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Stratosphere and Polar Vortex Watch

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Nice one @Recretos, that EC Jan plot is a beauty.... you beat me to it rendering the data. I had a confusing Grib error that I had to dig into notes from @Interitus to resolve.

It's certainly not messing around for January...

Correction - DECEMBER

image.thumb.png.ae872564ef84ffa42fd65d5d566237f8.png

 

 

 

 

Edited by lorenzo

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20 hours ago, Kirkcaldy Weather said:

 

 

7 hours ago, Kirkcaldy Weather said:

18z GEFS

1880754958_gensnh-8-7-384(1).thumb.png.05911e7c5c8eb2158343c5e63c4a4522.png369904406_gensnh-14-7-384(1).thumb.png.5e8515c47d329051cc52635539827921.png1186830587_gensnh-16-7-384(2).thumb.png.6d654be513d41bada6b66f5a12a8608f.pnggensnh-18-7-384.thumb.png.008ff37f819639a802937a376b3d2bc6.png  there are more but those are the pick of the bunch.

hi..... excuse me for asking, im confused here.. i dont understand the relationship between these two sets of charts, one showing warming, the others showing a split vortex.

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8 minutes ago, mushymanrob said:

 

hi..... excuse me for asking, im confused here.. i dont understand the relationship between these two sets of charts, one showing warming, the others showing a split vortex.

Meteociel only has 10 hPa temperature charts but you really want to see the heights and isobar to see what the vortex does, which you can on wetterzentrale 

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27 minutes ago, mushymanrob said:

 

hi..... excuse me for asking, im confused here.. i dont understand the relationship between these two sets of charts, one showing warming, the others showing a split vortex.

And it wasn’t a split vortex anyway rob - not sure why Matt saw it as such

plus one chart is temps and the other heights/anomolys 

Edited by bluearmy

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As heights are a function of temperature, if you only have the heights you can make a rough deduction where the warming is

50_nh_31.thumb.png.1751d44a50b106ee3292324ce9852fdf.png

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54 minutes ago, mushymanrob said:

 

hi..... excuse me for asking, im confused here.. i dont understand the relationship between these two sets of charts, one showing warming, the others showing a split vortex.

The Meteociel charts are a few random GEFS members at 10hPa for T384. Matt Hugo is showing 30hPa charts for (yesterday's) ECM at T240. Nitzan Cohen (a Swedish TV weatherman, apparently) is showing the 50hPa chart for the ECM T240. None of them is showing a split.

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Now we have the ECM seasonal on board with a significant weakening event my confidence is growing for January/February. Perhaps no real sign of an SSW just yet but we don't necessarily need one if we've got a weak enough vortex anyway. 

The GEFS are still going for a significant weakening, not a million miles away from a reversal though not quite there yert

latest_u1060_ens.thumb.png.1b9b3f4aa2efbbf582e6068f00181cfa.png

Worth noting the GFS Op isn't at all interested and departs massively from it's ensembles & ensemble mean, the higher resolution could be picking up on something that the ensembles aren't so it can't really be discounted at this stage, it's been fairly consistent with that signalling. 

Perhaps *some* signs of a coupling between Trop/Strat towards the end of the month but as these charts are based on GFS Op data, the usual caveats apply, we've seen a forecast coupling a couple of times this season only for it to be completely dropped on the next update

COUPLE.thumb.png.f073382a4f7684193c3eeee104553c92.png

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1 hour ago, bluearmy said:

 

plus one chart is temps and the other heights/anomolys 

yes i understand that, i couldnt see the relationship though like i can with the synoptic charts.

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https://twitter.com/peacockreports/status/1193579773081063425

I've noticed a lot of interest lately in a weakening of the #polarvortex as a possible route to a #cold #December in #Europe. However, when I factor the expected lower-atmospheric momentum cycles, the most analogous years suggest even a very weak vortex is unlikely to cause that.

 

EJByeO4W4Ao56fs.jpg

Edited by sebastiaan1973

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1 hour ago, sebastiaan1973 said:

https://twitter.com/peacockreports/status/1193579773081063425

I've noticed a lot of interest lately in a weakening of the #polarvortex as a possible route to a #cold #December in #Europe. However, when I factor the expected lower-atmospheric momentum cycles, the most analogous years suggest even a very weak vortex is unlikely to cause that.

 

EJByeO4W4Ao56fs.jpg

The only factor to throw into this one - and I'm only playing devil's advocate here because I am also not seeing a frigid or blocked December (at least until the final third at the earliest) - is that we have an atmosphere in transition from a Nina style starting point. For most of the year we have had a gradual decline in GLAAM from the high levels of last winter to much more of a Nina like -2. We are currently in an atmospheric state where the Nina mid atlantic ridge is therefore not out of the question, and the fact that modelling is seeing some retrogression of heights over Scandy towards Greenland supported by mid atlantic Nina forcing and a jet running south (low solar impacts?) fits the mould temporarily in November. We are going through a fast 7-8-1-2 MJO orbit at present too, adding more weight to the current quite cool/cold cyclonic pattern remaining in place under some element of northern blocking.

The bit i'm struggling with at the moment is the strongly positive IOD (which favours the development through next year of a Nina ENSO base state) sitting alongside what appears to be a rising GLAAM profile since mid autumn. For me the shift back to a more traditional cyclonic westerly pattern in December looks the form horse as your graphs suggest above, not least because the MJO will be back over Africa and seasonal wavelengths plus "normal" vortex impact on the troposphere means that westerlies should win out. BUT reading more deeply into the IOD (a factor which has hit internet forums this year in a way not seen before because the current positive value is so strong) it would appear we have an ENSO / IOD disconnected state at the moment. In other words the IOD is strongly positive but the bigger ENSO state has remained neutral. Given this disconnect the rising trend in GLAAM is a bit of a surprise as the Indian Ocean is applying negative forcing, and indeed is so strong that it has almost caused a fixed wave pattern across the pacific with a solid band of cold water holding sway. Why,therefore, is GLAAM rising towards a more Nino style response when the IOD forcing remains negative? (How many more disconnected states are we going to end up discussing this year?! The word "disconnect" seems to have become the climactic norm....)

I'm beyond my knowledge base here - something over the years that has happened many times!!! - and I need to do more learning....but going back to your post I'm wondering if the atmospheric response to ENSO conditions is quite so simplistic as to suggest that neutral GLAAM means westerly impact. For a range of reasons I think a westerly December for the first 2/3 at least is where we will go.....but I'm not 100% sold on it. The trend (and the trend may be the key) towards a rising GLAAM profile (atmospheric response closer to the seasonal prediction of a weak Nino) in the context of a stubbornly positive IOD is puzzling (maybe it is only temporary?) and in any case we have a strat/trop relationship over the pole that is not following the script at the moment. Doesn't mean it wont click for December - but there is a disconnected state there that is now being further ramped up as a discussion area by wave 2 forcing enhanced further by a strong siberian tropospheric high perhaps built by higher than average snow cover and rate of snow/ice growth in general.

It's not an easy call. Pattern matchers and analog users over in the US are coming up with contradictory predictions. Glosea is remaining firm on a very +AO/+NAO winter but the seasonal ECMWF has shifted its position somewhat. All of this adds real spice to forecasts for beyond December. Your diagrammes I would therefore agree with in terms of suggesting a westerly December of the balance of probability - but there is a whole lot going on that makes it a less than certain call, and frankly nothing this season would surprise me. Glosea was 80% certain of a warm autumn but clearly didnt get jet forecast correct and we are likely to end up cool. I guess all this uncertainty is what makes our weather hobby so much fun. 🙂

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Catacol, if i may suggest that you actually answered your own question. The +IOD is is imprinting a strong trade winds in the Indian Ocean and dragging down GLAAM but because it is a standing wave rather than moving west to east it by its nature may encourage weak downstream forcing in the central to east Pacific driving 7-8-1-2 orbits when the MJO superimposes itself in the central/east Pacific, that in turn causes a relative spike in GLAAM even if the MJO will wade until it repeats its orbit against the +IOD/-GLAAM background. This may also be encouraged by the generally positive sub-surface anomalies. 

Models generally suggest that the +IOD signature will weaken to neutral by January (currently +2 standard deviations) albeit that may just be a reversion to the climatological mean. 

Should it persist though then perhaps it indicates that while the base winter pattern may be close to -GLAAM/Nina state, for a few weeks at ~60 day intervals (when the MJO forcing is of high enough amplitude) we may see the background signal overridden. 

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Briefly returning to 3-D plotting, Unidata Integrated Data Viewer (IDV) has made this available for a decade. Here is an isosurface of model absolute vorticity of the above image -

18121000en17.thumb.gif.88786970a1db7e42529960d8b51bc35b.gif

Slight drawback in that it cannot natively create the potential temperature levels as used on stratobserve, here it is the GFS isobaric levels between 100 mb - 3 mb approximating the 400-1200K.

Find out more about IDV and download - https://www.unidata.ucar.edu/software/idv/

 

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2 hours ago, summer blizzard said:

Catacol, if i may suggest that you actually answered your own question. The +IOD is is imprinting a strong trade winds in the Indian Ocean and dragging down GLAAM but because it is a standing wave rather than moving west to east it by its nature may encourage weak downstream forcing in the central to east Pacific driving 7-8-1-2 orbits when the MJO superimposes itself in the central/east Pacific, that in turn causes a relative spike in GLAAM even if the MJO will wade until it repeats its orbit against the +IOD/-GLAAM background. This may also be encouraged by the generally positive sub-surface anomalies. 

Possibly not the right place for this debate - but its a good one to have. The boost to atmospheric AAM caused by the current phases in the MJO cycle is understood - my slightly furrowed brow is the result of a consistent increase in the AAM budget since the start of October regardless of MJO phase (slight stalling when it became a very suppressed signal) and the fact therefore that the atmosphere would appear to be responding in a more consistently surprising (Nino) way than can be explained by passage of the MJO. I am wading my way through Stuecker's technical paper from 2017 on ENSO/IOD relationship and while we can perhaps explain the arrival of the strong positive Indian Ocean event by the strength of GLAAM last winter (though I never found anyone explain convincingly last year why a weak El Nino was accompanied by such a consistently high level of GLAAM) it doesn't explain the consistent turn around in GLAAM over the last 6 weeks. We all have our levels of understanding and ceilings to conceptual grasp - and I have clearly hit a ceiling as I stare at the combination of the IO temperature profile and GLAAM increases - but I feel relatively confident enough to state that the current relationship is unusual. Stuecker does define strong IOD events that are out of step with ENSO signature as "independent." My translation of that word is to describe them as a disconnect - and we have heard that word a lot in recent years.

Ultimately if we end up with an atmosphere that begins to show a more Nino style signature I am not going to complain one bit. We know that Nina winters where ocean and atmosphere connect are not good towards the back end and any cold outbreaks tend to cluster around early season ridging, and if we can combine a weak (disconnected) vortex with Nino ENSO forcing and favourable arctic conditions to produce a disrupted or ideally split/disintegrated vortex then we are good to go on the hunt for cold come Jan/Feb. I'm going to throw out a winter forecast very shortly (my first stab at doing so) and vortex disruption around New Year is pretty high on my list of hoped/expected for factors that might turn the winter towards something less horrific than the Glosea probability forecast. That element of the forecast is the product more of November observations of the pattern and a belief in the relevance of low solar activity in helping maintain a disempowered jet and possibly a less cold core vortex than it is of a reading that ENSO forcing might created favourable momentum transfer to disrupt the vortex via GP's infamous "torpedo" - but if GLAAM continues on an upwards curve and sticks 2 fingers up at the state of the IOD then so much the better. It only strengthens the argument that the vortex may be heading for a tricky time in January, and when I read yesterday of the ECMWF seasonal suggesting vortex misery my good mood only improves.

Your final point about sub surface anomalies must be another ceiling I've hit because I struggle to comprehend why sub surface temperatures would impact on GLAAM - but I like to be offered challenging concepts to chew over, and again I expect my grasp of physics is simply too poor to grasp that one!

Lots to look forward to. So much fun had already, and it's only Nov 14th.

Edited by Catacol

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GEFS 12Z anim_yor1.thumb.gif.f4d5bdf9c24494fff3235372a1497928.gif gensnh-15-7-384.thumb.png.c78b6c9808abe96a1241848b1858811a.pnggensnh-20-7-384.thumb.png.02b92bc9323c95d3f695120481fd9a40.png1714862098_gensnh-18-7-384(2).thumb.png.19b1c8f451ad3ad512ebc221ff7bcf85.png again quite a few others with weaker signs of warming.

Look forward to the winter forecast @Catacol best of luck 😀

@Mike Poole another single run going for a reversal of the zonal winds again a CMC / GEM ensemble member image.thumb.png.7a9ece995e3b3a942ddeb91481e1d0e7.pngimage.thumb.png.41c7e7e749f3acd1935ccf11dfaceac9.png 

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Okay so the plots from last night looking at January >>> scrub that... these are for next month 🙂

Thanks to Simon Lee for messaging to highlight as the way the dataset presents on Copernicus caught him out too!

EJQ2JrcWsAE16o0.thumb.jpg.10e39290abf833174e1670d3d2ee6ee2.jpg

 

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7 minutes ago, lorenzo said:

Okay so the plots from last night looking at January >>> scrub that... these are for next month 🙂

Thanks to Simon Lee for messaging to highlight as the way the dataset presents on Copernicus caught him out too!

EJQ2JrcWsAE16o0.thumb.jpg.10e39290abf833174e1670d3d2ee6ee2.jpg

 

Looks to me like these are for 6 months and very little chance of an SSW - unless i have totally misinterpreted the data.

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Have a look at the ensemble members dropping below the 0 line for December..

Here is a box and whisker plot Simon posted representing the shift from the EC Model from Nov > Dec..

image.thumb.png.46ecb7bc3e7b29304f25281cfd2b616f.png

The thing that caught me out was this box forecast time 2020-01-01 - which anyone in their right mind would load in and say cool - this is January, however due to the way the data is encoded this is reflective of the month prior, in this case December.

image.thumb.png.3adfecec9ef0a74ea103dcc0c9add1c0.png

Edited by lorenzo

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