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

[TSNWK]

25 minutes ago, bluearmy said:

Beginning to see a trend on ec46 for many members keen to increase zonal flow fairly sharply beyond next mid month and then some quite even sharper reductions towards month end and into December. A long way off but something to watch  

Maybe I've been on the happy pills! Or just don't understand but in my deluded view the above is indication of vortex ramping up followed by a warming into December:) 

[bluearmy]

2 hours ago, TSNWK said:

Maybe I've been on the happy pills! Or just don't understand but in my deluded view the above is indication of vortex ramping up followed by a warming into December:) 

Possibly yes - need to see the number of runs showing a drop increasing over the next couple weeks 

[TSNWK]

1 minute ago, bluearmy said:

Possibly yes - need to see the number of runs showing a drop increasing over the next couple weeks 

Indeed.. we do like a trend! thanks for response 

[Rain All Night]

6 hours ago, bluearmy said:

Beginning to see a trend on ec46 for many members keen to increase zonal flow fairly sharply beyond next mid month and then some quite even sharper reductions towards month end and into December. A long way off but something to watch  

Is it standard procedure for the vortex to have these periodic surges while it's forming in the autumn, as opposed to the winds just smoothly rising?

[bluearmy]

2 hours ago, RainAllNight said:

Is it standard procedure for the vortex to have these periodic surges while it's forming in the autumn, as opposed to the winds just smoothly rising?

I think it’s more likely to see increases followed by a small drops rather than a straight line increase - yes 

todays ec46 is more enthusiastic re general 10hpa slowdown by early December then last few days so the trend is maintained 

[frederiksen90]

Warming underway in the stratosphere in late November and early December. It becomes clearer every day in EC46. Really exciting trends. Note that it is the entire hemisphere that gets warmer at 10 hPa. So not just a shift. It looks like 2009 I think. Dynamic November with low pressure in the UK and intensifying Ural block for the next 3-4 weeks:

 

https://charts.ecmwf.int/streaming/20231025-2000/62/render-worker-commands-74964888f5-5qg8g-6fe5cac1a363ec1525f54343b6cc9fd8-cVwWNR.png

 

With eastern QBO and EL Niño. And the same pressure anomalies and trends in the stratosphere already now

Edited October 25, 2023 by frederiksen90

[Rain All Night]

3 hours ago, bluearmy said:

I think it’s more likely to see increases followed by a small drops rather than a straight line increase - yes 

todays ec46 is more enthusiastic re general 10hpa slowdown by early December then last few days so the trend is maintained 

LOL at that one guy:

Edited October 25, 2023 by RainAllNight

[Jacob]

7 hours ago, RainAllNight said:

LOL at that one guy:

Maybe there is hope for a snowy winter after all!

[bluearmy]

11 hours ago, frederiksen90 said:

Warming underway in the stratosphere in late November and early December. It becomes clearer every day in EC46. Really exciting trends. Note that it is the entire hemisphere that gets warmer at 10 hPa. So not just a shift. It looks like 2009 I think. Dynamic November with low pressure in the UK and intensifying Ural block for the next 3-4 weeks:

 

https://charts.ecmwf.int/streaming/20231025-2000/62/render-worker-commands-74964888f5-5qg8g-6fe5cac1a363ec1525f54343b6cc9fd8-cVwWNR.png

 

With eastern QBO and EL Niño. And the same pressure anomalies and trends in the stratosphere already now

The output for week 6/7 is certainly consistent overall but the strength of the Siberian anomoly is ebbing and flowing somewhat. By next week we should see what the model wants to do with that anomoly. that assumes the blocking to our east  remains on the ec46 agenda for November 
 

[Mike Poole]

7 hours ago, bluearmy said:

The output for week 6/7 is certainly consistent overall but the strength of the Siberian anomoly is ebbing and flowing somewhat. By next week we should see what the model wants to do with that anomoly. that assumes the blocking to our east  remains on the ec46 agenda for November 
 

Interesting signs. 

I will be very interested to see how this new daily ECM 46 performs this winter.  With 137 vertical levels (same as the ECM op) it ought to really be the best tool for stratospheric developments that we have access to, although I note the horizontal resolution is 4x less so that might be an issue.  

It was pretty poor on debut during the summer to be honest, but then, so were all the other models and the teleconnection forecasts as well, at predicting the medium range evolution.  With the stratosphere vortex in play (obviously it isn’t in summer) predictability ought to be higher in winter, so this model ought to do better at predicting the winter patterns, so let’s see if it does…

[frederiksen90]

Is there an early sudden stratospheric warming coming? EC46 continues the strong signal of warming in 10 hPa and it gets stronger and stronger also into December. Note that it is the entire hemisphere that gets warmer than normal, so the heat spreads from the North Pole across Europe. This could indicate much more of a stretched vortex that heralds a split rather than a displacement with resulting heating. And there is a strong signal of Ural blocking into November, which could form a backbone for Northern Scandinavia-Greenland. It is very favorable for wave 2 which are precursor patterns to a split.

https://charts.ecmwf.int/products/extended-anomaly-10t/overview/valid_time?base_time=202310260000&projection=opencharts_north_pole&valid_time=202311060000

[bluearmy]

Yes Fredricksen, we see the next week on ec46 for the first time this evening and it’s certainly impressive 

[blizzard81]

55 minutes ago, bluearmy said:

Yes Fredricksen, we see the next week on ec46 for the first time this evening and it’s certainly impressive 

Is there a scale available? The deepest maroon must be quite up there. 

[bluearmy]

26 minutes ago, blizzard81 said:

Is there a scale available? The deepest maroon must be quite up there. 

It’s as strong as the scale goes (for now) 

[Mike Poole]

5 hours ago, blizzard81 said:

Is there a scale available? The deepest maroon must be quite up there. 

Complete with scale

You can see clearly the cluster that are going for the SSW in the 10 hPa zonal winds:

 

I count 14/100 with reversal at some point.  But note also the mean dipping sharply below  climatology in the last week.  

Definitely one to keep an eye on

Edited October 27, 2023 by Mike Poole

[Cheshire Freeze]

An early warming of some description has looked quite feasible for a number of weeks now.

It’ll be interesting to see how this all develops (if at all).

[MattH]

The highly useful addition this season, for us all, is the ability to see previous runs of the EC46 in terms of the various plots, but, importantly the 10hPa temperature plots, etc. Some would argue being run every day isn't useful, but as long as the data is analysed correctly, then more data the better IMO and that applies to the 10hPa data from the EC46, etc. It is definitely worth looking at the plots in a 'Base Time' instance, as you can get a much better feel for how the model is evolving every 24 hours for a given week period...

https://charts.ecmwf.int/products/extended-anomaly-10t/overview/base_time?base_time=202310260000&projection=opencharts_arctic&valid_time=202312040000

The initial warming is around the late Nov and early Dec period, between the 27th Nov and 4th Dec and it is the last few days that the anomaly has increased in terms of temperatures and this snowballs forward into the following week or two.

Caution is required as experience tells these signals can often become far more watered down much nearer to the present day and if this were a La Nina/wQBO season I would be wondering what the model is doing really. However, that isn't the case, of course. The eQBO is now well bedded in, especially above 30hPa and quite significantly so with the zonal wind now just passed -25m/s at 20hPa and isn't going anywhere in the coming months.

This kind of warming will more than not be linked to wave-breaking events from within the trop and if one looks at the anomalies predicted, while the Aleutian low is somewhat lacking, for now, the Ural blocking is almost semi-permanent. Potentially, too, one would expect the N Pacific low to make more and more of an appearance moving forward as oceanically and atmospherically El Nino takes hold too.

https://charts.ecmwf.int/products/extended-anomaly-z500/overview/base_time?base_time=202310260000&projection=opencharts_north_pole&valid_time=202311200000

Two of the best plots in this instance are the D+11 ALZ ENSM plot along with the ever-highly useful CDAS GPH plot...

https://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/alens500_maps.d11.2.gif

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/hgt.ao.cdas.png

So, Dec SSW is certainly rare, we've been here before with such long lead time anomalies, to then come to nothing but if you strip all that back, as a bare minimum what it does do is provide evidence to the long-standing predictions that the sPV and most likely tPV will not 'rule the winter roost' this season and, overall, be more disrupted than normal and also with the eQBO/Nino mix increases the chances, with a scientific basis, of an SSW at some point.

The interest in this winter continues to grow...

Regards, Matt.

[Jacob]

Would this have a similar effect to an SSW?

Edited October 27, 2023 by Jacob
Forgot to add a photo

[bluearmy]

26 minutes ago, Jacob said:

Would this have a similar effect to an SSW?

That’s effectively a model prediction for twelve days time of a fairly notable neg AO in the trop up to around 300hpa 

the main take away that any model op run at day 12 is nigh on useless but having said that, we are already in a period of neg AO which likely continues for much of the next couple weeks.  reversals around 500 hpa are just part and parcel of the usual ebbs and flows in the trop, especially at this time of year.  As we head through autumn you’d usually expect to see less neg AO occurring. 

reversals high up in the strat are more relevant as they would be expected to drive a strong neg AO in the trop which is more sustained - IF they downwell through the strat into the trop 

[bluearmy]

Ec46 remains consistent on its 10hpa anoms for end nov into first half December 

[Mike Poole]

What’s interesting is that the signal for warming on the ECM 46 in the previous week (27/11-04/12) has increased significantly with recent runs, you can see it here for the last 9 runs, plots are all for the same 7 day period:

[Catacol]

1 hour ago, Mike Poole said:

What’s interesting is that the signal for warming on the ECM 46 in the previous week (27/11-04/12) has increased significantly with recent runs, you can see it here for the last 9 runs, plots are all for the same 7 day period:

Suggests the signal for a strong Ural/Kara block is growing, as identified in the useful JMA monthly a couple of weeks ago

Should this come off - and note also that low pressure signal in the north pacific, then we have some interesting stratospheric vortex watching on the horizon in the early part of winter. A disrupted vortex early doors, especially when the eQBO is in full swing backed up by an active tropical pacific NINO, should provide plenty of interest for winter weather watchers over the next few months...

 

[bluearmy]

Just a sniff on todays 46 that the week 6/7 10hpa anomoly might be extending towards the Canadian sector. The spv displaced towards svaalbard 

[blizzard81]

40 minutes ago, bluearmy said:

Just a sniff on todays 46 that the week 6/7 10hpa anomoly might be extending towards the Canadian sector. The spv displaced towards svaalbard 

Is that good or bad news for us?

[bluearmy]

12 minutes ago, blizzard81 said:

Is that good or bad news for us?

Possible Canadian warming would usually be positive for nw European cold