1227 replies to this topic

[Catacol_Highlander]

Forgive my very long term inspired question, but if I understand GP correctly he felt as far back as October that he had a sense of the winter to come. Has anyone ever taken a domino approach to this? In other words if the Oct wave and following winter gives rise to the probability (if GP is proven correct [again] ) of a major strat warming in March on the back of another wave then how far down the line can we go? What does this suggest in terms of pattern for the summer, and is it possible even then to give a call on the following autumn and winter?

A daft question I expect... but there must be grogs out there with more time and expertise than I have got who have looked at this. How close are experts to being able to give a 12 month approximate forecast, or do the variables just get too complex to deal with?

Edited by Catacol_Highlander, 18 February 2012 - 17:57 .

[phil n.warks.]

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.

[Mr_Data]

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

[492]

Mr_Data, on 21 February 2012 - 10:41 , said:

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]

chionomaniac, on 22 February 2012 - 09:15 , said:

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]

chionomaniac, on 22 February 2012 - 09:15 , said:

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]

damianslaw, on 22 February 2012 - 22:10 , said:

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?

[THE EYE IN THE SKY]

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 by THE EYE IN THE SKY, 23 February 2012 - 19:38 .

[CreweCold]

Cloud 10, on 23 February 2012 - 19:11 , said:

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

ecmwfzm_u_f240.gif ECH1-240 (1).gif

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.

[Mr_Data]

chionomaniac, on 22 February 2012 - 09:15 , said:

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-...st=f240&lng=eng

http://wekuw.met.fu-...0&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]

BLAST FROM THE PAST, on 26 February 2012 - 10:51 , said:

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]

cooling climate, on 26 February 2012 - 16:19 , said:

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 by BLAST FROM THE PAST, 26 February 2012 - 23:47 .

[chionomaniac]

Mr_Data, on 25 February 2012 - 06:43 , said:

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...t/ann_data.html

[Don]

chionomaniac, on 28 February 2012 - 09:54 , said:

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]

chionomaniac, on 28 February 2012 - 09:54 , said:

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-...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