Stratosphere Temperature Watch 2012/2013

[bluearmy]

This warming is definitely something for later on in winter - I am more concerned with the upcoming split, presently.

we know from experience that a split may not always leave the bits in a favourable position ed. the extended gfs op runs are hinting at a more displaced reformed vortex post this split. i suspect its not worth looking that far ahead until the split story is clear.

[garbagebags]

Would I be right in thinking that the "default" for the PV is that it "wants to be" a nice tight circle around the Arctic and only when it is poked and prodded by high pressures does it "bulge" out? A bit like a water balloon. And then it trys to spring back? Would that be right?

[Radiating Dendrite]

Would I be right in thinking that the "default" for the PV is that it "wants to be" a nice tight circle around the Arctic and only when it is poked and prodded by high pressures does it "bulge" out? A bit like a water balloon. And then it trys to spring back? Would that be right?

Sounds a good analogy to me.

I think the holy grail is when the water balloon bursts!

[bluearmy]

the fi gfs op 30 hpa forcasts have the split vortex (stronger on the asian side) coming back together (though stretched) and the canadian side pivoting in our direction as the warming the other side of the hemisphere displaces the whole thing towards the atlantic.

is this maybe the reason for the mobility showing up in the trop to our north in late week 2 gfs op runs ?

[chionomaniac]

the fi gfs op 30 hpa forcasts have the split vortex (stronger on the asian side) coming back together (though stretched) and the canadian side pivoting in our direction as the warming the other side of the hemisphere displaces the whole thing towards the atlantic.

is this maybe the reason for the mobility showing up in the trop to our north in late week 2 gfs op runs ?

Probably, but (experience shows ) that I would still take the positional placement and any vortex reformation with a large pinch of salt at this stage. I have seen the reverse occur following a split - notably Feb 2009 when initially the vortex wasn't modelled to hang around the east of Canada until much later on.

Still happy with this at 70 hPa

And it's moving on up!

Edited November 20, 2012 by chionomaniac

[sub zero]

An increasingly west based NAO then come Feb? Hmmm - best hope for some intrusion from the Beast then...

On a "help me" please note GP - you said in an earlier post that a west based NAO was not a problem in Dec but could be a problem in Feb. I understand the potential synoptics of a western based NAO but am a bit puzzled by the month vs month distinction. Can you elaborate a bit?

I think GP is saying the vortex is ridging towards Canada, so low heights in eastern Canada..

I dont believe this wouldnt give us a west based NAO..

maybe GP can clarify

[Glacier Point]

Worth speculating on position of the post split vortex scenario..

First thing is that the initial split may not be the end of it. We've seen wave 2 showing some unpredictability and I suspect we've not bottomed out on vortex splitting, probably not until around 5th December will have the full picture (that's an awful long way out).

Thereafter, the general trend to take the warm plume over the North Pacific in towards Canadian sector looks very plausible and is the one I would go for. That means any reformed (and weaker) pv will be displaced towards Greenland, Svalbard, Barents. Curiously, the trospheric response may actually be for ridging in these areas as the dominant ridge over Canda disrupts the flow over N. America locking down the -NAO pattern. Even if it is west based, December's wavelengths tend to favour an elongation of the ridge across to Iceland preventing the returning southerly jet from pivoting northward in the Atlantic.

Edited November 20, 2012 by Glacier Point

[Catacol]

Worth speculating on position of the post split vortex scenario..

First thing is that the initial split may not be the end of it. We've seen wave 2 showing some unpredictability and I suspect we've not bottomed out on vortex splitting, probably not until around 5th December will have the full picture (that's an awful long way out).

Thereafter, the general trend to take the warm plume over the North Pacific in towards Canadian sector looks very plausible and is the one I would go for. That means any reformed (and weaker) pv will be displaced towards Greenland, Svalbard, Barents. Curiously, the trospheric response may actually be for ridging in these areas as the dominant ridge over Canda disrupts the flow over N. America locking down the -NAO pattern. Even if it is west based, December's wavelengths tend to favour an elongation of the ridge across to Iceland preventing the returning southerly jet from pivoting northward in the Atlantic.

Ah - thank you. I think I understand this - use of the word "ridge" in your previous post had me a bit confused with the vortex diagram compared to what I was expecting to hear based on recent comments. Do I assume then that tropospheric wavelengths tend to shorten as winter moves forward?

A vortex displaced to Greenland/Svaalbard combined with tropospheric blocking underneath in the same region has my head spinning a bit. That sounds like a potential setup for a recurrent pattern of northerlies and occasional easterlies through Dec/Jan as we sit in the eddy of that blocking canadian/greenland high, with Feb a 50/50 month alternating between siberian driven easterlies and occasional mild south westerlies. This assumes the warming over Canada that you are hinting at.

I am a self confessed novice, but I am starting to wonder if we are on course for the coldest overall winter in a while. Coldest since 95/96? Maybe colder?

[Vertical Limit]

Worth speculating on position of the post split vortex scenario..

First thing is that the initial split may not be the end of it. We've seen wave 2 showing some unpredictability and I suspect we've not bottomed out on vortex splitting, probably not until around 5th December will have the full picture (that's an awful long way out).

Thereafter, the general trend to take the warm plume over the North Pacific in towards Canadian sector looks very plausible and is the one I would go for. That means any reformed (and weaker) pv will be displaced towards Greenland, Svalbard, Barents. Curiously, the trospheric response may actually be for ridging in these areas as the dominant ridge over Canda disrupts the flow over N. America locking down the -NAO pattern. Even if it is west based, December's wavelengths tend to favour an elongation of the ridge across to Iceland preventing the returning southerly jet from pivoting northward in the Atlantic.

Hi GP, in view of the lastest ECM32 day output (from Matt Hugo) which hints at a more zonal/mild pattern to emerge mid december onwards, are you suggesting the opposite may ocurr or at least it might be a continuation of the blocked pattern that looks likey to be inplace by early December. I think you may be but I'm not 100% sure!

[Glacier Point]

I can buy the idea of some moderation in the 'tropospheric fire' as the +AAM signal peters out although our analogue guidance tends to keep the colder pattern for longer and plotting a course through a period of intense pressure on the stratosphere from beneath is going to be higly problematic. However, stratospherically, I suspect we'll be kept glued to developments because the instant the upstream ridge decline / movement poleward takes place, that will be the cue to wave 1 activity which will set the clock ticking for the next phase of intense blocking centred on mid January through early February.

Edited November 20, 2012 by Glacier Point

[bradymk]

Hi GP, in view of the lastest ECM32 day output (from Matt Hugo) which hints at a more zonal/mild pattern to emerge mid december onwards, are you suggesting the opposite may ocurr or at least it might be a continuation of the blocked pattern that looks likey to be inplace by early December. I think you may be but I'm not 100% sure!

sorry to be a bit off topic for this post mods but just wanted to add to vertical limits post where he said mild mid december onwards. Matt did actually say he thinks that it may turn colder later on december rather than mild mid month onwards.

[Don]

I can buy the idea of some moderation in the 'tropospheric fire' as the +AAM signal peters out although our analogue guidance tends to keep the colder pattern for longer and plotting a course through a period of intense pressure on the stratosphere from beneath is going to be higly problematic. However, stratospherically, I suspect we'll be kept glued to developments because the instant the upstream ridge decline / movement poleward takes place, that will be the cue to wave 1 activity which will set the clock ticking for the next phase of intense blocking centred on mid January through early February.

Hi GP, sorry a bit of topic, but do you see the recent increase in solar activity having any bearing on your winter thoughts at the moment?

[chionomaniac]

Winter 62/63 and 78/79 began with a Canadian warming (anybody got data for 46/47)

In my root around for information I found this old thesis - nice clear explanation of the processes involved for someone, like me, new to the subject.

http://www.dtic.mil/.../u2/a227731.pdf

I woud say that the definition given (in this paper) for a SSW (or MMW) has been superceded by Polvani et al.

That is a reversal of mean zonal mean winds at 10 hPa and 60N from westerly to easterly. Once this has occurred then a SSW cannot be declared 20 days prior to or after that date. I can put up the papers from Polvani when I get home if anyone would like further reading.

I like the definition of Canadian warming ( but don't know if Polvani has subsequently reclassified that), but also think that any warming greater than 25C that does not cause a SSW can be classified as a minor warming.

[Glacier Point]

Such a lot to keep tabs on at the moment. This stratospheric vortex has really had a hard life. First it can't manage to propogate downwards. Then it gets nibbled and then munched by wave 2 activity. Then a warm plume develops over the Pacific which may or may not work its way towards the Canadian sector. Then we have a large increase in westerly winds over 30-40N which might further enhance tropaves and wave 1 and wave 2 actvity in the next 2-3 weeks.

Then, up pops GFS12z which increases temps at the very edge of the stratosphere by 20C in the space of a day or two over Asia at the extende range. Over the top ?

[Isolated Frost]

Such a lot to keep tabs on at the moment. This stratospheric vortex has really had a hard life. First it can't manage to propogate downwards. Then it gets nibbled and then munched by wave 2 activity. Then a warm plume develops over the Pacific which may or may not work its way towards the Canadian sector. Then we have a large increase in westerly winds over 30-40N which might further enhance tropaves and wave 1 and wave 2 actvity in the next 2-3 weeks.

Then, up pops GFS12z which increases temps at the very edge of the stratosphere by 20C in the space of a day or two over Asia at the extende range. Over the top ?

One could suggest that the GFS 12z would really disrupt any previous GLAAM and Mountain Torque readings with this predicted warming?

[AWD]

The GFS is continuing its trend of a warming over the Pacific side of the vortex;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121120/12/276/npst30.png

Shifting it towards Canada eventually;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121120/12/384/npst30.png

Interesting times ahead!

[chionomaniac]

Such a lot to keep tabs on at the moment. This stratospheric vortex has really had a hard life. First it can't manage to propogate downwards. Then it gets nibbled and then munched by wave 2 activity. Then a warm plume develops over the Pacific which may or may not work its way towards the Canadian sector. Then we have a large increase in westerly winds over 30-40N which might further enhance tropaves and wave 1 and wave 2 actvity in the next 2-3 weeks.

Then, up pops GFS12z which increases temps at the very edge of the stratosphere by 20C in the space of a day or two over Asia at the extende range. Over the top ?

That CW could still be a good call yet - just a little delayed.

[chionomaniac]

I woud say that the definition given (in this paper) for a SSW (or MMW) has been superceded by Polvani et al.

That is a reversal of mean zonal mean winds at 10 hPa and 60N from westerly to easterly. Once this has occurred then a SSW cannot be declared 20 days prior to or after that date. I can put up the papers from Polvani when I get home if anyone would like further reading.

I like the definition of Canadian warming ( but don't know if Polvani has subsequently reclassified that), but also think that any warming greater than 25C that does not cause a SSW can be classified as a minor warming.

Polvani's SSW papers

http://www.columbia.edu/~lmp/paps/charlton+polvani-JCLIM-2007.pdf

http://www.columbia.edu/~lmp/paps/charlton+polvani+etal-JCLIM-2007.pdf

[cooling climate]

Below is a chart showing the zonally averaged zonal winds at

high latitudes in the stratosphere and as you can see easterly

winds are starting to develope in the higher troposphere and into

the lower strat at 80-90 latitude north with more neutral zonal

winds extending a lot further south than they were several days

ago. I would expect to see some stratosphere warming starting to

show up in the next few days.

[chionomaniac]

Stratospheric warming has been showing up for the best part of a week, cc, so I'd be concerned if it didn't show up in the next few days!

Latest

Edited November 20, 2012 by chionomaniac

[Glacier Point]

Something else going on at 1 hPa not obviously related to lower level developments..

GFS again going for a rapid rise in temperatures towards early December over Russia..

2nd December

6th December

We saw last year warming pools in this area move their way into the Pole.

[Dampdorset82]

Something else going on at 1 hPa not obviously related to lower level developments..

GFS again going for a rapid rise in temperatures towards early December over Russia..

2nd December

6th December

We saw last year warming pools in this area move their way into the Pole.

How will this affect the pattern? will this increase or decrease the potential for cold? Thanks

[MattH]

Morning, just a quick summary, but it's looking good!...Few charts that stand out;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha1_f240.gif - Wave 1 really gets going by D10 from yesterday 12Z ECM.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif - Signs of Wave 2 making a come back as well still.

The broader pattern towards a split by the end of November into early December remains and the warming event continues to grow as well.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf30f240.gif

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf50f240.gif

If you flick through the zonal mean wind charts as well there is definitely a reduction in speeds between say 50N and 80N towards the end of the forecast period;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=u&lng=eng#fig11

10hPa and 30hPa zonal wind at 60N signaled to decrease with time by early December;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=fluxes&alert=1&lng=eng

There's not much sign of any significant warming yet, but I presume that will take place with time once the above factors get to work, but from what I can see of the 12Z ECM from yesterday's it maintains good consistency with the GFS model and clearly there are plenty of variables there which are likely to really nibble away at the vortex come the turn of the month. All good signs from what I can tell!...

Regards to all,

M.

[BLAST FROM THE PAST]

Can anyone shed light on whether the stratos and tropos are behaving similar to autumn 2002?

BFTP

[Suburban Streamer]

Can anyone shed light on whether the stratos and tropos are behaving similar to autumn 2002?

BFTP

not had a look myself but this link gives u plenty of info to compare with - just select the year and variable....

http://acdb-ext.gsfc...t/ann_data.html

Edited November 21, 2012 by Suburban Streamer