heights) in the models?
• What is causing the Polar vortex to be weaker as a result?

2010 was synoptically a 100 year event.  Any SSWs I've seen, Easter 2008, Feb 2009, Jan 2010 and what not has been a short affair vs Nov/Dec 2010.

 

 

8 hours ago, Mike Poole said:

Yes, my own conclusion is that that is becoming true for the second half of winter.  But I have always pointed to 2009 and 2010 as evidence that a severe cold spell can occur in early winter without a SSW.  These years are recent enough in the scheme of climate change to still be highly relevant possibilities, as we are seemingly going to find out this year! 

7 hours ago, Ali1977 said:

That’ll do , what a chart with another shot of WAA heading up through Greenland. This is gaining traction here, not just a cold spell now , maybe an extreme type event (longevity rather than extreme temps) 

 

 

[Trom]

3 hours ago, Rayth said:

I see you @s4lancia

And I raise you 

 

Nice to see the operational and control in relative tandem.  Gives you a bit more confidence when the op is tracked by its low resolution brother.

[TSNWK]

6 minutes ago, sheikhy said:

Ecm mean 06z fantastic at 144 hours!lets hope for a slight eastward adjustment on 12z!!control similar to the 00z!!!!

Is it? In what sense please compared with 00z 144 mean?

[sheikhy]

7 minutes ago, TSNWK said:

Is it? In what sense please compared with 00z 144 mean?

Well on the mean its more of a direct hit for us and not as far west!!on the control it takes it further west similar to this morning 00z op run!!!!still cold mind you with snow opportunities but just want it slightly further east!!!06z mean.....

 

Edited December 2, 2022 by sheikhy

[bluearmy]

7 minutes ago, sheikhy said:

Ecm mean 06z fantastic at 144 hours!lets hope for a slight eastward adjustment on 12z!!control similar to the 00z!!!!

         

some subtle differences 

alignment slightly more e-w which is not what we want unless the trough gets further south 

slight detachment over Finland from the vortex source 

the spreads firming up on the most likely position of the trough and the ridge.  

Id rather see that trough a little further south for reasons already stated many times.  

note that spread n of Sandi - given the slight detachment of the low heights, I wonder if we are tending towards the runs where the trough separates away and we see the heights extend east 

[Eastern Scotland WX]

Got my popcorn ready for the 12z runs. 

[snefnug]

1 hour ago, bluearmy said:

The isobars around the low centred n Italy T324 can be followed back to se europe where temps are fairly high - but the system is not stationary and the run moves it north east and the isobars revert to a cold source. If the pattern was fairly stationary then the risk would be that much less cold uppers would work their way around to reach nw europe. 

Thank you @bluearmy 

[Optimus Prime]

It does look cold once that north / north easterly sets in towards the end of next week

The 1981 -2010 mean is slightly colder than the 61-90 mean fir December but the first half averages above the 61-90 (second half is below) so this anomaly suggests daily mean temperatures around freezing for the UK as whole. 

Surely means snow will fall almost anywhere where there is precipitation.

Edited December 2, 2022 by Optimus Prime

[sheikhy]

9 minutes ago, bluearmy said:

         

some subtle differences 

alignment slightly more e-w which is not what we want unless the trough gets further south 

slight detachment over Finland from the vortex source 

the spreads firming up on the most likely position of the trough and the ridge.  

Id rather see that trough a little further south for reasons already stated many times.  

note that spread n of Sandi - given the slight detachment of the low heights, I wonder if we are tending towards the runs where the trough separates away and we see the heights extend east 

Yeh noticed that detachment earlier blue!!dont think ecm will back away from that now i think its a new development thats popped up!!!as you say hopefully it goes far enough south before heading west southwest!!!

[ItNeverSnowsInWindsor]

4 minutes ago, sheikhy said:

Yeh noticed that detachment earlier blue!!dont think ecm will back away from that now i think its a new development thats popped up!!!as you say hopefully it goes far enough south before heading west southwest!!!

Some places could do well from this high risk high reward scenario but not for southern locations I fear.

[bluearmy]

3 minutes ago, prolongedSnowLover said:

Some places could do well from this high risk high reward scenario but not for southern locations I fear.

This is where I am at the moment - snow line somewhere through the midlands 

but I’m still wondering if something from left field is going to pop up and move the momentum in a different direction - you’d be surprised to see the initial drive of the trough change now but that could be short lived if we see it detach and the ridge re enforced to the north. 

[Rain All Night]

My understanding at the moment is that we're getting a step down in temperatures this weekend, and then most likely a further step down in the latter part of next week, which may be enough to result in snow for northern parts. I expect many will be looking for greater detail on that second part in this afternoon's outputs, though for me down here on the south coast I am more interested in what may develop beyond day 7, which may be asking a bit much at this stage.

[bluearmy]

Icon shows pretty good continuity from its 00z run 

not as cold as the other models because the trough can’t get far enough south due to the euro low getting too close on its way ne

it has the deepening Azores low late on too and it wouldn’t be a huge stretch to see that becoming a big player of the run went further 

[Kasim Awan]

4 minutes ago, bluearmy said:

Icon shows pretty good continuity from its 00z run 

not as cold as the other models because the trough can’t get far enough south due to the euro low getting too close on its way ne

it has the deepening Azores low late on too and it wouldn’t be a huge stretch to see that becoming a big player of the run went further 

creeping north.. would be a shame to miss out on that cold convective easterly.

Edited December 2, 2022 by Kasim Awan

[Snowman.]

Would like to see a better alignment for the cold to give us dirty southerners a better chance. 
 

Realistically, you need more of an ENE flow coming out of Norway and Scandi. Less moderation on the cold. Cleaner flow with less disturbances would better from the initial blast as well. Get the cold in and all that.