Stratosphere Temperature Watch 2012/2013

[Glacier Point]

No suprise to see the longer range ECM signalling a rise in pressure to the North and lowering pressure to the south. This is not related to the stratosphere but the lead up to this around mid month (troposperically) will likely have a significant on the stratosphere during the first week December.

A strong build of pressure over Eastern Europe and Western Russia has a teleconnective influence on Wave 2 activity and I'd be very suprised if we didn't see strong wave 2 response in the stratosphere during early December (wave 2 being more responsible for vortex splits). That places us around late December for a stratospheric influenced pattern.

[and wouldn't you know it, we have another tropical wave favouring high latitude blocking mid January - good trop / strat / trop/ strat feedbacks]

Edited November 6, 2012 by Glacier Point

[bluearmy]

No suprise to see the longer range ECM signalling a rise in pressure to the North and lowering pressure to the south. This is not related to the stratosphere but the lead up to this around mid month (troposperically) will likely have a significant on the stratosphere during the first week December.

A strong build of pressure over Eastern Europe and Western Russia has a teleconnective influence on Wave 2 activity and I'd be very suprised if we didn't see strong wave 2 response in the stratosphere during early December (wave 2 being more responsible for vortex splits). That places us around late December for a stratospheric influenced pattern.

stewart, i presume thare remains a decent chance that the current cold upper strat will propogate down and lead to a more mobile period following the potential colder spell early dec and possibly again late dec early jan as you referred to in your post. otherwise it seems we are only taking the blocked bits from any strat influence and ignoring the mobile bits.

[Glacier Point]

Nick, for any downwelling cold strat influence we need a strong thermal gradient across the tropical and polar stratosphere. At levels below 50 hPa, we don't have this, so any possible signal at 10hPa and 30hpPa is fighting to get through.

Add to that, the lag time for downwelling is 21 days. That takes us to end of the month, when as if luck would have it, the tropopsheric teleconnectors are signalling -NAO. It would be logical to assume that the lower stratosphere would also favourably respond given light polar westerlies.

If you take last year and this year, you have a classic case study as to why an early season cold vortex event can succeed (La Nina and strong solar activity) and why it finds it very hard to engage to lower levels (ENSO neutral / low solar / second season east QBO).

[geoffw]

so GP, are you saying we could have a winter like 62/63 influenced by the stratosphere?

[johnholmes]

Geoff

2+2=4 not any number you think of!

[Liam J]

so GP, are you saying we could have a winter like 62/63 influenced by the stratosphere?

How did you arrive at this??

[Severe Siberian icy blast]

No suprise to see the longer range ECM signalling a rise in pressure to the North and lowering pressure to the south. This is not related to the stratosphere but the lead up to this around mid month (troposperically) will likely have a significant on the stratosphere during the first week December.

A strong build of pressure over Eastern Europe and Western Russia has a teleconnective influence on Wave 2 activity and I'd be very suprised if we didn't see strong wave 2 response in the stratosphere during early December (wave 2 being more responsible for vortex splits). That places us around late December for a stratospheric influenced pattern.

[and wouldn't you know it, we have another tropical wave favouring high latitude blocking mid January - good trop / strat / trop/ strat feedbacks]

Gp, I could listen to you all day long, that's very interesting times ahead, so the Russian high isn't A result of strat conditions, is it the mjo phasing 8-1 later that points to the high anomalies? But it's the high that has a knock on affect later on by causing the wave breaks into the strat?

[chionomaniac]

I think that the main thing that we are learning this autumn is how favourable tropospheric patterns can delay the prevailing onslaught from the underlying (upper) stratospheric conditions - but we really need a host of factors together for this.

GP, I had looked at the temperature differential at the lower strat level previously, but had thought that this year did not look too different in that respect to other years, and had therefore discounted this as an influential factor. Is this not the case or have I misread this?

Otherwise I see signs that the mean zonal negative winds are encroaching further down the strat - will that wave activity pick up enough before they influence too much?

(PS not had time to look at your winter thoughts video yet - will hopefully do so later)

[summer blizzard]

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

Not strictly stratospheric but we got the second lowest October Ao value on record losing out to 2009 by 0.024.

August and September values were also close.

[MattH]

Without sounding like a stuck record, I do believe we really are in unknown territory, so-to-speak, so far this season. From the charts and information I keep looking at, there continues to be a major split down the middle in terms of how it may go. I did produce a blog last week stating that I thought the cold upper strat temps would have an impact on the troposphere with time and personally I believe that is the way it will go.

Clearly, compared with some in this thread, I am not that knowledgeable about the subject in question. That being said, in my opinion, I find the ECM 32 outcome hard to imagine by the end of November and into early December without a major re-shuffle of the 'cards'. At the moment at least, there are a lot of factors stacked against a progression towards more blocked conditions by the start of December and whilst I do have faith in the ECMWF model, that 4 week block is always subject to weekly changes simply because it is 4 weeks away etc.

I have a feeling this coming winter may well end up noteworthy, but it'll take time. It won't be an 09/10 style setup, or not going off what is developing at the moment. Clearly, and again, there are many factors which point towards the potential development of more blocked conditions and a greater risk of cold outbreaks, but I can't help think now that if this is to happen this winter it may well be during the latter half of December or into January. I think this idea has been echoed in some previous posts as well.

As ever not having a clear-cut outcome/idea at this stage is certainly making for an interesting time, albeit frustrating, and in a way we could all end up being wrong, but at the moment my money is on a zonal spell developing and persisting through the end of November and well into December, before potential changes then take place as December progresses.

Regards to all.

Matt.

[chionomaniac]

Can't really disagree with that Matt - except for the mass of conflicting tropospheric signals!

We have said (and GP has also confirmed above) that it appears that the troposphere is controlling the atmosphere presently, whilst the upper stratospheric coil is tightened unrelentingly. I do wonder how much the descended eQBO influences matters - after all we have seen a descended wQBO inhibit matters and encourage the cooling strat to downwell last winter - so why not the opposite this year?

Without the wave breaks that coil is likely to be sprung from above. It is like the race between the tortoise and the hare - but who will win? ( Give me some sleeping tablets - aka wave breaks for the hare!)

[Snowman.]

Yep.. not a lot to inspire us at the moment, was trying some reverse psychology.. iirc - Think Matt said the ECM 32 final long term out look was due on the 8th. Reminds me of a post from the AmWx thread.

What's the Strat Doing?.... it's all cold and Vortexy.

It looks like it's trying warm up a tad but I suspect it usually does this...

[Snowman.]

so GP, are you saying we could have a winter like 62/63 influenced by the stratosphere?

Wow that escalated quickly!

[Duane S.]

Can't really disagree with that Matt - except for the mass of conflicting tropospheric signals!

We have said (and GP has also confirmed above) that it appears that the troposphere is controlling the atmosphere presently, whilst the upper stratospheric coil is tightened unrelentingly. I do wonder how much the descended eQBO influences matters - after all we have seen a descended wQBO inhibit matters and encourage the cooling strat to downwell last winter - so why not the opposite this year?

Without the wave breaks that coil is likely to be sprung from above. It is like the race between the tortoise and the hare - but who will win? ( Give me some sleeping tablets - aka wave breaks for the hare!)

I can't help thinking the easterly QBO may well be the main (probably amongst several others, to varying different degrees) reasons that the stratosphere is not able to influence the troposhere, i.e. as in late autumn / early winter 2011 (yet... !).

I may be taking this out of context but I remember reading that there are no real discernable differences in solar MAX or MIN years when an eQBO is present and that the same applies in solar MAX years whether there is a wQBO or eQBO.

Enso is in a fairly neutral state but possibly even less connected as we are in an e-QBO. MJO low amplitude.

Conclussions?? Goodness only knows but it would seem logical (I'm aware it is a very simplisic take) that the QBO could be offering up a direct opposing force to the descending zonal westerlies right now?

[MattH]

Just a quick one, but the GFS 30hPa chart on the Netweather site continue to provide a far more promising outlook beyond the 21st of November in particular, especially if you compare;

this... - http://cdn.nwstatic.co.uk/gfsimages/gfs.20121107/00/372/npst30.png

with this - http://cdn.nwstatic.co.uk/gfsimages/gfs.20121107/00/57/npst30.png

Perhaps just 'something and nothing', but time'll tell. Could class this post as clutching at straws as well given the variety of other forecast data.

M.

[bluearmy]

Yesterday's ECM run took zonal wind forecast above 30m/s at 30 hpa for the first time this season. For the time being, it seems that most of this energy is headed towards 30-60N. Lets hope there is a brake on this soon. I know what Stewart posted yesterday but I also know that this game is full of surprises!

[chionomaniac]

I am going to jump off the fence. Now 60/40 split in favour of more +ve AO start to winter.

[phil nw.]

I am going to jump off the fence. Now 60/40 split in favour of more +ve AO start to winter.

Having had a glance through the ECM forecasts i can see why Ed.

Any signs of wavebreaking are minor and as Nick said above the increase in mean zonal winds is filtering further down.

The 00z dailly 500hPa outputs seem to reflect this trend.

[claret047]

I am going to jump off the fence. Now 60/40 split in favour of more +ve AO start to winter.

Hello Chionomaniac.

Sorry to be dumb, but is that good or bad for the lovers of cold weather?

kind Regards

Dave

[chionomaniac]

Hello Chionomaniac.

Sorry to be dumb, but is that good or bad for the lovers of cold weather?

kind Regards

Dave

It's bad for cold and to a certain extent is going against the met office extended forecasts and GP's forecast wave 2 break at the end of the month.

With a positive AO we have a stronger polar vortex and more zonal weather ( west to east ) rather than meridional ( south to north or north to south).

Edited November 7, 2012 by chionomaniac

[sebastiaan1973]

I am going to jump off the fence. Now 60/40 split in favour of more +ve AO start to winter.

To change the cooling temperatures in the stratosphere we need to see some tropospheric input for that. The Long Term weather charts are different every day. Till now I don't see deep North Pacific Low (except GEM0h). Perhaps I'm naieve but I believe in the SAI/ increased BDC and it has some time needed to come to full effect. In 10 days a lot can happen.

It's not like 2009/10. Perhaps we have to wait a little bit longer.

Edited November 7, 2012 by sebastiaan1973

[bobbydog]

Just a quick one, but the GFS 30hPa chart on the Netweather site continue to provide a far more promising outlook beyond the 21st of November in particular, especially if you compare;

this... - http://cdn.nwstatic..../372/npst30.png

with this - http://cdn.nwstatic....0/57/npst30.png

Perhaps just 'something and nothing', but time'll tell. Could class this post as clutching at straws as well given the variety of other forecast data.

M.

i was looking at those charts today, (before i read your post) along with the NH H500 & SLP charts. there does seem to be fairly good agreement between the models of a pattern shift after the next 2 weeks, which is what prompted me to look at the strat charts.

for better or worse remains to be seen but i dont see the models leaning towards a stronger vortex. i think the 06Z does but none of the previous runs do, nor any of the major models.

maybe hinting at a split vortex? (i think GP mentioned cross-polar ridging somewhere)

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=7&ech=204&size=0

[FrenchScotPilot1]

One thing I fail to get my head round is what causes the warming in the stratosphere from dissipation of planetary waves.

Ok the Rossby waves interact with the mean westerlies in the vortex but given the right circumstances why does this cause a warming? I've read the waves descend in the vortex and cause adiabatic compression but I still don't see it...

And during the summer, when the vortex is easterly, why are the waves not able to penetrate it?

It seems to be a bit of a mind puzzling situation just now but great professional posts guys, it is fascinating.

Stephane

[bluearmy]

I am going to jump off the fence. Now 60/40 split in favour of more +ve AO start to winter.

i think there are enough trop model indications that renewed greeny ridging is probable for the final third of november. it could well be thet we receive an early dose of winter late nov/early dec followed by a more mobile zonal period influenced by the current cold upper/mid strat. stewart seemed to think that trop events later this month would lead to strat developments that would feed back to the trop for late december. therefore, your zonal start to winter could well be several weeks of december and that wouldnt necessarily contradict GP too much ??

[chionomaniac]

One thing I fail to get my head round is what causes the warming in the stratosphere from dissipation of planetary waves.

Ok the Rossby waves interact with the mean westerlies in the vortex but given the right circumstances why does this cause a warming? I've read the waves descend in the vortex and cause adiabatic compression but I still don't see it...

And during the summer, when the vortex is easterly, why are the waves not able to penetrate it?

It seems to be a bit of a mind puzzling situation just now but great professional posts guys, it is fascinating.

Stephane

Hi Stephane and welcome.

I have always though it has been a mixture of adiabatic compression, diabatic transfer of heat from outside the polar vortex - through the surf zone, frictional heat and influx of ozone.

Surely during summer the waves dont enter because the thermal difference isn't strong enough to create Rossby waves strong enough to deflect that far?