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Stratosphere and Polar Vortex Watch


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At the moment when it comes to the strat and the effects of the current SSW ,writing off any wintry effects on the UK is incredibly premature.  One could make equally strong argument for saying that due to its timing it will induce another winter like 1947. But that would be premature as well. Only time will tell. The weather will do what it does.

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Some useful tropospheric developments upcoming which are likely to have stratospheric impacts towards the end of November and more particularly into December. A strong convectively coupled tropic

so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Ja

For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you migh

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At the moment when it comes to the strat and the effects of the current SSW ,writing off any wintry effects on the UK is incredibly premature.  One could make equally strong argument for saying that due to its timing it will induce another winter like 1947. But that would be premature as well. Only time will tell. The weather will do what it does.

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As i alluded to earlier in the week i think that even a break in the upper levels will harm the vortex even if slower and more subdued in effect. 

Looking at the Berlin chart (backed by GFS ensembles) we do still see two important factors (probably related).

1) The SSW is still downwelling ever more even if at a higher lattitude than we want (again this will at a minimum make the trop vortex struggle to hold)

2) The vortex is not at the upper levels recovering meaning that any wave impact when it comes may be amplified (unfortunately the timing of this is pretty late Jan). We are not however in a situation like 87/88/89 (i forget which) in which a strong SSW was followed by a record strong zonal wind a month or so later.

Moral of the story (and i am usually cautious and skeptical these days) is that things right now still look good with a likely second bout in a months time to finish the job.

I would also add that the chances of a cold early spring again are probably higher than average.

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43 minutes ago, Weather-history said:

iapenell didn't expect much of an early summer 2018 neither, nobody is full proof. We can only respect opinions and then judge after the event. 

In all fairness I have read a lot of his forecasts and they are more often than not completely wrong. 

He does a lot of pattern matching - I believe the atmosphere is too dynamic an environment for this to be successful. No two events are ever the same.

Edited by Radiating Dendrite
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This is the nearest comparison was when there was a sudden stratospheric warming that split in January 2013 was transitioning from an Easterly to Westerly QBO. Also we will be entering a solar minimum which enhances the chance of Northern Blocking.  The earliest time that cold weather will appear will be in late January/early February.

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1 hour ago, lassie23 said:

i meant for cold in the UK, see iapenells posts

I recall that one of his posts suggested building giant rockets to change the tilt of the Earth as a means of combatting climate change. Also, constructing a big wall in the Atlantic to somehow turn off the gulf stream.:oldsmile:

Anyway, back to the Strat and the current GFS increases (slightly) the intensity of the second warming at D10.

gfsnh-10-240.png?12

 

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2 hours ago, Singularity said:

In order to construct useful probabilities, we need to know how size and duration of reversal factor in when looking at wQBO winters, along with how descending wQBO i.e. westerly shear winters compare with the rest.

Using wQBO or eQBO as the only factor is insufficient.

 

Next winter is most likely going to be more or less opposite to this one - easterly shear (descending easterly QBO) but with the shear level higher up than this winter is seeing.

Totally agree with this - the terms wQBO and eQBO need to be better understood in terms of their specific shapes. We had eQBO only turning wQBO at 30hpa in October time....and the Singapore data clearly shows that the pattern of shear is rarely constant...ie all east or all west. So the label is only as good as the detail contained in an analysis.

This is the kind of information that leaves us hanging a bit - we just don't have comparable data. Neither 1979 nor 2013 saw the same QBO shape as far as I can tell. Current values (excuse the wonky formatting) are

2018

hPa  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC

 10   -64   -248  -216   -87     29      95     90    119   160   173    231

 12  -213  -361  -387  -273   -48     74     72    134   156   166    216

 15  -386  -352  -378  -373  -301      4     68    137   149   154    202

 20  -338  -327  -342  -347 -349   -311   -81     64    131   135    182

 25  -309  -316  -321  -318  -324  -350  -348  -109    47    117    156

 30  -292  -278  -287  -314  -315  -329  -330  -310  -109    44     118

 35  -238  -214  -212  -274  -289  -303  -319  -333  -325  -104    57

 40  -103   -84    -88   -178   -248  -295  -313  -318  -317  -266   -71

 45     -1     17     19     -63  -184   -247  -277  -277  -277  -287   215

 50    64     86     73      23    -88    -178  -232  -229 -240  -252   260

 60    94     76     69      63     28      -32  -102  -140  -153  -144  139

 70    53     12     31      62     50       9     -40   -54     -90     -82    -82

 80   42     -21    16      12       0       -1  -   12   -36      -51     -50    -77

 90  -23    -28      11   -79     -47     -54     -51   -68     -32     -68    108

100 -200  -34    -26   -110   -69   -133   -109  -124     -62    -99     -85

 

Values in Feb/March very different to those now = much easier propagation of the reversal downwards?

However it looks as though we should still be running easterly from 80-100hpa - will this impact on things if the split can get down to that level? More pertinently is there an article somewhere that explains in more detail how the QBO at the equator interacts with the vortex around the pole? 

Edited by Catacol
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Cheers @Catacol. I believe the easterly lower layers (noting some errors in the Nov numbers in the raw data file with minus signs missing... not seen that before!) may help the reversal to sustain in disconnected form relative to the mid-upper stratosphere, if it makes it down to begin with.

For QBO-vortex relationships, I can't find any papers specifically on the subject in my bookmarks but these two are of some relevance - whether they go into the detail you seek I'm not sure, but it may be a useful start:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007JD008481

https://www.jstage.jst.go.jp/article/jmsj/93/1/93_2015-007/_pdf

The importance of considering ENSO alongside the QBO is noteworthy; this hasn't really been brought up much on the forums. Trouble is, we don't really have data on enough historical cases for each combination from which to draw reliable conclusions.

 

Something that's just struck me this evening is that there's been a lot of focus on the hemispheric mean zonal wind reversal propagation, but not much on the regional variations such as over the N. Atlantic, which could be 'failing to see the wood for the trees', as an anomalous stratospheric ridge is expected above this area, below which lagged downward propagation of positive GPH anomalies should be possible for some 2-6 weeks starting around mid-January.

Just a thought. This anomalous ridge above the N. Atlantic is where the tropical cycle is so important, and why we want to be seeing the eastward propagation continue across the Pacific at a fast enough pace to lend reinforcements before the stratospheric warming from the near-term events begins to wane.

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9 minutes ago, Singularity said:

Something that's just struck me this evening is that there's been a lot of focus on the hemispheric mean zonal wind reversal propagation, but not much on the regional variations such as over the N. Atlantic, which could be 'failing to see the wood for the trees', as an anomalous stratospheric ridge is expected above this area, below which lagged downward propagation of positive GPH anomalies should be possible for some 2-6 weeks starting around mid-January.

Just a thought. This anomalous ridge above the N. Atlantic is where the tropical cycle is so important, and why we want to be seeing the eastward propagation continue across the Pacific at a fast enough pace to lend reinforcements before the stratospheric warming from the near-term events begins to wane.

Yes Singularity a good point. I was thinking about this the other day. Propagation is shown hemispherically on the charts that we see and this may sway some plots. Focusing on the Atlantic sector would give a better indication I would have thought. 

I came across this on twitter from Simon Lee who raises the same point and created an Atlantic plot. see below: although a couple of days out of date now unfortunately!

 

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Yes, I have been thinking of other variables that might be prompting doubts on this SSW propagating down into the troposphere and I did self-moot the fact that we are in the process of transferring into a wQBO, which may be an obstacle to complete propagation.  However, one would think that there would a lag of a few months (4 or 5 months) from the start of transition in the uppermost layers of the stratosphere to the wQBO affecting the tropospheric patterns.  

The fact that we are having another major SSW taking place so soon after the SSW in February this year leads me to contemplate that, in a warming world, we will see more of these SSWs in winter.  This is due to anomalous warmth persisting into autumn creating more and more vertical heat flux and wave-breaking into the polar vortex.  What do others think?

David, Northallerton

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1 hour ago, Yarmy said:

I recall that one of his posts suggested building giant rockets to change the tilt of the Earth as a means of combatting climate change. Also, constructing a big wall in the Atlantic to somehow turn off the gulf stream.:oldsmile:

Anyway, back to the Strat and the current GFS increases (slightly) the intensity of the second warming at D10.

gfsnh-10-240.png?12

 

Okay that's crackers ? 

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1 hour ago, Singularity said:

Cheers @Catacol. I believe the easterly lower layers (noting some errors in the Nov numbers in the raw data file with minus signs missing... not seen that before!) 

Yes - didn't want to amend the raw data in case there was some reason for those missing minus signs....but I'll amend now for accuracy.

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1 hour ago, Catacol said:

AMENDED

2018

hPa  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC

 10   -64   -248  -216   -87     29      95     90    119   160   173    231

 12  -213  -361  -387  -273   -48     74     72    134   156   166    216

 15  -386  -352  -378  -373  -301      4     68    137   149   154    202

 20  -338  -327  -342  -347 -349   -311   -81     64    131   135    182

 25  -309  -316  -321  -318  -324  -350  -348  -109    47    117    156

 30  -292  -278  -287  -314  -315  -329  -330  -310  -109    44     118

 35  -238  -214  -212  -274  -289  -303  -319  -333  -325  -104    57

 40  -103   -84    -88   -178   -248  -295  -313  -318  -317  -266   -71

 45     -1     17     19     -63  -184   -247  -277  -277  -277  -287   -215

 50    64     86     73      23    -88    -178  -232  -229 -240  -252   -260

 60    94     76     69      63     28      -32  -102  -140  -153  -144  -139

 70    53     12     31      62     50       9     -40   -54     -90     -82    -82

 80   42     -21    16      12       0       -1  -   12   -36      -51     -50    -77

 90  -23    -28      11   -79     -47     -54     -51   -68     -32     -68    -108

100 -200  -34    -26   -110   -69   -133   -109  -124     -62    -99     -85

 

Values in Feb/March very different to those now = much easier propagation of the reversal downwards?

However it looks as though we should still be running easterly from 80-100hpa - will this impact on things if the split can get down to that level? More pertinently is there an article somewhere that explains in more detail how the QBO at the equator interacts with the vortex around the pole? 

Amended - cant edit the original post.

...and forget 80-100ha....surely still running negative at 50hpa and below?

Edited by Catacol
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This study uses reanalysis datasets and numerical experiments to investigate the influence of the occurrence frequency of the individual phases of the Madden–Julian oscillation (MJO) on the interannual variability of stratospheric wave activity in the middle and high latitudes of the Northern Hemisphere during boreal winter [November–February (NDJF)]. Our analysis reveals that the occurrence frequency of MJO phase 4 in winter is significantly positively correlated with the interannual variability of the Eliassen–Palm (E–P) flux divergence anomalies in the northern extratropical stratosphere; that is, higher (lower) occurrence frequency of MJO phase 4 corresponds to weaker (stronger) upward wave fluxes and increased (decreased) E–P flux divergence anomalies in the middle and upper stratosphere at mid-to-high latitudes, which implies depressed (enhanced) wave activity accompanied by a stronger (weaker) polar vortex in that region. The convection anomalies over the Maritime Continent related to MJO phase 4 excite a Rossby wave train that propagates poleward to middle and high latitudes, and is in antiphase with the climatological stationary waves of wavenumber 1 at middle and high latitudes. As the spatial distribution of the convection anomalies during MJO phase 7 has an almost opposite, but weaker, pattern to that during MJO phase 4, the occurrence frequency of MJO phase 7 has an opposite and weaker effect on the northern extratropical stratosphere to MJO phase 4. However, the other MJO phases (1, 2, 3, 5, 6, and 8 ) cannot significantly influence the northern extratropical stratosphere because the wave responses in these phases are neither totally in nor out of phase with the background stationary wavenumber 1.

https://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-17-0476.1

So phase 4 was not so good for 'our' SSW?

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3 hours ago, johnholmes said:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

Anyone care to suggest what this may mean in terms of surface weather and how long before the effects, if any, are felt?

It was a serious request would anyone care to reply please?

This is the central theme of this entire thread. I think if you read back a couple of pages, you will find your question answered more than once. 

- The trop. response between SSWs differs between events. No guarantees given.

- The stratospheric vortex will likely be out of business for a while

- The standard time until the first trop. response is 10-14 days, but can be less, more, or the response may never come

- EC shows a modest signal for downwelling at +240, but nothing convincing yet

Edited by Ruben Amsterdam
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3 hours ago, johnholmes said:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

Anyone care to suggest what this may mean in terms of surface weather and how long before the effects, if any, are felt?

It was a serious request would anyone care to reply please?

I know you had a theory that this generally leads to HLB in the trop within a week to ten days JH.  this time may not be so straightforward but on the other hand ...........

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