Stratosphere Temperature Watch 2012/2013

[LomondSnowstorm]

What a load of rubbish. If this warming does occur, its fairly early in the season. Sorry to be to the point.

Agreed, the modelling of the strat has been pretty consistent and accurate so far with the timing not really changing at all since we started to see it coming on the horizon. Not to mention that the MJO phase isn't stuck for weeks at a time and is likely to move to a more favorable phase at some point in the next 4 weeks.

[Mark Bayley]

I think he is using reverse physcology

To be fair some of the MJO forecasts aren't exactly favourable, take the ECM for example plumping for a higher amplitude phase 3/4 as we enter Jan.

Although if one takes a look at models they will note there's not only variability, but also most, as BA notes, keep fairly low amplitude.

http://raleighwx.ame...nuaryPhase4.gif

Although this is the strat not the MJO thread. Also i fail to see where this event is being pushed back, as evidenced by my post on the previous page!

Edited December 23, 2012 by Mark Bayley

[Dorsetbred]

i think it might be better to forget the warming i really think its to late in the season.

i also feel this warming is not coming any closer and as has been noted the mjo is against us i think winter 12/13 needs to be forgotten as a so close but no cigar.

PLEASE, PLEASE, don't post this type of post in this thread and cause a degeneration as seen in the MOD thread. Thank you

[Glacier Point]

Recretos - superb post there.

So maybe we can give this some credability. Last few GFS runs have really ramped up 1 hPa values at the end of the run. 12z for reference:

Translated to the Berlin site, that would be close to going off the scale.

10 hPa warming is showing up around 7th/8th. Most effective downwellers showed a characteristic warming at the top layer of the stratosphere.

[Recretos]

WoW! Thanks everyone for a positive feedback on my GFS skill post. I really appreciate it. Its nice to see your work being accepted in the community.

To throw a comment or two on the latest runs.

We all see how things are shaping up, so I am just going to point out something interesting in the last runs, more evident in the last 12z. Something wants to sneak in through back door, to put it that way.

Basically I am talking about the actual downwelling of warmth from the top, maybe less, maybe more expected.

288h-312h, blowtorching at the top.

At 288h, we can see the main "warm core" at 3mb and some warmth around, but still no secondary warm core just yet.

In the meantime at 5mb, the area of focus is chillin for now.

Going further on, a secondary warm core starting to appear on 3mb. 7mb still chillin in that area at the time.

At 360h, finally reaches 5mb.

At 372h appearing on 7mb.

And at 384h, some clues on 10mb, but this is too much of a detail to be focusing on at this time (384h).

And the animation.

Now I don't want go give the appearance of being too hasty. It looks good and all, but I don't want to give it too much credibility for now, at least not until it becomes a consistency. It is getting a bit more defined in the last few runs, with the 12z being the most "aggressive" on this downwelling so far. Another thing worth considering is the ECMWF. It clearly showed that its not buying the super warming from GFS in the uppermost stratosphere, at least not for now.

And I think it is still too early to start speculating about possible effects on the troposphere if everything would come into fruition. Lets first get a clear picture what exactly is going to come into fruition.

Seriously though, if a warming were to happen, then how much time lag would there be in this case before we start seeing tropospheric impact?

There is certain variance from event to event, but for a general idea, you can look at this composite from Reichler&Baldwin.

And about the MJO, its in a weaker phase 3 for now, but the models are basically taking it all over the place.

Tho there is not really that much similarity between the phase 3 and the current pattern and the pattern forecasted for the near future. Maybe in some points, but the phase 3 composite is basically just a composite, so we should look at it in the same spirit we are looking at ensemble means.

In the meantime, 12z GEFS wants to bring AO above the "surface". If it really comes above in this time frame, I really hope the stratosphere slams it back down, in the whack'a mole style. (a bit of wishcasting there )

And just on a side note, it is interesting to see there was some upwelling recently in the ENSO 3.4 area.

Best regards.

Edit: GP beat me to the downwelling part.

Edited December 23, 2012 by Recretos

[chionomaniac]

How many cans of beer did that one take you Recretos?!!!!!

The main thing that I have noticed in the FI strat forecasts is that the warmings do tend to get watered down somewhat as they come into a more reliable timeframe and resolution - but also the exact positioning of the upper vortex is hard to model that far out. So we will se a trend of displacement followed by splitting for a few runs - then this will reverse back whilst the warming is maintained more or less.

At this point I am just sitting back and watching the stratosphere because at some point when the distorted vortex reaches the higher resolution we will be able to see what tropospheric affects that this may have.

[bluearmy]

The main thing that I have noticed in the FI strat forecasts is that the warmings do tend to get watered down somewhat as they come into a more reliable timeframe and resolution

i has noticed that ed but wondered if the stronger warming would be better maintained. mark made a post on the previous page showing the intensity of a strong warming being the same T348 down to T192.

[chionomaniac]

i has noticed that ed but wondered if the stronger warming would be better maintained. mark made a post on the previous page showing the intensity of a strong warming being the same T348 down to T192.

It's definitely watered down ba. That is why I posted so many charts. One forecast suggested 10 hPa temps for the 29th of over 9ºC - no where near that in reality.

I think though there is a trend for a wave 2 split following a wave 1 displacement. I also (slightly) share your concern regarding the residual vortex positioning (remember the stage will be set but will the actors perform?). I think though that it is too early to be overly concerned by this yet though.

[AWD]

Temperature at the 30hpa level on the rise again.

[Mark Bayley]

It's definitely watered down ba. That is why I posted so many charts. One forecast suggested 10 hPa temps for the 29th of over 9ºC - no where near that in reality.

I think though there is a trend for a wave 2 split following a wave 1 displacement. I also (slightly) share your concern regarding the residual vortex positioning (remember the stage will be set but will the actors perform?). I think though that it is too early to be overly concerned by this yet though.

Yes there has been some variability in intensity during the forecast period so far, although im going to keep saving charts for 31st to see how it changes. So far for those ones i've been keeping there seems to be some reasonable consistency.

For those interested you can view past models runs here

http://www.meteociel...ech=204&carte=1

Edited December 23, 2012 by Mark Bayley

[chionomaniac]

Yes there has been some variability in intensity during the forecast period so far, although im going to keep saving charts for 31st to see how it changes. So far for those ones i've been keeping there seems to be some reasonable consistency.

For those interested you can view past models runs here

http://www.meteociel...ech=204&carte=1

The 12Z probably wouldn't give a technical SSW and the vortex would reposition back over the pole if the run was to continue. In fact, I dont think that I have seen a run (haven't looked at them all) that has suggested a technical SSW yet - so I am still very cautious that we are dealing with long range forecasts. Yes, we are pretty guaranteed to see a warming, but we are no way guaranteed to see complete vortex disruption.

[bluearmy]

Yes there has been some variability in intensity during the forecast period so far, although im going to keep saving charts for 31st to see how it changes. So far for those ones i've been keeping there seems to be some reasonable consistency.

For those interested you can view past models runs here

http://www.meteociel...ech=204&carte=1

you can see past 7 days runs on 'instantweathermaps.com' to make comparisons at all levels.

[Ian Brown]

Thanks to Recretos and all the other contributors in this excellent thread, it will be interesting to see how it all plays out.

The concern is that allowing for the time lag of the various factors, the +ve NAO/AO set-up that we are seeing on the NWP will be strongly established, so whilst we could see a change in pattern it may not be enough to result in a reversal of pressure patterns.

[chionomaniac]

Thanks to Recretos and all the other contributors in this excellent thread, it will be interesting to see how it all plays out.

The concern is that allowing for the time lag of the various factors, the +ve NAO/AO set-up that we are seeing on the NWP will be strongly established, so whilst we could see a change in pattern it may not be enough to result in a reversal of pressure patterns.

Over the whole NH, I think that we will see considerably different pressure patterns - even without a technical SSW.

The difficulty, Ian, is whether or not the change of pattern will benefit our small island. Currently we have seen a few runs suggesting a displaced vortex that splits down to the troposphere. I don't think that the initial split that is forecast presently to be favourable - but with any split we do not know where the stronger vortex remnants will be positioned after that.

We know from previous work such as Cohens, that Greenland will be a favourable area for blocking if we do see a SSW.

[Robbie Garrett]

Quick question, to help with my knowledge.

What we are seeing now is not a SSW (Sudden Stratospheric Warming) which won't show up on the models, but a possible Major Warming event?

[Panayiotis]

Quick question, to help with my knowledge.

What we are seeing now is not a SSW (Sudden Stratospheric Warming) which won't show up on the models, but a possible Major Warming event?

We are not currently seeing a SSW and is forecasted to happen on the 2nd week of January (not certain and if this warming occurs it should be seen on the models) and yes we are seeing a major warming event now/happening. Edited December 24, 2012 by Panayiotis

[Recretos]

I did a correlation between the stratosphere/polar vortex dynamics and North Hemisphere snow cover a while ago, how snow cover affects the stratosphere. But since the main question at the moment is how the stratosphere is going to affect us, I decided to do some reverse correlating.

Usually we take a parameter like geopotential height for example, and we correlate it with certain indices, like ocean temperatures, wind oscillations, pressure oscillations, etc... and we apply a certain time lag to the parameter, to see how a certain index affects the parameter over time, to see how dominant it is, if at all. Main example being SST Indices like ENSO, and how and where they affect pressures rising or falling. But this time I decided to do reversed correlating, by correlating the index to a parameter. And since we are working around with the stratosphere, I applied a 1 month lag to the index, so the stratosphere activities happened up to 1 month prior to the calculation of the specific index. That should be a good time setup for SSW induced effects.

Now there are 2 main problems.

- I cannot choose specific years, meaning that I have to apply a certain time span in which the parameter and the index are correlated. The problem being, that SSW and non-SSW years get mixed up, and we get a very noisy correlation. I am sure that if I could apply specific years (at least 7 years with SSW events, because correlations of specific years or less than 3 years have no meaning), I could get a much more clear correlation and I could also make separate correlations for split and displacement events.

- I can only apply monthly lag. I cant apply like a 2 week lag. 1 month is a long period in meteorology, so I could overshoot or undershoot a correlation maximum.

With all that taken into consideration, I must say that in general, these correlations are nothing special and don't present any new ideas, besides from what has already been mentioned in here, and also by Chionomaniac a post or two ago. So despite the fact we can all read the papers (still trying to find time to do that, because I think I will soon have enough basis covered to dig into it), I sometimes like to go a step further, to "look behind the curtain".

We know from previous work such as Cohens, that Greenland will be a favourable area for blocking if we do see a SSW.

Down to the charts. I only found 2 indices that seem to have a better response to major strat. activity, more specifically polar vortex displacements. The TNA (Tropical North Atlantic) and AMM (Atlantic Meridional Mode). I think I could find more, but I would have to apply specific years.

First up is TNA. You can see how noisy the correlation is, but there is a still defined signal for a P.V. displacement. So i could say that this basically represents a positive TNA mode in general.

Now if we look how wintertime positive TNA correlates with 500mb geopotential heights.

Next up is AMM (Atlantic meridional mode) correlation. Very noisy correlation again, but the signal is there. And looking at the right image, with only Jan. presented, the displacement signal is a bit more obvious.

And how wintertime AMM correlates with 500mb heights.

Now I must point out that both TNA and AMM are indices based on surface parameters like pressure, wind or SST. They are kinda similar in a way. But the point I am trying to make here is, that I was correlating stratosphere with indices that are semi-dominated by the 500mb pattern. So basically I used these indices merely as "agents" to correlate stratosphere and 500mb pattern. I could simply correlate the stratosphere directly to a geopotential height index like NAO, but the correlation is just too noisy and overgeneralised. So I basically "filtered" and bypassed that by correlating to specific indices that respond to patterns and then re-correlated the indices and 500mb height, to see the corresponding pattern for the specific phase of the index that correlated with the displaced vortex. I hope I haven't over complicated the explanation. So basically the real picture here is, that stratosphere dynamics, which in this case translates to an SSW, affect the pattern below. And that pattern semi-affects different indices. So by looking how certain indices and patterns changed after SSW events in the satellite era, you can go back before satellite era to reconstruct patterns using this key combinations.

So now that you know all this (some already know all that ), I can show you the overall pattern resulting in respected AMM mode. Above is the positive mode and negative below. So to have a positive mode, you see what kind of a "global setup" is required, wanted or dominant for the specific mode. To filter it for you: the above correlation for displacement and positive AMM and TNA is basically a correlation between generally displaced polar vortex (probable SSW displacement) and the global setup you see in the upper part of this graphic. So I only used AMM and TNA to filter through all the general data noise.

Furthermore, we can see negative AAM (Atmospheric angular momentum) above, and positive below.

How about splits,I hear you ask?

Well, it is hard extract certain SSW mode connected indices because the correlations are made over a certain time span (1980-2012 in my case), but there is one I can show you, so you can at least see how the split signal looks like. In this case, it looks quasi-connected to TNH (Tropical/Northern Hemisphere).

The respected TNH phase translates into the 500mb pattern on the left. On the right, I added a composite of split SSW Jan/Feb. Of course there are differences between specific years, but just as the correlations are a multi year extraction, the same has to be applied to the corresponding season pattern composite. And besides that, we have here only one of many indices from which we could extract 500mb anomalies to make for more specific connections.

Problems can emerge when it comes to practicality, because it is hard to generalise specific SSW modes response based on some correlations. Every event is specific in its own way, having slightly different dynamics, different global setups that lead to different tropospheric patterns prior to SSWs, and so on.... And as I have pointed out the two problems in the start, I cant fine tune the signal for either displacement or split. A much easier way is of course to just look at past events and use reanalysis to see how it resulted. But as Chionomaniac has pointed out, Greenland seem like an "average" target, regardless if we are talking about a SSW split or displacement. And of course I was only looking for some connections between SSW and 500mb patterns, and not really how exactly the SSW makes the pattern change. I think there have been many scientific papers linked already that explain that matter, and I must admit that I cant wait to go through all of em. I tried to read some, but I thought that it would be better to get some "first hand" basics first, so it will be easier for me to assimilate the info in the papers.

We will see how this years events will turn out. The fact is that in this "age of technology", we have lots of good tools to analyse and predict these dynamics, so I think we can all learn a lot from these events, regardless if we are newcomers or if you are pros.

Cheers.

[syed2878]

excelent posts over the last cuppal of days recretos.

[lorenzo]

I think we all need to order in some Slovenian Beers ! More fantastic work Recretos. Nothing as technical from me am afraid just a couple of charts from JMA and NOAA..

First EP Flux looking a little more favourable recently and indicative of a poleward shift.

A better looking height chart at 100mb, clear ridge in play this at 240 hours.

And, of course the temperature charts which are in themselves a thing of beauty..

Within this am wondering if there is a second wave of top down warming following the first beginning at the top of the strat, another pulse of warming visible south of the US on the 1 hpa run working it's way round.

Have not reviewed these specifically for a few days but the largest sections of the atmosphere now being suitably carved up by the warming.

Leads me to wonder whether this is displace then split, looking more likely for a split also now.

In terms of where the chips fall after the warming event in terms of blocks, yes there is some luck involved and no one in this thread has said, look it is guaranteed easterly, guaranteed Northerly, guaranteed increased chances - yes. Looking at previous displace warmings of which there is a small dataset couple of things in Nino years.

1 Lowering of Pacific heights. 2 Increase in greenland heights. 3 2/3 main troughs of cold in NH.

Might have to go looking through split events also now to see what signature if any they created.. Am thinking that +ve NAO outlook on NWP is a definite red herring, it looks like a stayer but come Boxing Day FI will leave us wondering what we were actually seeing..

[masheeuk]

i think it might be better to forget the warming i really think its to late in the season.

i also feel this warming is not coming any closer and as has been noted the mjo is against us i think winter 12/13 needs to be forgotten as a so close but no cigar.

Do you by any chance live near or under a bridge. Why would you want to try and damage this discussion the same way that others here have been?

[winterof79]

I am not very good with the strat etc...but is that goodbye Mr Vortex if you run the sequence on meteociel?

http://modeles.meteo...nh-10-264.png?0

http://www.meteociel...mode=10&carte=1

[bluearmy]

very strong wave 1 coming into the top of the strat early jan whilst the activity centred around 15hpa continues throughout the upcoming 10 days.

Also some wave 2 continues to be progged and although not particularly strong, it may well be enough to split what will be left of a weaker vortex (as latter ncep output shows)

whilst the initial warming may not resut in a technical SSW, this new warming coming into the top of the strat may well cause that to happen by mid jan.

[Grimsby Snow Lover]

very strong wave 1 coming into the top of the strat early jan whilst the activity centred around 15hpa continues throughout the upcoming 10 days.

Also some wave 2 continues to be progged and although not particularly strong, it may well be enough to split what will be left of a weaker vortex (as latter ncep output shows)

whilst the initial warming may not resut in a technical SSW, this new warming coming into the top of the strat may well cause that to happen by mid jan.

Im a complete novice when it comes to the strat, what is the significance of wave 1 and wave 2? Many thanks GSL

[Cloud 10]

Steep fall in zonal wind speed forecast at the top of the stratosphere.

[lorenzo]

@GSL Both waves have their own characteristics on how they affect the Vortex.

Wave 1 - displacement Polar Vortex

Wave 2 - split Polar Vortex

Although if a warming continues apace then there may be little left to displace or split. Vortex = shredded.

Or we could achieve the outcome no one wants . Vortex = all but shredded - with just the tiniest fragment of Vortex parked above the UK stopping blocks. This kind of sums up the lottery and why we are sitting back and watching things unfold.

I think the fact that we are even examining the outcomes of the fallout and what is predicted tropospherically shows how much this thread has moved along this winter.