Wrt SSW I'm inclined to remember correlation isn't necessarily causuation and, further, that it has to be that causation is less likely the more correlation is infrequent. 

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Someone tell me that I've simply not be paying attention but there are Stratosphere 10hPa charts on Meteociel.

 

The 12z run shows two major warmings but one starts in NE Russia and moves slowly east before fading. The second starts over North Africa and moves east to Siberia. The one constant is that the stratosphere at that height remains cold over our part of the world throughout.

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

 

Then:

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

 

Something else to watch.

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Remember also that you dont need a SSW to get Northern Blocking although it can help.

Note the 2009 Chart and there was no warming in November/December 2009 prior to the UK going into the freezer.

SSW's seem to trigger a Scandy High where as a Greenland High seems independant of these events (at least thats my take on it but could be totally wrong)

Either way we need something dramatic to break us out of this 1,000metre deep weather rut

Andy

Im not sure but if an SSW occurs say in Nov 2009/2010 would that not be against a MUCH less developed PV meaning it's far easier to displace?

The PV this year looks it did back in the mild winters and perhaps needs stronger forcing to displace?

But i defer to other learned members as im probably talking bobbins (was in the pub from 12-4)

Dount whether the establishment of a polar vortex is relevant to be honest. If a strong SSW event occurs, it is going to change the pressure distribution regardless.

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Having read around I would say that yes the SSW link is overstated, certainly in its relation to any blocking appearing and influencing our shorelines. Interesting reading though.

Remember also that you dont need a SSW to get Northern Blocking although it can help.

Note the 2009 Chart and there was no warming in November/December 2009 prior to the UK going into the freezer.

SSW's seem to trigger a Scandy High where as a Greenland High seems independant of these events (at least thats my take on it but could be totally wrong)

Either way we need something dramatic to break us out of this 1,000metre deep weather rut

Andy

Im not sure but if an SSW occurs say in Nov 2009/2010 would that not be against a MUCH less developed PV meaning it's far easier to displace?

The PV this year looks it did back in the mild winters and perhaps needs stronger forcing to displace?

But i defer to other learned members as im probably talking bobbins (was in the pub from 12-4)

Dount whether the establishment of a polar vortex is relevant to be honest. If a strong SSW event occurs, it is going to change the pressure distribution regardless.

SSW's dont occur that early Joe. i think its obvious that if the flow in the strat is reversed, blocking will find it easier to establish itself in the trop. what is repeated over and over again is that high lat blocking is no guarantee that it will be cold in nw europe. early on in the season, before the p/v is well eastablished, any small warmings in the upper strat will find it easier to affect the developing vortex. i think this vortex is so strong and well set, it will take a very strong warming, propogating right down to deliver deep cold to the mid lattitudes.

Still toying with a second warm up in early January.

http://images.meteociel.fr/im/167/gfsnh-10-372_wil6.png

The first warming event seems to be peaking around now.

http://images.meteociel.fr/im/6452/gfsnh-10-6_skt4.png

With a second possible around 07 January.

http://images.meteociel.fr/im/9665/gfsnh-10-264_lkj0.png

No idea what impact if any they might have.

Cheers Matt

http://176.31.229.228/modeles/gfs/run/gfsnh-10-384.png?6

Does this signify a much better SSW event that could have a positve effect on removing the such low heights over the pole? If so, the end of January / Feb could be interesting if the warming has any effect.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-384.png?6

Does this signify a much better SSW event that could have a positve effect on removing the such low heights over the pole? If so, the end of January / Feb could be interesting if the warming has any effect.

That would actually be a third in the recent series, after the one just passed.

And a second around 06 January.

http://images.meteociel.fr/im/570/gfsnh-10-204_cdq3.png

Strong warming for mid January crops up on 12z too.

http://images.meteociel.fr/im/5372/gfsnh-10-384_ouw7.png

They seem to be coming in roughly weekly bursts.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-384.png?6

Does this signify a much better SSW event that could have a positve effect on removing the such low heights over the pole? If so, the end of January / Feb could be interesting if the warming has any effect.

 

It has not guarantee of filtering down to cause any effect and even if it does have the effect speculated by some any split it is a pure lottery as to where in the Northern hemisphere might get a cold blast. I see nothing to suggest a split in the PV is likely anytime soon.

 I see nothing to suggest a split in the PV is likely anytime soon.

It could just be coincidental, but...

PV now.

http://images.meteociel.fr/im/8941/gfsnh-0-6_dwa5.png

PV (split) in a week.

http://images.meteociel.fr/im/6068/gfsnh-0-168_dpz4.png

As far as I can see this is driven by a height rise following warming. Whether any of that is connected I have no idea. But it seems to me a split in the PV has been modelled for a while now?

 

 

Following another batch of warming you end up with this.

http://images.meteociel.fr/im/9034/gfsnh-0-336_zyu2.png

This would I think be the third in the recent series.

http://images.meteociel.fr/im/7294/gfsnh-10-312_vub5.png

It pushes towards the pole.

http://images.meteociel.fr/im/8138/gfsnh-10-336_ule6.png

And there's a hint of further warming at 384.

The cyclical element in terms of the stratosphere/troposphere relationship indicates that the second half of January is when we should see the vortex begin to show noticeable signs of weakening. It looks very much to me like one of those classic winters which lives up to the old folk lore: 'as the days grow longer the cold gets stronger'  As much as this December just finished very much contrasted with December 2010, I think there is every chance that the converse will hold true in terms of temperature and NH pattern, and February 2012 will contrast with Feb 2011. A much earlier final warming of the stratosphere seems likely this time.  In fact I think when the vortex does disintengrate it will never recover, and high latitide blocking will dominate the latter winter and much of the Spring - especially with increasing -QBO downwelling. Look at how long the +QBO downwelling and westerlies have prevailed since October.

The third warming is being consistently modelled on GFS and looks like a big one.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-348.png?12 

I would also like to clarify something, I think that these warmings are not actual SSW events, merely warmings of the upper srat that could trigger an SSW. An SSW is where the zonal winds at 30hpa reverse. It does seem odd to me that a sudden warming of the srat, as we are seeing forecast above, is not actually known as a SSW, but a wind reversal is. If anyone could expand on or explain thus, please do.

The third warming is being consistently modelled on GFS and looks like a big one.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-348.png?12

I would also like to clarify something, I think that these warmings are not actual SSW events, merely warmings of the upper srat that could trigger an SSW. An SSW is where the zonal winds at 30hpa reverse. It does seem odd to me that a sudden warming of the srat, as we are seeing forecast above, is not actually known as a SSW, but a wind reversal is. If anyone could expand on or explain thus, please do.

An SSW is said to occur when the mean zonal mean winds reverse at 10 hPa and 60N. No other SSW can be recorded in the following 20 days and the winds need to recover back to positive or it will be a final warming.

 

We as yet have not had a SSW this winter - in fact we have not had any reversal at any level of the stratosphere. However the warmings that we have experienced in the stratosphere so far and those that are forecast, are now having an effect of the mean zonal winds closer to the troposphere. The mean zonal winds at 100 hPa are forecast to reduce as the vortex reduces. In time I expect this to have an effect tropospherically with more disruption of the tropospheric pv increasing as the month progresses. This will weaken the vortex which will increase the chance of high latitude blocking throughout this month.

I suspect that any blocking to affect us will materialise from the NE, already the GFS strat charts are suggesting splitting to occur in the lower vortex following a displacement further aloft.

No SSW is forecast of yet, but with the likelihood of further wave breaking into the stratosphere following a strong Asian Mountain Torque event the next set of warming could be lower and more pronounced now that the strat has already taken a 'hit'. I still suspect a SSW is in the offing before the end of the month.

 

c

The third warming is being consistently modelled on GFS and looks like a big one.

http://176.31.229.228/modeles/gfs/run/gfsnh-10-348.png?12

I would also like to clarify something, I think that these warmings are not actual SSW events, merely warmings of the upper srat that could trigger an SSW. An SSW is where the zonal winds at 30hpa reverse. It does seem odd to me that a sudden warming of the srat, as we are seeing forecast above, is not actually known as a SSW, but a wind reversal is. If anyone could expand on or explain thus, please do.

An SSW is said to occur when the mean zonal mean winds reverse at 10 hPa and 60N. No other SSW can be recorded in the following 20 days and the winds need to recover back to positive or it will be a final warming.

 

We as yet have not had a SSW this winter - in fact we have not had any reversal at any level of the stratosphere. However the warmings that we have experienced in the stratosphere so far and those that are forecast, are now having an effect of the mean zonal winds closer to the troposphere. The mean zonal winds at 100 hPa are forecast to reduce as the vortex reduces. In time I expect this to have an effect tropospherically with more disruption of the tropospheric pv increasing as the month progresses. This will weaken the vortex which will increase the chance of high latitude blocking throughout this month.

I suspect that any blocking to affect us will materialise from the NE, already the GFS strat charts are suggesting splitting to occur in the lower vortex following a displacement further aloft.

No SSW is forecast of yet, but with the likelihood of further wave breaking into the stratosphere following a strong Asian Mountain Torque event the next set of warming could be lower and more pronounced now that the strat has already taken a 'hit'. I still suspect a SSW is in the offing before the end of the month.

 

c

 

Interesting to read this, maybe a few who keep going on about SSW will have a read to 

So an SSW is all about Zonal wind reversal at 10hpa caused by a warming of the strat. If the warming of the strat does not cause a wind reversal it is merely a warming and not referred to as SSW.

A warming is only called an SSW when it causes the winds to reverse. Right?