Stratosphere Temperature Watch 2011/2012

[TobyT]

Same here, I was sceptical at first but this winter this thread has been fascinating. Just wish I could get my head around some of the science involved.

This sums up my sentiment, Thanks to all who post on here, its such a fascinating subject and I like others are learning all the time.Keep up the good work.

[chionomaniac]

We are currently in the middle of a forecast period with the upper to mid stratosphere undertaking a remarkable warming up when we compare to early winter.

I have to say that I have kept quiet on the model thread recently, as I have found the daily difference of stratospheric modeling inconsistent with being able to give a reasoned tropospheric forecast.

Overall the picture is very promising but when analysing in more detail there are areas of the forecast that could be better - but there is still change for that.

The GFS gives an easier, more straightforward forecast to explain. Here we see the forecast upper warming completely reverse the vortex at the top of the stratosphere (1hPa).

ECM close to agreement here and mean zonal mean wind reversal is forecast on both.

Moving down the stratosphere the forecast displacement seen on the vortex differs. At 10 hPa the ECM suggests that the vortex is trying to reclaim pole position - whereas the GFS is holding the vortex at bay - both suggest further warming

I think the bif=g difference here may be due to different modelling of the E-P flux - suspect that the GFS forecast (if we could see it ) is less equatorwards than the ECM and that could be critical for downwards polar propagation.

As a result the forecast warming at 30 hPa (GFS) looks the most promising that we have seen yet and more central than the ECM.

So looking towards the troposphere, I feel that there is very little to be gained looking further than 6-8 days ahead.

If one scrolls down the folowing link it is possible to see a section of the vortex become sectioned east of Scandinavia and head south before weakening.

http://wekuw.met.fu-...ast=all&lng=eng

It leaves an opening in this process for height rises to develop over Scandinavia from days 6-7 and that is what is being modeled. I suspect how far south this segment of vortex is critical - the further south it reaches the better chance of tropospheric undercutting.

GFS is similar but with differences in keeping a large segment of vortex over the Canadian Arctic. Promising as the weakend vortex has split allowing those rare Svalbard height rises.

I now feel that a great opportunity to get winter started is coming into a closer timeframe and hopefully patience will be rewarded.

c

Ps just seen the positive feedback. Cheers all.

Edited January 11, 2012 by chionomaniac

[Yorkshiresnows]

Indeed which is why in my opinion this is the best thread on the forum. Last year I was sceptical about the impacts of the stratosphere but CH was right this is because of my lack of knowledge on this subject. Im still struggling to understand this subject but thanks to CH and others im learning all the time.

Totally Agree. Very interesting, informative and exciting.

Please keep up the great work CC.

Y.S

[Glacier Point]

Just scrolling through ECM and GFS forecasts 10hPa through 70hPa does appear to suggest some downwelling of the warming currently taking place. I think the remants of our first warming wave are still around 100hPa and this second wave appears to catch up in the extended timeframe. From around day 10 the 30hPa layers and below seem to take on a dramatic shift with the vortex being squeezed into a sausage shape aligned across the Pole. Definately something going on there.

GFS continues to toy with this idea of a third warming although tendency of late has been to deflect this away from the pole somewhat.

With angular momentum likely to slide (a good thing for cold tropospherically), we aren't likely to see any significant mountain torques in the next few weeks until early Feb when I suspect a big MJO wave passing through the Indian Ocean will trigger off another round of warmings in the stratosphere. This is only speculation, but I suspect a bit of cooling at the top layer wouldn't be a bad thing in helping along the warming lower down.

Edited January 11, 2012 by Glacier Point

[BrickFielder]

I expect forecast to be a bit tricky in the 8 to 10 day range as the displacement of the stratospheric vortex might or might not end. Perhaps I can show in charts what I mean about the end of the displacement.

Notice how in this chart the blue low area is centered towards the UK. Now a couple of days later the forecast chart looks like this.

The blue low area is shifting back towards the pole, or perhaps splitting. Not quite sure whether this evolution is right or whether we have a different kind of warming. The following chart suggest perhaps a split at the lowest level.

Notice how the warmer air at the lowest level of the straophere on this chart is making its way round towards the UK from the US. That to me suggests a higher risk of high pressure in the atlantic and towards the UK. The following stratosphere vorticity chart out at tend days suggests a negative AO.

So interpretting this and putting any sort of confidence on things is difficult. Because of the potential transition I would give a low confidence on my thougths which are :

Perhaps ironically the end of the stratospheric warming is giving us a chance of colder weather. Because the colder weather is not really stratospheric warming induced the chance of sustained blocking is limited. My best guess is that we will get a chance at some northerly weather followed by an easterly period. At this point without further changes to the stratosphere I cannot see the cold spell lasting more than a week.

So do we get another warming or not and here I am trending towards saying Yes based on the fact that we should have had some wave breaking over Greenland recently. Charts perhaps give hints but its too early to tell.

Still some variation on Windy and mostly wet will be nice however long it lasts (probably going to regret saying that, I usually do). The old Maxim that whatever the east coast of the US gets, we get soon after might actually hold true for once in the 8 -16 day range, so perhaps worth watching their weather for once. Beyond that I would be guessing, but I think another cold spell in February is likely.

[Isolated Frost]

I would like to say thanks for that BF.. I had a check round the archives and you have some really good posts so it's nice to see you back. Good use of the ECM strat charts as well.. I agree re the end of strat warming.

Wave breaking over greenland is indeed crucial and that could really decide the tropospheric outcome of the upcoming february.

[chionomaniac]

I just don't trust the ECM 8-10 day forecasts. The T+240 chart, that looks like a scream mask, looks to send the vortex back to a more central position too quickly and I suspect it may be because of the difficulties in modeling a vortex under strain at this point.

Will be interesting to see tomorrows update.

[cooling climate]

We are currently in the middle of a forecast period with the upper to mid stratosphere undertaking a remarkable warming up when we compare to early winter.

I have to say that I have kept quiet on the model thread recently, as I have found the daily difference of stratospheric modeling inconsistent with being able to give a reasoned tropospheric forecast.

Overall the picture is very promising but when analysing in more detail there are areas of the forecast that could be better - but there is still change for that.

The GFS gives an easier, more straightforward forecast to explain. Here we see the forecast upper warming completely reverse the vortex at the top of the stratosphere (1hPa).

ECM close to agreement here and mean zonal mean wind reversal is forecast on both.

Moving down the stratosphere the forecast displacement seen on the vortex differs. At 10 hPa the ECM suggests that the vortex is trying to reclaim pole position - whereas the GFS is holding the vortex at bay - both suggest further warming

I think the bif=g difference here may be due to different modelling of the E-P flux - suspect that the GFS forecast (if we could see it ) is less equatorwards than the ECM and that could be critical for downwards polar propagation.

As a result the forecast warming at 30 hPa (GFS) looks the most promising that we have seen yet and more central than the ECM.

So looking towards the troposphere, I feel that there is very little to be gained looking further than 6-8 days ahead.

If one scrolls down the folowing link it is possible to see a section of the vortex become sectioned east of Scandinavia and head south before weakening.

http://wekuw.met.fu-...ast=all&lng=eng

It leaves an opening in this process for height rises to develop over Scandinavia from days 6-7 and that is what is being modeled. I suspect how far south this segment of vortex is critical - the further south it reaches the better chance of tropospheric undercutting.

GFS is similar but with differences in keeping a large segment of vortex over the Canadian Arctic. Promising as the weakend vortex has split allowing those rare Svalbard height rises.

I now feel that a great opportunity to get winter started is coming into a closer timeframe and hopefully patience will be rewarded.

c

Ps just seen the positive feedback. Cheers all.

The heights that we are seeing on the synoptic charts that are building across the Arctic on the eastern side from

the bering sea area are surely a response to the warmings we have and are seeing. I know lower down in the

stratosphere they show up as lower pressure but maybe as they down well from 10 and 30 hpa into the

tropopause they are being displaced further west.

Edited January 11, 2012 by cooling climate

[chionomaniac]

The heights that we are seeing on the synoptic charts that are building across the Arctic on the eastern side from

the bering sea area are surely a response to the warmings we have and are seeing. I know lower down in the

stratosphere they show up as lower pressure but maybe as they down well from 10 and 30 hpa into the

tropopause they are being displaced further west.

I suspect that they are - the feedback from before the New Year. It was always going to be a case of when the ball started rolling it would carry on gathering momentum.

Edited January 11, 2012 by chionomaniac

[picog]

For the first time this winter, we are above the long-term average temp at the 30 hPa level.

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html

[BrickFielder]

Just scrolling through ECM and GFS forecasts 10hPa through 70hPa does appear to suggest some downwelling of the warming currently taking place. I think the remants of our first warming wave are still around 100hPa and this second wave appears to catch up in the extended timeframe. From around day 10 the 30hPa layers and below seem to take on a dramatic shift with the vortex being squeezed into a sausage shape aligned across the Pole. Definately something going on there.

GFS continues to toy with this idea of a third warming although tendency of late has been to deflect this away from the pole somewhat.

With angular momentum likely to slide (a good thing for cold tropospherically), we aren't likely to see any significant mountain torques in the next few weeks until early Feb when I suspect a big MJO wave passing through the Indian Ocean will trigger off another round of warmings in the stratosphere. This is only speculation, but I suspect a bit of cooling at the top layer wouldn't be a bad thing in helping along the warming lower down.

Hi GP.

I was definately in the camp that thought significant mountain torques due to the MJO were the main source of warmings and I am not quite so confident about that now. Rather I think it might be one source, with lesser mountain torques playing a significant part depending on their latitude. By significant mountain torques I am thinking about across Asia/Himalayas , US/Rockies and South America. By lesser mountain torques I am thinking about Greenland and Norway in which case the state of the AO may play a part and the MJO in a different way. I would be interested to here your thoughts on this ?

[lorenzo]

From a paper I found by Cohen and Jones MIT last revised in June re Tropospheric pre-cursors and Stratospheric coupling, this is an extract from the concluding remarks, might be useful?

Until recently, vortex displacements and splits have been mostly grouped together probably because, as shown by Charlton and Polvani (2007) and as we show here, following both events the tropospheric response most closely resembles a negative annular mode pattern for both events.

However, prior to both events the tropospheric forcing and the upward propagation of energy emanating from the large tropospheric waves display similarities, but also important differences in the presented analysis. A distinct tropospheric precursor is identified thirty days or even six weeks prior to the stratospheric vortex displacement event.

The precursor to a vortex displacement involves two of the three main centers of action in the Northern Hemisphere, with a strengthened Siberian high and a deepened Aleutian low.

In contrast for vortex splits, the tropospheric precursor resembles a meridional shift in the major storm tracks, more so than a strengthened center of action.

A second important distinction is in the upward anomalies of wave-driven energy.

The upward pulse in Wave Activity Flux has origins in the lower troposphere prior to the main upward pulse. However from our analysis this is more clearly seen for vortex displacements than vortex splits and therefore vortex displacements are more easily associated with boundary forcings such as snow cover and possibly even ENSO when compared with vortex splits.

[syed2878]

Hi guys i must admit i wasn't clued up or knew much about the strat. Thanks to cheo, bf and many of u guys i've learned a lot over the last few months. A question to cheo or if any of u ladies and gents. Where on the net would i be able to get mor information about the strat? I would like to read up on it and learne mor about the stratosphere. Thanks in advance.

[chionomaniac]

Hi guys i must admit i wasn't clued up or knew much about the strat. Thanks to cheo, bf and many of u guys i've learned a lot over the last few months. A question to cheo or if any of u ladies and gents. Where on the net would i be able to get mor information about the strat? I would like to read up on it and learne mor about the stratosphere. Thanks in advance.

If you have read this thread and understand it then that is a good start. I can then direct you to some papers.

[chionomaniac]

No real change this morning.

Points to note are that at 1hPa the mean zonal mean winds are forecast to reverse today.

This reversal is still not being felt at the 10 hPa level. I feel that there is almost a block towards the warming becoming intergrated at a lower level.

10 hPa

Here the stratospheric warming has warmed throughout the polar stratosphere and the centre of the vortex is not in the same area as the coldest pool. I suspect that is because the cold pool is still intact below 10 hPa and to some extent this is still driving the vortex below not allowing the upper reversal down until this area has warmed sufficiently.

20 hPa

The current warming will not be affecting the troposphere for a little while yet. The drip feed is still occurring slowly, but surely changing the composition of the tropospheric vortex.

[sebastiaan1973]

Well, at 120h a new wave arrives at 10hpa. Fading away slowly in 10 days time.

Edited January 12, 2012 by sebastiaan1973

[Paul]

For those who like the follow the strat temps, we've added a few new charts to our GFS viewers today:

For our extra subscribers we have stratospheric temperatures at 10hpa, 30hpa and 100hpa:

http://www.netweather.tv/secure/cgi-bin/premium.pl?action=gfs;sess=

For those who don't subscribe we also have the 30hpa temperatures in the datacentre:

http://www.netweather.tv/index.cgi?action=nwdc;sess=

Following along later today or tommorrow we have a tutorial about the stratosphere and it's affects.

[chionomaniac]

Cheers Paul.

It's great to have the 10 hPa and 30 hPa side by side as the run progresses and watch the differences between the two levels.

Edited January 12, 2012 by chionomaniac

[lorenzo]

Great to watch in animation form, particularly the very latter stages of that run at 30Hpa level !! A good addition, look forward to the guide coming out.

[Isolated Frost]

Wow- a massive edition for netweather extra, easily the largest wealth of data around now, fantastic!

[syed2878]

Hey cheo if u can email me the links to those papers or put them on here. Thanks.

[phil nw.]

No real change this morning.

Points to note are that at 1hPa the mean zonal mean winds are forecast to reverse today.

This reversal is still not being felt at the 10 hPa level. I feel that there is almost a block towards the warming becoming intergrated at a lower level.

10 hPa

Here the stratospheric warming has warmed throughout the polar stratosphere and the centre of the vortex is not in the same area as the coldest pool. I suspect that is because the cold pool is still intact below 10 hPa and to some extent this is still driving the vortex below not allowing the upper reversal down until this area has warmed sufficiently.

20 hPa

The current warming will not be affecting the troposphere for a little while yet. The drip feed is still occurring slowly, but surely changing the composition of the tropospheric vortex.

Re.The warmings not propogating to the lower levels Ed.

I just had a glance through some of the other ECM data and what i see underlines this.

The first 3 images show the temperatures at 3 timepoints.

Some warming down to 30hPa at T120 but no further-- with signs of cooling again at T240hrs.

This is reflected in the mean zonal winds forecasts here.

correlating well with the temperature forecasts.Winds slowing in the midterm T120 in response to some warming to mid-levels but again on the increase at T240.

On the face of it an argument can be made for -AO not holding for too long unless further warmings come along to reinforce this.

What we can see in the shorter term is the 100hPa forecasting matching to the trophospheric outlook,ie.Scandi. troughing,Vortex moving from Greenland to Canada with ridging in the Atlantic.

The unknown is how long this trend will hold without further warmings at lower levels.

Edited January 12, 2012 by phil n.warks.

[Partholon]

So what you're really saying is it's beginning to look fairly bleak now for sustained blocking. If there is no further warming the vortex will probably quickly reorgainse itself and move back over Greenland. One positive is the CFS temperature chart for February, but those can change frequently.

[phil nw.]

So what you're really saying is it's beginning to look fairly bleak now for sustained blocking. If there is no further warming the vortex will probably quickly reorgainse itself and move back over Greenland. One positive is the CFS temperature chart for February, but those can change frequently.

Looking out 10days,as far as the ECM data goes,the vortex is forecasted to be a little stronger wrt the zonal wind speeds so in time that would work against high latitude blocking maintaining.

Maybe Chiono can add his imput when he has time as this is only my reading of it and he may well have another view

I think at the moment the warmings we have had,although at the top,have weakened the vortex.

There`s no doubt about that so there is a window now and this can be seen by trophospheric 500hPa modelling the way the PV is being pulled about and partly split.

We can only wait and see when the next warming comes and for cold lovers ,the sooner the better,because of time lagging.

Edited January 12, 2012 by phil n.warks.

[geoffw]

so basically cooler from time to time but deinately no cold! i thought there was a high chance of a large SSW leading to a below average feb?