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Stratosphere and Polar Vortex Watch


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26 minutes ago, Glacier Point said:

Displacement forecast for mid December, but expectation would be for full on warming event to occur towards the end of the month. MJO wave passage through the Indian Ocean will likely delivery the knock out punch.

 

Hi - rookie question! Knowing that warming events can be either a blessing or a curse (twice really if you don't like either mild or cold!)  what indicators are there  - if any - as to whether or not this could lead to cold further down the line for W Europe please?

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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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10 minutes ago, Catacol said:

Nothing is ever certain in weather....but I tend to ignore those who argue a significant warming impact on the vortex can lead to warm rather than cold. The reality is that, given an average degree of stratospheric/tropospheric coupling the loss of strong westerly circulation in the stratosphere relaxes the tropospheric vortex, and the westerlies that tend to bottle up the cold at high latitude weaken. It is true that, like a spinning top coming off its axis as velocity slows, a meridional effect can pull mild are from the south in this circumstance BUT in overall terms the global average impact is for cold air to spill out of the arctic to lower latitudes.

In general terms it is a win/win despite the chances of short term variability. And a vortex disruption/displacement and maybe even a split/disintegration this early in the season under weak Nino ENSO conditions (with likely further blocking episodes ahead) could potentially spell the end of the vortex as a force to be reckoned with for the rest of winter.

Perhaps someone with a nose for the archives could go back and tell us when we last had a vortex disintegration in a weak Nino year in December. Would be interesting.

Having said all that, and laid the ground for snowy celebrations - the warming hasnt happened yet. Much can happen in 4 weeks of weather...........

A bit further up I linked to a tweet withan article that showed that shows t2 anomalies for split and displacements. I stumbled by the tweet by coincidence yesterday but I had already looked at hellmann figures for the Netherlands after all major warmings and it didn't look good 

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Assuming that the seasonal model-forecasts cannot account for stratospheric conditions, in two months' time (and that all but one of them suggest widespread cold anomalies over Europe, come Jan and Feb) any destruction of the stratospheric vortex can only make things better still...I don't ever recall seeing so many simultaneous pointers toward a cold winter, than I'm currently seeing...?

The only caveat I'll keep in mind is that Gavin P's top two analogues produced decidedly mild winters.

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8 hours ago, Ed Stone said:

Thank you, Jethro. That's a question I would have asked, myself, had I not been afraid of feeling a right twit!?

I don't care. If you don't know something I'd rather be thought a fool and find out by asking, than not learn.

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My impression from reading around is that the deal with displacement events is that they nearly always (due to the more dominant role of the Asian mountains meaning the warming and anomalous anticyclone develop over the N. American side) push the vortex toward some part of Eurasia from Canada/Greenland, which entails either a passage or take up of residence closer to the eastern North Atlantic. During this time, eastern N. Atlantic cyclogenesis can be enhanced, bringing the UK near or above average temps overall with bouts of wind and rain... however, the situation can change drastically if the displacement is large enough send the polar vortex right across to Siberia. Then the increased potential cyclogenesis region is over the continent where it struggles to achieve much, and more of a ridge-friendly environment establishes across the eastern N. Atlantic. This is not a sequence that involves propagation of anomalies downward like we see with the split-SSW events; it's simply the absence of the usual stratospheric temperature gradient that aids ridging in the eastern N. Atlantic.

I've also seen musings that a displacement far enough away from the pole could achieve similar results with the vortex in line with countries as far west as Scandinavia, but if I recall correctly, we chased such potential last Dec only to be disappointed. So it seems to me that it's how far east it goes that matters as to whether we experience the less common of the outcomes.

 

If I'm spouting any nonsense here, please do let me know - I've got a lot on my mind these days so please excuse me if get some things muddled up on occasion! ?

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Increasingly strong Wave 2 attack pops into view at the end of next week. Beginning to wonder if the vortex really has much chance of surviving this ongoing process. 

ecmwfzm_ha2_f240.thumb.gif.df65c2c49dc02196da1109c4b9ebf50a.gif

 

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3 minutes ago, Catacol said:

Increasingly strong Wave 2 attack pops into view at the end of next week. Beginning to wonder if the vortex really has much chance of surviving this ongoing process. 

ecmwfzm_ha2_f240.thumb.gif.df65c2c49dc02196da1109c4b9ebf50a.gif

 

And I right in thinking if there was a (major) SSW early in winter the PV wouldn’t be able to recover for the rest of winter ?

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2 minutes ago, Raythan said:

And I right in thinking if there was a (major) SSW early in winter the PV wouldn’t be able to recover for the rest of winter ?

Never say never....but the timing looks near perfect given that the major attack and potential collapse looks like happening just as the usual period of vortex intensification comes to an end. If we lost all high lat blocking and the pacific went quiet then it could recover potentially - but that just doesn't look like the form horse at the moment. Some decline in the surprisingly high levels of AAM and accompanying pacific wave looks likely because I cant see how the 6 month best fit trend upwards can be maintained - but even assuming this I doubt the collapse would be so quick as to allow a westerly pattern to reestablish. There will be periods when the atlantic makes inroads for sure, but through the heart of winter these look to be separated by longer spells of increasingly entrenched continental cold with growing potential for battleground snow.

It looks exactly as RJF called it weeks and weeks ago.....and he uses the planets for this forecasts. Pause for thought, and not for the first time.

I'd love to see what GP has supplied his paying customers....! National run on de-icer in the offing??

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8 minutes ago, Catacol said:

 

I'd love to see what GP has supplied his paying customers....! National run on de-icer in the offing??

Ha ! I think his uptick in posting is a clue in itself ? , ironically since this years earlier SSW I think the atmosphere has behaved abnormally , heaven knows what another knock out blow would cause , I was actually trying to find historical records of SSW to see if two occurred within a 12 month period , ironically it could ruin mine and Stewart's passion of Horse Racing for a few weeks , you can’t de-ice a race track ! 

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1 hour ago, Raythan said:

And I right in thinking if there was a (major) SSW early in winter the PV wouldn’t be able to recover for the rest of winter ?

You'd be wrong unfortunately, last we went from (almost) record weak to very strong in a few days 

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1 hour ago, Raythan said:

Ha ! I think his uptick in posting is a clue in itself ? , ironically since this years earlier SSW I think the atmosphere has behaved abnormally , heaven knows what another knock out blow would cause , I was actually trying to find historical records of SSW to see if two occurred within a 12 month period , ironically it could ruin mine and Stewart's passion of Horse Racing for a few weeks , you can’t de-ice a race track ! 

I have a theory that what we've seen last winter strat wise and what we're potentially seeing unfold this year, is the reason cold winters tend to cluster. 

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1 hour ago, Raythan said:

Ha ! I think his uptick in posting is a clue in itself ? , ironically since this years earlier SSW I think the atmosphere has behaved abnormally , heaven knows what another knock out blow would cause , I was actually trying to find historical records of SSW to see if two occurred within a 12 month period , ironically it could ruin mine and Stewart's passion of Horse Racing for a few weeks , you can’t de-ice a race track ! 

A bit above I link to an article with the exact date of all but the most recent ssws, there have been many years with subsequent ssws and even winters with multiple ssws. Most of these winters were quite unremarkable though 

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12 minutes ago, ArHu3 said:

A bit above I link to an article with the exact date of all but the most recent ssws, there have been many years with subsequent ssws and even winters with multiple ssws. Most of these winters were quite unremarkable though 

Is it just me or do you always put a downer on everything?!?!

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3 hours ago, Paul_1978 said:

Is it just me or do you always put a downer on everything?!?!

 

Anyway from december 98 to March 2010 there have been 13 major ssws, have any of these winters been memorable? 

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