Stratosphere temperature watch - 2016/17

[Paul_1978]

That's exactly what I was going to say! 

[Gael_Force]

Are we in the territory of a Canadian warming yet?

 

 

 

[Glacier Point]

The 06z and 00z GFS, with ensemble support, look very consistent with 00z EC deterministic at day 10.

The GEFS interpretation of this is for a reversal in zonal winds at 10 hPa at 60N, so we are in the realms of a technical stratospheric warming with a 10-12 day time frame. 

The evolution of this, a substantive displacement followed by a likely wave 2 split of the primary vortex centred over Siberia, looks to take a few more days on top of this (say 14-20).

Time to wheel these out....

 

From: http://www.inscc.utah.edu/~reichler/research/projects/TS/TS.shtml and http://www.atmos.colostate.edu/~davet/ao/ThompsonPapers/ThompsonBaldwinSolomon.pdf 

The zonal wind profile in the lower and middle stratosphere and mid troposphere is a whole lot more negative compared to almost all weak vortex events, so the lagged times may vary somewhat this time round, probably a lot more progressive and responsive to stratospheric lead.

So assuming first lagged influence gives target date of 10th December for first tangible stratospheric impact (some argument could be made for instantaneous type response to fast propagation waves).

[bluearmy]

tbh, given how weak the vortex and zonal flow is, will be interesting to see how far south and how high up a reversal can get. in addition, not sure how much effect any reversal will have on the trop which already exhibits a neg AO signature. we are already beginning to see the gefs playing with a  more west based -NAO profile - might this be due to immediate effects from a reversal retrogressing the pattern further  ??

[Glacier Point]

Could be Nick, although the warming / split signal won't be in view until another few days. Then we should start to get an idea from GEFS / GFS ops on where the bits of the primary vortex go. I suspect there will be a strongly -AO signal projected across the NH, including Arctic ridge, which is currently lacking. 

[Hocus Pocus]

A quick,question from a novice like me. Could such an event not have the same impact as the one in 2009/10 ( I think it was back then ) when a SSW reversed an already established cold NH pattern for our part of the world?

[Gael_Force]

2 minutes ago, Hocus Pocus said:

A quick,question from a novice like me. Could such an event not have the same impact as the one in 2009/10 ( I think it was back then ) when a SSW reversed an already established cold NH pattern for our part of the world?

Winter 62-63 had early Canadian warming and later SSW only reinforced the cold. It will surely depend on other factors but I know Kev Bradshaw has written about SSWs scuppering early cold patterns. To me, this is the early pattern that has usually been harbinger of cold in the UK but every situation is unique in itself.

 

[Recretos]

Well, 06z GEFS is not much different than the 00z, with reversal also at 60N. Here are some of my graphics. 

   

And a funny fact, the ECM46 (old ECM32), actually had a wrong trend of strengthening the vortex. It is an older run, but as fresh as I can get it free. 

And an animation I did yesterday from GFS data, showing the anatomy of the upcoming dynamics. 

 

 

[bluearmy]

That ecm 32 is from 24 October Andrej - is that a consistent signal from the weeklies back then ??

[Recretos]

It was mainly neutral to positive, but not really into negative SSW territory. And that is the latest run that I can get for free. All the rest since that date are behind a paywall.

And here is 10mb wind speed, to show how the jet flows.

  

And the GEFS forecast which shows descending negative zonal means from the strat over time. 

 

Edited November 16, 2016 by Recretos

[WINTRY WALES]

Hi all

Does anyone know what happened to chinomaniac?? He used to be posting in this thread so often.

[seaside 60]

12 minutes ago, WINTRY WALES said:

Hi all

Does anyone know what happened to chinomaniac?? He used to be posting in this thread so often.

From what I have read on here he is very busy with life and work.

I am sure he will be back soon.

[Recretos]

The control run, getting out of control on the 12z GEFS. 

 

[summer blizzard]

5 hours ago, Gael_Force said:

Winter 62-63 had early Canadian warming and later SSW only reinforced the cold. It will surely depend on other factors but I know Kev Bradshaw has written about SSWs scuppering early cold patterns. To me, this is the early pattern that has usually been harbinger of cold in the UK but every situation is unique in itself.

 

A common occurrence is that these warming events can simply result in a high very close to the UK and even potentially a little east. In late Dec 12 we saw a SSW which simply resulted in a change from a slightly above average cyclonic pattern to a slightly below average anticyclonic pattern after a ~10 day easterly, it was not until wave breaking in late Feb that we got the real action in March. In winter 09 we actually saw a wonderful winter pattern delivering the coldest Dec-Jan in perhaps 15 years before the SSW in early Feb screwed the pattern and we had super mild second half to Feb and a very warm April as the high got shunted a little east but too far south. 

It perhaps depends on the state of the vortex beforehand but if the default pattern is already good then sometimes it can be better to pat the weak vortex softly a few times than have one knock out that disturbs an already good background pattern. 

[damianslaw]

Re: post above, I think you are mixing up winter 09/10 and winter 08/09. In late Jan 09 we had a SSW which delivered a cold snowy first half to Feb but a very mild wet second half to the month.

I'm not sure we had a SSW in winter 09/10 from memory. February remained predominantly cold, with the cold lasting well into March, indeed Spring 2010 was preety cold overall. Winter 09/10 overall the coldest in terms of consistency and length since winter 78/79.

[summer blizzard]

7 minutes ago, damianslaw said:

Re: post above, I think you are mixing up winter 09/10 and winter 08/09. In late Jan 09 we had a SSW which delivered a cold snowy first half to Feb but a very mild wet second half to the month.

I'm not sure we had a SSW in winter 09/10 from memory. February remained predominantly cold, with the cold lasting well into March, indeed Spring 2010 was preety cold overall. Winter 09/10 overall the coldest in terms of consistency and length since winter 78/79.

Winter 09 did refer to Jan onward, it's how i always describe a winter. We did get a warming in Jan or Feb 10 but i don't know if it was an official SSW. 

[lorenzo]

Martineau calls them Jan - visuals here

http://p-martineau.com/ssw-animations/

Both years, Jan then Feb:

24 Jan 2009

09 Feb 2010

Great page love it ! http://esrl.noaa.gov/csd/groups/csd8/sswcompendium/

Love it when 2009 gets a mention - properly indecent viewing.

 

 

 

[summer blizzard]

11 minutes ago, lorenzo said:

Martineau calls them Jan - visuals here

http://p-martineau.com/ssw-animations/

Both years, Jan then Feb:

24 Jan 2009

09 Feb 2010

Great page love it ! http://esrl.noaa.gov/csd/groups/csd8/sswcompendium/

Love it when 2009 gets a mention - properly indecent viewing.

 

 

 

Great viewing, a wave 2 pincer. 

In terms of what drives the AO and how negative i'm curious, on just about all stratospheric aspects we are at near record low or high values for the time of year (where we want to be), are there any factors that actually suggest we'll see a +AO December or would your bet be on -1< which is what my punt would be based on the values seen. 

[Duane S.]

Berlin D10 a hair's breadth away from a reversal. We can go through many a winter without seeing such a chart, certainly at this time of the year!

Let's hope luck is on our side whilst the atmosphere gets all shaken up. 

[beng]

59 minutes ago, s4lancia said:

 

 

Quick question - given the model is forecasting the upper vortex to be displaced towards Siberia whilst pressure rises at 10hPa towards Alaska/Canada - does that also tend to force the vortex in the troposphere towards Siberia too? If not always, what kind of factors would need considering too? I'd assume the answer is a 'not necessarily' type answer - otherwise warmings would nearly always produce similar broad-scale outcomes at the surface (in terms of where blocking sets up) - but as we've seen to our costs in terms of cold in the past, that varies. Thanks in advance to anyone that answer.

[Summer Sun]

 

[MattH]

1 hour ago, Summer Sun said:

 

The importance here I think is the consistency over the GEFS in terms of pretty much all the ENS members falling below zero and obviously indicating a wind reversal, to an extent the GFS DET can do what it wants, as is often does, both within the stratosphere and within the troposphere. Clearly at longer time frames too it can flip-flop around like a fish out of water, but it is the increasing consistency from the GFS ENS and also the lack of ENS spread too from around the 25th and 26th onwards, which is clearly when the winds at 10hPa 65N are set to reach or drop below 0m/s. As everything in forecasting, model consistency is key to the confidence of a forecast and I still want to see the consistency continue in the coming few days, but given everything I've seen and discussed with Tony (Lorenzo) as well with regards to the early part of the winter forecast, then a SSW is certainly likely now perhaps before the end of November which would be quite impressive, especially compared with 12 months ago. Even if it doesn't manage it in November than given the broader northern hemispheric patterns over the last few weeks then you would think one would hapeen in December (SAI index, Russian high, sea ice et al).

As was discussed in here a few days ago mind it isn't as though a SSW is required to completely change the northern hemispheric pattern, that has obviously been disjointed and clearly not very +NAO like, for example, for weeks. As myself and Tony have been discussing of late too, the $64,000 dollar question is; If a SSW does occur, especially if it is a split, as some of the models suggest, where do the two (or more) vortices end up after the split? - I think it was Stuart (Glacier) that highlighted some thoughts on this and it certainly looks possible that a cross-polar build of +ve heights is likely into the Greenland region, with then two vortices then left over, one over parts of Scandinavia or Russia and the other slipping around to parts of Canada or Alaska, that setup certainly has some similarities to 2009 I believe, but don't quote me on that one.

Using the 00Z GFS by the 30th, I've, albeit crudely, highlighted this possibility visually. Note the potential region of higher pressure (red circle) and then two separate regions of lower heights and vortices moving away from each other to essentially 'sit' either side of the higher heights over the polar region. Determining the location of these vortices could well be crucial as to the weather that we experience across our 'little corner of the globe' moving forward into December.

All-in-all despite some uncertainties months back, over things like the QBO and ENSO phase, for those who are after cold weather and cold synoptics then I don't we could ask to be in a better position so early in the season. If the winter is generally cold and blocked through December and into January, before a possible change late on I don't think the 'coldies' will grumble at that. Personally I always think colder synoptics are better through December and January given that general time of year, lack of solar influences etc. A cold -5C to -10C 850mb air mass in December/January often has more potency that it does during February and into March for example.

Fascinating model watching ahead, and importantly foundations for a potentially very interesting December with some seasonal and festive weather certainly possible too.

Regards to all,

Matt.

[Singularity]

One thing I've been pondering over is whether, if we did see a west-based negative NAO as a result of tropical forcing (of which I'm still a bit skeptical, but not as much as I once was), could the placement of the positive GPH anomaly in the stratosphere as shown by GFS/GEFS and ECM then encourage an eastward trend in the blocking position through the first half of Dec, taking it toward Greenland then Iceland, potentially (eventually) bringing some deeply cold air with it from the Canadian Arctic?

Complications could occur with blocking E/NE of the UK though given the unusually weak zonal state and scope for the tropospheric vortex to drift to more southern parts of Eurasia through early Dec. Hard to see the southerly shifted jet romping into the UK such as some recent GFS runs have shown. The 06z is closer to showing what I mean.

[Nouska]

On 16/11/2016 at 11:52, Nouska said:

This seems a very plausible explanation - something the seasonals might not capture. Yes, the disruption and the almost reversal signature but not the micro detail. The warming coming off the Russian ridge is maybe good for longer term but has actually produced a Yin Yang pattern which keeps Atlantic feed in shorter term. The best route, from historical, is for the 'bulge' to be from central Canadian Arctic and thus 'tail' sweeping on a westward trajectory through Siberia to Europe.

 

 

I've dragged over a quote from the model thread, made yesterday.

On the subject of a more central Canadian 'bulge' and not necessarily fearing a west based NAO. I've made a gif of the JMA extended four week forecast and hope this might illustrate the point I was making.

Whether it turns out to be accurate or not, it does show the tail finally sweeping in the direction needed to get cold air closer to home.

 

[Interitus]

GEOS forecast from 16/11 (delay in data published on webpage) actually went for a 10mb 60°N reversal on 26/11 of -1.89 m/s. For comparison ECM 1.88 m/s at same time.

Edited November 18, 2016 by Interitus