Stratosphere Temperature Watch

[johnholmes]

yes C that is the best idea so I hope all of us can keep to that suggestion

[chionomaniac]

The excellent link provided by diamond dust on the model thread has a fascinating animation that shows exactly how the recent easterly came about:

http://earthobservatory.nasa.gov/images/im...o_200901-02.mov

One can see quite clearly how the vortex split sent a trail of easterly outflow right across the UK and out into the Atlantic. This wasn't the result of easterly wind propagation (which we are still awaiting to see if this affects us) but was a direct result of the vortex splitting MMW right down to the troposphere. I don't think you can see any clearer, a cold effect correlation from an MMW. For those in the model thread who are still uncertain about how an MMW may be linked to cold weather on these shores I suggest they watch this and then perhaps they may be more willing to listen to those who suggest that MMWs are linked to cold events.

It may well be a good idea to keep an eye on this as it may give us an idea to see if there are any more outflows either from east or north.

c

[Fozfoster]

The excellent link provided by diamond dust on the model thread has a fascinating animation that shows exactly how the recent easterly came about:

http://earthobservatory.nasa.gov/images/im...o_200901-02.mov

One can see quite clearly how the vortex split sent a trail of easterly outflow right across the UK and out into the Atlantic. This wasn't the result of easterly wind propagation (which we are still awaiting to see if this affects us) but was a direct result of the vortex splitting MMW right down to the troposphere. I don't think you can see any clearer, a cold effect correlation from an MMW. For those in the model thread who are still uncertain about how an MMW may be linked to cold weather on these shores I suggest they watch this and then perhaps they may be more willing to listen to those who suggest that MMWs are linked to cold events.

It may well be a good idea to keep an eye on this as it may give us an idea to see if there are any more outflows either from east or north.

c

fascinating animation we wait with anticipation for the next phase.

[chionomaniac]

This is more than theory though. Look at the stratospher/troposphere/model sequence/surface response so far this winter-

Average conditions prevailed in the stratosphere to start the winter, and we witnessed an Asian mountain torque event that precipitated a couple of negative zonal anomalies to propogate to the troposphere. This lead to the blocked and cold period we witnessed through xmas, New Year and nearly the first third of January.

Now, at the same time as we were enjoying the first cold spell, we saw a distinct cooling in the stratosphere and it was no coincidence that towards the middle of January we saw the increase in westerly zonal winds, associated with that cooling, and this manifested itself in the return of the northern jet and a zonal pattern as we know for most of the rest of the month.

Now, while the zonal period was in full swing, we have witnessed another mountain event, a much larger one than the previous one. This is one of the main factors behind triggering the unprecedented MMW that has produced a reverse (easterly) switch in zonal winds in the stratopshere and these have been monitored (as per stratosphere thread) in terms of their propagation process towards the troposphere (and hence towards the time when the models start to pick up on the downwelling of the negative zonal winds in response to this) We must remember that this is a much larger scale feature than pre xmas, and we are talking about a reverse switch of polar westerly winds (which drives the low pressure and polar vortex) to a sustained easterly switch that rips up the polar vortex and kills off the energy of the zonal winds.

So this brings us up to the present day and the final burst of westerly zone winds which are the precursor 'switch' prior to the polar easterlies. The model disagreement, as GP suggests, is down to how they handle this pulse of energy before it dissipates. As he suggests, ECM is more superior in modelling the upper atmosphere and it has called each successive pattern correctly all this winter. Before the GFS. That includes the switch back to zonality earlier in January. On that occassion, GFS was hanging on to the blocking longer than ECM, although it is acknowledged that ECM was a day or two progressive with the return of the atlantic.

Similarly, I would suggest the same is true here and at worst the ECM is trying to bring in the high latitude blocking in rsponse to the MMW a day or two too soon - and merely briefly postphoning the ineveitable.

Sorry about the long post but I think this hopefully will demonstrate how the stratosphere is a very dominant driver in our winter patterns - especially from january onwards when the state of the stratosphere, cold or warm, in turns impacts on the strength of the polar westerlies, which in turn impacts as one of the main determinators on jet strength and the ability of blocking to hold. There are others, like the GlobalWind Oscillation which measures low pressure strength etc, but as even Met Office spokesmen have suggested, this event has already made its impact in terms of the pre emptive effect on the atmosphere. They have also suggested thats effects will be felt for some weeks to come. So it is fact not theory.

The publicity that this event has taken attention, shows that it is not only winter cold forum members who eshew the virtues of a warm stratosphere.

Just thought I would copy Tamara's great post from the model thread into here. It sums up brilliantly a lot of thoughts about how the stratosphere and troposphere are dynamically interconnected. I think the majority of my post winter analysis has been written for me!

Edit I hope thats OK T

Edited February 7, 2009 by chionomaniac

[Guest North Sea Snow Convection]

Just thought I would copy Tamara's great post from the model thread into here. It sums up brilliantly a lot of thoughts about how the stratosphere and troposphere are dynamically interconnected. I think the majority of my post winter analysis has been written for me!

I will certainly be letting you do the final analysis .

Your comprehension and analysis of the chart numbers etc has been seond to none on here. Another GP,JH,SM in the making??

Putting aside the hopes for cold weather in association with the MMW, I'm going to repeat that we couldn't have wished for a better test case to learn from than this one. Simply amazing - we are very lucky

[chionomaniac]

I will certainly be letting you do the final analysis .

Your comprehension and analysis of the chart numbers etc has been seond to none on here. Another GP,JH,SM in the making??

Putting aside the hopes for cold weather in association with the MMW, I'm going to repeat that we couldn't have wished for a better test case to learn from than this one. Simply amazing - we are very lucky

Thanks, but your input has been second to none on this thread.

I agree we have been so lucky to get such a great test case to monitor.

And the forecast is still holding out with negative zonal winds - but only just!

[Guest North Sea Snow Convection]

Thanks, but your input has been second to none on this thread.

I agree we have been so lucky to get such a great test case to monitor.

And the forecast is still holding out with negative zonal winds - but only just!

Yes - and also we have already got quite a few 'easterly' days under our belts already as well as the forecasted one's.

Was the CWD the 23rd Jan??

[chionomaniac]

Yes - and also we have already got quite a few 'easterly' days under our belts already as well as the forecasted one's.

Was the CWD the 23rd Jan??

Yes

[Gerry]

CWD of the 23rd, that gives us a potential of 15 days minimum when blocking is most likely to occur, with propogation time of maybe 10 + days this event has every chance of seeing us through into March before its statrs to deminish. Keep up the good work all of you its been fascinating

[johnholmes]

Just thought I would copy Tamara's great post from the model thread into here. It sums up brilliantly a lot of thoughts about how the stratosphere and troposphere are dynamically interconnected. I think the majority of my post winter analysis has been written for me!

Edit I hope thats OK T

yes I agree the post, almost certainly lost beneath reams of other posts in the model thread, is a pretty fair summation of how the two parts of the atmosphere do seem to have inter acted this winter.

I'm no expert, but its pretty much how I see it. No doubt someone with a greater understanding may pick holes in it though.

[chionomaniac]

The forecast for the mean zonal winds suggest a crossover from net easterly to net westerly around the 16th Feb. That would leave us having a period of easterly middle stratospheric winds of close to 25 days. That would be far in excess of any other events and could therefore give a sustained tropospheric knock on effect well into March.

Looking at the strength of the vortex it is worth comparing what we see now at the 30 hPa level to the start of January.

Jan 8

Now (T+144)

As one can see there is a comparable difference to now and then and hopefully everyone can see how a strong stratospheric vortex influenced the troposphere and drove the Atlantic mid Jan.

Looking again lower down at the 100 hPa level we see that the split vortex is rejoining together. This is occurring on the other side of the NP towards the Pacific end leaving the tropopause layer on our side with no significant vortex. Even the vortex remaining is showing signs of weakening.

Compare this to recent years when the polar vortex has been situated near Greenland and we can consider ourselves very fortunate to see a change this year.

So far this year the correlation between stratosphere and troposphere has been stunningly accurate, more so that I thought it would be so when I started this thread. Amazingly, when the stratosphere has led me to believe that the troposphere will behave in a certain way, following a slight time lag, this has occurred every time. I don't believe this is down to luck and, as Tamara has shown in more detail, all indications are that the stratosphere is a strong driver of the troposphere and subsequent weather patterns below. With that in mind I fully expect that GP's / Tamara's expectations for the rest of February will bear fruit. Those who dismiss this type of long range forecast when the odds are stacked in the favour towards colder patterns, do so at their peril.

c

Edited February 8, 2009 by chionomaniac

[Guest North Sea Snow Convection]

The forecast for the mean zonal winds suggest a crossover from net easterly to net westerly around the 16th Feb. That would leave us having a period of easterly middle stratospheric winds of close to 25 days. That would be far in excess of any other events and could therefore give a sustained tropospheric knock on effect well into March.

Looking at the strength of the vortex it is worth comparing what we see now at the 30 hPa level to the start of January.

As one can see there is a comparable difference to now and then and hopefully everyone can see how a strong stratospheric vortex influenced the troposphere and drove the Atlantic mid Jan.

Looking again lower down at the 100 hPa level we see that the split vortex is rejoining together. This is occurring on the other side of the NP towards the Pacific end leaving the tropopause layer on our side with no significant vortex. Even the vortex remaining is showing signs of weakening.

Compare this to recent years when the polar vortex has been situated near Greenland and we can consider ourselves very fortunate to see a change this year.So far this year the correlation between stratosphere and troposphere has been stunningly accurate, more so that I thought it would be so when I started this thread. Amazingly, when the stratosphere has led me to believe that the troposphere will behave in a certain way, following a slight time lag, this has occurred every time. I don't believe this is down to luck and, as Tamara has shown in more detail, all indications are that the stratosphere is a strong driver of the troposphere and subsequent weather patterns below. With that in mind I fully expect that GP's / Tamara's expectations for the rest of February will bear fruit. Those who dismiss this type of long range forecast when the odds are stacked in the favour towards colder patterns, do so at their peril.

c

Another excellent summary

Anyone reading that would have a hard case in trying to suggest that the Strat/troposphere interaction isn't a crucial part of trying to do an LRF.

It is no coincidence that the avoidance of a major cooling event to start the winter, such as occured at the beginning of the last two winters, and then the magnitude of what is an unexpected MMW (especially within the context of the expectations from looking back at the early part of this thread) has played a huge part in making this a very different winter to what was anticipated, also even by the Met Office.

Arguably this might suggest that stratospheric modelling is very much in its infancy,and maybe is not given sufficient prominence?? Research into likely stratospheric patterns ie cold, stable (= more likely mild wet westerly driven at the surface) or warm and unstable (= more likely cold and dry easterly driven at the surface) is a major tool in the run up to the winter season and the fate of our weather patterns is crucially dependant on the state (or likely direction of the state) of the stratosphere and how it will interact down to the surface through the season.

Edited February 8, 2009 by North Sea Snow Convection

[Yeti]

Two excellent posts. The question is, is this winter a one-off or is this the beginning of a trend towards a less cold stratosphere during the coming years? A period of cool summers normally predates cold winters, and cold winters tend to come in groups.... let's hope we are approaching such a group - and that the second of february really does bring what we want and indeed expect from reading this superb thread

[chionomaniac]

Two excellent posts. The question is, is this winter a one-off or is this the beginning of a trend towards a less cold stratosphere during the coming years? A period of cool summers normally predates cold winters, and cold winters tend to come in groups.... let's hope we are approaching such a group - and that the second of february really does bring what we want and indeed expect from reading this superb thread :lol:

Let's hope it is a trend Yeti.

Latest forecast look to have delayed the reversal of zonal winds back to westerly and kept them easterly for a little while longer. I am wondering now whether we will get a months' worth of easterlies then a final warming?

Temperatures at the 30 hPa level are also not dropping.

c

[Guest North Sea Snow Convection]

Let's hope it is a trend Yeti.

Latest forecast look to have delayed the reversal of zonal winds back to westerly and kept them easterly for a little while longer. I am wondering now whether we will get a months' worth of easterlies then a final warming?

Temperatures at the 30 hPa level are also not dropping.

c

Getting closer to the time period of 1979 when that late Feb FW occured!

Time is fast running out for any vortex recovery to any real extent.

Judging by the model output the intense blocking is not too far away now - the atlantic maybe having a last hurrah now for quite some time I think.

[sandstorm2]

This topic has been a marvellous addition to the winter discussion area. Hats off to Chinomaniac and north sea snow for all the info they have provided, it was certainly the right year to start this off. The phenomenal warming of the strat. is now going to deliver at sea level with a lot of northern blocking. Perhaps the recent cold has only been nature getting us acclimatised to what is coming for the rest of February!!

SS2

[Rollo]

This topic has been a marvellous addition to the winter discussion area. Hats off to Chinomaniac and north sea snow for all the info they have provided, it was certainly the right year to start this off. The phenomenal warming of the strat. is now going to deliver at sea level with a lot of northern blocking. Perhaps the recent cold has only been nature getting us acclimatised to what is coming for the rest of February!!

SS2

Agree with everything you say SS2 but you omitted Glacier Points name and he as far as I know was the instigator of the thread-his input has been a revelation as far as I am concerned.

[Guest North Sea Snow Convection]

Agree with everything you say SS2 but you omitted Glacier Points name and he as far as I know was the instigator of the thread-his input has been a revelation as far as I am concerned.

I have always followed GP's posts and threads and although they are technical and I don't understand everything that is said, I agree very much that his general background input is invaluable. One of the factors that kick started my own interest in the stratosphere, once I realised how much an influence it can be on our winters. The case in point here noticing the last two winters, which were doninated by a very cold stratosphere from the start of the season until a time when it was too late to influence the winter season itself.

The hardest part is fitting the jigsaw of the stratosphere/troposphere relationship into the the other teleconnection tools to get the rounded overall picture and likely outlook. That is where GP excels and often appears ahead of the models

Edited February 9, 2009 by North Sea Snow Convection

[Gray-Wolf]

I'm still not convinced that I am seeing the type of 'blocked' forecast I had imagined to see after such a major event. Again I'd be questioning the propagation of this warming as I have a feeling that we are witnessing a 'top down' event rather than the more studied 'bottom up' event. Boyle's law doesn't give a hoot how the gas is compressed (from the top or from the bottom) but the bottom up approach depends upon surface synoptics to produce the wave to impact the strat and ,as such, there are already teleconnections in place for the impacts to 'appear' further on in time. Top down does not depend upon such connection being present and so the 'result' is far less certain.

If ,over the next 2 weeks, we see the type of major blocking I expect I'll withdraw but if ,as I suspect, we just continue on with a cool ,-ve PDO influenced pattern and the Atlantic ever present I will need to question further.

[Guest North Sea Snow Convection]

I'm still not convinced that I am seeing the type of 'blocked' forecast I had imagined to see after such a major event. Again I'd be questioning the propagation of this warming as I have a feeling that we are witnessing a 'top down' event rather than the more studied 'bottom up' event. Boyle's law doesn't give a hoot how the gas is compressed (from the top or from the bottom) but the bottom up approach depends upon surface synoptics to produce the wave to impact the strat and ,as such, there are already teleconnections in place for the impacts to 'appear' further on in time. Top down does not depend upon such connection being present and so the 'result' is far less certain.

If ,over the next 2 weeks, we see the type of major blocking I expect I'll withdraw but if ,as I suspect, we just continue on with a cool ,-ve PDO influenced pattern and the Atlantic ever present I will need to question further.

You might well have forgotten the significant Asian mountain torque event in January that was a major factor in kick starting the MMW.

Not sure what sort of blocked appearance of pattern you had in mind, but as you suggest, watch on for the second half of Feb.

[chionomaniac]

To SS2 thanks, and hopefully we are going to see the northern blocking that an unprecedented MMW can deliver.

I agree with Rollo and NSCC regarding GP's input not just with the stratosphere but with the whole teleconnection picture. He has by far the best medium and long range forecast success here with the reanalysis of previous patterns. I am sure that he would have had Feb spot on until the MMW threw a spanner in the works! But adjust to the spanner he has, and I am sure that the rest of Feb will be close to as called.

Regarding GW's worry about anything significant regarding Northern blocking we shall see. The ECM/GFS ensembles over the last couple of runs do look like producing something significant. We shall see when winter is over and assess how the SSW and previous stratospheric state may have influenced the troposphere then, rather than before it has occurred.

Looking at the propogation of the zonal wind anomalies, after a period of tropospheric negative wind anomalies we have something of an antinode of temporary westerlies ( as seen by the beige colour 200-100 hPa) before I expect the next node of negative zonal wind anomalies hit the troposphere for the second half of February. A temporary respite methinks.

c

Edited February 9, 2009 by chionomaniac

[sandstorm2]

Agree with everything you say SS2 but you omitted Glacier Points name and he as far as I know was the instigator of the thread-his input has been a revelation as far as I am concerned.

Yes you are perfectly correct, apologies to GP for not including him, and yes he is a revelation with his knowledge.

SS2

[BLAST FROM THE PAST]

I'm going to dig a little further but I believe that this MMW is down to the current solar phase we are in. This winter has very much delivered bang on in line with the HALE cycle and the unusual behaviour of the sun 'quiet, stiil producing cycle 23 flares etc the changeover of cycle 23 to 24'. Who'd have thought we would have had the winter we have?

Re longterm trend, well IMO we have entered the approach to a deep solar minima and it is only likely to get quieter and so more of the same I fancy [with a little more down the line].

BFTP

[JoeShmoe]

I'm going to dig a little further but I believe that this MMW is down to the current solar phase we are in. This winter has very much delivered bang on in line with the HALE cycle and the unusual behaviour of the sun 'quiet, stiil producing cycle 23 flares etc the changeover of cycle 23 to 24'. Who'd have thought we would have had the winter we have?

Re longterm trend, well IMO we have entered the approach to a deep solar minima and it is only likely to get quieter and so more of the same I fancy [with a little more down the line].

BFTP

The GFS 12z tonight shows the sort of blocking thats been speculated about on this thread ...

[JoeShmoe]

The GFS 12z tonight shows the sort of blocking thats been speculated about on this thread ...

However the UKMO and ECM say no .. and would likely setup a milder second half of febuary with the HP sat over Sern UK of pattern. No northern blocking there in afraid

mmmmm