An SSW will show fairly shortly in the stratospheric models as a signal for the polar vortex to break down completely under the barrage of cumulative warmings caused by a wave breaking feedback already set up that will just keep gathering momentum. 

All that is needed now is for the updated forecasts to verify and we will have that SSW. In fact if the predictions verify, a few weeks down the line it could be quite a spectacular pattern change

No reason at all to change this supposition despite forecasting variations of intensity and timing of the warming process which change from day to day. The trend is the same, thats all that matters, and it remains only a matter of time before the polar vortex gives way, maybe even as a final warming for the season.

It's like a sand castle built on strong foundations thats all - that takes a few extra spade fulls of digging around its more robust outside before it caves in completely. Shows it is best to view forecasts for this part of the atmosphere in a similar way one would with the model output - even though the stratosphere is a more stable environment than the troposphere.

The uncertainty of the process is more uncertain than the growing certainty of the end result

11 January

http://images.meteociel.fr/im/6028/gfsnh-2012010806-10-84_xha0.png

16 January

http://images.meteociel.fr/im/9309/gfsnh-2012010806-10-192_eio6.png

19 January

http://images.meteociel.fr/im/5408/gfsnh-2012010806-10-264_gdx7.png

11 January

http://images.meteociel.fr/im/6028/gfsnh-2012010806-10-84_xha0.png

16 January

http://images.meteociel.fr/im/9309/gfsnh-2012010806-10-192_eio6.png

19 January

http://images.meteociel.fr/im/5408/gfsnh-2012010806-10-264_gdx7.png

That gives the Polar Vortex a damn good kicking! Will be interesting to see how the synoptics pan out.

This winter, which has been so dismal, is getting more interesting by the day. Even if we don't end up with cold and snow in our neck of the woods, it will be fascinating to watch the consequences of this forecast SSW unfold in the coming weeks.

11 January

http://images.meteociel.fr/im/6028/gfsnh-2012010806-10-84_xha0.png

16 January

http://images.meteociel.fr/im/9309/gfsnh-2012010806-10-192_eio6.png

19 January

http://images.meteociel.fr/im/5408/gfsnh-2012010806-10-264_gdx7.png

That gives the Polar Vortex a damn good kicking! Will be interesting to see how the synoptics pan out.

This winter, which has been so dismal, is getting more interesting by the day. Even if we don't end up with cold and snow in our neck of the woods, it will be fascinating to watch the consequences of this forecast SSW unfold in the coming weeks.

Wonder how that compares to Dec 2010

Wonder how that compares to Dec 2010

http://images.meteociel.fr/im/6451/gfsnh-2010120806-10-138_sho2.png

It is a heartbreaking business being a coldie in the UK - very rarely rewarded.

The progged SSW is delayed and not so intense:

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=temps&alert=1&lng=eng

The strat warming is looking like a two stage affair now, still starting on 15 Jan but subsiding a bit into the 16th before rising again by the 17th. The full magnitude of the second stage of warming is not visible to us as the plot ends whilst the temp is still heading upward.

I read some posts over on Netweather about how the warmings appear not to be impacting the lower levels of the strat and as you can see from the plot, this has been the case so far. Today, however, the lower strat temp should approach the long term average, having been rising  during the past day or so. As for the big event, we can see the delayed (by about 24 hours) response of the lower strat to the first stage of upper strat warming, but none is yet evident to the second stage, hopefully because the plot doesn't extend far enough ahead (seems likely).

Reason to remain hopeful, then, even if the models have backtracked from wonderous charts in the medium range.

 Still looks pretty good to me. End of the month could be very interesting.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-72.png?12

http://176.31.229.228/modeles/gfs/run/gfsnh-10-120.png?12

http://176.31.229.228/modeles/gfs/run/gfsnh-10-144.png?12

http://176.31.229.228/modeles/gfs/run/gfsnh-10-240.png?12

http://176.31.229.228/modeles/gfs/run/gfsnh-10-300.png?12

http://176.31.229.228/modeles/gfs/run/gfsnh-10-360.png?12

So... the warming continues to be modelled and GFS is showing some signs of PV disruption in the longer term.

The effect of warming so far has mostly been to change things on the other side of the pole, or so I gather.

The bigger warming event for 15th-16th January looks capable of affecting our side of the pole and I believe that this is reflected by those hints in the GFS output (and the GEFS and ECM ensembles) which suggest increasingly cold zonality as the PV is displaced and some blocking attempts to develop to our west and northwest. Some runs break down the PV completely.

Will we get something out of this one? We can only hope.

Today is the day when the forecast SSW starts to happen in earnest.

Fingers crossed that it leads to some proper winter weather in our neck of the woods!

I think the stratosphere is now in a new phase as the polar westerly zonal wind anonalies that have influenced our weather over recent months are now flushed out of the system. Therefore the stratosphere is going to be warmer overall from here on in as recurrent series of wave breaking under the new strengthening easterly QBO regime assert themselves instead. With that in mind I think the day to day stratospheric forecasts from the models should be used in terms of watching the overall trend rather than day to day variances. Much as looking for longer term trends in the tropospheric model thread

Following the second warming due in the next week, it might not be a bad thing if there is a pause and some relative cooling at the top layer as this might actually assist in knocking the top warming lower down to increase the influence on the overall weather patterns. This can be said on the basis of anticipating a fresh surge of wave breaking that is likely to occur thereafter (months end)  to reinforce the momentum from the top level again - as part of the longer term trend as described above. It lends itself to an eventual complete breakdown of the polar vortex as less and less impact is required from these warming injections to break up the remaining weakening vortices.

Bear in mind that whilst we saw quick results from the SSW in late Jan 2009, this came unexpectedly as part of an unfavourable polar westerly stratospheric background, thus the short sharp warming was a one off and therefore the polar vortex quickly re-grouped, despite being blown apart as a result of the one off shock to the atmosphere. And look how late, in the end, the final warming of the stratosphere was back then. The situation this time round is quite the opposite, and although it is a slower less dramatic development, it is a much more sustained one in terms of the background pattern assisting further warmings to prolong the potential effects in weeks to come.

So from my humble viewpoint I'm less concened with apparent water treading of the situation in the very short term and much more encouraged by what the medium and longer term looks to bring from end of January onwards. Of course we cant guarantee anything, but the prognosis for February and beyond can only get better in terms of chances from a cold point of view so plenty of winter left. As we know, we have historically seen potent Feb cold spells. so as the days get longer, the cold can get stronger for sure

Also the implications are that the start to Spring may also be very different to last year

cherrs Matt for the good reading

Nordic sea, you could be right about a late winter in a starting Spring

But let me ask this could also be in other hand an warmer event then the previous one, because despite the PV core is more on the Artic region, there is a streching more to the South, that could lead to have some space for a possible split, it's also a possbility to considered insn't it?

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t30_nh_f240.gif

cherrs Matt for the good reading

Nordic sea, you could be right about a late winter in a starting Spring

But let me ask this could also be in other hand an warmer event then the previous one, because despite the PV core is more on the Artic region, there is a streching more to the South, that could lead to have some space for a possible split, it's also a possbility to considered insn't it?

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t30_nh_f240.gif

There could be any number of surprises in the coming days - whatever the strength of any individual warming spike may (or may not be) the important part I was stressing is that the trend looks a longer term one than 2009 which means that rather than one short opportunity, as Feb 2009 produced there are likely to be more over the coming weeks 

Well the SSW looks like its not  propagated to the lower atmosphere, but long term IF it does we could be hit by some of the modelled northwesterlies that people have linked in the model discussion thread. If anything the PV looks to be regaining strength and La Nina is seemingly strengthening at the same time, this only bodes badly for any significant cold.

It is happening now - the encouraging thing is the way the temperatures remain elevated - also notice the new warming forecast at the end:

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=temps&alert=1&lng=eng

In previous years, any warming has been shown as a sharp rise, followed by an equally sharp fall, without the temperatures remaining elevated.

 

Well the SSW looks like its not  propagated to the lower atmosphere, but long term IF it does we could be hit by some of the modelled northwesterlies that people have linked in the model discussion thread. If anything the PV looks to be regaining strength and La Nina is seemingly strengthening at the same time, this only bodes badly for any significant cold.

 Why do you think La Nina is strengthening. It's been steady for three months or so and is forecast to weaken?

http://www.cpc.ncep.noaa.gov/products/CFSv2/images3/nino34Sea.gif

 

 

Well the SSW looks like its not  propagated to the lower atmosphere, but long term IF it does we could be hit by some of the modelled northwesterlies that people have linked in the model discussion thread. If anything the PV looks to be regaining strength and La Nina is seemingly strengthening at the same time, this only bodes badly for any significant cold.

Rubbish!

http://www.weather.unisys.com/surface/sst_anom.gif

 

 

Well the SSW looks like its not  propagated to the lower atmosphere, but long term IF it does we could be hit by some of the modelled northwesterlies that people have linked in the model discussion thread. If anything the PV looks to be regaining strength and La Nina is seemingly strengthening at the same time, this only bodes badly for any significant cold.

Rubbish!

http://www.weather.unisys.com/surface/sst_anom.gif

I Like the -tives anomalies lol another wellcome factor the PV is also weakning and a solar cycle maximun that looks more a minimum... lol

http://www.osdpd.noaa.gov/data/sst/anomaly/2012/anomnight.1.12.2012.gif

 

 

Well the SSW looks like its not  propagated to the lower atmosphere, but long term IF it does we could be hit by some of the modelled northwesterlies that people have linked in the model discussion thread. If anything the PV looks to be regaining strength and La Nina is seemingly strengthening at the same time, this only bodes badly for any significant cold.

Rubbish!

http://www.weather.unisys.com/surface/sst_anom.gif

What....the sea surface temps are rubbish? 

This SSW appears to be having little effect to me. The PV still looks very strong.

This SSW appears to be having little effect to me. The PV still looks very strong.

What polar vortex?

http://www.wetterzentrale.de/pics/Rhavn001.gif

The one near Hudson? The one north of Alaska? Eastern Russia? Or the one over Scandinavia? A strong polar vortex is a single big low, not 4 small ones.