Stratosphere Temperature Watch

[BLAST FROM THE PAST]

have you read my blog where I attempt to give the actual data as seen this autumn-winter?

Thank you John for that, very intersting. The rhythm of Nov, Dec, Jan [not so much last 3rd Jan] correlated nicey with RJS and my signals. I think the MWW/SSW are directly linked to solar output and magnetic fields from within our Milky Way B) I wonder why this 'bigger' event doesn't seem as yet to have had as much/or more effect than the 1st two. This will be the interesting research.

BFTP

Edited February 13, 2009 by BLAST FROM THE PAST

[cheeky_monkey]

Do you think it has delivered cold to the country CM?

personally i dont think so..but then im yet to be convinced of the whole warming link....especially when the cold spell started many including some respected posters on here stated the two were not linked and the effects of the warming would be felt from mid month onwards..hence what was happening at the beginning of feb was a bouns and the real cold would be felt later.

now that scenrio seems to be an unlikely outcome...its now well the cold spell must have been a result of the warming event.

as i have said before because a link has yet to be proved or disproved it is easy to move the goal posts to fit anyway anybody likes.

also nobody answered my orginal q? posted in at 13:33..it was nicely side stepped.

just remember im playing devils advocat here...i dont necessarily disagree with the theory but i have yet to see it played out for real in a convincing manner.

[chionomaniac]

It is all well and good playing devils advocate CM, but when you have a question answered rather than moving on and asking the next relevant question you just ask the same one again. That to me suggests something a little more than playing devils advocate.

The fact that you don't believe that the February cold spell had anything to do with the MMW says it all really. I have shown a number of times how the vortex split led to the cold easterly and subsequent cold pool and there has been a number of other links provided from NASA and The Times where a met man said there was a direct link but you can carry on believing what you want to believe. Have you read JH's blog showing how the stratrospheric fluctuations have influenced us this season or is JH another poster that you feel doesn't carry much weight behind his opinion? Regarding other posters suggesting no link in the early days of the easterly - this was due to the fact that they were saying that it had no link to protracted downwellings from the stratosphere which can cause northern blocking and subsequent cold. This would occur at a later timeframe and is the part that is not guaranteed and we are yet to see and may not see. This in my eye is the area of most uncertainty as to why some MMWs produce productive propagation and others do not. However the question of this MMW already producing cold has already been answered and there is no doubt that it has.

Regarding the CWs query they may set the the tone and jet stream pattern for that winter however they may not have done. The point I was originally trying to make was that unless you have a detailed winter analysis of the whole stratosphere for each of those dates then we will not know exactly how the stratosphere may have affected the outcome of those winters. Which timely brings me on to why this thread was set up - to do just that. If you would like to know how the stratosphere may be influencing this winter already then do read JH's blog. If not then please don't come back and the same question again.

[Guest North Sea Snow Convection]

personally i dont think so..but then im yet to be convinced of the whole warming link....especially when the cold spell started many including some respected posters on here stated the two were not linked and the effects of the warming would be felt from mid month onwards..hence what was happening at the beginning of feb was a bouns and the real cold would be felt later.

now that scenrio seems to be an unlikely outcome...its now well the cold spell must have been a result of the warming event.

as i have said before because a link has yet to be proved or disproved it is easy to move the goal posts to fit anyway anybody likes.

also nobody answered my orginal q? posted in at 13:33..it was nicely side stepped.

just remember im playing devils advocat here...i dont necessarily disagree with the theory but i have yet to see it played out for real in a convincing manner.

It was widely felt that what happened at the start of Feb was a bonus. The MMW had immediate effects but these were also considered a precursor to further effects from mid month as the main body of negative zonal anomalies propagate into the troposphere. What was was not foreseen (nor could have been) was the exact effects of the breaking up of the vortex, in terms of location, as a result of the initial warming. These were widely expected to transfer from where the main body of the vortex was over Canada, towards Siberia, but we have been unlucky enough to see this migrate towards Greenland instead, with the result that the further downwelling of the negative anomalies is now held up until this energy is dissipated by some displacement mechanism from within the stratosphere, which will in turn further weaken the residual tropospheric energy and allow the pressure rises that had been envisaged for this time.

Instead we have seen the models backtrack abruptly in the last couple of days with low heights, where rising pressure was anticipated, with a stubborn Azores High and shortwaves preventing a route back to cold conditions. However, there is an increasing backlog of negative zonal anomalies, and at some stage the situation has to give, and the effects envisaged mid month will happen. Again, we cannot be prophets and determine exactly how this will manifest itself. However, the effects should be much more favourable - when that happens. It is a waiting game now, but we have to accept that in terms of the winter timeframe, the clock is ticking fast.

You should realise that one can only go on the best information and data available from models, CPC etc, at a given time -and this is data that METO use. Therefore your constant repeating of the same questions and demanding instant proof of correlation with this event are are rather like asking people to have a crystal ball and anticipate complex evolutions that depend on dynamics of physics. And especially for a process that is nowhere near finished yet! .

I too am sceptical that you may not be just playing devils advocate and suspect perhaps are just enjoying people having to keep repeating themselves and using up a lot of their spare time in covering the same ground.

Edited February 14, 2009 by North Sea Snow Convection

[TEITS]

You should realise that one can only go on the best information and data available from models, CPC etc, at a given time -and this is data that METO use. Therefore your constant repeating of the same questions and demanding instant proof of correlation with this event are are rather like asking people to have a crystal ball and anticipate complex evolutions that depend on dynamics of physics. And especially for a process that is nowhere near finished yet! .

What an excellent post Tamara.

Personally I feel sorry for you and CH. You have both made some excellent posts on this thread in what is a very complicated and complex subject. The problem is many assumed this warming would instantly bring a cold spell like 1963 when at no stage did you or CH ever promise this. What you did correctly say is having the right ingredients could bring a decent cold spell but having the right ingredients doesn't mean your going to bake an excellent cake every time!

So instead of CM asking you and CH to be prophets what other members including myself should do is try and learn more about this fasinating subject. This is what I intend to do over the summer months and hopefully come next winter I shall have a better understanding.

[Guest North Sea Snow Convection]

What an excellent post Tamara.

Personally I feel sorry for you and CH. You have both made some excellent posts on this thread in what is a very complicated and complex subject. The problem is many assumed this warming would instantly bring a cold spell like 1963 when at no stage did you or CH ever promise this. What you did correctly say is having the right ingredients could bring a decent cold spell but having the right ingredients doesn't mean your going to bake an excellent cake every time!

So instead of CM asking you and CH to be prophets what other members including myself should do is try and learn more about this fasinating subject. This is what I intend to do over the summer months and hopefully come next winter I shall have a better understanding.

Thanks Dave - that is much appreciated

Like others, I am very disappointed atm that things so far haven't panned out right in terms of hopes - but from a watching and studying perspective this remains a highly enjoyable and exciting study. And it isn't over yet by a long way - irrespective of what the surface conditions will or won't be.

[chionomaniac]

Latest Update.

We are experiencing a period of mean slack zonal winds in the middle stratosphere as a result of the recent MMW. These are still forecast to stay negative for the foreseeable future but only just!

The current problem we have at the tropospheric level with milder weather encroaching is being caused by a segment of the Canadian split lower stratospheric vortex residing over the south and west of Greenland. This has the effect of firing short waves over the top of the Azores high stopping any southwards movement of cold air and preventing favourable Northern blocking from occurring.

The question is can this shift which could potentially open the floodgates for colder air to arrive at our shores. There are signs that the vortex segment will move slightly westwards to sit over Eastern Canada.

Whether this is far enough to lead to rises in pressure to our north is debatable. However I can see potential from these forecast charts for pressure rises to the northeast which has been a recurring theme this winter. Whether there is enough of a window to get the whiff of an easterly in 10 days time remains to be seen as the Azores high could just be too strong.

All in all it could be that the extreme strength of the MMW has worked against the propagation by the lack of return of westerlies further up. These, as suggested by NSCC and GP, could have given the impetus to drive the negative zonal winds deeper into the troposphere. Having said that there is another pulse of downwelling right over the NP that looks like it may be occurring in the next couple of days and I will be keeping an eye out to see if this can induce unseen changes on the models.

This winter has been fascinating to watch unfold and even though we may not have seen the MMW effect us in the way we would have wanted (there is still time) it has been interesting to see why that isn't the case so far. The monitoring will continue.

c

[tundra]

I posted this in the model thread a couple of days ago and i think it highlights quite well why we are having trouble getting cold weather in the UK at present.

Chionomaniac i couldn't agree more that the strength of this warming has played against us for the time being with the upper stratophere being akin to a large mill pond at the moment without a strong downwelling push from above.

Again going back to 1985 that strong warming was followed by a marked reversal in temperatures in the stratosphere and also a strong increase in westerly zonal winds in the upper stratosphere.

Having said this i am surprised at the sheer lack of blocking further north and with a major part of the warming having taken place over Greenland we have seen no blocking in this area YET.

Who would have thought we would see the vortex moving in a westerly direction from Canada, the complete opposite to what was forcast. Even forcasters on Accuweather were taken in, saying the cold we saw at the beginning of the month would be nothing compared to what was to come.

I really do believe we haven't seen nothing yet and maybe the end of February and the first two to three weeks of March could well deliver the coldest weather of the winter and perhaps snowiest.

Also just to remember the second really cold wave of weather in 1985 did not come until around mid February some four weeks after the first wave.

[johnholmes]

yes IF the vortex does go west sufficiently that then allows the flow to create a downwind ridge of it with the UK then on the cold side of that ridge. Even more so, perhaps a trough in the upper flow to the east allowing a full blown northerly. In the right circumstances that can be a fairly prolonged affair IF the wavelength is the necessary length.

Its possible but far from certain it will happen. Watch for the main vortex actually moving first.

and as you say ch a fascinating winter to watch with the aid of the models, even if they have not given the cold lovers exactly what they want.

For almost 60% of this winter so far my temperature has been around 2C below the very long term average, 1942-now; I have to go back many years to find similar statistics, and also the days with snow for here. Nothing like many have had but outside normal expectations for here.

Edited February 14, 2009 by johnholmes

[mountain shadow]

Out of interest and with zero disrespec to the excellent forecasters on this thread. Is there a cut off date as to whe we can say the Strat warming will have no impact on the UK?

Also, if the Strat warming doesn't propogate to the H500 level, I believe it is of equal significance as to the reasons why it didn't than anything else.

[chionomaniac]

One of the reasons that we have not received the cold that we might have expected from such an unprecedented MMW is due to the lack of propagation of easterly winds from the stratosphere to the troposphere. This can be seen quite clearly from the chart below from yesterday.:

During the recent easterly there was a far greater propagation of easterly winds down to the troposphere which has yet to reoccur. However there is a glimmer of hope on the horizon. At T+240 the forecast suggests greater propagation that we have been expecting all along. So something to watch here;

c

[Guest North Sea Snow Convection]

Out of interest and with zero disrespec to the excellent forecasters on this thread. Is there a cut off date as to whe we can say the Strat warming will have no impact on the UK?

Also, if the Strat warming doesn't propogate to the H500 level, I believe it is of equal significance as to the reasons why it didn't than anything else.

I'm afraid there are no guarantees The weather gods might know lol!

Might also be worth reading GP's latest post on the angular momentum thread which indicates that negative zonal anomalies in association with the MMW are making very slow progress into the troposphere. My own personal take is that an effect will still be felt. But the longer the wait the more people are going to question it, because the days are getting longer and they won't get snow. Which is what the impatience boild down to.

Edited February 15, 2009 by North Sea Snow Convection

[johnholmes]

quick request

can some give the definition of MMW again please?

thanks

[Guest North Sea Snow Convection]

A major mid-winter warming is defined to occur when the zonal mean zonal winds at 60N and 10hPa become easterly during winter (NDJFM). The first day on which the daily mean zonal mean zonal wind at 60N and 10hPa is easterly is defined as the central date of the warming

[Guest North Sea Snow Convection]

One of the reasons that we have not received the cold that we might have expected from such an unprecedented MMW is due to the lack of propagation of easterly winds from the stratosphere to the troposphere. This can be seen quite clearly from the chart below from yesterday.:

During the recent easterly there was a far greater propagation of easterly winds down to the troposphere which has yet to reoccur. However there is a glimmer of hope on the horizon. At T+240 the forecast suggests greater propagation that we have been expecting all along. So something to watch here;

c

Lets hope we can reel that prediction in!

Edited February 15, 2009 by North Sea Snow Convection

[Glacier Point]

Those zonal mean sections depict nicely the concentration of flow across 30-40N. They also show the importance of considering the wider hemispheric pressure anomaly pattern. Right now there are large upper tropospheric anticyclones situated across Africa, the West Indian Ocean and parts of the Central Pacific. These are shown by OLR plots (dark brown shading = +ve OLR).

These are stradding the Tropics 20-30N and driving strong jet flow across 30-40N.

There are some indications that the flow downstream of 180 W is becoming slightly more amplified which can be seen as possible sources of Rossby Wave Dispersal to help shift the polar vortex around. Worth monitoring to see if we can get either a Pacific or Atlantic ridge amplified enough to trigger the full effects of the MMW.

[Guest North Sea Snow Convection]

The feedback pattern in the Pacific of this winter maybe has a lot to answer for our frustrations. With too much shortwave energy from the pacific feeding the PV over Hudson Bay area. This has repeatedly enlarged and contacted during the season and during times when it has grown, it has had the knock on effect of in turn throwing energy eastwards again, like a relay baton, towards Greenland. I don't fully understand the angular momentum principle, but the sequences as described are probably tied in with the ebbs and flows of this?

Anyway, I think the latest episode of this sequence is occurning again now, and accounts for the spoiler shortwaves. It is also preventing the MMW from progressing and why we are not seeing, as yet, the split vortex dissipating.

So do we need the whole pacific/atlantic pattern to change first? We have also struggled to get and maintain a -NAO regime this winter. Perhaps the underlying La Nina pattern is still trumping/ overruling the strong stratospheric signal. So maybe in line with many Springs where the atmosphere is pedisposed to a nina, that will be the time instead for deliverance.

Edited February 15, 2009 by North Sea Snow Convection

[J10]

One of the reasons that we have not received the cold that we might have expected from such an unprecedented MMW is due to the lack of propagation of easterly winds from the stratosphere to the troposphere. This can be seen quite clearly from the chart below from yesterday.:

During the recent easterly there was a far greater propagation of easterly winds down to the troposphere which has yet to reoccur. However there is a glimmer of hope on the horizon. At T+240 the forecast suggests greater propagation that we have been expecting all along. So something to watch here;

c

Sorry to ask a really silly question, but can you explain those charts to me.

This has been a fantastic thread to read and helpfully the projections in about 10 days will materialise.

[Erl Happ]

Right now there are large upper tropospheric anticyclones situated across Africa, the West Indian Ocean and parts of the Central Pacific. These are shown by OLR plots (dark brown shading = +ve OLR).

Very useful observation chionomaniac. There is amplified evaporation occurring from the tropical ocean driving the uplift of water into the equatorial stratosphere which has cooled as the Arctic stratosphere has warmed. This represents a strong amplification of the Hadley cell. Rising air at the equator is balanced by descending air in those subtropical high pressure cells. Descent via the Arctic Vortex is prevented by the increase in stratospheric temperature. The air has to descend somewhere. I wonder what is happening in Antarctica? My guess is a cold spell.

The amplification of the Hadley cell should push the subtropical high pressure cells away from the Equator opening up a wider cloud free zone over the tropics. An increase in upper troposphere temperature tends to remove ice cloud and that increase in upper troposphere temperature tends to happen between the equator and 65°N as the Arctic warms.

What this adds up to is strong cloud loss and a warming tropical ocean. A bit more of this and we might have an El Nino on our hands.

Seems to me that the Arctic is loaded with ozone and any further solar activity will tend to keep it warm. If that is the case you may not see the anticipated cool weather.

Looking at the intensity of this event and the duration of the warming in the Arctic together with the depth to which the warming has occurred this is the sort of very special occurrence that might be expected to occur only in the midst of a protracted solar minimum.

Sorry Glacier Point. I see that I should have been congratulating you on your observation re the high pressure cells.

[chionomaniac]

Sorry to ask a really silly question, but can you explain those charts to me.

This has been a fantastic thread to read and helpfully the projections in about 10 days will materialise.

These charts are a cross section of the atmosphere from the equator to the North Pole. They measure the mean zonal winds form the top of the stratosphere (1 hPa) to the bottom of the troposphere (1000 hPa). Effectively the red/orange colours depict mean westerly winds and the blue colours depict mean easterly winds at that point of the atmosphere. The second chart shows that the easterly winds are propagating down into the troposphere between 70-90N which would have the effect of promoting northern blocking. (100-200 hPa is the tropopause level - the boundary between the stratosphere and the troposphere)

Hope that helps.

c

Edited February 15, 2009 by chionomaniac

[Glacier Point]

Looking at the intensity of this event and the duration of the warming in the Arctic together with the depth to which the warming has occurred this is the sort of very special occurrence that might be expected to occur only in the midst of a protracted solar minimum.

Sorry Glacier Point. I see that I should have been congratulating you on your observation re the high pressure cells.

Certainly the behaviour of the (protracted) west QBO points to an unusual solar-induced / co-opted event:

http://www.cdc.noaa.gov/data/correlation/qbo.data

It's worth considering also that the AO has demonstrated a marked shift downwards over the last two weeks:

http://www.cpc.ncep.noaa.gov/products/prec...ex/ao.sprd2.gif

This is likely to continue for the forseable future given that the normal momentum fluxes are going to get inhibited by the warming event and dropping angular momentum preventing any poleward flux of mean zonal winds.

Edited February 15, 2009 by Glacier Point

[bluearmy]

Seems to me that the Arctic is loaded with ozone and any further solar activity will tend to keep it warm. If that is the case you may not see the anticipated cool weather.

wouldnt a warm arctic be good for us - the cold has to go somewhere???

[Stratos Ferric]

Feb56 No event

62/63 CW and MWW

Feb 69 CW

Feb 78 CW

78-79 CW and MWW

81/82 CW

Jan85 MWW

Feb 86 No event

Jan 87 MMW

Feb 91 MMW

95/96 No event

The majority of those winters either had Canadian Warmings to start those winters or MMWs in those winters. No one has ever said that MMWs are a prerequesite to cold winters but raise the chances of HLBs that can increase the chances of cold. We all know that there are many other factors that influence cold weather so unless you look in detail at the exact stratospheric conditions of those winters ( we know that you have better things to do with your time-post 646) then the exact correlation may still go unmissed!

c

Have you tested the other tail? Do all winters with Canadian warming lead to cold spells hereabouts. If not then we might be looking at a poor correlation wiothin which it is possible to cherry pick - inappropriately - an apparent pattern.

It's a bit like me saying that every morning when I go for the train a train comes, therefore my arrival presages that of the train. A more thorough assessment of the facts MIGHT reveal a rather different pattern, onto which I have conveniently alighted.

wouldnt a warm arctic be good for us - the cold has to go somewhere???

What happens if you leave your fridge door open?

Edited February 15, 2009 by Stratos Ferric

[chionomaniac]

Have you tested the other tail? Do all winters with Canadian warming lead to cold spells hereabouts. If not then we might be looking at a poor correlation wiothin which it is possible to cherry pick - inappropriately - an apparent pattern.

That was a poor statistical correlation I agree. It was made quickly just to show that those winters weren't event free stratospherically. I have pointed out in further posts that unless a more thorough analysis is done of all winters then true correlations can't be made one way or another.

c

[Guest North Sea Snow Convection]

It is actually interesting to try to come at the significance of stratospheric warming events in terms of increased chances of winter cold weather from another angle. And that is wrt the Canadian Warmings, which are early season events (Nov, Dec) and are linked to the intensification of the stratopsheric Aleutian High and the tropospheric Aleutian Low pressure system. The nature of these events are minor compared to MMW events and generally only leads to a very temporary reversal of polar westerlies at best, but are still enough to disrupt the polar vortex from its normal frequent winter routine for a while, and at an early stage of seasonal development, and thereby provide the opportunity for cold weather in the early winter and perhaps the better start to winter - may mean increased chances for a better stratospheric environment for the rest of the winter and all that entails for the weather patterns.

To try and illustrate this and correlate the importance of these CW's it is worth looking at some facts. There have been 22 CW between 1951/52 and 1981/82. But only 3 since 81/82! Now, we often speak of the warming trend of winters over this period since the 80's, so food for thought there perhaps?

Why should these figures be as they are though with the drop off in occurence of CW's?

How about shifts in the PDO? We know the PDO shift to positive was 1976 so a good lag time correlation to the figures supplied above in terms of the domination of El nino events (in turn in context of what I describe in a moment about the pacific).

We also know of the recent PDO shift back to negative, so what of the future here? The implications of a negative phase ie a cooler pacific and fewer El Nino's meaning less tropical activity over the longer term. This might have favourable implications for the Aleutian Low and a better pacific set-up which in turn might increase the frequency of CW's again. This in turn might alter the AO/NAO patterns with a better feedback set-up created in the late autumn/early winter. More -AO/NAO means more cold. So it is a virtuous cycle. In this suggested supposed scenario it might mean we would be getting back to a warmer winter stratospheric cycle and this in turn might mean that we are not relying on late season events to kill off a strong dominant PV and not having high latitiude blocking arriving only in late Feb/Mar and well into the Spring when it is too late for any real cold weather.

To back the possible significance of what I am suggesting - note that over all the above occurences seen of the CW , 75% of them saw a -AO/NAO over that period.

So if we can correlate this sort of link and trend with the CW, what could we do with the MMW? And thereby reinforce the importnace of having the stratosphere on our side for winter. The other aspect is that of the solar minimum and its disposition to the sort of intensity of SSW that we are currently seeing. Maybe some regime changes that might mean better times ahead.

That might put a little meat on the bones for discussion regarding Cheeky Monkey's question and SF's comments just now.

Edited February 15, 2009 by North Sea Snow Convection