Stratosphere Temperature Watch 2012/2013

[bluearmy]

looking at the latest day 10 charts on ncep, the vortex split at 100hpa is there from day 5 onwards. at day 10, its now showing at 70hpa. will it continue to work up as per the gfs op run has shown recently ? incidentally, the pressure of the aleutian ridge is displacing the stretched axis of the canadian chunk towards n greenland and the n atlantic. that is responsible for the extra energy coming our way in the modelling. if the split becomes more marked, i assume that this will retreat somewhat, allowing the atlantic ridge to be thrown further north and west.

[Suburban Streamer]

what i'm not understanding is this whole thing about a cold strat not being conducive to hlb.

my limited understanding tells me that the most fundamental part of a warming in the strat is the (lagged) effect it has on the vortex in terms or disruption/displacement. But if, through wave breaking etc, we manage to disrupt/displace/weaken the vortex then do we really need a warming if we can achieve disruption without?

From reading GP's posts, he seems to think the pv maybe on the brink of collapse by early december and bearing in mind the lag from any warming - it seems safe to say that if his progged severe weakening of the vortex by early december comes to frution, it won't have come about through warming?

And if thats the case then do we need to change the goalposts slightly and instead of saying u can't have prolonged HLB with a cold strat, change it to u can't have prolonged HLB with a strong vortex? Which isn't much different.

Most probably (as usual), i am looking at something very complex, in an extremely simplistic way!

[chionomaniac]

I think this sums it up well to date. The wave 2 activity looks set to wane, but the 12Z ECMWF from yesterday clearly shows wave 1 potentially on the up now. The 00Z GFS continues to show the vortex becoming very elongated by early December, if not still splitting and also with the pronounced region of warmth developing over Asia at the 30hPa as well. As ever this is clearly a long way off, but the more consistency then in theory the greater the risk of things developing like that.

Must admit given that the deterministic models are now coming into alignment (of sorts) with the ECMWF 32 day, I still find it hard to believe we are likely to progress towards a more meridional/blocked pattern by late November given the state of the strat. I guess it shows that despite a very active and cold strat, if other variables are counterbalancing it, then blocking and potentially colder weather is still possible.

M.

I think that we are still in infancy terms in respect of learning about the strat, Matt. There are certain things that we know that are more likely to happen. Periods of warming tend to lead to more tropospheric HLB's and periods of cold can lead to periods of Vortex Intensifications (VI's).

However, we also know that there are blocking precursors to SSW's (and therefore lesser events) and it is this that we should hope for over the coming weeks to disrupt the stratosphere.

http://www.columbia.edu/~lmp/paps/martius+polvani+davies-GRL-2009.pdf

[chionomaniac]

And another FI GFS split with the best forecast warming so far at 30 hPa.......

And to edit one of these is the correct shape.

Edited November 18, 2012 by chionomaniac

[bluearmy]

because he can - classic ed ! (actually i just crossed my legs)

[Duane S.]

what i'm not understanding is this whole thing about a cold strat not being conducive to hlb.

my limited understanding tells me that the most fundamental part of a warming in the strat is the (lagged) effect it has on the vortex in terms or disruption/displacement. But if, through wave breaking etc, we manage to disrupt/displace/weaken the vortex then do we really need a warming if we can achieve disruption without?

From reading GP's posts, he seems to think the pv maybe on the brink of collapse by early december and bearing in mind the lag from any warming - it seems safe to say that if his progged severe weakening of the vortex by early december comes to frution, it won't have come about through warming?

And if thats the case then do we need to change the goalposts slightly and instead of saying u can't have prolonged HLB with a cold strat, change it to u can't have prolonged HLB with a strong vortex? Which isn't much different.

Most probably (as usual), i am looking at something very complex, in an extremely simplistic way!

I think you make a very good point actually. I stand to be corrected, but I would say (in this situation, i.e. with a unmatured vortex) repeated wave breaking would be enough (again, depending on the wave type/strength etc), a warming would be a bonus. And yes your re-phrased sentence (you can't have prolonged HLB with a strong vortex) is technically more accurate than the former (you can't have prolonged HLB with a cold strat).

[tcc]

I think you make a very good point actually. I stand to be corrected, but I would say (in this situation, i.e. with a unmatured vortex) repeated wave breaking would be enough (again, depending on the wave type/strength etc), a warming would be a bonus. And yes your re-phrased sentence (you can't have prolonged HLB with a strong vortex) is technically more accurate than the former (you can't have prolonged HLB with a cold strat).

I think the difference this time is that the cold strat was not all the way through, which means any kind of warmth will have an effect.Obviously these minor warmings wouldn't have an effect if the strat/PV was in full force i.e very cold.

[MattH]

I think that we are still in infancy terms in respect of learning about the strat, Matt. There are certain things that we know that are more likely to happen. Periods of warming tend to lead to more tropospheric HLB's and periods of cold can lead to periods of Vortex Intensifications (VI's).

However, we also know that there are blocking precursors to SSW's (and therefore lesser events) and it is this that we should hope for over the coming weeks to disrupt the stratosphere.

http://www.columbia....es-GRL-2009.pdf

Agreed and thanks for the link, I'll take a look through it when I get chance...

Must admit despite the seasonal models, which like any model we would be wrong to ignore, I am certainly of the mindset that despite a vortex which has characteristics of this time last year, there is something 'different' about this year and of which, with time, will hopefully lead to the vortex being displaced or split.

I'm not one for stats and perhaps someone could correct me, but I would imagine it's difficult to find a set of stratospheric data which matches the current conditions which then continue throughout the coming 3 months without the vortex being disrupted at some point. May well seem simplistic, but again, I'm in the mindset, that given the variables which have been discussed in the last few months (expected QBO, Eurasion snow cover, SST's et al) that despite the current state of the vortex as the winter progresses it'll get beat down by a variety of features including the usual wave 1 and 2 activity and potential warming events etc.

Must admit I'm finding the consistent GFS Det quite interesting a longer range as well, of which you have highlighted again. Whilst some model runs may well do it, there has definitely been some consistency for this split to take place at approx the turn of the month, along with this warming 'event' situated over Asia, so it'll be very interesting to see if that consistency continues and actually becomes reality with time.

Quietly, I've got quite high hopes for this winter in terms of it not being a mild, wet, windy and zonal mess from start to finish.

Cheers, Matt.

[chionomaniac]

With regard to the GFS strat forecasts they have been remarkably consistent from T+240 onwards. However, we have now reeled both the distorted/split strat forecasts with corresponding warming into the ECM range. So, this week, I would hope to see some type of warming forecast at the 10/30 hPa level on the ECM as well as the NCEP charts on the cpc website.

If we see this, then a CW in December may not be out of the question and that final hurdle of a cold strat can be worked on.....

[phil nw.]

At the lowest level 100hPa

stretched but not yet broken.

We can see the ridging in the pattern over the Atlantic and the Pacific where the more pronounced block is modelled.

A nice chunk of vortex to our ne-we just need that split for some cross-polar heights and the floodgates will open.

[Glacier Point]

Must admit despite the seasonal models, which like any model we would be wrong to ignore, I am certainly of the mindset that despite a vortex which has characteristics of this time last year, there is something 'different' about this year and of which, with time, will hopefully lead to the vortex being displaced or split.

I'm not one for stats and perhaps someone could correct me, but I would imagine it's difficult to find a set of stratospheric data which matches the current conditions which then continue throughout the coming 3 months without the vortex being disrupted at some point.

Cheers, Matt.

... the final piece of the jigsaw slots in nicely.

For the observed and projected mean temperature profile for late November into December, with an assumed ridge (warmer) to the Northern Pacific region and cold core located to towards Greenland and NW siberia, our analogues are as follows:

Rolled forward, no great change suggesting a displaced vortex scenario.

[Catacol]

... the final piece of the jigsaw slots in nicely.

For the observed and projected mean temperature profile for late November into December, with an assumed ridge (warmer) to the Northern Pacific region and cold core located to towards Greenland and NW siberia, our analogues are as follows:

Rolled forward, no great change suggesting a displaced vortex scenario.

A little bit of stat research on these analogue years GP has identified. DJF Cets of those analogue years:

1970: 3.30

1983: 4.27

1996: 3.03

2003: 4.70

2009: 3.53

Looking at them overall a below average set of winters this with the exception of 2003. The 1960 - 2010 CET winter average Dec - Feb is about 4.28.

In all bar 2009 there is a trend for winter to get colder as it progresses though it is worth recognising that only 2 really "mild" months are present in any of these winters: Jan 83 which was the second warmest since 1960 and Dec 2002. These 2 mild months had a big bearing on the overall Cet of the years as listed above.

3 out of the 5 had Feb Cets of sub 3 degrees.

Of the total of 15 winter months here 11 of them fall below the 1960 - 2010 average.

My conclusion? I am not really a stats man, but having taken a look at the figures I am now putting a small wager on GP going for a cold winter, perhaps an overall CET of around 3.5 with an overall shape to it of a coldish December, a slightly milder January and then a potentially bone chilling February. I might get time later to take a look at Dec 02 and Jan 83 to see just why they were so mild. I am not skilled enough to be able to imprint any of the current ENSO/QBO/Solar/SST factors on top of this analogue, though I await GP's info on all this with real excitement.

EDIT: Jan 83 was a horrible month: high pressure in charge to the south throwing warm air at the UK with low pressure running west to east throughout. Yuck. Dec 2002 much more interesting: a really "nearly" month with blocking to the east and a good number of days under an easterly. Last 10 days saw the mild win out, and the overall monthly temp rather skewed after a pretty cold first 20 days or so.

Edited November 18, 2012 by Catacol_Highlander

[MattH]

I wish this chart was at T+24hr !

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121119/00/384/npst30.png

Still out in the far reaches of no-mans-land, but still, as discussed yesterday it is certainly showing some consistency.

12Z ECMWF from yesterday out to 240hr not as interesting, as yet, but potential for wave 1 and 2 activity, the latter peaks in the next few days then declines before potentially re-developing at day 10;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha1_f216.gif

Still plenty of potential in time...

Matt.

NB: The 00Z GFS Det at surface levels evolves a synoptic pattern which has similarities to Nov/Dec 2010 late in the run...

[bluearmy]

The wave 2 stuff is upgraded in the short term and the strengthening of the zonal wind thereafter looks less convincing than recent runs. we have a split showing at the bottom of the strat on ecm or the first time. cant see the ultra consitent gfs fi 30hpa forecasts being so wrong and if correct, we have much to keep us interested over the next few weeks and possibly beyond.

[AWD]

If I read these charts right, looks like a signal for a decent warming over the Pacific side of higher Strat levels;

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t70_nh_f240.gif

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t100_nh_f240.gif

[bluearmy]

starting to 'snowball' now (pardon the pun!).

find me a depressing chart this morning (current mid strat temps aside)

Ed's 'monkey nuts' a plenty on the ncep heights output

Edited November 19, 2012 by bluearmy

[UV-RAY]

starting to 'snowball' now (pardon the pun!).

find me a depressing chart this morning (current mid strat temps aside)

The days still young ba, give it a few more runs and I'm sure we'll see some.

[Glacier Point]

Consider a 20 day time lag from strong ridge development through to wave 2 activity registering in the stratosphere..

Current GFS projection at 30mb

Pattern centred on 20 days previous

This would appear to correlate with the stratospheric ridges, more particularly North Pacific.

Rolled forward another 5 days, should we look for the angle of attack to change, perhaps from a ridge originating in Siberia ?

Before another wave (wave 2) of attacks in the North Pacific timed for mid December based on current GFS ensemble means ?

Questionable how much of a vortex will be left by then.

Following this through..

The 1st wave 2 attack is now registering for the 20 day lag centred on 30th November. GFS 06z showing a massive ridge penetrating the Arctic at 30 hPa.

The possibly modification of the angle of ridge showing up at the end of the GFS run:

If we were right about the wave 2 activity (and so far this looks like an extremely good call and therefore excellent 'tool' added to our kit bag), then no reason to suggest that the continued disruption of the vortex throughout December will take place (possibly with a reduced level of 'forcing' as the +AAM signal diminishes a touch).

That in itself sets an interesting prospect - further tropospheric feed back and development of Aleutian low in response to hemispheric realignment - more wave 1 activity (vortex displacement) into January ?

[Bristawl Si]

Following this through..

The 1st wave 2 attack is now registering for the 20 day lag centred on 30th November. GFS 06z showing a massive ridge penetrating the Arctic at 30 hPa.

The possibly modification of the angle of ridge showing up at the end of the GFS run:

If we were right about the wave 2 activity (and so far this looks like an extremely good call and therefore excellent 'tool' added to our kit bag), then no reason to suggest that the continued disruption of the vortex throughout December will take place (possibly with a reduced level of 'forcing' as the +AAM signal diminishes a touch).

That in itself sets an interesting prospect - further tropospheric feed back and development of Aleutian low in response to hemispheric realignment - more wave 1 activity (vortex displacement) into January ?

Great thread this one - learning something new all the time - i don't profess to understand everything though!

Seems like you're building to a good winter forecast - when is it going to be published? Cheers BB

Edited November 19, 2012 by Bristle boy

[Glacier Point]

Forecast will be filmed this week, available some time after.

[BLAST FROM THE PAST]

The SH event has shown that repeated wave activity has assisted the ozone transpost from the tropical stratosphere to the SH polar stratosphere.

Here is the 2003 SH wavenumber 1 pattern for that year:

And the early winter wavenumber 1 pattern NH 2003.

- hopefully we see something similar this year.

C

Are we seeing this? BFTP

Edited November 19, 2012 by BLAST FROM THE PAST

[Rollo]

Forecast will be filmed this week, available some time after.

Looking forward to it GP, like Bristol Boy I am learning but in my case very slowly,thanks for your great input.

[FrenchScotPilot1]

I think that we are still in infancy terms in respect of learning about the strat, Matt. There are certain things that we know that are more likely to happen. Periods of warming tend to lead to more tropospheric HLB's and periods of cold can lead to periods of Vortex Intensifications (VI's).

However, we also know that there are blocking precursors to SSW's (and therefore lesser events) and it is this that we should hope for over the coming weeks to disrupt the stratosphere.

http://www.columbia....es-GRL-2009.pdf

Very interesting read. For some reasons I thought SSW lead to HLB (and not the other way around) but once again it all seem connected.

Blocks look like a good ingredient for SSW which in turn reinforce the blocks, however not all blocks end up in SWW. As usual it depends on conditions.

The same way as we need low level and high level vorticity anomalies to be positioned exactly right with each other to lead to their coupling and explosive cyclogenesis.

So complex but yet extremely fascinating!

Edited November 19, 2012 by FrenchScotPilot1

[snowking]

C

Are we seeing this? BFTP

Just quickly to comment on o-zone levels

http://exp-studies.tor.ec.gc.ca/ozone/images/graphs/gl/current.gif

Starting to see increases all around really, less depletion over the tropics, and a slow increase across the northern mid latitudes

Still down overall in terms of anomaly

http://exp-studies.tor.ec.gc.ca/ozone/images/graphs/gl_dev/current.gif

But that's a lot better than it had looked.

O-zone depleting over the southern polar regions fairly rapidly which is expected but still promising in the fact that hopefully it means the BDC is getting to work to aid the northern hemisphere

SK

[Cloud 10]

Forecast will be filmed this week, available some time after.

Filmed on location perhaps?