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Stratosphere Temperature Watch 2012/2013


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post-12276-0-40650600-1356784922_thumb.p

I honestly struggle to see how the stratospheric vortex will be maintained by the end of January- Brickfielder's post a while back highlighted the different scenarios, it's possible we could go through them all- propagation into the tropo-vortex would then become the crux of the analysis in the next few weeks

`

It's having one last laugh now, but it's about to get torn apart... whether we get lucky or not is another question, but isn't it fun watching it crumble alone?!

This is a displacement SSW right? just want to make sure I am getting this right.

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post-12276-0-40650600-1356784922_thumb.p

I honestly struggle to see how the stratospheric vortex will be maintained by the end of January- Brickfielder's post a while back highlighted the different scenarios, it's possible we could go through them all- propagation into the tropo-vortex would then become the crux of the analysis in the next few weeks

`

It's having one last laugh now, but it's about to get torn apart... whether we get lucky or not is another question, but isn't it fun watching it crumble alone?!

BTW can we use this graphic for a blog? How should we credit it if so?

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Just by viewing these temperature charts we can see the warming filtering down to the lower levels

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

with consequent reduction and then reversal in the Zonal Winds

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

Good to see the warming getting down to the trophosphere by day 10.

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A couple of thoughts as we stand on the brink of a major mid winter warming..

The last few GFS runs have pointed towards a large junk of the residual split vortex centred initially over Hudson Bay with a general trend to retrogress this as the entire upper and middle stratosphere demonstrates a negative (westward) gyre. 12z t300 a good depiction of this.

post-2478-0-31966600-1356815181_thumb.jp

That suggests a large poleward flux of ozone through the North Atlantic around the eastward flank of the cut off vortex from the mid and low latitudes as colder air is pulled into the tropical stratosphere. The last few runs indicating warming around Greenland are consistent with ozone flux.

The question arises how quick if any will the propagation be of -ve zonal wind anonalies ?

I suspect the answer to this may be quicker than a conventional event given the state of the atmosphere ahead of the warming lower down in the mid and lower stratosphere and troposphere and the trospheric longwave pattern projected days 11-15.

If we look at zonal wind anomalies there is a persistence of -ve zonal wind anomalies.

post-2478-0-85609700-1356815108_thumb.jp

That means less wind shear for any wave working its way down.

The programmed GEFS mean height anomaly pattern for days 11-15 depicts a developing -ve EPO pattern with a ridge over the NE Pacific extending into Alaska and troughing into the mid West USA and Canada with +ve heights over the mid Atlantic.

post-2478-0-64735100-1356815136_thumb.jp

That largely coincides with the 10hPa GPH forecast for around day 13, meaning that the trosphere doesn't have to move much towards the upper level flow.

An instant tropospheric reaction to the warming is possible, but perhaps we should be focussing more around days 10-14 following the warming (5th Jan) for the first real impact ?

That would also be my interpretation for the first real impacts on the 500 synoptics which would roughly

take us to the 15th-20th and by which time we could as you say be in quite a favorable position from

the off.

I must admit the prospects are quite mouth watering but to early in the day for any serious speculation.

Edited by cooling climate
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I still feel that the 500 mb charts will start to show a marked change in the pattern from that currently in about 2-3 days time. So I would suspect, using my very simplified idea from the Stratosphere spike of 23 December, that by 14-17 January we MAY see blocking starting to show up.

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Wonderful wonderful trend in FI tonight. That warming over Greenland in the split displaced vortex couldn't be better positioned. How close will the forecast be to verification I wonder.

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121229;time=18;ext=384;file=npst10;sess=a4811469fcc97c4e3d2740800927b9bb;

I sense that the model thread will be getting busy again............

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Wonderful wonderful trend in FI tonight. That warming over Greenland in the split displaced vortex couldn't be better positioned. How close will the forecast be to verification I wonder.

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121229;time=18;ext=384;file=npst10;sess=a4811469fcc97c4e3d2740800927b9bb;

I sense that the model thread will be getting busy again............

Something i have noticed is the temp forecast tend to be pretty consistent in general locale but the heights forecast varies run to run after approx day 11.

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The latest ECM run has the SSW on the 5th, with mean windspeeds a little slower than previous runs, but nevertheless still easterlies.

http://maidenerleghw...r.com/strat.php

Very very nearly a technical SSW on the 4th ! Nice to see the consistency in the forcast though. It's been showing as the 5th, give or take a day or two, for quit a while now and never really wavered.

Edited by s4lancia
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I think it's quite remarkable we get a SSW. Posted Image

Recent studies have suggested that El Niñoâ€Southern Oscillation (ENSO) may have a considerable impact on

Northern Hemisphere wintertime stratospheric conditions. Notably, during El Niño the stratosphere is warmer than

during ENSOâ€neutral winters, and the polar vortex is weaker. Oppositeâ€signed anomalies have been reported during

La Niña, but are considerably smaller in amplitude than during El Niño. This has led to the perception that El Niño is

able to substantially affect stratospheric conditions, but La Niña is of secondary importance. Here we revisit this

issue, but focus on the extreme events that couple the troposphere to the stratosphere: major, midâ€winter stratospheric

sudden warmings (SSWs). We examine 53 years of reanalysis data and find, as expected, that SSWs are nearly twice

as frequent during ENSO winters as during nonâ€ENSO winters. Surprisingly, however, we also find that SSWs

occur with equal probability during El Niño and La Niña winters. These findings corroborate the impact of ENSO on

stratospheric variability, and highlight that both phases of ENSO are important in enhancing stratosphereâ€troposphere

dynamical coupling via an increased frequency of SSWs. http://www.columbia.edu/~lmp/paps/butler+polvani-GRL-2011.pdf

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Just the thought that the current two week upper strat height pattern could be showing in the trop by the end of jan is mouth watering.

The last few runs do show the colder strat temps putting up a better fight than looked likely post displacement until a second warming comes in to split the remnant before it can attempt to push back towards the pole. This does show that the forecast post T300 cannot be taken for granted. I assume in a post SSW scenario, verification would drop somewhat at two week range ??

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Just been reading through some of research into SSW's and some interesting results pop up re propogation.

Firstly the propogation downward into the troposphere is much more likely if the NAM or otherwise known AO is either neutral or positive initially.

I suppose this is logical given that we could view the PV as a balloon, fully inflated, theres more air to release, less inflated less.

Another interesting thing I read,a sharp reversal of zonal winds at the 10hPa level doesn't guarantee a strong response from the troposphere.

The research suggested its lower in the stratosphere that has more impact on the troposphere.

These may have been covered previously but I thought I'd just add them in here.

Heres the link to one of the research papers:

http://cims.nyu.edu/~gerber/pages/documents/gerber_orbe_polvani-GRL-2009.pdf

Edited by nick sussex
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Another run, another secondary warming, this time more concentrated on Greenland/NE Canada, but continues right through until the end of the run.

Posted Image

The aleutian low potential also there once again down the line, promising further wave breaking activity

SK

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Yes an increasingly split vortex being modelled on this run chaps-100hPa at days 5,10 and 15

post-2026-0-72209700-1356888529_thumb.pnpost-2026-0-74771100-1356888538_thumb.pnpost-2026-0-28185600-1356888548_thumb.pn

It doesn`t look like cross-polar ridging yet but a nice gap opening up around Greenland/Iceland for some height rises as you suggest Ed.

It looks more likely that we can get a complete split further on though if more wave breaking does occur.

Edited by phil n.warks.
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And while on the topic of cold and snow, the GFS and ECMWF models show significant stratospheric warming across the North Pole and Canada towards the middle of January. With the NAO expected to fall rapidly at that time, and with the AO expected to rise rapidly at that time, it's about to get very cold for many across the United States. The split & temporary collapse of the polar vortex we've seen in recent years has been interesting.. Considering it tends to happen after solstice, one of these years it's not going to set back up for the rest of winter. http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2319#yourcomment

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