Stratosphere Temperature Watch 2014/2015

[skatefan]

The current tropospheric pattern with the extremely strong Scandi positive anomaly is catching my eye big time. 

 

 

This is something that we expected with the high SAI and it has not failed.

 

However, look at the upcoming pattern - here are the ECM cumulative anomaly charts

 

Days 1-5

get_orig_img-3.gif

 

Days 6-10

get_orig_img-2.gif

 

Watch that westward progression of the Scandi high - this is often seen prior to a displacement event in the strat

 

Here are the slp anomalies from Cohens paper to watch out for prior to displacement SSW's

 

Screen Shot 2014-11-16 at 21.30.28.png

 

Compare to what is programmed. So any sign of a 'big' wave 1 strat warming.

 

You bet!

 

NH_TMP_1mb_384.gif

 

Game on.

 

That's the point I tried making yesterday evening. The Skandi-high is troposferically holding on due to stratosferical weakening and displacement. Both Gfs and ECM support this up to T240.

 

Chio: in line with your image of two dancers: the troposferic one leads the dance here because the stratosferic dancer allows it or is not able to the take the lead.

 

I expect the first cold spells late nov/early dec. It won't be "big-time" but the first dance sets the tone...

[MattH]

Following on from Ed's post yesterday there could be signs of this now within the latest EC charts. Some of the most interesting charts are above 5hpa but I guess this is were you would expect the initial development and then for it to work it's way down with time. By 240hrs the upper part of the vortex is really starting to get a sweat on and this is highlighted nicely by the ZMS D10 chart and the waves graph in terms of a significant wave 1 development, as forecast with temps above 3hpa heading into a positive value.

Not had time to look at the 00z GFS but again using the anom graphic Ed highlighted last night then I think all eyes need to be on the look out for a major wave 1 event by months end and then a poss sig displacement. $64,000 question though surely iswhere does the displaced vortex end up (Ed?).

If the Scandy high pressure and +ve pressure anom charts are indeed correlating to Cohens work then the within the next 7 to 14 days the vortex could be well be getting a bit hot under the collar!...

Cheers. Matt

Edited November 17, 2014 by MattHugo

[bluearmy]

Wow - that wave 1 geopot is massive. Note that the GFS is taking that strat top warming stronger and poleward week 2.

A good test to see how the ecm ens deal with any trop responses now they have vision to the top of the strat. Last time we went through this, the ecm ens only went up to 5hpa. Still sometime to go on this - can't see a SSW within the next 18 days or so. Could easily be 21 though and the ECM ens should see that timescale by the end of next weekend.

 

Incidentally, i noticed Joe B using netweather's 30mb strat charts to illustrate a point in his blog on weatherbell. he clearly uses the site - he shouldnt by shy about popping in to share his thoughts. i suspect he sees things progressing in a similar fashion to most of the more knowlegable on here.

Edited November 17, 2014 by bluearmy

[Recretos]

Interestingly, the Para GFS is a bit different than the ECM this time. Will be interesting to see who emerges victorious.

 

 

 

 

And some wave 2/3 fun and games in the FI.

 

 

 

 

 

Hi again and sorry for another off topic post. 

I want to ask from where do you obtain these GRIB2 files you are talking about.

I know this page: http://www.nco.ncep.noaa.gov/pmb/products/gfs/index.shtml.upgrade

And from there, there is this page for example: http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/

Where you can download what you want(seemingly). But i don't get it how exactly and where exactly to go and what means what.

 

So for example if i want the 0.25 grid files of the new GFS for a grid of 40° to 45° north, 10° to 15° east and for let's say geopotential heights of 500 hPa, where do i have to go to download them?

 

Can you also explain from where i can obtain these 3 different formats (a,b full)?

 

 

Many thanks in advance!

 

Well you cannot really specify areas, but the files have specific parameters and vertical layers in them, so you just chose the right file. Every file has the full globe coverage. 

 

You can start here regarding files:
http://www.nco.ncep.noaa.gov/pmb/products/

 

Regards

Edited November 17, 2014 by Recretos

[Snowman.]

 

2nd warming maybe at 10?

[bluearmy]

 

2nd warming maybe at 10?

But as per most recent GFS back ends, no support on the parallel at 10 hpa.

[Swave Snow]

But as per most recent GFS back ends, no support on the parallel at 10 hpa.

 

 

Parallel is delayed this evening apparantly

[bluearmy]

And there was me thinking what a splendidly consistent model we had found !

[MattH]

Morning all...

Few comments which are both strat and trop related so apologies if this could be in the model output thread, if someone wants to paste it there, feel free.

First off and without sounding like a stuck record, this really is a waiting game. Few days of ridged conditions, a temporary N'ly aside, in terms of some 'proper' winter synoptics we are, in my opinion, weeks away.

Despite the signal remaining strong for the top of the strat to get blow-torched as highlighted by the 1hpa chart below, which is impressive mind, further down the strat after some short term disorganisation the vortex becomes located over Greenland and is quite solid, despite further wave 1 activity and warning over on the Asian side of the N Pole.

We have been seeing trop charts, from the usual global models, showing an increasingly organised PV setting up shop over Greenland by the back end of Nov, and this isn't any real surprise and something I do believe will happen. As a prediction, late Nov into early Dec could well be rather zonal and unsettled with at least a spell of +NAO conditions if not +AO too.

Now, this is may not seem like a step in the right direction but again as many have said on here it's a waiting game and the 'goodies' may not be achieved until at least mid to late Dec, which is what I continue to believe will be the case.

Ed's sig wave 1 warming is still there by month end (esp on ECM ENS) and the 1hpa ECM chart really does look good, but clearly it's about as high up as you can get. This process of getting the warmth down to lower levels of the strat (to help displace, split and disorganise it) is going to take time.

May not be the best start to winter in terms of cold synoptics, in fact early Dec may look quite grim with a solid PV over Greenland and Atlantic conditions. But for those hoping for cold weather (me included) we just have to hope the likes of the QBO, SAI et al do what they are hypothesised to do in time etc.

Cheers. Matt.

[Recretos]

Not really much to add to what Matt has said. This current upcoming split wont really do any special good, troposphericaly speaking, tho it is very welcome strat-wise. 

 

Later on, the main activity will be confined to the more upper layers of the stratosphere, and it really is very decent activity. Still, not much out of it for the troposphere (naturally), but as long as things are stirring up there on the top, the vortex cannot be one large single entity as it wants to be. There is also some slight disconnect between the upper/mid/low strat layers. The reason is that the troposphere is slightly more on the dominant side as far as lower strat goes. So we will need that upper strat activity to start taking over more than just the upper layers, combined with more constant dynamics. Just one wave of activity isnt going to cut it. We need constant battering, to put it that way, and some help from the trop. patterns. 

 

Now there are of course many positive points, like the temperature and wind profiles. Here is a comparison of the ECM forecast, and analysis of last year. I use the both hemisphere projection, because there is a little glitch in the software and I cant plot just one, but nonetheless it gives a nice perspective. 

 

 

 

 

 

 

Now for those of you that cant see those "positive points" right away on the graphics above, I have made three new graphics just for you. It is the difference between this year and last year, centred on 27.11 as far as ECM forecasts go and in a relatively good range of skill. It is the difference on this date between this year and last year. Data from this year is based on the Para GFS forecast (it is perhaps a bit different than ECM, but it gives a good general idea nonetheless), and data for last year is based on reanalysis from ECMWF ERA-Interim (accessible from the data portal me and Matt were talking about). It shows nicely just how weaker the mid-upper strat vortex really is, and as far as temperature goes, it has a pretty non-hospitable environment. It looks really cool (no pun intended), at least to me, and its a good indicator how different things are up there. It is interesting to note how the QBO phase also has its own temperature profile.

 

 

Wind-wise, the QBO difference is visible right away, since the phase is different to last year (we are in a QBO-, so that is why the negative difference relative to last year, and the positive above it). The polar jet is quite weaker at this point, because of the wave onslaught. 

 

 

And the geopotential height difference, which also tells its own story of the vortex strength and the wave onslaught. I used the MERRA dataset for this one, because the ECMWF ERA gpm data is not coded in a compatible format with GFS, tho wind and temperature are. With this graphic you kinda get the fell what those wave graphics from FU-Berlin might mean.

Here is also interesting to note how the QBO also has its own geopotential height profile.

 

 

Not to mention that the ECM forecast has an even weaker vortex (slightly) and a warmer wave as the GFS. 

 

I really love playing around with data. Hope you like it. 

 

Regards.

Edited November 18, 2014 by Recretos

[Interitus]

 

With other words, are there sometimes features of the troposphere(like a surface low deepening too much over a warm sea) that will "lead" the stratosphere?

Long term(in months scale-climate) we know this happens with snow extent, sea ice cover, great mountain ranges like Rocky mountains and Himalayas, etc, that effect strongly the stratospheric circulation, but what about short-term(scales of days or weeks-weather)? Can a prediction of a map in the stratosphere that one says oh look this will definitely evolve this way after 10 days, be actually "destroyed" and a tropospheric event to lead the stratosphere to behave completely differently?

 

This is actually a very good question relating to the nature of troposphere-stratosphere coupling which doesn't have a simple answer. Early research considered the 'top-down' control of the troposphere by the strat looking at the relationship between the season-long AO signal and the strength of the strat vortex or stratospheric northern annular mode (NAM). But it soon becomes apparent that tropospheric responses can be seen in reanalysis at sub-monthly timescales i.e. within weeks or even days, which leads into more recent research such as the polar annular mode (PAM) which describes the latitude of the strat vortex.

While the NAM typically tends to vary slowly over perhaps a month, the PAM was extracted from daily data and varies over a couple of weeks.

 

Of course it is a two-way street with the troposphere affecting the strat. The major wave activity flux areas upwelling and affecting strat are around the jet exits over the north Atlantic and Pacific. In particular it can be seen that in positive NAO conditions with a strong jet flow over the Atlantic can act to almost immediately strengthen the strat vortex. Much research examines how tropospheric waves impact the strat vortex or are refracted away towards the equator.

 

Finally, there are some researchers that examine the coupling at the actual synoptic scale of individual weather systems rather than averages eg Colucci - Stratospheric Influences on Tropospheric Weather Systems - http://journals.ametsoc.org/doi/pdf/10.1175/2009JAS3148.1

 

Anyway this is an active area of research and the above only scratches the surface so try searching for troposphere stratosphere coupling, or visit.......

 

 

A recent paper titled 'Weakening of the stratospheric polar vortex by Arctic sea-ice loss' that may be of interest. I quite like the sea ice theories, and its good to see recent papers by Cohen, Overland etc.. start to combine the effects of both increased snowfall and decreased sea ice (with links to the stratosphere, rossby waves, jet stream dynamics etc..)

 

Abstract

Successive cold winters of severely low temperatures in recent years have had critical social

and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although

these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the

mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by

conducting observational analyses and model experiments, we show how Arctic sea-ice

loss and cold winters in extra-polar regions are dynamically connected through the polar

stratosphere. We find that decreased sea-ice cover during early winter months (November–

December), especially over the Barents–Kara seas, enhances the upward propagation of

planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric

polar vortex in mid-winter (January–February). The weakened polar vortex

preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low

temperatures in mid-latitudes.

 

http://www.nature.com/ncomms/2014/140902/ncomms5646/full/ncomms5646.html

 

Edit: I remembered there is a topic for articles in the advanced discussion. Please move there if more appropriate

 

 

....the Technical Teleconnective Papers thread is the place for these - https://forum.netweather.tv/topic/73911-technical-teleconnective-papers/

 

Yes Cohen included sea ice in last year's 'Warm Arctic, Cold Continents' paper which examined the effect of the record low ice cover of 2012-2013 - http://www.tos.org/oceanography/archive/26-4_cohen.pdf

However, the emphasis tends towards the impact on snow cover which of course is his main area of research. What some other researchers such as Magnusdottir have found is that sea ice can have an effect on Arctic pressure patterns without including the snow extent so it would be good to be able to discern the individual components. So this upcoming paper from Magnusdottir et al. might be particularly interesting - The role of sea surface temperature, Arctic sea ice and Siberian snow in forcing the atmospheric circulation in winter of 2012-2013

It looks at the same winter as Cohen et al. and from the abstract their simulations suggested that the surface forcings favoured a negative NAO but interestingly the effect doesn't seem very large -

In our model, the combined NAO response to tropical/North Atlantic SST, Arctic sea ice and Siberian snow anomalies accounts for about 30% of the observed NAO anomaly.

[knocker]

There is a video on this link that may be of interest.

 

This is what happens to the stratosphere when the polar vortex completely breaks down: http://www.slate.com/blogs/future_tense/2014/11/17/polar_vortex_definition_here_s_what_s_really_happening_with_stratospheric.html â€¦

[karyo]

The 18z has a much weaker vortex and the current warming is more significant than on previous runs. Also, it shows the beginnings of a new Asian warming towards the end of the run.

 

Let's hope this is a new trend (especially about the new warming) and not a one off!

 

Karyo

[joggs]

Just out of interest,its true to look at the same run of a certain time as the previous days run(like for like)but does that hold true with re the strat forecasts as with the trop output on the mod thread?

Sorry if it seems a silly question.

[Duane S.]

Same theme on yesterday's ECM, wave 1 continues to increase and wave2 activity picking up again later on as well. Ok we may not be benefiting right now tropospherically but at least the upper vortex is not going to get its own way!

Ep flux starting to head in our favour?...

[snowking]

Ep flux starting to head in our favour?...

image.jpg

That's certainly what caught my eye this morning S4L - early days of course but it would certainly be nice to see that become a trend over time

Otherwise much as we were really, continued attacks on the upper vortex, lead primarily by some very strong Wave 1 activity, though signs after waning of some further Wave 2 action towards the end of the run again helping to keep the vortex humble.

SK

[feb1991blizzard]

Yes, every little warming helps, its going to be a while before we start seeing stonkers by where the bright reds (high temps) get right into the core of the vortex in the mid strat, I want to see a wave 2 (split) SSW with the daughter vortices far apart (North Pacific and Siberia) and a massive area of +ve heights over Greenland before I start counting down the days to the LIA but hopefully it will happen in late December.

[Cloud 10]

Same theme on yesterday's ECM, wave 1 continues to increase and wave2 activity picking up again later on as well. Ok we may not be benefiting right now tropospherically but at least the upper vortex is not going to get its own way!

Ep flux starting to head in our favour?...

image.jpg

 

Liking the sudden drop in zonal wind speeds at the top of the stratosphere between days 4&5,i assume that's a big uppercut from the wave 1 activity?

 

day 4..  day 5..

[phil nw.]

The wave 1 activity at the top is certainly slowing the upper vortex down in the ECM forecasts,as shown in previous posts.

A look at the effect at the top through the temperature forecasts shows the warming up there.

Day1 and then projected Day 10.

 

 

although there's no sign of any down welling below around 5hPa yet, the top warming does hinder a mean zonal wind increase which remains fairly static at lower levels.

A look at 2 charts supplied by the CPC site,one for this season and one from last year for the mean zonal winds speeds.

 

 

show a levelling off,which is against the normal seasonal trend and compares well to this time last year.

 

All signs of a weaker vortex with forecasts of further wave 1 action to reign in it's potential strength which keeps us in the game with the PV vulnerable to further disruption from any future wave 2 action.

 

 

Edited November 19, 2014 by phil nw.

[Recretos]

One in a hurry. 

 

[karyo]

thanks for the update Phil. Should we be worried that the warming is not downwelling?

Karyo

[Recretos]

thanks for the update Phil. Should we be worried that the warming is not downwelling?

Karyo

 

The troposphere looks very "resistful" for now, also pulling low and some mid strat to its own gameplan. The upper strat and the waves better step up to the game.

[mountain shadow]

I notice the solar flux index is moderate at 167 units, Ed indicated in his opening post that readings of 110units or less can increase the likliehood of warmings.

 

Whatever happens in the Stratosphere this Winter, I don't think we'll get much help from the Sun.

 

http://www.wm7d.net/hamradio/solar/index.shtml

[phil nw.]

The troposphere looks very "resistful" for now, also pulling low and some mid strat to its own gameplan. The upper strat and the waves better step up to the game.

Yes indeed Rectros.Still looking very cold at 30hPa but better that top warming than nothing until hopefully some further action!   

[phil nw.]

thanks for the update Phil. Should we be worried that the warming is not downwelling?

Karyo

Early days yet karyo.

No reason to be concerned at this early stage and at least the top warmings keep the vortex on the back foot.