Stratosphere Temperature Watch 2013/2014

[SMU]

http://modeles.meteociel.fr/modeles/gfs/runs/2013121912/gfsnh-10-372.png?12

 

I Spy with my little eye -16c

 

Optimism level +1.

 

Same profile as last year-

 

remember

-16c at 264

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2012121412-10-264.png?12

 

became 0c

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2012122012-10-288.png?12

6 days later

 

S

[phil nw.]

Yes guys it's ramping up following on from previous runs.Looks like a strong Asian mountain torque event?

Once it get's into the ECM range then we can start to monitor the downwelling and the decrease -hopefully-of the zonal winds into the lower levels.

[snowking]

Yes guys it's ramping up following on from previous runs.Looks like a strong Asian mountain torque event?

Once it get's into the ECM range then we can start to monitor the downwelling and the decrease -hopefully-of the zonal winds into the lower levels.

Indeed!

 

[karyo]

This is brilliant guys and so good to see the warming getting upgraded on recent runs! As snowking mentions, this warming appears to keep going which is what we want now that the vortex is so strong.

Karyo

[bluearmy]

the warmings shown on fi gfs charts have tended to verify though the temp profile of the vortex didnt end up as stretched as the fi charts showed. with themps as high as -16c now modelled at 10hpa and considerably higher further up, we can see how stretched the vortex becomes and ultimately, split. given how strong the zonal winds have become, if there is a split, i would expect it to propogate quickly down with a quick trop response (as per the 12z run). bit like pulling at that elastic band - once it goes - BOOM!

[Cheshire Freeze]

the warmings shown on fi gfs charts have tended to verify though the temp profile of the vortex didnt end up as stretched as the fi charts showed. with themps as high as -16c now modelled at 10hpa and considerably higher further up, we can see how stretched the vortex becomes and ultimately, split. given how strong the zonal winds have become, if there is a split, i would expect it to propogate quickly down with a quick trop response (as per the 12z run). bit like pulling at that elastic band - once it goes - BOOM!

 

Indeed. January has the potential to be a very wintry month IMO, potentially severe. Perhaps starting to see the first signs of this now in the extended NWP.

Edited December 19, 2013 by CreweCold

[phil nw.]

the warmings shown on fi gfs charts have tended to verify though the temp profile of the vortex didnt end up as stretched as the fi charts showed. with themps as high as -16c now modelled at 10hpa and considerably higher further up, we can see how stretched the vortex becomes and ultimately, split. given how strong the zonal winds have become, if there is a split, i would expect it to propogate quickly down with a quick trop response (as per the 12z run). bit like pulling at that elastic band - once it goes - BOOM!

I recall reading somewhere Nick that propagation seems to occur more readily in a +ve QBO state.

If so then yes we shouldn't have to wait too long.

[Tamara]

If we look at the anomalous state of the PV (which is currently very strong as assisted by the +QBO) then this is dependant as always on the wave activity flux entering the stratosphere during the preceding period. We know that EP Flux has started the winter low in line with the westerly QBO enhanced zonal wind shear in the lower stratosphere.  This is having the effect of enhancing the polar night jet (PNJ) at the troposphere/stratosphere boundary and in simple terms means that planetary wave breaking entering from the troposphere is significantly mitigated in slowing down the mean zonal winds in the stratosphere.

 

Hence we see less effect on the strong vortex than we might hope for and might be suggested by forecasts.

 

This needs to kept in mind when we start to look at any forecasts such as the current GFS forecast. Topographical MT forcings are also influenced/mitigated by the shear effects in the lower stratosphere as suggested above and caution should be applied to the tropospheric interpretation of the effect that this has on the strong vortex and consideration given that the modelling might not be taking the relative strength of the PNJ into account and hence overstating the suggested vortex squeeze/split and consequential surface synoptic pattern

 

It also seems that troposphere/stratosphere interaction is alterted through sequential changes in EP flux as a way of breaking down the eastward momentum of the energy budget in the lower stratosphere.  On this basis we need to see increased signals for poleward EP flux as a means of breaking down the westerly zonal mean zonal wind anomalies in the stratosphere and allowing the vortex to squeeze and split.

 

For westerly QBO, broadly neutral ENSO, and -PDO years there have been no significant warmings over the last 50 to 60 years in January. With the solar state in the equation then late January and February holds better possibilities as often stated on here. With the above dynamics in mind, then we require the +QBO to weaken significantly in coming weeks to not just allow this potential Asian MT to be as effective as possible, but we also require the persistence of the Eastern Pacific ridge to sustain and increase the wave 2 activity on the vortex. As wavelengths grow through the winter, the wave activity should become increasingly effective, but its quite an ask to expect any forecasted warming to work effectively as early as from the first part of January

 

We saw the strong Eastern Pacific ridge in winter 08/09 just like now,, so we get an idea of what might be possible over the coming weeks if the above factors play out favourably and wave activity is sustained. But on the basis of the energy budget above and the resistance from the vortex as described, then we probably require nothing less than a major warming to be meaningfully effective and we should ask how likely this is to happen before the end of January and more especially February.

 

Here is hoping that I am being over cautious

[Recretos]

Indeed the GFS 12z operational run has stepped up the game from its cousin control run 06z. But I wont start cheering before there is some consistencywith the variety of models and in the GFS itself.

 

This is the 3D profile of the upper layers, (1,5,10 and 30). 3D height is geopotential height of the respected level, and temperature in color. It is fixed on 384h, and basically just turning around, so it is visible from all sides. 

 

GFS_Profile.mov

 

In the upper stratosphere, the vortex is having a slight difficulty breathing. Of course, this is just a part of the forecast. 

 

 

 

 

As for the GEFS. The control run remains fairly warm at -25°C, and GEFS mean goes further up to -28°C, reaching a new highest forecasted temperature.

 

 

 

 

About the MT: yes there is an E. Asian MT in progress, though I doubt at the moment that this is really the root of the current GFS FI fun and games. 

 

 

 

Tamara has spared me quite a few words, by being the lovely voice of reason, amidst the slowly growing excitement from the GFS.  

 

Best regards.

[BLAST FROM THE PAST]

If we look at the anomalous state of the PV (which is currently very strong as assisted by the +QBO) then this is dependant as always on the wave activity flux entering the stratosphere during the preceding period. We know that EP Flux has started the winter low in line with the westerly QBO enhanced zonal wind shear in the lower stratosphere.  This is having the effect of enhancing the polar night jet (PNJ) at the troposphere/stratosphere boundary and in simple terms means that planetary wave breaking entering from the troposphere is significantly mitigated in slowing down the mean zonal winds in the stratosphere.

 

Hence we see less effect on the strong vortex than we might hope for and might be suggested by forecasts.

 

This needs to kept in mind when we start to look at any forecasts such as the current GFS forecast. Topographical MT forcings are also influenced/mitigated by the shear effects in the lower stratosphere as suggested above and caution should be applied to the tropospheric interpretation of the effect that this has on the strong vortex and consideration given that the modelling might not be taking the relative strength of the PNJ into account and hence overstating the suggested vortex squeeze/split and consequential surface synoptic pattern

 

It also seems that troposphere/stratosphere interaction is alterted through sequential changes in EP flux as a way of breaking down the eastward momentum of the energy budget in the lower stratosphere.  On this basis we need to see increased signals for poleward EP flux as a means of breaking down the westerly zonal mean zonal wind anomalies in the stratosphere and allowing the vortex to squeeze and split.

 

For westerly QBO, broadly neutral ENSO, and -PDO years there have been no significant warmings over the last 50 to 60 years in January. With the solar state in the equation then late January and February holds better possibilities as often stated on here. With the above dynamics in mind, then we require the +QBO to weaken significantly in coming weeks to not just allow this potential Asian MT to be as effective as possible, but we also require the persistence of the Eastern Pacific ridge to sustain and increase the wave 2 activity on the vortex. As wavelengths grow through the winter, the wave activity should become increasingly effective, but its quite an ask to expect any forecasted warming to work effectively as early as from the first part of January

 

We saw the strong Eastern Pacific ridge in winter 08/09 just like now,, so we get an idea of what might be possible over the coming weeks if the above factors play out favourably and wave activity is sustained. But on the basis of the energy budget above and the resistance from the vortex as described, then we probably require nothing less than a major warming to be meaningfully effective and we should ask how likely this is to happen before the end of January and more especially February.

 

Here is hoping that I am being over cautious

Looking good for 92 Tamara

 

BFTP

[Interitus]

The strength of the vortex may be a bit of a red herring with regards to a potential stratospheric weakening. According to the MERRA data since 1979 the 10mb wind has reached daily record levels in the last couple of days but there have been stronger December values achieved in 1980, 1982, 1985, 1988, 1989, 1990, 1991, 2007 and 2008. Interesting here is the gap in the 1990s and early 2000s at a time when winter tropospheric AO was in a particularly +ve phase.

Averaging the windspeed from 150mb to 10mb to get an idea of the overall strength also gives higher December values in 1980, 1982, 1988, 1989, 1990, 1991, 1992, 2004, 2007 and 2011.

When including January and February 10mb winds then there are many more higher values and there is little affect on subsequent weakenings, Here are spells of 10mb winds stronger than present and the conditions that followed (with MW minor warming, FW final warming)

1980 Jan/Feb - Feb/Mar SSW

1980/1 Dec/Jan - Feb MW / Mar SSW

1982/3 Dec/Jan - Feb MW

1984 Jan - Feb/Mar SSW

1985/6 Dec - Mar FW

1988 Jan/Feb - Mar SSW

1988/9 Dec/Jan/Feb - Feb SSW

1990 Jan - Feb MW

1990/1 Dec/Jan - Jan/Feb MW

1992 Jan - Jan MW

1993 Jan - Mar MW

1996 Jan/Feb - Mar MW

1997 Jan/Feb -

2000 Jan - Mar SSW

2005 Jan - Feb MW / Mar SSW

2007/8 Dec/Jan - Feb SSW

2008/9 Dec/Jan - Jan SSW

 

Only 1997 appeared devoid of significant reduction in zonal wind.

 

 

 

For westerly QBO, broadly neutral ENSO, and -PDO years there have been no significant warmings over the last 50 to 60 years in January.

 

This is more a function of how rarely this combination of circumstances arises and one must question its significance with regards to SSW. There is also the matter of which data sources to use, but with Berlin QBO, JISAO PDO and NCEP ENSO strictly >-0.5 <0.5 there are only 4 years since 1951/2.

1962 - vortex split in February (Mitchell et al)

1967 - nothing noted

1979 - February SSW

1991 - January/February MW

Given a typical January SSW frequency of maybe 15-20% then this result isn't too unexpected. Moreover, NCEP ENSO for example represents a moving goalpost as it is adjusted for climatology. The current figures consider DJF 1968, though at -0.6, to be a neutral period - and there was an SSW in Jan 68.

The previous 1971-2000 figures put 1968 in a -ve phase, but somehow DJF 2009 at 0.8 is considered to be within a neutral transitional period, and there was a big SSW in Jan 2009.

 

 

[lorenzo]

Quick set of charts from the strat. interesting now to compare in real time the projected activity against the OPI wave prediction posted by Sebastaan a couple of pages ago.  Beginning to think that the Italians using October data to predict the key planetary wave events impacting the vortex over winter really are onto something..

 

Asian Torque responsible for the uptick in MT activity.

 

30hPa & Vorticity at 240hrs

 

Wave 2 & Heat Flux

 

GFS Temps, important to cross check with what GFS is looking at compared to the ECM, as we have been here before with ECM.

 

EPS weekly - later into January.. - tells it's own story.

 

Lining up well for Feb, vortex is a heavyweight and this is akin to landing a lucky uppercut in Round 6. Still a few rounds of hits needed..

[Tom Quintavalle]

 

 

We saw the strong Eastern Pacific ridge in winter 08/09 just like now,, so we get an idea of what might be possible over the coming weeks if the above factors play out favourably and wave activity is sustained. 

 

Hi Tamara,

 

That was such an informative and well explained post above, imho, thank you. 

 

Having looked at the NH archived 500 charts, interesting to note that, just as you've mentioned 2008/09, the winter of 1990/91 also featured a strong Eastern Pacific ridge in the Alaska/Aleutians area and like 08/09, especially in the latter half of December.

As we now know, again like 2009, a stratospheric warming took place as we moved further on into Jan/Feb of 1991, which no doubt aided the formation of HLB (like Feb 09, over Scandinavia) and the resultant wintry spell, over the UK.

 

As you state some teleconnecting factors are broadly similar, to those winters and now (although the PDO was far more negative in Dec 1990 and 2008, see table below).

 

http://jisao.washington.edu/pdo/PDO.latest

 

It will be interesting to see how the synoptic pattern evolves over the next couple of weeks in the East Pacific region but having had a quick glance at the forecast models this morning, there's no sign of any significant high pressure ridging gaining a foothold in that area, for the forseeable future. The pattern looks pretty flat and mobile, at this juncture, as it has done for a while.

 

As has been stated by many of the posters on this thread and indeed by some on the MOD thread, we are going to need a major disruption to the PV, as we move inexorably towards the 2nd half of winter, to have any chance of seeing some HLB developing, further on into Jan/Feb. But at the moment though, any assistance towards that scenario seems distinctly lacking, in the East Pacific region.

 

Tom.

Edited December 20, 2013 by Kentish CZ

[chionomaniac]

 

 

 

This is more a function of how rarely this combination of circumstances arises and one must question its significance with regards to SSW. There is also the matter of which data sources to use, but with Berlin QBO, JISAO PDO and NCEP ENSO strictly >-0.5 <0.5 there are only 4 years since 1951/2.

1962 - vortex split in February (Mitchell et al)

1967 - nothing noted

1979 - February SSW

1991 - January/February MW

Given a typical January SSW frequency of maybe 15-20% then this result isn't too unexpected. Moreover, NCEP ENSO for example represents a moving goalpost as it is adjusted for climatology. The current figures consider DJF 1968, though at -0.6, to be a neutral period - and there was an SSW in Jan 68.

The previous 1971-2000 figures put 1968 in a -ve phase, but somehow DJF 2009 at 0.8 is considered to be within a neutral transitional period, and there was a big SSW in Jan 2009.

This is the reason that I have said that a SSW is not out of the question this year - the previous statistics do suggest that some type of mid/late winter warming is possible.

 

It is interesting to see that latest uptick in forecast wave 2 activity to begin around the start of next year. My thoughts are that the vortex will recover from this, but be more susceptible to further wave activity later in Jan /Feb.Stratospherically I think we are seeing no surprises whatsoever this winter, but this forecast wave activity does need to be monitored just in case we see a bonus surprise.

[bluearmy]

missed the chance as the 00z extended are now updating but would have liked to see the 12z ecm control in its latter stages. we dont see the ecm strat data beyond day 10 so our only inkling as to whether the ecm sees developments in two weeks as per the gfs is to see if there is any kind of quick trop response  as per yesterdays 12z gfs op.  the last two gfs ops have shown that there will not always be one modelled so need to keep tabs on this.  wasnt paying much attention but i do recall an ecm control looking very blocky over the pole - perhaps yesterdays 00z run.

[sebastiaan1973]

Solar flux remains around or just above 150. See below.

 

2009 was an exception with low solar activity, around 70 Solar flux (given wQBO). Other SSWs with wQBO around 160 or more. So fingers crossed solar flux remains this high or preferably even higher.

 

[Recretos]

missed the chance as the 00z extended are now updating but would have liked to see the 12z ecm control in its latter stages. we dont see the ecm strat data beyond day 10 so our only inkling as to whether the ecm sees developments in two weeks as per the gfs is to see if there is any kind of quick trop response  as per yesterdays 12z gfs op.  the last two gfs ops have shown that there will not always be one modelled so need to keep tabs on this.  wasnt paying much attention but i do recall an ecm control looking very blocky over the pole - perhaps yesterdays 00z run.

 

The EPS control has some height rises around 2-4/1, but you cant tell if it is related to the strat or not, tho it could be possible. The EPS mean has the overall vortex divided into two entities, one over the Canadian sector (connected with the main core in the lower strat) and one over E Asia. It is pretty much in line with the control run, but less intense since it is a 50-member average of course.  AO does drop just slightly, proportional to the trop. pattern, but not really going negative since it is calculated at SLP.

 

  

 

 

ECM32 mean and control are similar as their medium range cousins in this range. 

 

 

Further out, the control and the mean go for a reorganisation of the tropospheric P.V. complex. 

 

 

 

Tho in the end, the control run raises a high in the polar circle out of nowhere, pretty much like it would just drop out of the sky (hint hint? ). And the overall energy of the tropospheric P.V. complex is pretty dispersed around. 

 

 

 

As for the GEFS, it goes along with the ECMWF.

 

      

 

 

To sum it up, I don't see any type of trop-strat response that we would expect to see. Actually we don't even have anything firm in the stratosphere to begin with.

Best regards.

 

P.S.: The variety of models+ensemble means (aside of GFS op, tho it is also not as good in the 6z run), have almost unanimously stepped down their game for the stratosphere in the last two runs. I will swing around later in the evening with some 12z products when they become available. 

Edited December 20, 2013 by Recretos

[bluearmy]

recretos, the 06z gefs mean at T384 looked interesting. also, given that any dramatic effects on the strat are still a fortnight away (if they actually verify), its a little too early to be looking for a trop response (even an 'immediate one'). i'm just hunting for clues at the moment re ecm extended strat. if the output continues to look promising on fi gfs, we should start to look for runs which split the trop vortex as per yesterdays 12z gfs op

[Cheshire Freeze]

First bit of dark orange >-30 showing up now

 

[ITSY]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=0&mode=10&carte=1

 

temps up to -12C by the end of the run and edging closer towards the pole, so by all accounts a warming event of sorts COULD begin in the next couple of weeks. Certainly a straw worth clutching to at the very least!

Edited December 20, 2013 by ITSY

[phil nw.]

If this 10hPa warming forecasted in later frames of the GFS verifys then i guess the effects on the troposphere wouldn't show up in 500hPa modeling or even ECM 32day suites at this time.

If there is to be downwelling- a big if i know-then we are probably looking 2-4weeks further on approx.

The extent of the coldest part of the pv as time goes on looks to be shrinking and the squeeze on the vortex shape is consistently modeled but as yet it's still to penetrate the core.

Encouraging though to see this warming extending with each run-let's hope it will undermine the vortex before it fades.

Edited December 20, 2013 by phil nw.

[feb1991blizzard]

First bit of dark orange >-30 showing up now

 

 

 

Yes, it needs to be maintained and get into the core of the vortex to force a split though, worth monitoring over the next few days.

[bluearmy]

 

If this 10hPa warming forecasted in later frames of the GFS verifys then i guess the effects on the troposphere wouldn't show up in 500hPa modeling or even ECM 32day suites at this time.If there is to be downwelling- a big if i know-then we are probably looking 2-4weeks further on approx.

 thats the question phil re SSW's. recent ones have seen an immediate trop response before the generally accepted series of predicted downwellings occur over the next couple of months. we just dont know until it occurs but the modelling should gves us clues. (as will the predicted flux). IF the warming continues to show and starts to come closer and show the strat vortex splitting, then it is not unreasonable to expect a big trop ridge to be thrown into the arctic and the trop p/v to split apart quite soon afterwards. unlikely before w/c 6th jan and maybe even the week following. what odds on a SSW with a destroyed vortex to follow (and an eastern canandian remnant continuing to fire up the jet across the atlantic!)

[aginob]

hi together

 

off topic

http://forum.netweather.tv/topic/78821-models-source-question/?p=2867035

 

for user recretos

respect for your posting and models ( northern hemisphere )

one model is with  black background

one model is with white background

is possible have the source ? or direct link ?

thanks !

Edited December 20, 2013 by aginob

[Recretos]

@aginob: Hi and welcome.
There is no source of these graphics, because I plot them myself, from the raw model data a.k.a. "GRIB" (gridded binary file) system or OPenDAP, GEMPAK, netCDF, etc. Depends on the model, or if it is reanalysis data, etc..

 

You wont found these graphics anywhere on the internet except here on netweather when I post them, or if someone else plots and posts them.  I usually try and plot as much various models that I can find, including monthly ensembles, but I am surprised how many monthly/seasonal EPS' have a low model top (making it quite useless for strat. forecasting)

 

As for the black/white background: That is just my experimenting with the graphical design of the product. And sometimes I change it for better visibility, etc...

 

Hope I answered your question, even tho it might not be the answer you were hoping to get.

Edited December 20, 2013 by Recretos