Stratosphere Temperature Watch 2011/2012

[Glacier Point]

The Jan 87 E,ly was a very rare set up because a segment of the PV was sat underneath the Arctic HP that was moving S. This is why the upper temps were as low as -20C in the SE!

I will add if you revisit the Nov 2010 Stratosphere thread you will note nobody predicted the extreme cold that was coming in late Nov/Dec even when it was only a couple of weeks away. Only the Met O knew what was coming!

But, during September 2010 we were identifying the potential for ridge extension in the Atlantic and by early December when this first popped onto the long range ensemble means, we were able to give it credence at a distance of 15 days out.

http://forum.netweather.tv/topic/58354-in-depth-technical-model-discussion/page__view__findpost__p__1943136

Additionally, the current strong polar vortex was discussed and forecast back in September.

http://forum.netweather.tv/topic/58354-in-depth-technical-model-discussion/page__view__findpost__p__2137480

Of interest here is this passage in relation to the importance of the QBO and upper atmopshere

"If this were the only variable at play, we would expect angular momentum to decrease and the ridge to shift back to our west. However, the sun continues to be active and the QBO has begun to show a slow evolution towards an easterly phase similar to other east QBO years under increasing solar activity. We may well be looking at the start of a 3 month period of low heights to our north.

Of particular interest here is the development of a westerly wind in the upper atmosphere between 80N and 40N. This type of wind development will aid lowering of pressure at the mid and lower layers and is likely to continue to at least the end of October, probably November (QBO analogues are interesting here in suggesting the coldest part of the winter not to be like last year, more towards February and strongish polar vortex to develop early and be centred in the Canadian Arctic)."

Take a look at this link:

http://www.geo.fu-be...pole/index.html

Very interesting table from lots of angles.

While these are running monthly averages for cold in the stratosphere, it does look as though we are entering a period of extreme stratospheric cold. GP cryptically alluded to the possibility of overspin of the vortex...

Is there a more detailed historical breakdown of weekly/daily stratospheric temps on the net? Apologies if that is a dull question - I am a lurker in a learning phase.

Is there any analogue data for what happens to temps in the stratosphere if it gets severely cold? There has to be a bounce back at some point, but if the cold is the severe is the bounce back "bouncier"? If the cold is so severe that wind speeds up there get very high, is there any data for what happens next? What is the out and out measured record for stratospheric cold?

So many questions... :-)

This is an interesting thought. If the depth of the stratospheric cold is such, then any rise could have a destabilsing effect, particularly as the warming mechanism is almost entirely chain reactionary.

[chionomaniac]

Take a look at this link:

http://www.geo.fu-be...pole/index.html

Very interesting table from lots of angles.

While these are running monthly averages for cold in the stratosphere, it does look as though we are entering a period of extreme stratospheric cold. GP cryptically alluded to the possibility of overspin of the vortex...

Is there a more detailed historical breakdown of weekly/daily stratospheric temps on the net? Apologies if that is a dull question - I am a lurker in a learning phase.

Is there any analogue data for what happens to temps in the stratosphere if it gets severely cold? There has to be a bounce back at some point, but if the cold is the severe is the bounce back "bouncier"? If the cold is so severe that wind speeds up there get very high, is there any data for what happens next? What is the out and out measured record for stratospheric cold?

So many questions... :-)

One of my favourite tables that.

There is a lot more info here:

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

The bounce back is difficult to forecast, but there are a number of factors previously discussed that suggest that this will occur.

If one looks at the stratospheric vortex over the Antarctic winter it gets a lot colder and the vortex a lot stronger with only one ever recorded SSW( and most researched!). This is because there is no interaction with land masses to affect it. So the wheels don't necessarily fall off a very fast bike without something to prompt this. It is the wave interaction that is the stick in the spokes for the Arctic winter.

[BLAST FROM THE PAST]

I think the extremity of the (or any) event would be nigh impossible to forecast.

How about extremity of blocking? Or is it that ridges and troughs are anticipated in certain locations and heights and depths etc are finer details that can only be gleaned as enter such a period?

Also interesting point made re any 'warming' bounce back.

cheers BFTP

Edited November 30, 2011 by BLAST FROM THE PAST

[chionomaniac]

How about extremity of blocking? Or is it that ridges and troughs are anticipated in certain locations and heights and depths etc are finer details that can only be gleaned as enter such a period?

cheers

BFTP

Yes, I wouldn't have been able to forecast the extremity of the blocking, but when we were in that period there was another upward vortex split that recharged the extent of the cold spell.

[TEITS]

C

with regards to TEITS comment of 2010, I think his suggestion is that the 'extremity' of the cold spell wasn't picked up on, not that there was a cold spell coming? I think that even GP had forecast heights to our NW at a latitude much lower than what happened. thats how I read it. Maybe TEITS can clarify?

BFTP

Yes thats exactly what im saying mate. My interpretation was that during Dec any cold spells would be shortlived and not severe due to N,lys via an Atlantic HP. What we experienced was completely different because the blocking over Greenland resulted in the cold spell being prolonged and severe.

[BLAST FROM THE PAST]

C

Thanks for that

TEITS

Yep thought that is what was meant, thanks

BFTP

[chionomaniac]

Yes thats exactly what im saying mate. My interpretation was that during Dec any cold spells would be shortlived and not severe due to N,lys via an Atlantic HP. What we experienced was completely different because the blocking over Greenland resulted in the cold spell being prolonged and severe.

I remember posting in the MO thread at the time suggesting just that TEITS. I remember stressing that this would not be a transitory affair due to the extent of the split up in to the stratosphere.

[UV-RAY]

Perhaps.

It seems to me that there is a small minority determined to disparage the stratospheric / tropospheric relationship rather than try to learn and understand more about it.

Not at all the subject fascinates me, though for novices like myself I sometimes find the evidence relating to cold and stratospheric warming events conflicting.

[chionomaniac]

Not at all the subject fascinates me, though for novices like myself I sometimes find the evidence relating to cold and stratospheric warming events conflicting.

Sometimes there is conflicting evidence, I agree, especially with the cold, but often, as this post from the 21st October shows, the forecast can be spot on.

It's not too early to make an educated guess regarding the first half of November when one looks at the MJO forecasts and stratospheric profile. Any change in this would have to come in very soon and the stratospheric 10 day forecasts certainly don't suggest that blocking will be significant into November ( to the north west ) and through next month. Very different to last year in that respect. To repeat, Atlantic / Iceland trough with a strengthening polar vortex through November the likely scenario presently.

This was made against a backdrop of other forecasts suggesting Autumn cold ( not GP I hasten to add).

Edited November 30, 2011 by chionomaniac

[karyo]

I logged on the netweather and saw this thread top of the list so I thought there were some news and updates! All I see is analysis and disagreements about what happened last year! lol

Anyway, the stratospheric outlook remains cold but maybe with a small warming at the 10 hpa level http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php in a few days time. If we can't get a major warming before the end of Dec/Jan then let's hope that we get some smaller warming events before then.

Karyo

[kold weather]

I think its pretty obvious really that the stratosphere has a huge role to play, I do think other factors can still over-rule it, of course the ENSO signal probably being the main one, but as long as we stick to a weak feature then we should be ok in that respect...

Its going to be interesting to see how it all plays out...frankly I'd be amazed if we don't have a SSW given just how super cold we are going, its going to be next to impossible to hold record cold for any length of time I'd imagine.

I suppose my question is it the absolute warming (IE to a certain level) that causes blocking to form or is it just the relative warming within a certain area of the Arctic that causes the whole thing to buckle so to speak.

The interesting thing I've noticed with recent winters is that actually a SSW has led to us going into slightly milder conditions, there are several winters where we've colder month either whilst the SSW is going on or just before...so that once again is the chicken and egg question. I get the feeling a SSW is far more useful when you are stuck in the mild zonal set-up rather than in winters such as 09-10, etc.

[TEITS]

I think its pretty obvious really that the stratosphere has a huge role to play, I do think other factors can still over-rule it, of course the ENSO signal probably being the main one, but as long as we stick to a weak feature then we should be ok in that respect...

I do agree the stratophere has a role to play but rather than say "factors can over-rule it" I would say its how these other factors interact with the stratosphere. This is why im generally dubious of LRF. For starters its difficult to understand all the variables but becomes a nightmare trying to figure out how these variables interact with each other.

As for last Dec and all im saying is the Met O obviously spotted a signal that nobody else did. They were continually predicting well below average temps in their forecasts even when this wasn't apparent in the model output. Make no mistake the cold spell during late Nov/Dec 2010 wasn't just incredible weather wise but synoptically extremely unusual for early winter.

[summer blizzard]

I think its pretty obvious really that the stratosphere has a huge role to play, I do think other factors can still over-rule it, of course the ENSO signal probably being the main one, but as long as we stick to a weak feature then we should be ok in that respect...

Its going to be interesting to see how it all plays out...frankly I'd be amazed if we don't have a SSW given just how super cold we are going, its going to be next to impossible to hold record cold for any length of time I'd imagine.

I suppose my question is it the absolute warming (IE to a certain level) that causes blocking to form or is it just the relative warming within a certain area of the Arctic that causes the whole thing to buckle so to speak.

The interesting thing I've noticed with recent winters is that actually a SSW has led to us going into slightly milder conditions, there are several winters where we've colder month either whilst the SSW is going on or just before...so that once again is the chicken and egg question. I get the feeling a SSW is far more useful when you are stuck in the mild zonal set-up rather than in winters such as 09-10, etc.

I think that the winters of 2009 and 2010 are highly relevant here and i will use them as examples because they both had opposite ENSO and QBO phases ongoing.

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra/t90n_30_2009_merra.pdf

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra/t90n_30_2008_merra.pdf

In regards to other phases overruling i am not so sure per say. I think what we have to remember is that we are one small island so that while we may not see anything cold from an SSW, its main effects are centered over the Arctic. We must remember that the CET>AO correlation is only 80% which means that one out of 5 occasions, we are likely to miss out.

I personally regard the QBO as far more important to stratospheric warming. I read somewhere that an SSW was several times more likely to occur with an -QBO than a +QBO. While we do know that they can work in tandom, we also know that the ENSO and QBO phases can operate independant from each other as winters 2009, 2010 and 2011 show.

Stratospheric warming is certainly not everything however i think that it is important to look at the individual event.

Taking 2009 as an example, if we look at February we see that there was a massive warming of the stratosphere with a very quick response from the AO which led to the first half of February 2009 seeing a very cold spell however we also had a very warm end to February as the stratosphere started cooling.

If we look at the winter of 2010 we see a slightly different pattern with a moderate event in November-December and another one in January-February, the key difference here is that the effects did not show until almost a month afterward in both cases and also that these events seemed to be more sustained, resulting in record low AO values. You will also note that the cool period when you apply the lack coincides very well with the mid Jan-Mid-February warmer period although the AO remained negative (just not to the same extent).

What we can draw from this is that either due to the scale of the warming or other factors, the atmosphere in 2009 was much more susceptible to stratospheric effects both in terms of warmings and coolings with quick effects while the more moderate sustained warmings in 2010 while not causing a reaction for around a month, did send the AO bonkers.

[johnholmes]

I think that the winters of 2009 and 2010 are highly relevant here and i will use them as examples because they both had opposite ENSO and QBO phases ongoing.

http://acdb-ext.gsfc..._2009_merra.pdf

http://acdb-ext.gsfc..._2008_merra.pdf

In regards to other phases overruling i am not so sure per say. I think what we have to remember is that we are one small island so that while we may not see anything cold from an SSW, its main effects are centered over the Arctic. We must remember that the CET>AO correlation is only 80% which means that one out of 5 occasions, we are likely to miss out.

I personally regard the QBO as far more important to stratospheric warming. I read somewhere that an SSW was several times more likely to occur with an -QBO than a +QBO. While we do know that they can work in tandom, we also know that the ENSO and QBO phases can operate independant from each other as winters 2009, 2010 and 2011 show.

Stratospheric warming is certainly not everything however i think that it is important to look at the individual event.

Taking 2009 as an example, if we look at February we see that there was a massive warming of the stratosphere with a very quick response from the AO which led to the first half of February 2009 seeing a very cold spell however we also had a very warm end to February as the stratosphere started cooling.

If we look at the winter of 2010 we see a slightly different pattern with a moderate event in November-December and another one in January-February, the key difference here is that the effects did not show until almost a month afterward in both cases and also that these events seemed to be more sustained, resulting in record low AO values. You will also note that the cool period when you apply the lack coincides very well with the mid Jan-Mid-February warmer period although the AO remained negative (just not to the same extent).

What we can draw from this is that either due to the scale of the warming or other factors, the atmosphere in 2009 was much more susceptible to stratospheric effects both in terms of warmings and coolings with quick effects while the more moderate sustained warmings in 2010 while not causing a reaction for around a month, did send the AO bonkers.

interesting ideas there SB.

I suspect there is still a heck of a lot we do not understand. Perhaps there is some fairly complex set of links between all the variables we know about that we have not yet found?

[Kentish Kiwi]

Is there any evidence to say that the colder the stratosphere prior to an SSW event, the greater its impact is? (if such a thing can be judge upon its 'impact'...) ie. whether this extremely cold stratosphere we are currently experiencing could ironically aid our prospects for cold should an SSW occur?

[Nick B]

I think its pretty obvious really that the stratosphere has a huge role to play, I do think other factors can still over-rule it, of course the ENSO signal probably being the main one, but as long as we stick to a weak feature then we should be ok in that respect...

Its going to be interesting to see how it all plays out...frankly I'd be amazed if we don't have a SSW given just how super cold we are going, its going to be next to impossible to hold record cold for any length of time I'd imagine.

I suppose my question is it the absolute warming (IE to a certain level) that causes blocking to form or is it just the relative warming within a certain area of the Arctic that causes the whole thing to buckle so to speak.

The interesting thing I've noticed with recent winters is that actually a SSW has led to us going into slightly milder conditions, there are several winters where we've colder month either whilst the SSW is going on or just before...so that once again is the chicken and egg question. I get the feeling a SSW is far more useful when you are stuck in the mild zonal set-up rather than in winters such as 09-10, etc.

Is there any evidence to say that the colder the stratosphere prior to an SSW event, the greater its impact is? (if such a thing can be judge upon its 'impact'...) ie. whether this extremely cold stratosphere we are currently experiencing could ironically aid our prospects for cold should an SSW occur?

Do you both mean, in that if you have a strong, organized and very active PV, that when an SSW occurs, it really has something substantial to disrupt, therefore the energy is sent further (and perhaps for a longer time period) and will therefore have more of an impact somewhere as a period of much colder weather?

[feb1991blizzard]

Given that 1985 is one of the anologue years in GP's pressure pattern forecast does anyone think there could be a repeat of Jan 1985 and rather than a split PV or a shredded PV occuring could it possibly move on mass a lot further south and if so what type of warming event would be needed to effect this process.

[BLAST FROM THE PAST]

Given that 1985 is one of the anologue years in GP's pressure pattern forecast does anyone think there could be a repeat of Jan 1985 and rather than a split PV or a shredded PV occuring could it possibly move on mass a lot further south and if so what type of warming event would be needed to effect this process.

I must admit I thought he referred to 84/5 but Jan would be coldest month....looking at his forecast 85/6 would be more of a match. Yes Jan 85 is repeatable...not forecast just repeatable.

BFTP

Edited November 30, 2011 by BLAST FROM THE PAST

[kold weather]

I'm pretty sure 84-85 is the year he is using because its a good match with the ENSO signal as well as the other factors.

[chionomaniac]

Looking at the 100hPa stratospheric charts this morning, subtle changes are likely.

From a period of cold zonality the heart of the polar vortex shifts slightly to the west of Greenland. This will leave us more open to milder zonality with the possibility of a warm ridge extension from the Azores over SE areas.

[BLAST FROM THE PAST]

I'm pretty sure 84-85 is the year he is using because its a good match with the ENSO signal as well as the other factors.

Feb was a cold month that winter at 2.1c with a decent cold spell in the middle but it was Jan at 0.8c which was THE winter month. So on that basis one would anticipate the winter waning as we go through Feb. It'll be interesting to see how it all evolves but with RJS thoughts in particular and the 84/5 analogue then JAN is the month for me if we get a true winter month.

C When would you expect that to take effect? About a week to ten days' time? BFTP

Edited December 1, 2011 by BLAST FROM THE PAST

[Gavin P]

The problem I have with 84/85 is that a lot of big drivers, PDO, AMO,ENSO and solar, were very differant that winter to now. The PDO was warm, now its cold. The AMO was cold, now its warm. We had a very weak La Nina that winter. This winter, whilst its still quite weak, its a stronger La Nina than 84/85. Solar activity was running down to the absolute minimum of cycle 21, now we're moving towards the maximum of cycle 24 (though its much weaker than you'd expect)

Personally I prefer the 1950's winters as a closer match to the current situation, and in particular 55/56.

[chionomaniac]

Feb was a cold month that winter at 2.1c with a decent cold spell in the middle but it was Jan at 0.8c which was THE winter month. So on that basis one would anticipate the winter waning as we go through Feb. It'll be interesting to see how it all evolves but with RJS thoughts in particular and the 84/5 analogue then JAN is the month for me if we get a true winter month.

C When would you expect that to take effect? About a week to ten days' time? BFTP

Yes and having just checked the ECM, something along those lines - perhaps not the T+240 chart.

Edit ; And even better demonstrated by the GFS 6Z

Edited December 1, 2011 by chionomaniac

[karyo]

A warming is forecast at the 10hpa level which may bring us to average values. This is not reflected at the 30hpa level and the zonal winds are continuing strong. It is a start though...

http://wekuw.met.fu-...ww/wdiag/ts.php

Karyo

Edited December 1, 2011 by karyo

[Glacier Point]

30 mb U winds showing a peak of 35m/s on today's data at 60N. This is at the top end of analogues, but the general suggestion of this being focussed at 60N is a solid one.

Probable further strengthening of the polar westerlies in the Pacific and Atlantic in time looks on the cards, and the trend for the shift of the core of the PV towards west of Greenland dropping into Canada looks rock solid to me (as per October winter discussion and winter forecast).

Edited December 1, 2011 by Glacier Point