Stratosphere Temperature Watch 2011/2012

[chionomaniac]

Yes thanks C.

We are getting there slowly it seems,realisticaly the effects on our 500hPa pattern will likely be further on,based on the mean Zonal wind forecasts.

T240 shows the reversal down to 10hPa levels so we are getting close if that verifies.

Obviously a little too far out for current Trophospheric modelling to pick out complete vortex changes yet--apart of course from the Aluetian ridging,which i have just highlighted in the Mod.Disc.Thread.

Surely we can`t be far away from some consistently cold charts showing in the FI frames at least you would have thought.

I am sure that they are not too far away Phil.

Just checked for consistency from the GFS and picked out the T+240 10 hPa temperature chart.

The temperature profile here has a broken vortex written all over it. Let's hope it is there tomorrow!

[kold weather]

CC, what is interesting is the GFS keeps on developing a stronger polar vortex again from say 240hrs onwards, doesn't make a huge amount of sense given the 2nd round of warming forecasted to begin and the other factors going on. I could understand the 18z GFS yesterday which just had us sat in the wrong area but with decent heights in the Arctic, but the latest GFS run keeps heights low pretty much throughout bar a brief flirt with it around 300hrs out, so what gives?

[bluearmy]

CC, what is interesting is the GFS keeps on developing a stronger polar vortex again from say 240hrs onwards, doesn't make a huge amount of sense given the 2nd round of warming forecasted to begin and the other factors going on. I could understand the 18z GFS yesterday which just had us sat in the wrong area but with decent heights in the Arctic, but the latest GFS run keeps heights low pretty much throughout bar a brief flirt with it around 300hrs out, so what gives?

this has been my take on the extended gefs (normal and parallel) for the past few days Kold. looking at the strat forecasts, i can only assume that a) the resolution of the ncep models post T192 is insufficient to cope with the developing -AO (surely not) or the ncep models are not taking upper strat profile forecasts into their output (again, surely not). would be nice if someone who has access to the extended ecm ens could let us know what these higher res ens runs are doing with the polar profile post t300.

Edited January 5, 2012 by bluearmy

[chionomaniac]

this has been my take on the extended gefs (normal and parallel) for the past few days Kold. looking at the strat forecasts, i can only assume that a) the resolution of the ncep models post T192 is insufficient to cope with the developing -AO (surely not) or the ncep models are not taking upper strat profile forecasts into their output (again, surely not). would be nice if someone who has access to the extended ecm ens could let us know what these higher res ens runs are doing with the polar profile post t300.

I don't think that the strength of the mean zonal winds has dropped significantly yet to allow a tropospheric change in the models. So with this in mind what we see so far looks accurate enough.

The drop is only showing on the ECM from day 7 onwards and not on the GFS output yet. And remember that the mean zonal mean wind figure may be slightly misleading because the vortex may be as strong as before, but just not as centrally placed. This would mean that the mean zonal mean winds at 60N show as reduced when in fact the vortex is still as strong but displaced from the pole.

[BrickFielder]

Well it is really not the kind of stratospheric warming you would really want. Warmings tend to take a number of courses depending on the orriginal source of the disturbance that caused the upward propagating wave that disturbs the vortex. These are either a displaced vortex, a split vortex or break down of the vortex. Here we appear to have a displaced vortex and at the upper most level it is displaced towards the UK and Scandinavia.

When we look at the vorticity charts for the lowest level modelled in the stratosphere we can see why it is not that good for snow lovers, since typically low pressure at ground level tends to congregate around the polar vortex at upper levels. At 8 days out the suggestion here would be high pressure towards southern england and low pressure systems skimming Scotland. That is actually a much more settled period really than we have now.

So how does that compare to the ECM Deterministic forecasts. Well its not far off.

A couple of days further out and things change a little and we get more of a ridge in the Atlantic and perhaps the hint of a northerly.

The trouble is having seen these types of model forecasts before low atmosphere dynamics will act against the upper level forcing to mute the signal. Thats why I think the ECM deterministic forecast probably has the picture right. In terms of weather this is probably a return to more unsetlled weather.

Looking further out you have to take into account that this displacement of the vortex has caused a fairly strong weather pattern with quite stormy weather towards the UK. This in itself is a disturbance which might cause an upward propagating wave which will disturb the vortex again in a little over a months time. My guess is that providing the wave does propagate (here conditions are not that ideal) then this type of disturbance (north atlantic based) would cause probably a split in the vortex. Again a guess would suggest that part of the vortex would be towards the UK intially, but would slowly move. If this comes of and its a big if then you might expect alternate cold and wet/stormy weeks through February.

As ever its just guess work beyond about 5 days out.

Edited January 5, 2012 by BrickFielder

[phil nw.]

Thanks Brick for your anaylsis,i wondered where you were all this time.Good to see you posting.

I must admit i am still gaining some understanding on the different types of warmings and their effect,if any,on our weather patterns.

However what you suggest about this type of warming leading to a displacement rather that a split is what i am been thinking for a while,indeed the GFS in particular seems to model this solution on it`s 006z run.

This would seem to suggest this Atlantic pattern may hang around a while yet,if the vortex get`s pushed this way,with the Alaskan heights ridgiing into the Arctic.

Edited January 5, 2012 by phil n.warks.

[chionomaniac]

Thanks for the analysis BF. It is always good to have your input.

If we were to choose a stratospheric disturbance a remote wave breaking displacement wouldn't be top of the list. However, I do believe that if we can see a total disintergration of the vortex then the longer term chances of obtaining cold may improve. There is still a lot of uncertainty in the lower stratosphere after around 7 days.

[BrickFielder]

The potential cross polar air flow coming up might be interesting from a cold air displacement point of view. My guess would be that this could spill cold air into some new areas, super charging the jetstream in places. The US comes to mind.

[nick sussex]

I'm not sure if you have this Chiono but it's incredibly interesting regarding research into the 2009/2010 winter in relation to the stratosphere:

http://www.atmos-che...-32535-2011.pdf

Theres alot there regarding the ECM and the EPS members.

The full link includes some other supplements to that research:

http://www.atmos-che...32535-2011.html

I see Brickfielders back, maybe you can also try and decipher this! Alot about wavebreaking and the increased model variability associated with it. It's not my forte especially when they include all those awful equations!

Edited January 5, 2012 by nick sussex

[kold weather]

while,indeed the GFS in particular seems to model this solution on it`s 006z run.

The problem with the 06z GFS IMO is it really doesn't take the AO negative for long at all, it seems like it briefly flirts with it then decides to power up the PV again and that seems to be going rather against the general idea you'd expect given all this warming going on aloft.

Now of course getting higher heights and pressure over the Arctic is far from the be all and end all but I'd like to see a GFS operational run actually go along with the ensembles and the ECM and actually do something other then a brief fling with a weak -ve AO...looks like our route to cold is being complicated thanks to the nature of the PV and where it is currently placed and forecasted to be.

[phil nw.]

The problem with the 06z GFS IMO is it really doesn't take the AO negative for long at all, it seems like it briefly flirts with it then decides to power up the PV again and that seems to be going rather against the general idea you'd expect given all this warming going on aloft.

Now of course getting higher heights and pressure over the Arctic is far from the be all and end all but I'd like to see a GFS operational run actually go along with the ensembles and the ECM and actually do something other then a brief fling with a weak -ve AO...looks like our route to cold is being complicated thanks to the nature of the PV and where it is currently placed and forecasted to be.

Yes it`s tricky to know why some Op runs go against the background trend.However the displaced vortex over our side of the Pole has been modelled quite a few times Kold.The only explanation can be that the warming is not into sufficiently low levels in the timeframe the trophospheric models are modelling-hence my views above.particularly p749.

If indeed if we are not forecasted to get a split then the milder GFS maybe on to something i suppose.

The trouble is we cant be sure how the weakened vortex will react-hence the variable modelling.

Edited January 5, 2012 by phil n.warks.

[BrickFielder]

Nick

Interesting report but I have only scanned it quickly. Some things I took from the report were :

If we accept the given threshold of the horizontal divergence as indicator of mountain waves, Greenland, northern Scandinavia, Iceland, and Novaya Zemlya can be identified as the most active locations for stratospheric mountain waves during the 2009–2010 winter.

and

It was shown that the magnitude of the divergence is directly proportional to the temperature anomaly in a limited area surrounding the resolved mountain waves.

This suggests to me that strong mountain waves associated with low pressure systems crossing mountains might confirm the idea that stratospheric warmings have their origins in tropospheric anomalous weather conditions, with the north atlantic being a key area.

As for a total disintegration of the vortex in the short term, then this is possible and certainly I would expect wave breaking across some of the regions mentioned in the article Nick highlighted. For evidence I think I would be looking for a split vortex at the very highest level in the stratosphere which is not really there in the forecasts yet. Even then I think it might take a week or so to work down to lower levels and affect our weather. Some interesting possibilities though.

[Paul]

Good to see you about BF

Thought people may be interested in the latest from Joe B on Twitter - he likes a ramp, but still...

10mb warming on European over the pole by 360 hrs reaches 50C!!!! This is a huge event and will have N hemisphere cold implications

[kold weather]

To be fair the GFS also shows warming at 10mbs around the same time, so both models do go for a second warming event. I've got to admit I'd be surprised if between the two of them the PV still keeps itself together without either becoming severely displaced (which in itself may open up cold oppertunties for somewhere) or spliting and weakening in the process. Whether or not the combined effect will eventually allow a full blown SSW or not.

[chionomaniac]

I'm not sure if you have this Chiono but it's incredibly interesting regarding research into the 2009/2010 winter in relation to the stratosphere:

http://www.atmos-che...-32535-2011.pdf

Theres alot there regarding the ECM and the EPS members.

The full link includes some other supplements to that research:

http://www.atmos-che...32535-2011.html

I see Brickfielders back, maybe you can also try and decipher this! Alot about wavebreaking and the increased model variability associated with it. It's not my forte especially when they include all those awful equations!

I have only just glanced through, Nick - but what I do find interesting is that the article discusses a lot of what was discussed on here at the time. Certainly interesting about the local wave breaking causing the split vortex and as BF points out that was very much associated with the Greenland area.

[Isolated Frost]

Just a little look at what the ECM predicted at 30hpa 9 days ago.

This is what happened.

Very good verification.. the only marginal difference is the high, with the +216 predicting lower heights and slightly cooler temps. The flow was almost perfect. I'd say it gives a lot of confidence for those forecasting using the tool.

[cooling climate]

Personally and this could be just wishfull thinking but I can see

no negatives in this major warming thats being forcast. I would

expect to see a very negative - AO and then -NAO develope

from this. Also looking at the height profiles from 10 hpa down

through 100 hpa I'm inclined to believe a cold pattern will develope

within the 10 to 15 day range.

The effects of the SSW ( if there is one) should be seen throughout

the stratosphere and troposphere for several weeks to come,

whether this means prolonged cold for the UK and Europe or polar

(Arctic) incursions from time to time depending on other teleconnections

is far to early to say but I really like what I am seeing at the moment.

My money is on a stonking easterly setting up within the next 3 to 5

weeks with a portion of the vortex trapped over central Europe.

Not a lot to ask for is it.

[weatherjunkie]

Wave 1 is expected to increase height amplitude and temperature amplitude congruent with the expected warming. Very nice heat flux from wave 1 between 5 and 10 hPa and even wave 2 by 240 indicating it wants to get going a bit. Pretty solid momentum flux as well by day 10 from wave 1 but this occurs at the top of the stratosphere. Very strong momentum flux from wave 2 by 240 in the Euro but again it as at the top of the stratosphere.

Looking at some forecasts, I expect to see IO convection increase at a pretty good amount around the 25th of January, perhaps setting off another Asian MT event to cap the month off and give the PV one more blow heading into February. This is the hope that I have for February in giving us the high latitude blocking that we all seek. As of now the warming will help but I'm sure most can't shake the feeling that we'll need 1 more warm push to set us free.

[fromey]

good evening all, never posted in here before because its way over my head but i have seen on twitter that joe b has posted this below

10mb warming on European over the pole by 360 hrs reaches 50C!!!! This is a huge event and will have N hemisphere cold implications.

can someone explain please.

cheers

fromey

[snowball]

10mb warming on European over the pole by 360 hrs reaches 50C!!!! This is a huge event and will have N hemisphere cold implications.

At 360 hrs... Does Joe B. actually know the value of these charts?

Edited January 5, 2012 by snowball

[weatherjunkie]

At 360 hrs... Does Joe B. actually know the value of these charts?

I believe what he was trying to get across was that the ECMWF was indicating a warming of 50C, not that the actual temperature reaches 50C.

JB along with quite a few meteorologists in the US are having a rough time with their winter forecasts. JB in particular is having one of his worst seasons that I can recall. He has made forecasts and then has came out with new forecasts only to rescind them week or so later. He generally does decent in the long range (1 month +) but he's a bit off his game as of late.

[sebastiaan1973]

These two charts are more or less the same as yesterdays. At 1 hpa we see on the longer term even reverse zonal winds. And a reducting at 30hpa from almost 40 now, till somewhat below 20 in the end.

At the 30hpa there is a big rising from around -80c to -50c.

[chionomaniac]

Yes, no major changes in the ECM forecasts today.

I have been thinking more about BF's post from yesterday and about how different types of wavebreaking events cause different types of tropospheric feedback.

Without doubt the best type of wave break that we will see is a local (central) wave break from the troposphere into the stratosphere centered around the Greenland area - as seen in 2009/2010 winter. This doesnt normally lead to a SSW but can lead to a spell of disturbed vortex and blocking.

The type of wave breaking event we are seeing now is from remote waves circling the edge of the polar vortex before rebounding back down towards the troposphere. This type of wave breaking is less favourable and less guaranteed to produce tropospheric effects than local wave breaking.

Thie remote type of wave break can cause a SSW or just disturb the vortex. So far we are seeing a mayor disturbance of the vortex but no complete collapse of the vortex in the middle stratosphere. The disturbance seen so far, is in the form of a displacement of the vortex towards Eurasia - however, the closer we get to the troposphere, the less pronounced this displacement becomes, and the tropospheric teleconnective influences and residual vortex strength of the tropospheric vortex override this signal somewhat. That is why we are yet to see any major blocking signals in the tropospheric output as of yet.

So far the forecasts suggest a displacement of the vortex (which may lead to pronounced negative mean zonal winds) but no complete disintergration of the vortex. Whereas the warming is good and will eventually filter through to the surface and perhaps allow local wave breaking, it is a far cry from having the complete disintergration of the vortex. I suspect that it is the complete disintergration of the vortex that we will need this winter to override the tropospheric polar vortex and La nina signal.

[johnholmes]

thanks once more chio for that post reacting to the one from Brick.

It is simple to understand and may well give the most likely explanation of why the bottom of the atmosphere seems reluctant to take on board what is happening at the top-putting it in simple layman terms!

[Don]

So, after the recent optimism on here, things are not looking so good with the stratosphere potential. It just seems that unlike the last few years things just aren't going our way this Winter!