Autumn & Winter 2023---2024 Stratospheric Polar Vortex. Events, Analysis, Discussions AND Outlooks

[Catacol]

21 minutes ago, bluearmy said:

Can anyone see what may have changed over past 36 hours ?  The 00z 26th data led to mean reversal. The data beyond that hasn’t. Given that modelling in the strat is supposed to be more reliable, surely something must have changed in the trop around the 31st ??.

Hard to see much at a trop level. Scouring the pacific jet and the poleward flux emerging from the Rockies region patterns look pretty much the same. Flux levels on the GFS likewise. I guess it would help to know the specific lag time between trop developments and impact at 10hpa but that is well beyond my understanding. For now I’ll just call it “inter run variability” and wait and see what transpires tomorrow. 

[Cheshire Freeze]

I personally think we needed the SSW to grasp the mooted cold Jan. It’s a bit of a gut punch to be honest.

We will get the vortex split eventually IMO but it’s looking likely later Jan now. Feb and March cold doesn’t really do it for me.

[blizzard81]

13 hours ago, bluearmy said:

Can anyone see what may have changed over past 36 hours ?  The 00z 26th data led to mean reversal. The data beyond that hasn’t. Given that modelling in the strat is supposed to be more reliable, surely something must have changed in the trop around the 31st ??.

Good question. My knowledge about all things Strat related is very limited but the one thing I've noticed people (like yourself) who are far more knowledgeable is that it is quite a lot more reliable in terms of long term forecasting. Have the strat gurus like Eric Webb etc made any comments about the sudden change in the extreme forecasts? It would be good to hear their thoughts on it. 

[Andy8472]

Little warming vs little core, interesting  

[Bricriu]

We can still get a cold spell without the reversal,  but I have to say some of the op runs are giving me a feeling of de Ja vu with the Iberian  High being the villain of the piece yet again. It will be extremely disappointing  if we end up with another late winter  cold spell when the prospect of a peak winter cold spell was  on the table . 

[bluearmy]

1 hour ago, blizzard81 said:

Good question. My knowledge about all things Strat related is very limited but the one thing I've noticed people (like yourself) who are far more knowledgeable is that it is quite a lot more reliable in terms of long term forecasting. Have the strat gurus like Eric Webb etc made any comments about the sudden change in the extreme forecasts? It would be good to hear their thoughts on it. 

They’ve all gone quiet after yesterdays ec46 came in line with the eps …. 

[bluearmy]

The 06z gfs op is a grim run in the strat with a strong flush into the mid and lower strat that hangs around 

the reversal barely makes it below 10hpa above 80N and the renewed reversal towards the end above 5hpa looks like it’s not gaining any traction (although that a long way off)

[blizzard81]

1 hour ago, bluearmy said:

They’ve all gone quiet after yesterdays ec46 came in line with the eps …. 

Predictable. Would be nice for them to offer their thoughts on the turnaround. Maybe even they don't know. The strat output these last couple of days has been as dismal as the weather has been for what seems an eternity. 

[Duane S.]

I definitely have to agree with this

Certainly some of the wilder zonal wind and warming predictions have tailed off over the past 48 hours, but we are very much in the game as we look towards and through January.

The 06z still showing a very strong warming up top but it doesn’t get much below around 5-7mb with any great gusto. 


 

Worth holding our nerve, to see if we’ve ’bottomed out’ on the rollercoaster today…

[Bricriu]

We need sufficient downwelling, otherwise I think any ridging northwards will be temporary before the Altantic  takes over again. Are we going to be in a typical Nino situation where we have to wait till February for proper blocking. It's a kick in the teeth if we do after all the hope of a decent cold  spell in January. I will take a cold spell at any time,but one during peak winter would be fantastic. 

Edited December 28, 2023 by Bricriu

[Catacol]

Whatever happens week 1 of January this story is not over. Significant poleward flux forecast on GFS today for end of that week.

 

 

And plenty of members still seeing reversal potential.

 

Lots of time for this tale to develop further.

Edited December 28, 2023 by Catacol

[Catacol]

…but no getting away from the disappointing nature of this update and the trend it represents.

2018 redux in the heart of winter looking a long shot now which is a great shame. Plenty of flux hitting the vortex at the outer reaches of reliable modelling so maybe chances come later.

[damianslaw]

8 hours ago, blizzard81 said:

Predictable. Would be nice for them to offer their thoughts on the turnaround. Maybe even they don't know. The strat output these last couple of days has been as dismal as the weather has been for what seems an eternity. 

Could be one of those cases where a moderate warming rather than the more risky game of a major SSW will be just enough to maintain a cold pattern

 Remember 2019 when the SSW resulted in persistant mild in the main.

There appears to be enough other factors without the SSW to induce a cold pattern.

[Fiona Robertson]

Just some more eye candy. EarthNullschool set to temp and 10hPa. Wee green circle shows temp of -9.5C which is a tad higher than I expected  10hPa over Scotland right now is -68C

[bluearmy]

There were signs on the ec op 12z yesterday that the spv was stretching later in the run. This is also clear on the eps mean. Berlin charts today show that at the top of the strat the spv is located ne Canada but as we drop down it sits towards Barents/svaalbard. Hence I guess why it’s stretched somewhat! 
 

anyway, moving forwards and todays 00z run splits the spv in the mid strat (presumably this runs all the way up from the trop and begins to show at 10hpa.  You could argue that it’s a trend but early days.  The gfs op sniffs it at 50 hpa around day 12 but the profile of the run doesn’t have the split. 

This isn’t reversal territory yet but the split pattern if verified would help to maintain a pronounced Atlantic upper ridge. Going back a decade I recall ed showing how a split in the strat prevented troughs making headway east and flattening the ridge. So despite the trop models showing that the ridge would topple, it didn’t.  I’d assume the nwp has come a long way since then! 

50/30/10 hpa

   

[bluearmy]

Interesting- 06z looks a decent trop run wrt the general ens guidance and because it has the trop split it also begins to split in the mid strat. Let’s see if we can get it up to 30 hpa 

the 00z op was very progressive with zonal flow low down and this op will not be the same !

[Bricriu]

Have we lost the Ural High in fi? That could be a disaster  going forward. I think the latest model runs could end up in major disappointment  if residual energy is still left over Greenland.

If that's the case any ridging high may collapse  on top of us. Well at least it would be cold and dry in that scenario.

[bluearmy]

1 hour ago, Bricriu said:

Have we lost the Ural High in fi? That could be a disaster  going forward. I think the latest model runs could end up in major disappointment  if residual energy is still left over Greenland.

If that's the case any ridging high may collapse  on top of us. Well at least it would be cold and dry in that scenario.

The eps 7 day means have trended away from a weak ridge in week 2. Looking through the 46 runs, n Russia has become ever more troughy as the runs have come in for week 2k.  Thereafter, week 15/22 was showing a mean high anomoly but yesterday lost that.  That could return I guess. 
Im not sure if things are as uncertain as we think when looking at weekly means because there is consistency.  But if week 2 or 3 is wrong, does that negate weeks 4 and 5?  there isn’t an answer 

[sebastiaan1973]

1 hour ago, bluearmy said:

The eps 7 day means have trended away from a weak ridge in week 2. Looking through the 46 runs, n Russia has become ever more troughy as the runs have come in for week 2k.  Thereafter, week 15/22 was showing a mean high anomoly but yesterday lost that.  That could return I guess. 
Im not sure if things are as uncertain as we think when looking at weekly means because there is consistency.  But if week 2 or 3 is wrong, does that negate weeks 4 and 5?  there isn’t an answer 

I think this is a consequence of negative AO developing.

[lorenzo]

Looking at heat flux anomalies Xmas Day has perhaps a stronger pulse vs Wednesday to consider your original question at the top of the page Nick, not sure if this answers in full it could in part explain some of the subsequent output.

 

Still a fair bit of time until the 7th to see how this one plays through. The animation from 00z this morning is neat to watch how the vortex ingests it's New Year shot of Heat Flux, distends and splits.

Weather Maps - Temperature

FLUID.NCCS.NASA.GOV

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Fluid provides applications for interactive analysis and visualizations of meteorological and chemical output from GMAO-supported forecast and reanalysis models

Lots of energy remaining over Greenland / Canada still and some chaotic filaments flaying off will make NWP jump around considerably I think.

Whether we do get a technical SSW with the u reversal, or whether we do get to +3 or 4 ms-1 seems almost moot with respect to - it's degraded either way and primed for the next MJO go around. Perhaps the old 1 / 2 needed for it this time round...

 

 

Edited December 29, 2023 by lorenzo

[bluearmy]

17 minutes ago, lorenzo said:

Looking at heat flux anomalies Xmas Day has perhaps a stronger pulse vs Wednesday to consider your original question at the top of the page Nick, not sure if this answers in full it could in part explain some of the subsequent output.

 

Still a fair bit of time until the 7th to see how this one plays through. The animation from 00z this morning is neat to watch how the vortex ingests it's New Year shot of Heat Flux, distends and splits.

Weather Maps - Temperature

FLUID.NCCS.NASA.GOV

---

Fluid provides applications for interactive analysis and visualizations of meteorological and chemical output from GMAO-supported forecast and reanalysis models

Lots of energy remaining over Greenland / Canada still and some chaotic filaments flaying off will make NWP jump around considerably I think.

Whether we do get a technical SSW with the u reversal, or whether we do get to +3 or 4 ms-1 seems almost moot with respect to - it's degraded either way and primed for the next MJO go around. Perhaps the old 1 / 2 needed for it this time round...

 

 

Thanks for looking Tony - maybe a clue there - Berlin has cross sectional heat flux and momentum flux still available but tomer’s gfs charts you posted are way better tools. 
 

the 06z gfs op showed the top of the strat above 70N being  positve/ negative/ positive /negative / positive within 12 days.  And decent levels of flow too. I can’t imagine that any model will cope well with resolving how that heads down and affects the trop 

[lorenzo]

Just spotted this on twitter for 30mb...

[TSNWK]

49 minutes ago, lorenzo said:

Just spotted this on twitter for 30mb...

But is it a mean chart or a cherry picked ensemble member? 

[bluearmy]

12 hours ago, lorenzo said:

Just spotted this on twitter for 30mb...

All on Berlin this morning Tony.  The 00z run pretty similar but rotated a few degrees east 

11 hours ago, TSNWK said:

But is it a mean chart or a cherry picked ensemble member? 

That’s the ec op

Edited January 1 by bluearmy

[Catacol]

19 minutes ago, bluearmy said:

All on Berlin this morning Tony.  The 00z run pretty similar but rotated a few degrees east 

That’s the ec op

Split all the way up to 10hpa on this run. 

GFS has a split also, not quite as early and not quite as high, but still there

We have missed the opportunity of the SSW, but we may yet get a trop led split that will aid any -NAO going forward. Knife edge stuff.