Stratosphere Temperature Watch 2011/2012

[phil nw.]

I just looked at the time series of Strato.Temps. at the different levels and it`s clear from these that the Warmings we had around late December and in January were limited to the top and mid-levels.

The mid-January warming propagated down the furthest and was likely the trigger for enough of a vortex disruption to give us that Siberian block for the south and east of the UK in early February.

Much of the Winter though as can be seen was dominated by a colder than normal Stratosphere and indeed it`s cooled again in February.

I would just like to add that the link between the Stratosphereic state and the Trophospheric outputs are clearly there,although we have to take into account the time lags that can be involved.

Thanks Chiono for all the information in this thread and i am sure more members will follow this with interest and continue to gain a better understanding as time goes on.

[Weather-history]

I think the question is now when will the final warming happen?

[492]

I think the question is now when will the final warming happen?

According to GFS 10hpa charts a warming started on the 18 February and is predicted to continue for a couple of weeks. It does not look as strong as the January warming but is nevertheless a warming. What effect this might have on March temperatures remains to be seen. I believe that It is thought that the warming in late December and early January contributed to the anomalous ridge over northern Russia in late January and during the first half of February that led to the extreme cold over Europe. The synoptic pattern during this time was highly unusual with high cells of 1060 hpa moving westwards at around 60 Deg north whilst maintaining their central pressure over a two week period. Was this extreme setup caused by the stratospheric warming or was it only part of the jig saw. The synoptic setup we have just experienced can only have occurred a few times in the last one hundred years. Winds from Siberia do not normally reach the UK but this year they actually did. Are we actually witnessing a more extreme climatic period and is the Stratophere behaving normally.

[chionomaniac]

There are certainly signs of another upper based stratospheric warming projected at the 1hPa level. I do not expect this at present to be anything like the January warming, but yet again it does seem to be linked to an increase in wave 1 activity - a feature of this winter.

I do suspect that the timing will be right regarding another cold spell from mid to late March if this wave activity continues to grow.

Further down the stratosphere we are still seeing weaker mean zonal winds but this is being displayed with a regular but weaker vortex. Everything we see during the next period is unlikely to have too much influence from a northern wind vector.

[Don]

I do suspect that the timing will be right regarding another cold spell from mid to late March if this wave activity continues to grow.

So it sounds like the second half of March could be similar that of 2008?

[damianslaw]

There are certainly signs of another upper based stratospheric warming projected at the 1hPa level. I do not expect this at present to be anything like the January warming, but yet again it does seem to be linked to an increase in wave 1 activity - a feature of this winter.

I do suspect that the timing will be right regarding another cold spell from mid to late March if this wave activity continues to grow.

Further down the stratosphere we are still seeing weaker mean zonal winds but this is being displayed with a regular but weaker vortex. Everything we see during the next period is unlikely to have too much influence from a northern wind vector.

What is causing the PV to remain stuck to eastern greenland like glue for so long and also the positive NAO for so long - surely things should start changing soon.. no doubt just in time to ruin another summer!

[chionomaniac]

What is causing the PV to remain stuck to eastern greenland like glue for so long and also the positive NAO for so long - surely things should start changing soon.. no doubt just in time to ruin another summer!

Prior to the stratospheric warming in January the polar vortex was strong and centrally placed.

The wave number 1 activity set off off a displacement of the vortex in January, however, the vortex was displaced towards the Atlantic sector and this has remained the case, more or less, since then. I think that this has influenced the fact that Greenland height rises have failed to establish. Some may say that this is down to luck but I believe that we are just not able to predict this scenario yet. The strength of the stratospheric vortex may be initially linked to the lack of ozone but the breaking of the vortex is linked to how the troposphere interacts with stratosphere through mountain torques and wave breaking events.

Conditions were ripe for wave breaking to occur and disrupt the stratosphere this January and it did. So we have a situation where we expected this to happen but will still find the exact tropospheric repercussions of this difficult to forecast.

[Cloud 10]

Speaking of the vortex,could this be the start of its demise?

[TEITS]

Well these say it all for this winter.

Still something I just don't understand though. I understand that sometimes a split in the PV can be unfavourable for blocking for the UK. However what I confuses me is how can have we have such promising Stratospheric forecasts i.e the posts in this thread on Feb 4th which then resulted in the AO returning to positive values only 10 days later and which has remained positive for the rest of the month?

Edited February 23, 2012 by THE EYE IN THE SKY

[Cheshire Freeze]

Speaking of the vortex,could this be the start of its demise?

Yes, I believe it's the beginning of the end

[damianslaw]

Doesn't the PV usually weaken in March regardless of the strat.. and northern blocking is much more likely in spring than in winter. It seems we were unlucky this Feb - the way the strat has behaved this Feb reminds me of Feb 09 when it promised to deliver cold right through to the end of the month, but alas conditions flipped to bring anamolous mild for the second half of the month.

[Weather-history]

There are certainly signs of another upper based stratospheric warming projected at the 1hPa level.

It is very noticeable on the ECM charts

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=1&forecast=f240&lng=eng

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=f240&var=t&lng=eng

[BLAST FROM THE PAST]

I agree it wasn't anything to do with luck, the position of the displaced vortex and the positve AO was predisposed. RJS foresaw this in his LRF and method and I think there is a lot of room here for collaberation between teleconnection 'experts' and RJS to work together or at very least touch base.

BFTP

[cooling climate]

I agree it wasn't anything to do with luck, the position of the displaced vortex and the positve AO was predisposed. RJS foresaw this in his LRF and method and I think there is a lot of room here for collaberation between teleconnection 'experts' and RJS to work together or at very least touch base.

BFTP

He had a mediocre winter long range forcast and completely missed the ball as far

as February forcast in the US. I also don't recall seeing him forcast a positive AO

for february either. None of this belongs in this thread anyhow.

[BLAST FROM THE PAST]

He had a mediocre winter long range forcast and completely missed the ball as far

as February forcast in the US. I also don't recall seeing him forcast a positive AO

for february either. None of this belongs in this thread anyhow.

Well don't post it then

BFTP

Edited February 26, 2012 by BLAST FROM THE PAST

[chionomaniac]

It is very noticeable on the ECM charts

http://wekuw.met.fu-...st=f240&lng=eng

http://wekuw.met.fu-...0&var=t&lng=eng

Getting back on topic, it is noticeable that during February the stratosphere has cooled dramatically following the dramatic warming in January. It is quite common to see this type of rebound in temperatures if the warming occurs early enough in the season. However the mean zonal winds which have a delayed response to the temperature profile have yet to increase above average and March could be an interesting months if they follow the temperature profile. Mad March winds anyone later in the month?

Currently the vortex is still avoiding Siberia so I expect to see some continuance of height rises towards the NE but without any extra oomph it does not look likely that these will move westwards.

c

Data for temp and wind profiles found here:

http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

[Don]

However the mean zonal winds which have a delayed response to the temperature profile have yet to increase above average and March could be an interesting months if they follow the temperature profile. Mad March winds anyone later in the month?

c

Would this mean an increasingly zonal later half of March with the only chance of cold weather coming from cold zonality?

[lorenzo]

http://acdb-ext.gsfc...t/ann_data.html

Nice Link C, I dislike the 'bashing' or 'disdain' or changes brought about by Strat profile altering. Wish folk would consider these shifts were predicted a fair few months in advance. If it ain't IMBY it hasnt happened I guess. Seriously, look at Europes spell of cold.. it was on our door step and thinking about scale, not too far away in the bigger scenario of things, the cold in Europe didnt appear by accident..

[karyo]

There is a forecast foe a significant cooling of the stratosphere: http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php

If this verify, it will bring the temperatures to much colder than average values for the time of year. Any ideas what the cause of this might be?

At least that should be good news for the Arctic ice.

Karyo

[Cheshire Freeze]

There is a forecast foe a significant cooling of the stratosphere: http://wekuw.met.fu-...ww/wdiag/ts.php

If this verify, it will bring the temperatures to much colder than average values for the time of year. Any ideas what the cause of this might be?

At least that should be good news for the Arctic ice.

Karyo

Well if your a 'poo pooer' of the thought that the Arctic will be iceless in a matter of years, I guess it would be nature beginning to attempt to redress the balance in terms of ice extent.

As for the actual reason, I have no idea.

[Cloud 10]

Things certainly warming up at the top of the stratosphere.

Still very much below normal temperatures lower down at 10hpa,and forecast to remain so.

And much the same below average story at 30hpa.

Seems to be a similar pattern to last year with a "late vortex" which seemed partly responsible

for the under-whelming summer.

[Cloud 10]

Can anyone explain this rather intense looking area of reverse zonal winds shown

on this ECM 168hrs chart?

[bluearmy]

Can anyone explain this rather intense looking area of reverse zonal winds shown

on this ECM 168hrs chart?

It does look a bit OTT but the 12z op run from yesterday did stick up an arctic high in fi and generate a -AO by day 10. i suspect the 12z from today will be rather less enthusiastic in this dept.

[Cloud 10]

It does look a bit OTT but the 12z op run from yesterday did stick up an arctic high in fi and generate a -AO by day 10. i suspect the 12z from today will be rather less enthusiastic in this dept.

ECM still going for some sort of arctic high within a fairly reliable timeframe,which should make for some

volatile model output!

[Glacier Point]

Want to try something here.

Forecasts indicate with some agreement a high amplitude and eastward propgating wave to develop in the next 15 days. Here is the ECM ensemble forecast which is representative of GFS and UKMO.

Currently very negative, these mountain torques reversing could potentially trigger remote wave breaking and disruption of the polar vortex.

So key timelines to watch for:

- MJO moving through phase 3/4 and developing high amplitude - - 1st March

- Strong positive mountain torques and rapid increase in tendency in relative angular momentum -- 1st - 10th March

- Rapid increase in high and middle stratosphere temperatures -- 12th through 22nd March

- Blocking signatures in the troposphere developing -- 22nd March through 11th April.

Update to this.

Well done ECM... correct MJO forecast as today we are in phase 3:

Forecast continues to show eastward migration towards phases 5 and 6 (as also UKMO but GFS not so keen), which should see that vital crossing between phase 3 and 4 to trigger Asian Mountain torque (suggested at around 6th - 7th March):

Mountain torques are not active at the moment, but frictional torques, which are the prelude to positive mountain torques, are well up:

Stratospheric temperature forecasts still a little outside of the range of the 'natural' timeframe, although GFS notable at 1hPa at day 10 and then 10hPa day 10 through day 15 suggesting large displacement of the vortex and warming, especially over the eastern part of the hemisphere.