Model Output Discussion - moving into Winter

[Derecho]

There's something satisfying about seeing the -5C isotherm well south of the UK. Clean as a whistle.

[ICE COLD]

Lovely  

[Catacol]

6 minutes ago, Singularity said:

The AAM drop will initiate a poleward propagation of westerly momentum anomalies and they usually overpower blocking highs... but when one of those effectively extends well up into the stratosphere (in terms of positive geopotential height anomalies), that momentum can be diverted southward, resulting in a strong, flat jet stream that's well south of the UK.

That's what we're seeing in the modelling for later next week.

The thing is, this also encourages retrograde motion of longwave features to the north, such as blocking highs. So, we're left looking at whether that happens in one smooth transition, or 2+ steps that keep the UK in a cold weather regime for longer.

I expect the latter becomes more likely the stronger the stratospheric support for the initial blocking feature is.

This month, we also have the added possibility of a cold surge out of East Asia across the Pacific initiating new MJO activity, or something similar to it, over the tropical West Pacific sometime in the 2nd half. So, there exists a possibility that the HLB pattern gets reinforced, in which case it would become a very big deal how much the pattern has retrograded. At least some retrograde is pretty much inevitable, so I daresay the question would actually be whether there's been enough retrogression to place a blocking high close to our northeast (or even due north of us) by then.

Got way ahead of myself there, best concentrate on next week for a while yet!

Agree with all that. MJO reignition has been posited for a while. Your excellent technical description of wind flow changes as negative torque kicks in makes proper sense of my glib rhetorical question

Edited December 1, 2022 by Catacol

[Allseasons-Si]

Is ECM running this gfs op?

V similar.

[Ali1977]

Looks like the colds losing the battle, however it’s very well entrenched with very cold nights - and obviously a very good NH profile still 

[blizzard81]

3 minutes ago, Johnp said:

Why are your posts always duplicating?

He posts from his basement which has a prominent echo.

[Eagle Eye]

This is why you stay up for the pub run even when you can't go to the pub 

 

[Vikos]

Not sooo good

[Ice Day]

Just looking at the macro scale for a minute, look how the PV has pretty much lifted out of Canada altogether, which is exactly what we'd want to see.  There's so much going our way at the moment, it's somewhat dizzying!

 

[Cheshire Freeze]

1 minute ago, Vikos said:

Not sooo good

Greater pressure on the strat this run...which should serve us better going forward

[Paul_1978]

4 minutes ago, Ali1977 said:

Looks like the colds losing the battle,

What? Are you sure?!

[northwestsnow]

Well, it's day 10 and we have surface cold 

[damianslaw]

8 minutes ago, Catacol said:

Shameless theft from Twitter - but a great image showing cold continuity in the medium term. Note on this EPS image that the trough has deepened out to our east. Much better than having it deeper out west. Again - looks like ongoing continental flow from the North through East quadrant ongoing. 

Those analog comparisons aren’t too shabby either…

Those analogues are notable, all the big guns in there, 2010, 2009, 1981, 1978. 

[snowspotter]

1 minute ago, Vikos said:

Not sooo good

Hmmm yeah if you’re that worried about a 10 chart from one model run . Personally I’m not too distraught 

[feb1991blizzard]

6 minutes ago, Eagle Eye said:

Stratosphere'e looking a bit wavy 

it looks like that one will fizzle out but there is some good pre cursor trop patterns to Ssw's either been modelled or just gone - there used to be a paper on it posted in the strat thread, it was split into displacements and split events, it showed 25 day pre event trop patterns, would like to see it to check my memory is ok, thats why i have been confident for a while of an SSW.

[Eagle Eye]

The Greenland high goes up up up the ziggurat lickety split and down comes the cold.

So, I think we can say this model run was, all right dudes.

[damianslaw]

9 minutes ago, Snowy L said:

Greenland High actually getting reinforcements from Canada! Has the Atlantic ever been more dead than this.

 

Its been preety dead for most of 2022!

[Vikos]

Just now, snowspotter said:

Hmmm yeah if you’re that worried about a 10 chart from one model run . Personally I’m not too distraught 

Just comparing like everybody else...

[cold snap]

Sorry to say this but this isn't a great run.

Mild air never far away. Could be a blink and you miss it event.

Iberian low playing havoc and mild air trying to push up from the south west 

[Johnp]

I think we all know GFS is just doing it’s thang, with another low just lumbering around. 

I doubt this will verify personally. 

[IDO]

Interesting both ECM and GFS agreeing, when we see a new synoptic:

Both keeping the tPV on the Asian side rather than the trough to Scandi. Rather hit or miss for me, very messy on the GFS.

I suppose the GFS will give us some clues as to where the ECM would go post D10. Not my pick of the envelope, but beggars cannot be choosers, so this trend looks viable. 

 

[terrier]

Well I said it earlier that the gfs18z was seen stumbling out the pub. Seems like it’s had a few tonight. Hopefully we can build on this in the morning and into the weekend. But it certainly looks like we are heading into a memorable spell for December. Certainly beats westerly winds and a raging Atlantic which we usually see at this time of year. 

[MJB]

So different to the run just 6 hours ago and into the deepest FI

[Downburst]

11 minutes ago, Eagle Eye said:

This is why you stay up for the pub run even when you can't go to the pub 

 

Imagine you got locked in during a snow storm and all you’d get was crisps

[Connor Bailey Degnan]

Vast majority of GFS blew the Atlantic up in 2010 in fi. Amazes me people looking for a breakdown before we potentially see the real deal end of next week. Just no pleasing some. We are all set for a potentially brilliant cold spell.