Stratosphere Temperature Watch

[bluearmy]

chio, it appears an immediate downwelling response, looking at GP's 'in depth' post. i know you are keen on this type of response to an MMW.

[karyo]

chio, it appears an immediate downwelling response, looking at GP's 'in depth' post. i know you are keen on this type of response to an MMW.

I eas expecting to see loads of posts and analysis here today?

Surely, things are looking good!

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

Karyo

[weatherjunkie]

I eas expecting to see loads of posts and analysis here today?

Surely, things are looking good!

http://strat-www.met...t=temps&alert=1

Karyo

0z GEFS NAO Outlook

Predominately east based.

[karyo]

0z GEFS NAO Outlook

Predominately east based.

hi weatherjunkie,

what does the NAO outlook have to do with the stratosphere?

Karyo

[chionomaniac]

chio, it appears an immediate downwelling response, looking at GP's 'in depth' post. i know you are keen on this type of response to an MMW.

I have only just got to look at the model outputs today and I don't think there is much surprise at all. The projected northerly is in the timeframe that one could consider as a direct immediate response to the MMW. This is more in line with my thoughts that what occurs to the stratospheric vortex shapewise during a MMW will be transmitted quite quickly to the troposphere, whilst any blocking as a result of the longer term disruption of the vortex takes a lot longer to propagate.

Looking at the 100 hPa charts it is difficult to decide whether this northerly will be a toppler or not. Even if we do not see great height rises over Greenland (as there are still contradictory outputs here) I think that this northerly will be more productive than a toppler due to the Scandi trough holding its position giving a more sustained flow. It is a pity that the real cold that the Arctic has bottled up in the last week or so is not directly to the north of us but the flow will certainly be cold enough after a day or to.

The forecast MMW is looking to occur on the 27th Jan. It is not a massive dead on certainty and in fact presently it looks that reversal of the mean zonal winds at the 10 hPa level will only just occur at 60ºN and will not be prolonged like last year.

However i feel that the longer term propagation chances might be more likely if the upper stratospheric vortex reforms and pushes the negative anomalies down to the troposphere. I feel that the -QBO zonal stratospheric winds this year will help with this allowing the southerly jetstream to sit into place and giving a better chance of blocking further north - just like we have seen all winter.

c

[weatherjunkie]

hi weatherjunkie,

what does the NAO outlook have to do with the stratosphere?

Karyo

Nothing much. I thought that the graphic would be something people would like to see given predictions about high lat blocking in late Jan-mid February.

[chionomaniac]

Just to add to my earlier post that the pattern of warming leading to the MMW is not straightforward. In fact it appears that there are a series of warmings. One has already occurred. The second boost occurring now seen below leads to the projected MMW in 3/4 days time.

Then there is a lull:

Before another warming in 9 days time:

. Now the current warming is just enough to lead to (projected) zonal mean winds reversal for a around a day and a MMW. After this the displaced vortex almost shows some signs of recovery before the next warming comes into place. At this point I expect to see a greater reversal of mean zonal winds that will probably last longer than a day and the vortex may collapse completely at that point. The ECM zonal wind forecasts show these type of fluctuations at the 1 hPA level:

The reason that I mention this is because the effects of the displacement of the stratospheric vortex are quickly felt on a tropospheric level - remember those initial effects ( not the later delayed effects possible from mid Feb onwards) are likely to lead to the northerly as the trough drops into Scandinavia. However, if the full disintergration of the vortex is somewhat delayed and the displacement holds its shape for a little while until the next warming boost occurs, then we may see that the tropospheric vortex is held in the Scandi region for some time, with a series of recharging and then toppling northerlies occurring, before the next stratospheric pattern becomes clearer.

c

[lorenzo]

Great summary Chino, in your experience how quickly do the models adapt to this information (second warming phase) , or is it already factored into future output?

Surely the FI timeframe is decreased with the uncertainty over the vortex disintegration?

[chionomaniac]

Great summary Chino, in your experience how quickly do the models adapt to this information (second warming phase) , or is it already factored into future output?

Surely the FI timeframe is decreased with the uncertainty over the vortex disintegration?

Hi Lorenzo.

I don't think that a warming programmed in the stratosphere for around 10 days time will be factored into any tropospheric models yet. After all, perhaps the stratospheric models have it all wrong at that time frame!

[chionomaniac]

We are seeing a definite trend this morning of seeing the initial warming phase stretch and displacing the polar vortex over Eurasia creating a MMW (but only just). This is followed by another warming which is forecast to split the weakened vortex. The exact positioning of theses split segments will play an important part of where blocking will occur. One segment of the split vortex is forecast to reside over Pacific Siberia. The other has been forecast to reside any where from Scandi to Canada and this is the important bit for us. The tropospheric models are suggesting Canada which would allow height rises to our NE but is this going against other signals (eg MJO) so a wait and see there.

[chionomaniac]

Latest GFS stratospheric profiles are out. Here is the T+240 chart at the 10 hPa level. There is more displacement and less of a split on this chart (MMW in place whilst this residual vortex reduces). All I can say that if I could choose anywhere for a declining vortex to be situated it wouldn't be there! Let's hope for some more displacement as we get nearer to the troposphere (imagine this is a cross-sectional view of an elephant trunk tornado and touchdown doesn't occur under where the funnel appears from the cloud).

c

Edited January 25, 2010 by chionomaniac

[Methuselah]

Thanks for all the effort ch and GP...Maybe, when I'm back darn sarf, I'll ask you both to explain the details to me...I do like the 'elephant's trunk' analogy! :unsure:

[brogdale]

Thanks for all the effort ch and GP...Maybe, when I'm back darn sarf, I'll ask you both to explain the details to me...I do like the 'elephant's trunk' analogy!

Agreed Pete

The tornadic analogy is a good one Chiono, and I now get what you were saying over in 'the other place'.

I've gone back and had a look at a number of the 3D animations here:-

http://www.appmath.columbia.edu/ssws/index.php

and the propogating vortices do appear to naturally drift eastwards (going down through +ive zonality?) so maybe the progged position over us could come good if the trop effects are shunted eastwards of the upper PV...hence the model propensity to Northerlies?

[bluearmy]

Agreed Pete

The tornadic analogy is a good one Chiono, and I now get what you were saying over in 'the other place'.

I've gone back and had a look at a number of the 3D animations here:-

http://www.appmath.columbia.edu/ssws/index.php

and the propogating vortices do appear to naturally drift eastwards (going down through +ive zonality?) so maybe the progged position over us could come good if the trop effects are shunted eastwards of the upper PV...hence the model propensity to Northerlies?

but would the likely direction of drift be east? i would have though that in a -AO phase, the direction of drift of the 'trunk' would be west which would put it in the greenland area - hence chiono's comment.

[brogdale]

but would the likely direction of drift be east? i would have though that in a -AO phase, the direction of drift of the 'trunk' would be west which would put it in the greenland area - hence chiono's comment.

I'm not at all certain about that ba, just put it out there

However if you look at the progged downward propagation the underlying air column is +ive :-

http://strat-www.met.fu-berlin.de/cgi-bin/ecmwfzm?alert=1&forecast=f96&var=u

etc.

[chionomaniac]

I can finally get round to updating today's stratospheric profiles. The latest mean zonal wind forecasts suggests that we are very close to having a MMW. I suggested some time ago that the 27th (tomorrow) would be the most likely date and I will stick with that.

The forecast MMW shows that the mean zonal winds will only reverse for a short time before turning westerly again however this does not take into account the weakness or shape of the vortex. The forecasts are still fluctuating with the idea of a displacement MMW followed by a split.

I suspect that the next wave of warming will reverse the mean zonal winds again but that we shall have nothing like the extended negative mean zonal winds period that we experienced last winter. However I do think the propagation of the mean zonal winds to the troposphere will be rather more this year and already there are initial signs of this in the forecasts. The current polar mean positive zonal (westerly) winds seen below appear to be flushed out within 6 days.

Now

T+ 6 days

These downward propagating negative mean zonal wind forecasts do seem to change a lot so I now view them with some caution, however the pattern is consistent with northern blocking but I still haven't worked out looking at the 100 hPa forecasts where the 'elephant trunk' is likely to sit!

One of the things that I am seeing in the zonal wind projections is a linkage with the stratospheric negative MMW zonal winds with the -QBO winds. We mentioned prior to this winter how favourable this QBO phase is and I believe that it aids in the whole Northern Hemisphere stratospheric and tropospheric pattern which has helped with the jet stream positioning and lower stratospheric anomalies seen earlier this winter. I again believe that this will aid the propagation of the MMW down to the troposphere.

c

[chionomaniac]

Well by my reckoning today we should have a MMW! Looking at the forecast from yesterday we see that the mean zonal winds were forecast to reverse today ( at 60ºN) with the displacement of the vortex from the pole at 10 hPa.

Looking at the temperature forecasts we see another couple of rounds of warmings still about to occur.

Now this is where I think things become interesting. The displaced stratospheric PV is in a weakened state but not so much that the present reversal of zonal winds only lasts for a day or two. However when the next increase of temperature comes along the displaced vortex splits rather than getting displaced further as it weakens.

I like displaced vortices but I would much rather see splitting as I feel that propagation of the split to the troposphere is more favourable and after the two previous splits this winter we know what the result can bring.

The zonal mean wind forecasts suggest that propagation of negative anomalies to the troposphere is quick and the split is carried immediately to the 100hPa level.

The Scandi segment of vortex is the important one and what happens to this will dictate our pattern of weather.

c

Edit BTW that last chart posted shows an incredible amount of northern blocking.

Edited January 27, 2010 by chionomaniac

[chionomaniac]

Now this is where I think things become interesting. The displaced stratospheric PV is in a weakened state but not so much that the present reversal of zonal winds only lasts for a day or two. However when the next increase of temperature comes along the displaced vortex splits rather than getting displaced further as it weakens.

Well, latest GFS update flirts with the idea of a stratospheric split before sticking with the displacement route. That tells me that there is a lot of uncertainty with how this MMW is likely to proceed and how it is going to influence the troposphere. I think it is a very difficult call trying to suggest what could occur after the northerly and I will keep the updates going but with the proviso that there are likely to be changes in the outputs for a while yet.

[Rollo]

Thanks Chio-I am learning but a long way to go yet.

[cooling climate]

Certainly looks like a MMW in progress now.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

[chionomaniac]

Certainly looks like a MMW in progress now.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

But not quite! It appears that this MMW is struggling to get across the finishing line. I expected the mean zonal winds to become reversed at 10 hPA and 60ºN yesterday but it has not occurred yet even though the stratospheric PV is very displaced.

Not that it matters of course because as I have mentioned before if the winds reverse at 61ºN and not at 60ºN the effects at the surface are not going to be too dissimilar but in the records it would suggest that we haven't had a MMW. And the reason for the winds staying positive at 60ºN are complex but effectively due to the pattern of displacement and the fact that some of the reversed mean zonal winds are heading equatorwards to join the -QBO as the following chart shows.

However, there is further warming planned and enough propagation programmed towards the troposphere to warrant a period of northern blocking and a -AO.

The concern here has always been the pattern of vortex disruption felt at the troposphere as there has always been a segment of split vortex never too far away in the reliable timeframe. There are signs that the main body of vortex energy will transfer to the Canadian Arctic which will allow N/NE height rises and ridge building which will be encouraging for any easterly - but I reckon that we are 10 days away from that presently.

[chionomaniac]

However, there is further warming planned and enough propagation programmed towards the troposphere to warrant a period of northern blocking and a -AO.

The concern here has always been the pattern of vortex disruption felt at the troposphere as there has always been a segment of split vortex never too far away in the reliable timeframe. There are signs that the main body of vortex energy will transfer to the Canadian Arctic which will allow N/NE height rises and ridge building which will be encouraging for any easterly - but I reckon that we are 10 days away from that presently.

Right, great. This trend is reinforced by the latest GFS stratospheric output.

At the 10 hPa level we see that the displaced vortex gradually retrogress westwards as the stratospheric warming continues.

T+120

T+240

And this has a knock on effect at the 100 hPa level with the reduction of the intensity of the Scandi trough and subsequent increase in intensity in the Canadian trough.

T+96

T+240

This is now a favourable scenario to allow blocking to our N/NE . And lo behold the blocking forecasts reinforce this.

So very strong pointers towards that easterly scenario.

c

[chionomaniac]

Last one on the strat from me today before I bore you all rigid!

This is to highlight how quick propagation of the warming and the zonal wind anomalies is occurring.

The temperature anomaly charts shows 2 phases of warming and a third is about to take place - but look how quickly this warming has propagated down to the troposphere - very effectively.

And the mean negative zonal winds are following quickly too;

c

[chionomaniac]

Morning all, latest ECM report.

Still no MMW this morning. As far as I can make out the mean zonal winds haven't reversed at 60ºN at 10 hPa yet. In fact they are not now forecast to do so but this may change. As I have mentioned before, at this stage this is just a technicality as the amount of reversal between 60-90ºN is considerable and will have the same effect.

Furthermore the forecasts still suggest a further series of warmings so the vortex disruption will likely occur for some time and we could still technically cross the MMW finishing line.

Propagation of the mean zonal winds still looks good but the vortex positioning slightly less favourable today ( heads towards UKMO scenario) so it may take a touch longer to get that easterly in place.

c

Edited January 29, 2010 by chionomaniac

[Glacier Point]

Initial warming is occuring over Siberia as the vortex stretches to almost breaking point, but how long will it remain there is a key question?

If we look at stratospheric ozone concentrations, we can see that the core build up is towards the Canadian Arctic and western Greenland, as it has been all winter largely:

http://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/gif_files/sbuv17_nh_latest.gif

upper tropospheric and stratospheric temperatures largely tie in with ozone concs., so perhaps we should see the warmth now being generated tranfer readily across Greenland towards Canada. Interestingly, blocking in this locale has the support of tropical forcing centred east of the Dateline.