Stratosphere Temperature Watch

[Mr Maunder]

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.

I would not close your mind too much even if this event does not ultimately produce the hoped for northern blocking.

Looking back at other events (as has been stated in many posts) a warming event gives no absolute guarantees in terms of blocking and, as a result cold (and snow) for the UK. There have been other January warmings that have not resulted in any noticeably cold weather for the UK - for example 1967 (although to be fair this was not the most dramatic warming).

This warming has been a truly significant event and so, perhaps hopes are higher of it leading to truly cold weather. However, this is the first significant warming to place in the Internet age - so it is interesting just to observe and learn - whatever the outcome. Of particular interest will be to look back and try and see how the weather models were influenced by the effects of the warming and when that influence was first felt.

It seems to me pretty clear that we will get a February that is significantly colder than those we have been used to in an era when stratospheric cold has been dominating.

Warmings appear to have been much more common in the 1950s, 60s and 70s, but rather petered out in the 80's. Whether this is the start of a further consistent period of warmings only time will tell. But if it is, in my view expect some colder winter periods.

MM

[chionomaniac]

The easterly wind phase is looking like it is coming to an end judging by the latest forecasts.

What I have noticed is that an increase of westerly winds is forecast at the tropospheric level, and perhaps it is this that is sneaking under the radar that the models are picking up on, and preventing some of the propagation of the continued easterly middle stratospheric winds. We shall see.

c

[Yeti]

Quite worrying model runs today though and there appears to be no sign of heights around the arctic/split PV, in fact we see PV recovery on all three models. A worrying sign?

[Guest North Sea Snow Convection]

The easterly wind phase is looking like it is coming to an end judging by the latest forecasts.

What I have noticed is that an increase of westerly winds is forecast at the tropospheric level, and perhaps it is this that is sneaking under the radar that the models are picking up on, and preventing some of the propagation of the continued easterly middle stratospheric winds. We shall see.

c

I think we need to remember that everything is working on a lag time basis here. The westerly wind increase is the one that GP has referred to recently in advance of the main body of negative zonal winds. Remember that we are in the process of recording nigh on three weeks of polar easterlies, so there is an awful lot to potentially feed into the tropospheric system through this month.

The momentum of the atmosphere surely is against a tide of short phased westerly troposheric winds, when there is a cavalry of very strong negative easterlies pushing down hard on its tail. At worst all this is simply doing is delaying the inevitable IMO

I still see another sharp and sudden change in direction from the modelling is imminent. All immediate modelling is over focused and over reacted on this westerly phase atm (note the GFS again today with another knee jerk reaction + I think UKMO too). So surely this westerly pulse must be on borrowed time IMO. Notice the ECM, in modelling the upper atmosphere better, has reacted more measurably so far in terms of not trying to over flattern the forecast ridge nearby to us as much as the other two.

The way I look at this is that we are seeing the same process (but in reverse) to the brief burst of negative zonal anomalies that reached the troposphere at the start of the year. We know in the background that the stratophere was cooling fast while that happened and that it was only a matterof time before the impact of stronger westerly zonal winds removed the blocking during the first third of Jan. In this case the warming event is fully matured as we know, and propagation has been started. Therefore the time period of this wave of westerly energy should have a much shorter time than its counterpart opposite did at New Year.

That is how I see it anyway. Fingers crossed it happens that way.

Edited February 10, 2009 by North Sea Snow Convection

[Matty M]

Anyway know what went wrong here?

Thought the Blocking was meant to kick into the models over the last few days!

Looks like all were going to get is a Euro High blasting Southwesterlies up over the BI by 7 days time!

Theory binned IMO.

Lots of good work though folks and fair play

Edited February 10, 2009 by Matty M

[Weather-history]

Theory binned IMO.

What a stupid comment.

[Mark Bayley]

Anyway know what went wrong here?

Thought the Blocking was meant to kick into the models over the last few days!

Looks like all were going to get is a Euro High blasting Southwesterlies up over the BI by 7 days time!

Theory binned IMO.

Lots of good work though folks and fair play

How can the theory be binned?

Just because the GFS doesn't show us what we want? As GP and Tamara said they may be over reacting to something. I have been following the thread for the winter and have learnt quite a bit. In fact its been the best thread IMO. When ever i come on the forum this is always the first thread i visit! How a chart from the GFS showing something we don't want in 7 days time totally dismisses a theory is beyond me! I think we will see blocking. Its just will we be in the right place to get the cold?

From the model thread by GP with what the models may be over reacting to, don't understand much of it however i am learning ever so slowly

Slight but subtle variation from this morning's NWP - probably related to some reaction to in the models to an increase in the zonal winds across 70N. Remember how the GFS went bananas with this idea a few days ago so the models are not immune from seeing a data shift and developing a false projections from it (only careful analysis of NWP across a day or two can determine whether this is a correct assumption) ?

Edited February 10, 2009 by mark bayley

[Radiating Dendrite]

Anyway know what went wrong here?

Thought the Blocking was meant to kick into the models over the last few days!

Looks like all were going to get is a Euro High blasting Southwesterlies up over the BI by 7 days time!

Theory binned IMO.

Lots of good work though folks and fair play

A lot of people have put a great deal of time and effort in to this thread and I don't think your gloating is called for.

People only ever theorised possible outcomes and highlighted possible links. It appears that you read too much into the Northern Blocking theory (which has not been proven wrong or right may I add) and are now just annoyed that the models are not showing it happening AT THE MOMENT.

[Matty M]

Lads i know people have put loads of work into this and that's why i have said many thanks and fair play to them!

Just illustrating that it is looking ever more likely their predictions will be wrong.

Not gloating!!??? For i would have loved the most if their predictions had of come off!

Sorry for sounding like a prat!

[Paul]

Come on people, let's discuss this in an adult manner - this is a good thread which has run throughout the winter on which many people have been involved and many more people have learned from, let's not ruin it with petty childish squabbling.

In the same way that a day of cold runs for 7 days time doesn't = cold is certain, a day of milder runs doesn't mean that summer is around the corner, let's get some perspective here..

[Radiating Dendrite]

Come on people, let's discuss this in an adult manner - this is a good thread which has run throughout the winter on which many people have been involved and many more people have learned from, let's not ruin it with petty childish squabbling.

In the same way that a day of cold runs for 7 days time doesn't = cold is certain, a day of milder runs doesn't mean that summer is around the corner, let's get some perspective here..

Fully agree.

Apologies to Matty M.......prat! lol

[chionomaniac]

I think we need to remember that everything is working on a lag time basis here. The westerly wind increase is the one that GP has referred to recently in advance of the main body of negative zonal winds. Remember that we are in the process of recording nigh on three weeks of polar easterlies, so there is an awful lot to potentially feed into the tropospheric system through this month.

The momentum of the atmosphere surely is against a tide of short phased westerly troposheric winds, when there is a cavalry of very strong negative easterlies pushing down hard on its tail. At worst all this is simply doing is delaying the inevitable IMO

I still see another sharp and sudden change in direction from the modelling is imminent. All immediate modelling is over focused and over reacted on this westerly phase atm (note the GFS again today with another knee jerk reaction + I think UKMO too). So surely this westerly pulse must be on borrowed time IMO. Notice the ECM, in modelling the upper atmosphere better, has reacted more measurably so far in terms of not trying to over flattern the forecast ridge nearby to us as much as the other two.

The way I look at this is that we are seeing the same process (but in reverse) to the brief burst of negative zonal anomalies that reached the troposphere at the start of the year. We know in the background that the stratophere was cooling fast while that happened and that it was only a matterof time before the impact of stronger westerly zonal winds removed the blocking during the first third of Jan. In this case the warming event is fully matured as we know, and propagation has been started. Therefore the time period of this wave of westerly energy should have a much shorter time than its counterpart opposite did at New Year.

That is how I see it anyway. Fingers crossed it happens that way.

I see it that way as well.

Getting back to what this thread was set up for, namely the monitoring of the stratosphere/troposphere interphase and how events such as a record breaking MMW may impact the troposphere, we can see that after the initial intense vortex splitting propagation and resultant Easterly, there has been a smaller westerly tropospheric phase. This shows up on both the mean and mean anomaly zonal wind charts below:

Here is the anomaly chart and the brief westerly increase shows up as a beige oval in amongst the lighter green at the tropospheric level.

Looking at the mean zonal winds the same westerly phase shows up in yellow. Just above the start of Feb there is a small light green area at the surface which correlates to the Easterly at that time. The net westerly winds look set to reduce as further propagation looks set from the stratosphere.

Compare this to GP's propagation forecast on the 26th January and the similarities are there:

So all in all even though the models may show a huge variance the polar blocking forecast is still looking promising I would say. The question is where will it take place and will the results affect us favourably. This is the one that is less easy to answer and anyone who has followed this thread would realise that.

If I would like to hazard a guess then on todays lower strat (100hPa level) forecasts my bet would be Scandinavia from the following chart.

However tomorrow it may be elsewhere as the tropopause forecasts show the most variance. As ever only time will tell.

For those who would like to enter into the stratosphere debate you are welcome but please lets keep to the side of polite good reasoning and leave any final analysis of how the stratosphere has interacted with the troposphere to the end of winter when we can have a good look with clarity of thought.

I as ever will keep my fingers crossed that if blocking does occur that the cold is headed my way!

c

[Guest North Sea Snow Convection]

I see it that way as well.

Getting back to what this thread was set up for, namely the monitoring of the stratosphere/troposphere interphase and how events such as a record breaking MMW may impact the troposphere, we can see that after the initial intense vortex splitting propagation and resultant Easterly, there has been a smaller westerly tropospheric phase. This shows up on both the mean and mean anomaly zonal wind charts below:

Here is the anomaly chart and the brief westerly increase shows up as a beige oval in amongst the lighter green at the tropospheric level.

Looking at the mean zonal winds the same westerly phase shows up in yellow. Just above the start of Feb there is a small light green area at the surface which correlates to the Easterly at that time. The net westerly winds look set to reduce as further propagation looks set from the stratosphere.

Compare this to GP's propagation forecast on the 26th January and the similarities are there:

So all in all even though the models may show a huge variance the polar blocking forecast is still looking promising I would say. The question is where will it take place and will the results affect us favourably. This is the one that is less easy to answer and anyone who has followed this thread would realise that.

If I would like to hazard a guess then on todays lower strat (100hPa level) forecasts my bet would be Scandinavia from the following chart.

However tomorrow it may be elsewhere as the tropopause forecasts show the most variance. As ever only time will tell.

For those who would like to enter into the stratosphere debate you are welcome but please lets keep to the side of polite good reasoning and leave any final analysis of how the stratosphere has interacted with the troposphere to the end of winter when we can have a good look with clarity of thought.

I as ever will keep my fingers crossed that if blocking does occur that the cold is headed my way!

c

Hi again

At the time of posting this, I think that Scandinavia initially is a good possibility. John H and Gerry have tonight had a very good discussion through the CPC chart updates and the idea of ridging into Scandinavai followed by a retrogression towards southern Greenland looks well supported. And the 12hrs ECM has mirrored that evolution well tonight.

Our westerly beige blob is the only question mark in terms of amount of jet energy for favourable enough positioning of the initial possibly progged atlantic to Scandi ridge. Your careful analaysis this evening suggests to me that this may be modelled more favourably in the next day or so as further propagation from the stratopshere may be picked up by the models and could well nullify the more progressive beigeness of the recent GFS, and, to a degree the UKMO, although that has improved slightly from its wobbles and does also hint at heights to the NE as of the time of typing this.

Much as I said earlier today, the ECM continues much more steady in its modelling of the ridge and expectations of the beige blob energy and reinforces the point IMO that its performance of modelling the upper atmosphere/troposphere interaction is superior. That in turn gives cautious confidence that both the analysis of propagation progress that you excellently provide here, in tandem with the mirroring of that progress towards suface level through the CPC predictions and, fingers crossed, continuing consistent ECM modelling, will provide a favourable result in terms of blocking in an area to deliver for the UK in terms of the next renewed cold incursion.

And here's an endorsement and echo to your suggestion of good polite reasoning - and saving the performance rating of the MMW against 'did it deliver' till the end of the event and, moreover, the change in the season.

Edited February 10, 2009 by North Sea Snow Convection

[johnholmes]

two good constructive posts and now is certainly not the time to try and make judgements.

This area is new to me but I do feel, when used sensibly and in conjunction with other links, can be a useful tool at time distances well beyond normal synoptic forecasting.

The idea of the Scandinavian high is sensible from an old forecasters viewpoint using the empirical rules we had. Its not cast iron of course, never was, at best about 70% prob of being right. The one now in the offing is I would say maybe about the same.

I would judge that the warming will be finished by about the 3rd week in February maybe nearer the end of the month. That allows quite some time for other effects to support the idea of blocking. Both AO and NAO are a bit variable over the past few days. But overall I would suggest its 65-70% on for another cold spell to develop and with deep cold air.

Edited February 10, 2009 by johnholmes

[Mikel Nimbus]

Could it not be possible that the most potent effects of these stratospheric easterlies are seen in the troposphere at roughly the same time as each other? If you look at the recent pattern of easterlies in the stratosphere, the timing coincides well with the easterly zonality we experienced early last week. As winds are set to switch back westerly in the strat, so is our weather down in the troposphere.

If you think about it, the Jet Stream affects the direction of zonality and the Jet Stream is found at the beginning of the stratosphere (the tropopause). In that case, why shouldn't stratospheric winds have similar effects on our weather as the Jet?

[johnholmes]

interesting suggestion but I have no idea how tenable that is?

[Gray-Wolf]

http://earthobservatory.nasa.gov/IOTD/view.php?id=36972

Some info from Nasa on the SSW.

EDIT. Just noticed the wording and it all seems a little 'past tense' to me.......

Edited February 11, 2009 by Gray-Wolf

[chionomaniac]

http://earthobservatory.nasa.gov/IOTD/view.php?id=36972

Some info from Nasa on the SSW.

EDIT. Just noticed the wording and it all seems a little 'past tense' to me.......

Morning and thanks GW.

This was posted last week on the model thread but it allows me once again to those who have not caught it to view the vorticity animation which shows splendidly how last weeks easterly came about.

The crossover from easterly to westerly stratosphere at the 10 -30 hPa level is scheduled to occur around 19-20 Feb.

I am still not convinced despite the model outputs that the affects of the MMW are over with just last weeks easterly to show. Looking at the mean zonal wind profile to the equator to the North Pole there does seem to be some negative anomalies arising at the tropospheric surface in the nexyt couple of days which could be the next resurgence of propagation as expected. Will they cause an effect?

c

Edited February 11, 2009 by chionomaniac

[Mr Maunder]

Looking at the outputs from the GDAS and CPC Zonal Mean Time Series charts then, if we believe our eyes, it does suggest a potential second wave of easterlies in the tropopause.

The "beige blob" referred to in posts above is exactly that - a blob of westerlies which, at this moment at least, has now finished and, as a result, the easterly regime has now recommenced.

How long this return to an easterly regime lasts is the question, but another 8 - 10 days looks possible to me.

I regard what we are seeing as "real time" science - as we have just not had a warming in the internet age with all the range of information that is available to us.

How and when the various models take this easterly regime on board (if indeed they do) is one of the interesting areas of observation emanating from this whole event. It may inform us to which of the models are most sensitive to the downward effects of a stratospheric warming.

Let me say this - I expect to see this "second phase" reflected in the model outputs in the next three to four days and those outputs may mean quite significant change. I'm not trying to get hopes up, just saying it as I see it.

However, if I am wrong I shall not be too concerned and just admit I was mistaken and use it as part of the learning process.

MM

[johnny1972]

http://earthobservatory.nasa.gov/IOTD/view.php?id=36972

Some info from Nasa on the SSW.

EDIT. Just noticed the wording and it all seems a little 'past tense' to me.......

Have to say that for a novice like myself thats a very simple and interesting read which explains easily the SW.

[blitzen]

This question has probably been asked before and I have missed the answer: Has there ever been a strat' warming event which hasn't been followed by a cold spell? This has been a wonderful thread throughout the winter and I hope that it pays off for all of the people who have contributed. Personally, I think a warming of this magnitude will deliver something special quite soon.

[Iceberg]

The warming event and the placement of the warming event show up very well on the MSU Strato diagrams.

[chionomaniac]

This question has probably been asked before and I have missed the answer: Has there ever been a strat' warming event which hasn't been followed by a cold spell? This has been a wonderful thread throughout the winter and I hope that it pays off for all of the people who have contributed. Personally, I think a warming of this magnitude will deliver something special quite soon.

Yes , many times. What we look for is propagation of the warming event from the stratosphere into the troposphere. Look at a SSW on 30 Dec 2001. Here is the mean zonal wind anomaly profile for 2002:

The darker greens don't propagate further down than the 50 hPa level during Jan /Feb.

And now this year so far:

As one can see the level of propagation is a lot further down and therefore more likely to affect the troposphere.

If you look back to 2002 you will see that westerlies dominated Jan/Feb. That is why each SSW is different. This one is propagating well.

c

[Glacier Point]

Surely this thing must start to hit sometime soon ?

No sign whatsoever in the modelling of the sort of signature we would expect given downwelling -ve mean zonal winds on the outer reaches of the troposphere.

[chionomaniac]

Surely this thing must start to hit sometime soon ?

No sign whatsoever in the modelling of the sort of signature we would expect given downwelling -ve mean zonal winds on the outer reaches of the troposphere.

Yes one would think so.

I have been wondering for some time and as SM mentioned it in the model thread I thought I would bring it up here. Is it possible that the effects are more diffuse this time? Rather than promoting a strong polar block in one position is it possible that the negative zonal wind anomalies weaken the northern jet as a whole, with slacker low pressure systems (more akin to summer), circumnavigating the globe but not allowing the major release of cold as we would expect if HLBs were in place? Or is something major still around the corner?

c