Stratosphere Temperature Watch 2012/2013

[SMU]

You cant unless you have the derived formula + starting & Ending point of October.....

Its about snow advancement, so a good bet would take the starting point & the finishing point of october...-

you need the data coverage figures though

S

[chionomaniac]

Apologies, I think this is just a misinterpretation of my comments. What I mean is that the ECM seasonal model is obviously updated once a month and each update is then for the forth coming 4 months. So what I really mean is that the November ECM seasonal update will be the last one that covers Dec, Jan and Feb together. The Dec updated, in early Dec, will then cover Jan to April. So in essence the November update is the last one that captures the winter months before then progressing further.

M.

Ah I see - I was confused by that. I understand now thanks.

You cant unless you have the derived formula + starting & Ending point of October.....

Its about snow advancement, so a good bet would take the starting point & the finishing point of october...-

you need the data coverage figures though

S

They normally don't come through for a few days - but you don't need to be a genius to see that rate of coverage has gone well for October.

[bluearmy]

Looking at the mean zonal wind charts at the foot of the strat from yesterday's ECM 12z, I am struck by the jump day 9 to 10 . throughout the run, we lose the polar reverse zonality we've seen for ages and the flow at the bottom of the strat beecomes positive though not particularly strong. Then, day 10 it suddenly flicks neg again and looks like it goes quite high considering the day 9 chart. It's either an error or it must be caused by trop effects. There may be another chart on Berlin that supports this but I can't find it. Anyone more clued it got any ideas?

[lorenzo]

Where's Ed when you need him. At a guess Wave 2 and EP Flux.

[sebastiaan1973]

Bluearmy is it possible to illustrate your post with an illustration? Thanks!

[bluearmy]

Bluearmy is it possible to illustrate your post with an illustration? Thanks!

If I was able to I would Sebastian - on page 1 of the thread you will find the link to Berlin. Click on zonal winds and scroll down each days forecast.

[Glacier Point]

Looking at the mean zonal wind charts at the foot of the strat from yesterday's ECM 12z, I am struck by the jump day 9 to 10 . throughout the run, we lose the polar reverse zonality we've seen for ages and the flow at the bottom of the strat beecomes positive though not particularly strong. Then, day 10 it suddenly flicks neg again and looks like it goes quite high considering the day 9 chart. It's either an error or it must be caused by trop effects. There may be another chart on Berlin that supports this but I can't find it. Anyone more clued it got any ideas?

I'm guessing you're looking at the trop ? If so, probably related to encroachment of the Siberian ridge poleward with associated WAA.

[chionomaniac]

Looking at the mean zonal wind charts at the foot of the strat from yesterday's ECM 12z, I am struck by the jump day 9 to 10 . throughout the run, we lose the polar reverse zonality we've seen for ages and the flow at the bottom of the strat beecomes positive though not particularly strong. Then, day 10 it suddenly flicks neg again and looks like it goes quite high considering the day 9 chart. It's either an error or it must be caused by trop effects. There may be another chart on Berlin that supports this but I can't find it. Anyone more clued it got any ideas?

It's not an error, ba. Firstly, these charts at the tropospheric level out from day 7 are very unreliable.

If you go back to yesterdays 12Z ECM the change in mean zonal winds can be explained by a relocation of the heart of the polar vortex from the pole after being close to it for the days prior to day 10. (If my memory serves me correctly wasn't there a transfer of the pv to Scandi?)

[bluearmy]

apologies - should have looked more closely (still jet lagged). i appreciate that forecasts at day 10 are unreliable but it still looks very strange to see the change in zonal wind signal push so far up through the trop in such a short space of time. not sure i recall noticing such a shift being forecast within a 24 hour tmescale. however, a quick look back at the run from yesterday does show heights suddenly rising very suddenly siberian side of the pole at day 10. the mean week 2 output spreads today seem to favour ne greenland for the lowest heights. what is encouraging is that there doesnt appear to be any consistency with the fi forecast vortex placement and very few GEFS members seem interested in building any strong p/v at the end of their runs. the control being one of the best options and something of beauty for mid november.

[chionomaniac]

I have just been checking out some figures for the latest stratospheric temperatures and mean zonal wind profiles from the NASA site:

http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

So when looking at the temperatures the disappointing news is that at almost every level of the polar stratosphere the temperature is below average and the forecasts suggest that even further cooling is likely to take place.

So one would expect that the mean zonal winds for each level would show above average - evidence of the strengthening vortex. But alas that is not so! The mean zonal wind speed is pretty much also below average as well. So why is that?

Well my guess for this is two fold:

One and probably the main reason is due to the QBO. I suspect that we are seeing the perfect timing this winter for the easterly QBO to create resistance to the increasing polar vortex. To compare - a spinning top is less likely to gain as much speed if for every three pushes one way there is another push in the other direction - and I guess the eQBO must have some effect in creating this effect. In a westerly QBO regime we see the spinning top only spun the one way.

The second I would expect is due to the temperature contrast between the tropical and polar stratosphere. The less that this is, the less strength we see in the polar vortex.

We have still yet to see any evidence of an increased BDC this autumn - though it is early days for this. When this kicks in and we see the feedback from the Eurasion snow cover then prospects will increase.

In the meantime, looking at the surprising mean zonal wind speed values so far this autumn it demonstrates how many variables we have to take into consideration and how complex the stratospheric forecasting can be.

I think we will need to monitor the zonal mean wind speed at 60ºN very carefully alongside the temperatures, because evidence suggests so far that we can get away with a cooler polar stratosphere so far when other factors are in our favour.

Also we should be able to see the ECM chart forecasts at some point during this week which are a lot easier to read than the individual levels.

Last year here:

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=all&alert=10&lng=eng

c

[Methuselah]

Thanks for that, Chio. It's so good to seem some soundly reasoned expectations...

[BLAST FROM THE PAST]

Of note is the amount of blocking being seen and potentially later in the month with stratos as it is. Yes many many factors involved and I wonder if we'll ever discover what drives it all or whether as it seems that there is no singular driver?

BFTP

[UV-RAY]

What a fantastic post Chio for people like myself trying to get to grips with all this.

[cheeky_monkey]

Here is a question? If start warming does disrupt the polar vortex and encourage NH blocking are there areas that this blocking is more likely to occur or is it dependent on where the warming takes place?..or its just pot luck?

Edited November 1, 2012 by cheeky_monkey

[Vertical Limit]

Great post Chio - thankyou. Your thoughts and explanations make it a lot easier for a novice like me to get to grips with understanding the complexities of the Strat.

On a side note, I also would like to ask if there are any signals yet for a Canadian warming to occur or not, or is it still too early to tell?

Regards

VL

[chionomaniac]

Here is a question? If start warming does disrupt the polar vortex and encourage NH blocking are there areas that this blocking is more likely to occur or is it dependent on where the warming takes place?..or its just pot luck?

It isn't pot luck how a warming event occurs but it may seem so when we are not in the right position to recieve the cold ( we are only but a small island) - we may not understand the reasons why blocking occurs in certain places until after the event. Strat warming events take a certain path from inception to completion and recently there has been more understanding to both the precursors and how this may affect the troposphere.

We know that certain blocking patterns are precursors to mountain torques events which are a result of tropospheric Rossby wave deflections. If a Rossby wave is big enough and of enough amplitude then it can be deflected by mountain ranges into the stratosphere where it will break as it reaches the top. We know where the mountain ranges are, so we can predict where this occurs - normally in the wake of the Mountains - over the Atalantic or Pacific or both. From there, every wave break is slightly different and more difficult to predict whether it will rebound back through the vortex, be deflected out of the vortex by an unfavourable EP-flux, or be absorbed by the stratospheric vortex before it reaches the troposphere. All these scenarios will create different tropospheric responses - hence the difficulty in predicting what tropospheric response that we will see following a warming event.

As of yet there is no sign of a Canadian Warming - but I won't rubbish my forecast at this stage!

[MattH]

It isn't pot luck how a warming event occurs but it may seem so when we are not in the right position to recieve the cold ( we are only but a small island) - we may not understand the reasons why blocking occurs in certain places until after the event. Strat warming events take a certain path from inception to completion and recently there has been more understanding to both the precursors and how this may affect the troposphere.

We know that certain blocking patterns are precursors to mountain torques events which are a result of tropospheric Rossby wave deflections. If a Rossby wave is big enough and of enough amplitude then it can be deflected by mountain ranges into the stratosphere where it will break as it reaches the top. We know where the mountain ranges are, so we can predict where this occurs - normally in the wake of the Mountains - over the Atalantic or Pacific or both. From there, every wave break is slightly different and more difficult to predict whether it will rebound back through the vortex, be deflected out of the vortex by an unfavourable EP-flux, or be absorbed by the stratospheric vortex before it reaches the troposphere. All these scenarios will create different tropospheric responses - hence the difficulty in predicting what tropospheric response that we will see following a warming event.

As of yet there is no sign of a Canadian Warming - but I won't rubbish my forecast at this stage!

It's almost a case of get the event off the ground in the first place and then sit back and wait and see what happens. As you highlight the UK is a tiny island on the grand scheme of things and I think that's where a lot of people trip up. They often believe that if a warming event takes place then in about 2 or 3 weeks (as an example) the UK will be plunged into deep cold and an arctic setup. As you point out clearly, the end result is often the most difficult factor to gauge from what I have learnt along the way. Without question there are many examples of a warming event leading to more blocking and a disrupted polar vortex which, in theory, should lead to a heightened risk of colder weather, but those few hundred miles can make all the difference at times.

Referring back to your earlier post, I am sort of baffled by the setup so far this autumn. I use the word baffled lightly, as I understand what is going on, but the lack of a distinct 'path' as yet is most certainly creating conflicting signals. As you highlight perfectly in that particular post if you look above say 30hPa at the moment and especially above 60N it looks pretty grim, particularly when you factor in the current ozone levels, yet there doesn't seem to be any hurry for these more potent cold conditions to penetrate further south. Depending on what the rest of November throws up this autumn is likely to be a particularly 'blocked one' with it most certainly not being a mild, zonal and stormy autumn which can clearly develop across the UK with a succession of lows setting up across the UK.

I sort of hope that we don't look back and say, that the blocking arrived or was more dominant through autumn and essentially was present 'to soon'. There are many variables pointing towards a cold and more blocked winter which these have been discussed in depth for weeks now in various shapes and forms and clearly the most recent being the major increase in Eurasion snow cover. Despite these promising and interesting variables people need to keep a broad open mind on the up coming winter. When I say 'people' I clearly mean us lovers of more wintry synoptics as despite these variables, we could still get sucker-punched yet and end up with a zonal mass of mild and muck for the majority of the three winter months.

As ever time'll tell, but it remains an almost frustrating wait now to see how the next very important 4 weeks will develop, either 'good' or 'bad'.

Regards to all

Matt.

[chionomaniac]

I agree with you there Matt, the stratosphere could still deliver that sucker punch come winter and cold lovers need to beware.

I agree that this month is baffling which is why I had a good look at the mean zonal winds. The QBO winds descend the level of the stratosphere and spread out towards the pole as they do so. Timing is very much right to create the resistance in the lower strat against the strengthening upper polar strat vortex .

So far, probably because of this, I would say that the autumnal synoptics are very much tropospherically driven, but at some point if the stratosphere continues to cool then that may change to being stratospherically driven - and I wouldn't bet against the mean zonal winds increasing during the rest of autumn unless there is some hindrance from a warming event that would halt that increase.

Edited November 1, 2012 by chionomaniac

[EML Network]

Very well explained post by Chino.

It makes the mouth water that if we were to get a SSW event, combined with the Easterly QBO then potentially we could be in for a bit of fun and games ??

If ...at every level of the polar stratosphere the temperature is below average, then I would prefer for that to happen now rather than in January, it makes one wonder if this, combined with the ENSO state potentially coming out of neutral conditions and developing into either EL Nino or La Nina and the Snowfall advance over Northern Europe and Russia ...that the cards might be being stacked for a very cold final 3rd of Winter ?

If that does indeed come to pass and we have a bitterly cold Feb, I don't think anyone would be grudge having to wait a few more months..especially if we get a few cold shots every once in a while in between

Edited November 1, 2012 by EML Network

[chionomaniac]

To add Matt , you have made me go back and look again at the ozone levels. Now, we know that the BDC transports ozone from the upper levels of the tropical stratosphere eventually down to the lower levels of the polar stratosphere.

When we look at the ozone levels at 40 hPa they are high compared to the rest of the stratosphere - not ever having monitored this before I do not know whether this is exceptionally high for this level but it would add some credence to why the lower levels of the stratosphere are warmer and behaving differently to the upper levels. Just a thought.

Another area that will need further monitoring!

[Snowmadsam]

Another area that will need further monitoring!

Another thing to add to the list then...loads of potential this year...the problem is seeing how it will play out...

[syed2878]

an excelent post chio for some1 like me who's learning a nice sympol explaination. Thx.

[MattH]

To add Matt , you have made me go back and look again at the ozone levels. Now, we know that the BDC transports ozone from the upper levels of the tropical stratosphere eventually down to the lower levels of the polar stratosphere.

When we look at the ozone levels at 40 hPa they are high compared to the rest of the stratosphere - not ever having monitored this before I do not know whether this is exceptionally high for this level but it would add some credence to why the lower levels of the stratosphere are warmer and behaving differently to the upper levels. Just a thought.

Another area that will need further monitoring!

Yeah, good spot that. There is, without question, a distinct 'line' evident approximately around the 40hPa and 30hPa mark in terms of variables pointing towards more promising scenarios beneath this level, but above it the signs are ominous. Must admit those forecast charts from the NOAA website are OK, but they are all individual images. Sometimes it is beneficial to have a loop or be able to see all the images on one page rather than flicking back and forth.

I am tempted to get some of the images onto my webspace so they can all be viewed at once as the links to the images look 'static'. Clearly there is a lot images at different heights, so there's no way I can do them all, but may be of worth to do the important levels say 50hPa to 10hPa.

Also I have found this link on the well known WeatherOnline website to Ozone prediction from the GFS model. However, the lack of an outline for a landmass or even lat/lon lines, in my opinion, makes the images almost worthless. I'm not sure why they have been setup like this, might be worth an email;

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=ozon&HH=0&ARCHIV=0&ZOOM=0&PERIOD=&WMO=

Cheers, Matt.

[Glacier Point]

Some useful comparisons with last year reveal the differences that the lower stratosphere and troposphere are exhibiting.

Zonal wind anomalies

2011

2012

Mean height anomalies

2011

2012

Notice how this year at around 50 hPa and below the polar field is experiencing negative zonal wind anomalies and +ve height anomalies. That is a lot of atmosphere to try and turn around from above.

We know to our costs that not all upper events downwell, indeed,are we upwelling a negative wind anomaly from the lower stratosphere ? This would be consistent with the hard time that any cooling signal at 10 and 30 hpa is having right now.

I think the longer this goes on, with the stratospheric temperatures being prevented from free fall, the deeper into the boreal winter season we get and the greater the chance of a favourable tropospheric pattern leading to wave breaking. The pattern over the next week or so looks favourably aligned for Wave 1 activity with that deep North Pacific Low, so 20+ days to some form of disturbance to the PV ?

I think I mentioned this the other day, but I would almost want to see an upper level +ve zonal wind anomaly attempt to downwell, as it would meet a stiff resisting force with the resultant torque likely to generate some exciting activity around the mid stratosphere.

EDIT: 12z GFS shows no appreciable thermal gradient across the NH from pole to equator at 50hPa downwards right out to mid November with the exception of a warmer blob in the Pacific. That has got to be some resistance to any attempts for cooling from above to penetrate the lower stratospheric layers.

Edited November 1, 2012 by Glacier Point

[Duane S.]

Fascinating reading today's posts as always in this thread!

Looking at things very simplisticly, it does seem logical to my inexperienced mind that the Easterly QBO is the dominant force in inhibiting full vortex windup at the moment?

Could I be right in thinking though that this may be enough for now but as the strat cools through November resistance will be futile so to speak and to aid our chances of halting the formation of a vortex akin to Nov/Dec 2011-12 we will be looking for reinforcments from eg: a wavebreak event later in the month?