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Stratosphere and Polar Vortex Watch


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22 hours ago, Singularity said:

I feel a good view of the situation is that the forcing toward relentlessly mobile weather patterns is relaxing toward or perhaps a little below average during 1st half Feb.

674597551_ao200129.thumb.gif.adb51081aa0d3ad7f83dd5ab6a787838.gif

Whoa!

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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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49 minutes ago, Interitus said:

674597551_ao200129.thumb.gif.adb51081aa0d3ad7f83dd5ab6a787838.gif

Whoa!

Winter 2019/20 is dead going by that chart!  Some ensembles off the scale positive AO.

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20 minutes ago, Redbull165 said:

Sadly its game over.

umedel60.png

Don’t worry, next winter will be a strong rival to 62/63! ?

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Looks to me like we may still have some hope for early March but that February will be a dud, at least before the final third at the earliest. 

Our best hope right now looks to be from the latest forecast MJO wave which may be able to complete a better orbit into the higher phases albeit at a lower amplitude than the last. 

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You can see convection moving from the Indian Ocean into the Pacific albeit more weakly than a few weeks ago. It does not (yet) have a blob of trade winds to hit and kill it though. 

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3 minutes ago, summer blizzard said:

Looks to me like we may still have some hope for early March but that February will be a dud, at least before the final third at the earliest. 

Our best hope right now looks to be from the latest forecast MJO wave which may be able to complete a better orbit into the higher phases albeit at a lower amplitude than the last. 

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You can see convection moving from the Indian Ocean into the Pacific albeit more weakly than a few weeks ago. It does not (yet) have a blob of trade winds to hit and kill it though. 

Thats odd...when i click on that MJO chart, the one that comes up isnt that one...

i get the current one, not that from november..

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Just now, mushymanrob said:

Thats odd...when i click on that MJO chart, the one that comes up isnt that one...

Just how it's embeded, that MJO chart is actually from 2018.

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Despite the recent GFS runs in long range, from the analogues there is actually a decent chance of a SSW before the end of February, maybe 30-50% at a guess.

As an aside, interesting split forming on the 12z, probably won't be it, but is popping out at relatively short range so the FI is definitely not certain.

 

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2 hours ago, mushymanrob said:

Thats odd...when i click on that MJO chart, the one that comes up isnt that one...

i get the current one, not that from november..

That’s the correct one, it’s showing a November one because of cookies.

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13 minutes ago, Kirkcaldy Weather said:

If only we could get something like p8 from the gefs anim_cje9.thumb.gif.8510fbb89d225ae36986834058b122b3.gif though I think we will need a miracle for that unfortunately. ens_nh-stratUT_010hPa_20200130.thumb.png.4ca6888c2f075cd149ee34b95a55e0dc.png ens_nh-vortells_010hPa_20200130_f384.thumb.png.892cc24081d99bb5642d656fba6dc439.png 

Lol!  Fair play for digging that P8 out!  Cat in hell's chance!

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1 hour ago, Mike Poole said:

Lol!  Fair play for digging that P8 out!  Cat in hell's chance!

Always beautiful to see a split like that so had to post as unlikely as it is ?

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Naturally thanks to seasonal wavelengths, the PV will undergo a relaxing of its grip through February, though this year it will be starting from a very strong position. Could be one of those years where it suddenly snaps, rather than a gradual weakening..

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3 hours ago, Kirkcaldy Weather said:

If only we could get something like p8 from the gefs anim_cje9.thumb.gif.8510fbb89d225ae36986834058b122b3.gif though I think we will need a miracle for that unfortunately. 

No reversal - zonal wind 2.1 ms at T294 -

20013012_294_z10.thumb.png.1b8f5724d1e1d68b041b28fccaa464d0.png

 

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9 hours ago, Kirkcaldy Weather said:

P3 this time with a split, might as well post these for fun as there aint much else happening anim_dbk7.thumb.gif.94d4f50c60b530de191be578850913a5.gif

Temporary split, vortex reforms, min zonal wind 13.1 ms at T228

20013018_228_z10.thumb.png.baa023fd971ab5027e9646ea8b35ee5e.png

Try 00z p15, not split but big displacement, min wind -15.1 ms and bearing in mind above post from Knocker, the window for a split may be quite small in the short term -

20013100_384_z10.thumb.png.e7e62283715db9ae3efb87d9985e8291.png

Actually the latest GFS runs are ramping up the vortex later on as they're giving no coherent signal for other than transient wave 1 even, with the angular phase shifting in longitude all over the place.

 

 

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On 28/01/2020 at 20:47, Singularity said:

I feel a good view of the situation is that the forcing toward relentlessly mobile weather patterns is relaxing toward or perhaps a little below average during 1st half Feb.

This being thanks to that big MJO wave which, while it didn’t make it far enough east across the Pacific to initiate HLB, did get far enough to seriously soup-up mid-latitude blocking (to record strength across the UK for example). 

With that comes huge energy transfer into major mountain ranges, with wave deflection upward to assault the polar vortex via strat warming.

Now, the MJO looks to cycle back around to Indonesia. This suggests another round of MLB enhancement to come by mid-Feb. Potentially more strong wave breaking. So I can see where GFS is coming from with that second warming development.

In the meantime, we look to typical variation in jet meandering, to offer some most likely transitory cold snaps, which due to the Atlantic-side Arctic sea ice configuration may pack more of a punch than we’ve become used to this past decade. Main question is ‘direct hit, or glancing blow’. We know which one we tend to get...!

Did the MJO wave cause the UK high pressure? Easy conclusion to arrive at and it may be related but as well as a fairly short time lag, previous examples show that this was not the typical response. This graph shows three close analogues of MJO RMM1 over the 14 days to Jan 19th (x-axis day 0 - UK high pressure) -

1084912370_RMM1200119.thumb.png.0c6c39aebcfdb62263d794d48c9bbe95.png

These dates show a strengthened NAO with enhanced Azores high (your MLB?) and deepened Icelandic low, troughing to UK

mlb.thumb.gif.215c30a74af660cf4e65921f6bbd82c6.gif

One interesting feature they shared though appeared around 20 days later, with a significant negative EPO -

1202382706_EPO200119.thumb.png.027455847981d6a334a190b4cf189bd5.png

EPO.thumb.gif.da264412508bfd5097648f11e9fd9a49.gif

11/02/1986 -

epo860211.thumb.png.24362ce4425971e494ad2581a528edd5.png

19/02/1993 -

epo930219.thumb.png.eb50b276d9270d6710a423e2c38c5420.png

30/01/2007 -

epo070130.thumb.png.ddec14cf053e434bab2bdd6557cc6a02.png

They share not completely dissimilar features downstream also, though actual conditions varied for the UK. Various recent runs have been trying to replicate the 20 day -EPO this year also eg -

epo200209.thumb.png.d890f01675eaa4fdb8d682e54eba1816.png

As well as battling a strong troposphere vortex, since looking at this a couple of days ago it is now being complicated by a possible wave 1 downward reflection event into the area, encouraging a strong high pressure in the Kamchatka area and the rejuvenation of the Siberian high -

wave130300_012.thumb.png.c1fc3a285dc1f6d68b1c880fcfadde5c.png

kamchatka.thumb.png.bfe284bb7b7a71689f703e703d44ae23.png

 

 

 

 

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12 minutes ago, knocker said:

 

Interesting that it highlights the same Kamchatka high as my post above, however it's not set in stone and has gone on the next run. Whatever, further in the convo he adds -

This is interesting with regards to my post and downwards wave reflection. My speculation at the time ahead of the 2018 SSW was reflection acted to shift the heart of the troposphere vortex south towards northeast Canada (a known effect) with the centre of strat vortex attempting to follow and stretching, allowing the wave 2 to pinch it out or vis a vis his Scandinavia-Greenland dipole.

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Question: Does anyone know if the average u wind speed of the stratospheric vortex in winter has been increasing over the past 30 years?  I know the stratosphere has been getting colder, so I wonder if this is encouraging a trend towards a stronger stratospheric vortex, and our winters experiencing less northern blocking/cold weather. 

Or is it that the stratospheric/troposphere vortex is just becoming stronger specifically in the Greenland area? As a result of some other forcing such as the omnipresent NE Pacific ridge?  It seems, at least anecdotally, that North America has continued to see similar amounts of arctic outbreaks from the vortex breaking down in the past 30 years. 

 

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The general impression over the next 10 to 14 days or so is a relaxing spv (as forecast) ..... which may well then restrengthen higher up but perhaps not lower down.   the NH lala land tpv modelling may look increasingly amplified over the next few days although as @Interitus has pointed out above, it already is to a degree .....

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Uncertainty over how much the MJO will gain amplitude in phases 4-5-6 in the coming fortnight.

In Feb, 4-5 destructively interfere with the climatological Pacific and Atlantic ridges to varying degrees. So we’d be looking for internal events for vortex weakening beyond the season trend - which itself is likely trending stronger for longer as the GHGs block troposphere-stratosphere longwave radiation (so in answer to the question from oasis, I expect yes, colder stratosphere and stronger polar vortex tendency).

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19 minutes ago, Singularity said:

Uncertainty over how much the MJO will gain amplitude in phases 4-5-6 in the coming fortnight.

In Feb, 4-5 destructively interfere with the climatological Pacific and Atlantic ridges to varying degrees. So we’d be looking for internal events for vortex weakening beyond the season trend - which itself is likely trending stronger for longer as the GHGs block troposphere-stratosphere longwave radiation (so in answer to the question from oasis, I expect yes, colder stratosphere and stronger polar vortex tendency).

Is the stratosphere colder all over though? Not checked the data yet, but the strength of the vortex depends on the meridional temperature gradient - if it cooled more at lower latitudes for example, the tendency would be towards a weaker vortex.

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