[15 years since first Stratosphere Temperature Watch]

2 minutes ago, Don said:

Yes indeed wrt @Tamara @Paul! 

It would be great to hear some of your thoughts moving forward, ref to developments in the strat during February.  

Haha. They tend to be more private nowadays. But clues are in the first post. 

[15 years since first Stratosphere Temperature Watch]

11 minutes ago, Don said:

Great to hear from you Ed!

Thanks. I’ve always been in the background. I think we should note that @Paul gave me a platform to express my thoughts. And as much as I have not always seen eye to eye with @Tamara I certainly appreciate that she was invaluable with her thoughts in that first ever thread and continues to be on the forum. 

[15 years since first Stratosphere Temperature Watch]

Hi all

I know I don’t post often now but I’ve just realised that this winter is the 15th anniversary of the first Strat thread. How time flies!

 

I remember clearly that first year and a few  years after. I was convinced that the stratosphere played an important role in influencing tropospheric impacts and thought I would monitor this throughout the winter season. Well, I couldn’t have chosen a better season. That winter, we saw a record breaking split SSW of the Strat that led to almost immediate tropospheric impacts early Feb in the form of a severe easterly cold outbreak. 
Despite this being obvious to me, there were a lot of sceptics that still needed to be convinced. 
Yep, I didn’t get everything right back then as I was still learning like the rest of us, but now when I look back I see that we on this forum were at the forefront of leading the way - maybe not ahead of the scientists - but more often than not ahead of the meteorologists who had never been taught the relationship between the Strat and trop in a way that we take for granted now!

I guess I am proud of the work we undertook on this forum and we led the way. 
 

I don’t often post or tweet nowadays- I consider that the groundbreaking work was done back then and that there is little to add. However, I am still keeping a keen eye on things and understand a little bit more about the Strat trop interactions than I ever did. 
 

And I am definitely keeping an eye on the first third of Feb for something interesting to develop- initially trop based but then affecting the strat. A few things will need to fall into place first, but keep an eye out. 
 

Thanks to all those initial Strat believers

Ed

[Model Output Discussion - Christmas week and beyond]

2 hours ago, CreweCold said:

If anyone wants my opinion (and I know plenty won’t), there will not be a fruitful pattern for the UK in terms of widespread or sustained cold until if/when a SSW occurs.

We look likely to see some kind of wave 1 displacement event (with magnitude unknown at this point), however this will most likely not bear fruit for the UK. If we can follow up the displacement with more warming then we could see a SSW but that may not be until late January. If we don’t see a QTR from that then it could be back end February until we see anything of note…

Those ‘writing off’ January are not as crazy as they sound.

That’s not necessarily true. For two reasons. 
One that even if we get a displacement SSW, then it is hard to get this to propagate and then disrupt our side of the hemisphere. 
 

But…two, we can benefit from a scandi high that is often a precursor to this set up. 
 

But as ever, the Strat interaction with the trop and vice versa are all important at this turning point in winter. 

[Model discussion highlights]

1 minute ago, Ali1977 said:

Is this good news ref SSW type Synoptics? 

Yes, as it shows a great tilt/stress of the vortex from top to bottom by day 16, whereas today it is a perfect spinning top. 

Original post: https://community.netweather.tv/topic/98132-model-output-discussion-christmas-week-and-beyond/?do=findComment&comment=4778594

[Model Output Discussion - Christmas week and beyond]

3 minutes ago, Eagle Eye said:

Agreed, the polar-night jet sort of helping here because it increases thermal gradient when there are Eddy's integrating into the Strat (polar-night jet oscillation) which could possibly further the baroclinic tilt by helping the misalignment of the thermal gradient. So despite being Wave-1 dominant we may get lucky though I'm not entirely sure of how my mind came to that conclusion it just sort of does it's own thing from piecing together what I remember from reading about the polar-night jet oscillation about a month ago.

Also like to point out that EPS at day15 were trending the same way yesterday. 

[Model Output Discussion - Christmas week and beyond]

1 minute ago, Ali1977 said:

Is this good news ref SSW type Synoptics? 

Yes, as it shows a great tilt/stress of the vortex from top to bottom by day 16, whereas today it is a perfect spinning top. 

[Model Output Discussion - Christmas week and beyond]

Today. Mr Barotrope.

 

End of run. Mr Barocline. 

this is the trend that needs watching….

thanks to Zack Lawrence for producing these great images

[Model Output Discussion - Christmas week and beyond]

I suggest that we comment on the models rather than whether January is written off or not. 
Yep, we may have to fight a strong Strat pv propagating to the trop for a bit, but signs are growing that that could change. And an increase in west pacific convection could occur too. 
 

So , with an interesting spell of repeat cyclogenesis over the coming days, let’s see some posts on that. 
 

And follow the 10 day rule - unlikely to see much out to day 10 - but even with unfavourable background signals who really knows what will occur after that. 

[Model Output Discussion - Christmas week and beyond]

2 hours ago, CreweCold said:

Coupling has been the form horse for a number of days now. I’ve been rather bemused by talk of a disconnect continuing when there’s little in the trop pattern to maintain one. It doesn’t happen by magic.

At this time of year we require a really robust and clear cut pattern to maintain a disconnect…and this ain’t it.

Out of interest Crewe, have you considered the possibility of a positive NAM upwell as well as an upper positive NAM in situ. So that the positive upwell meets the increasing upper Strat VI that was not downwelling prior to the upwell. I will look into this in more detail in the coming days, but I think it is an interesting possibility. 

[Model Output Discussion - Christmas week and beyond]

53 minutes ago, jules216 said:

Where did Masiello pull out a theory of Scandi high in extended? All I see is a gallery of very mild Europe well in to 10-15d.

Just a point of order here. If you want an explanation of what Anthony saw, perhaps the first port of call should be to reply on that Twitter post, rather than commenting on it on here almost a week later. I think the post was quite self explanatory at that time too, but signals can and do change. 

[Model Output Discussion - Christmas week and beyond]

So, zonal is generally used to explain a strong flat jet stream from west to east with a base of low pressure to our NW.  If we consider different orientations then we can consider different outcomes. We can have flat west, slight tilt from the SW or slight tilt from the NW. All will give a zonal output but with varying amounts of mild or coolness.

Simple.

Once the jet stream has a more meridional and weaker flow then we lose the zonal output. 
 

 

[Polar Vortex / Stratosphere Watch 2022 / 2023]

7 hours ago, Don said:

Any more recent thoughts Chiono?

Lol yes. Basically the upper Strat is forecast to spin like a top. This is likely to filter down to the trop. But how long, and with what strength?  Normally, it would take a few weeks from VI. But I no longer can assume what normal is, so all bets are off, and we need to watch to see how the upper and lower Strat interact and then find why that is so. I know that this is not a lot of help, but it is where we are at. 

[Polar Vortex / Stratosphere Watch 2022 / 2023]

Just a moment...

AGUPUBS.ONLINELIBRARY.WILEY.COM

I think that this is fair enough sPV is PV. Anything trop based is jet stream variation. 

[Model discussion highlights]

1 hour ago, MattH said:

Just a quick one on the long-term, as now all monthly data has been reviewed it is clear that both MSLP and 500mb height anomalies are potentially set to become more focused (in a +ve way) to the N and NE of the British Isles through late Dec and into early Jan, potentially over Scandinavia. As we all know the Scandinavia block is often very difficult to achieve, especially in a W'ly, winter regime, but obviously that isn't the case.

Some further analysis of this has lead to an interesting outcome when using some GWO composite anomalies. The key here, could well be the MJO and whether it keeps progressing eastwards into the Maritimes and the W Pacific, through phases 4-5-6-7 over the next 2 weeks. The primary caveat here is that it needs to do this, but IF it does, then, in theory this would bring about the predicted rise in AAM and the GWO. As a prediction, were the MJO to progress eastwards then another GWO rise through phases 4-5-6 would be possible, as I've suggested below.

Now, using December 500mb height composite anoms for phases 4 and 5 of the GWO, we get the following...

Then if we take a look at the 500mb height anoms from the overnight EC46 through the 26th Dec to 2nd Jan time period and that is a pretty darn close match...

Obviously, as usual, this is all subjective and potentially all hinging on the movement and track of the MJO looking ahead, but it is always good to try and find some science behind the models and to why they suggest one thing and not another. Clearly, a Scandinavian high doesn't always bring cold, but that kind of pattern through late Dec and into Jan would certainly increase the risk!

Keep a close eye on the MJO looking ahead, along with EPS, GEFS 500mb height anoms through the 10-15 day period for something similar.

Cheers, Matt.

 

100% Matt. We have been teased over the last week or so with suggestions that the western Pacific will become active, but in reality all we see is a picture of confusion from the IO to the western PAC. The height anomalies to our NE been showing too for post Christmas - but are these aligned to the MJO uncertain- probably. If we can get a Scandi high then this would be promising both in a direct way and also indirect through Strat feedback disturbances. Winter is very much at a T junction. 

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4770604

[Model Output Discussion - the cold has arrived]

1 hour ago, MattH said:

Just a quick one on the long-term, as now all monthly data has been reviewed it is clear that both MSLP and 500mb height anomalies are potentially set to become more focused (in a +ve way) to the N and NE of the British Isles through late Dec and into early Jan, potentially over Scandinavia. As we all know the Scandinavia block is often very difficult to achieve, especially in a W'ly, winter regime, but obviously that isn't the case.

Some further analysis of this has lead to an interesting outcome when using some GWO composite anomalies. The key here, could well be the MJO and whether it keeps progressing eastwards into the Maritimes and the W Pacific, through phases 4-5-6-7 over the next 2 weeks. The primary caveat here is that it needs to do this, but IF it does, then, in theory this would bring about the predicted rise in AAM and the GWO. As a prediction, were the MJO to progress eastwards then another GWO rise through phases 4-5-6 would be possible, as I've suggested below.

Now, using December 500mb height composite anoms for phases 4 and 5 of the GWO, we get the following...

Then if we take a look at the 500mb height anoms from the overnight EC46 through the 26th Dec to 2nd Jan time period and that is a pretty darn close match...

Obviously, as usual, this is all subjective and potentially all hinging on the movement and track of the MJO looking ahead, but it is always good to try and find some science behind the models and to why they suggest one thing and not another. Clearly, a Scandinavian high doesn't always bring cold, but that kind of pattern through late Dec and into Jan would certainly increase the risk!

Keep a close eye on the MJO looking ahead, along with EPS, GEFS 500mb height anoms through the 10-15 day period for something similar.

Cheers, Matt.

 

100% Matt. We have been teased over the last week or so with suggestions that the western Pacific will become active, but in reality all we see is a picture of confusion from the IO to the western PAC. The height anomalies to our NE been showing too for post Christmas - but are these aligned to the MJO uncertain- probably. If we can get a Scandi high then this would be promising both in a direct way and also indirect through Strat feedback disturbances. Winter is very much at a T junction. 

[Model discussion highlights]

Took a break from this afternoons outputs - glad I have returned to a more positive outlook. 
Keeping an eye on that MJO, and the hints again of long term Scandi rises. MJO forecasts are nudging away from IO activity and now are focussed into activity in the western Pacific, and post day 10 Scandi height rises result. This is crucial imo to the next phase of winter. The trop PV is still massively disrupted, the Strat PV is trying to gets its act together, but no matter how hard it strengthens if the stoke is large enough into the Strat PV bike wheel, then it can be brought down. Feb 2009 is a classic example of this. 
 

So medium and long term hope, but definitely not guaranteed. 
 

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4768347

[Model Output Discussion - the cold has arrived]

Took a break from this afternoons outputs - glad I have returned to a more positive outlook. 
Keeping an eye on that MJO, and the hints again of long term Scandi rises. MJO forecasts are nudging away from IO activity and now are focussed into activity in the western Pacific, and post day 10 Scandi height rises result. This is crucial imo to the next phase of winter. The trop PV is still massively disrupted, the Strat PV is trying to gets its act together, but no matter how hard it strengthens if the stoke is large enough into the Strat PV bike wheel, then it can be brought down. Feb 2009 is a classic example of this. 
 

So medium and long term hope, but definitely not guaranteed. 
 

[Model discussion highlights]

41 minutes ago, Catacol said:

A pretty impressive forecast this. Forget UK cold for a moment - look at the hemispheric 4 wave blocking pattern and the amplified nature of it. And such a strong alaskan/polar anomaly. I am not being original in commenting on this - the initial debate and conversation is out and about on Twitter already. There are "proper" met people out there stating they have never seen anything like this before.

This winter has a funny feel about it. For the UK = Atlantic dead. TPV properly detached from the SPV. Rare triple Nina in place but constructive interference from the pacific enabling more of a Nino response. Pockets of record breaking temperatures, both warm and cold, scattered across the globe. Predictability is certainly not a feature at the moment. A fascinating watch. If we got an SSW in this amplified tropospheric context I cant help but think some parts of the hemisphere might experience some really extreme cold. 

It’s pretty much a mirror image of what we would expect to see. The mirror image trop pattern. 
 

oh and @MattH post is an excellent analysis of what is going on atm. Clear to understand and highlights exactly the position we are in. Post of the winter so far for me. 

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4767775

[Polar Vortex / Stratosphere Watch 2022 / 2023]

7 minutes ago, bluearmy said:

Do we have enough historical data to see what happens if we have a disconnected roaring spv and then we manage to get some sig trop waves up into there ???

I don’t think there will be anything to compare to, because the mirror image trop pattern is so unusual. But any strong Strat PV can be brought down if the trop wave activity is strong enough. Feb 2009 split SSW being a perfect example of that. 

[Model Output Discussion - the cold has arrived]

41 minutes ago, Catacol said:

A pretty impressive forecast this. Forget UK cold for a moment - look at the hemispheric 4 wave blocking pattern and the amplified nature of it. And such a strong alaskan/polar anomaly. I am not being original in commenting on this - the initial debate and conversation is out and about on Twitter already. There are "proper" met people out there stating they have never seen anything like this before.

This winter has a funny feel about it. For the UK = Atlantic dead. TPV properly detached from the SPV. Rare triple Nina in place but constructive interference from the pacific enabling more of a Nino response. Pockets of record breaking temperatures, both warm and cold, scattered across the globe. Predictability is certainly not a feature at the moment. A fascinating watch. If we got an SSW in this amplified tropospheric context I cant help but think some parts of the hemisphere might experience some really extreme cold. 

It’s pretty much a mirror image of what we would expect to see. The mirror image trop pattern. 
 

oh and @MattH post is an excellent analysis of what is going on atm. Clear to understand and highlights exactly the position we are in. Post of the winter so far for me. 

[Polar Vortex / Stratosphere Watch 2022 / 2023]

6 hours ago, bluearmy said:

I wonder what the record speed is for 1hpa ? 
current modelling has us approaching 100 m/s late week 2 

It’s definitely been above 100m/s I seem to remember. But not often

[Model discussion highlights]

9 minutes ago, chionomaniac said:

Just a little note on the GFS ensembles. This morning I suggested that the op was leading the way regarding the outcome from the 19th, when the ensembles were suggesting no return to cold

 

00z ensembles show divergence on the 19th - mainly mild option despite the Op

now look at the 18z GFS ensembles for the 19th. Yep they have all followed the op now. 
 

and within18 hours the divergence occurs around the 21st.  So the ensembles and op now agree for the 48 hours between th 19th and 21st. But the 21st takes us back into a level where it’s day 7-8 rather than day 6. Imo this is important regarding ops and ensembles. We need to be very careful when monitoring ops and ensembles around these timeframes because it is easy to be caught out by not looking at the exact time when divergence occurs

To recap in plain English, it was easy to see earlier today that from the 19th the ops on most models were ahead of the ensembles.The ensembles have now confirmed this. 
The next threshold is 22/23rd where there is no op lead now and ensembles are back in the game wrt longer term output. So we need to be more open minded from this point and use the ensembles more

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4767207

[Model discussion highlights]

Just a little note on the GFS ensembles. This morning I suggested that the op was leading the way regarding the outcome from the 19th, when the ensembles were suggesting no return to cold

 

00z ensembles show divergence on the 19th - mainly mild option despite the Op

now look at the 18z GFS ensembles for the 19th. Yep they have all followed the op now. 
 

and within18 hours the divergence occurs around the 21st.  So the ensembles and op now agree for the 48 hours between th 19th and 21st. But the 21st takes us back into a level where it’s day 7-8 rather than day 6. Imo this is important regarding ops and ensembles. We need to be very careful when monitoring ops and ensembles around these timeframes because it is easy to be caught out by not looking at the exact time when divergence occurs

Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4767206

[Model Output Discussion - the cold has arrived]

9 minutes ago, chionomaniac said:

Just a little note on the GFS ensembles. This morning I suggested that the op was leading the way regarding the outcome from the 19th, when the ensembles were suggesting no return to cold

 

00z ensembles show divergence on the 19th - mainly mild option despite the Op

now look at the 18z GFS ensembles for the 19th. Yep they have all followed the op now. 
 

and within18 hours the divergence occurs around the 21st.  So the ensembles and op now agree for the 48 hours between th 19th and 21st. But the 21st takes us back into a level where it’s day 7-8 rather than day 6. Imo this is important regarding ops and ensembles. We need to be very careful when monitoring ops and ensembles around these timeframes because it is easy to be caught out by not looking at the exact time when divergence occurs

To recap in plain English, it was easy to see earlier today that from the 19th the ops on most models were ahead of the ensembles.The ensembles have now confirmed this. 
The next threshold is 22/23rd where there is no op lead now and ensembles are back in the game wrt longer term output. So we need to be more open minded from this point and use the ensembles more