The trend continues to look good going forward. Even if we are unlucky enough to see the vortex break up produce vorticity initially in the wrong place (ie Greenland) it is highly likely that soon after, this too will be dislodged as renewed downwelling of existing warm anomalies further up the stratosphere are pushed 'south' towards the troposphere. The 30hpa layer continues its path with a second quite strong warming peak and shortly it looks as though we will see further wave breaking courtesy of MT which should manifest itself in forecasts towards the end of the month as a further peak at the top of the stratosphere - which in turn should be followed by yet another response from the 30pha layer.

This rise and fall, rise and fall is very conduisive for systematic top up warming and downwelling over a sustained period and is in quite a contrast to the sharp one off warming event in 2009 which means that an extended period of HLB looks likely. The only question is timing imo in terms of benefit to the UK. But its coming

 

I am still waiting to see the affect of these SSW on our shores. It seems clear to me that although SSW does occur there are massive factors involved that determine where any displaced cold moves to.

"our shores" is the key phrase. I think it must be beyond dispute by now that an SSW event does impact on the northern hemisphere and the amplification of the jet. It is largely down to the SSWs this season to date, that model output has become so uncertain - there was very little uncertainty in December, with the ensembles showing continued zonality all the way. The model output is now all over the place.

The problem for the UK, is that given our location at the eastern edge of a large ocean with warm currents, we are never guaranteed anything, however disrupted the polar vortex and the jet may become. If the pattern changes, but the components fall into the wrong location for us, we can still end up with mild dross, even when the zonal phase is over.

The METO themselves have today in terms of the outlook for February cited the very fact that it is the stratosphere that could be the major factor in terms of change from the overriding pattern of this winter to a much colder and wintry one. At this stage, with a further period of up to 2 weeks and beyond when effects could manifest themselves we can only watch and wait to see what unfolds.

We can only make suggestions as to what we think is likely to happen - much as they, in their profesional capacity are doing as well with greater insight and more objectivity than we can manage in our own homes

I am still waiting to see the affect of these SSW on our shores. It seems clear to me that although SSW does occur there are massive factors involved that determine where any displaced cold moves to.

You clearly missed it then - the effect was last week:

http://www.cpc.ncep.noaa.gov/products/global_monitoring/temperature/tn03797_30.gif

In case you hadn't noticed, we were stuck in a mega-zonal rut for a couple of weeks courtesy of a strong, unified polar vortex. The stratospheric warming dislodged and weakened the vortex - just as was predicted as early as Christmas - and we saw a pattern change as a result.

TY for that good news Matt

Tha possible situatio for a cut-off over Iberia it would be the cherry on the top of the cake

From some way out the cusp period of end of January and the start of February has seemed the most likely time for this noticeable pattern change to show its hand. We still don't know exactly how things are going to change for the BI, or to what extent, but what it has already shown is that the stratosphere/troposphere interaction is a very prominent one in determining cold or mild weather potential.

Without the recent and ongoing large scale changes in the stratosphere we may as well have been praying for longer days and Spring as the only way to get out of interminable atlantic westerlies and frequent dark, wet and windy days

What we can be fairly confident about is that the stratosphere is very unlikely now to return to the state it has been, this side of the summer, and a final warming will surely be much earlier than last year

From some way out the cusp period of end of January and the start of February has seemed the most likely time for this noticeable pattern change to show its hand. We still don't know exactly how things are going to change for the BI, or to what extent, but what it has already shown is that the stratosphere/troposphere interaction is a very prominent one in determining cold or mild weather potential.

Without the recent and ongoing large scale changes in the stratosphere we may as well have been praying for longer days and Spring as the only way to get out of interminable atlantic westerlies and frequent dark, wet and windy days

What we can be fairly confident about is that the stratosphere is very unlikely now to return to the state it has been, this side of the summer, and a final warming will surely be much earlier than last year

The rise and fall of the warming at 30hpa level in response to the higher level, as it come via pulses of wave breaking, is what is assisting the warm anomalies downwelling to the surface and translating to the break up of the polar vortex at the surface. Although we may at this stage have fallen an nnth short of a technical SSW what we are seeing nevertheless is sustained moderate to significant warming with the likelihod of a further warming peak to come in the near future as well. A case of watching the forecasts for that though

Arguably, for longer term cold outbreaks rather than some one off like Feb 2009, this type of warming evolution holds better potential - with chances for a cold spell increased in the UK because if one attempt falls just short, there is a better chance that another attempt will come around afterwards. Plus that in turn stands an even higher chance of succeeding because of the sustained attack on the vortex and not allowing it chance to regroup

Irrespective of short term question marks and differences being resolved by the models, the outlook from the stratosphere continues to show sustained warming and wave breaking with latest Mountain Torque event probably due to produce yet another warming spike to maintain a disturbed vortex and repel any attempts by it to reform through February and beyond.

I think the UK will be very unlucky indeed not to see an end product in terms of cold at some time

I noted in another thread that some were a bit bamboozled by the terminology used in here - that goes for me too. I think I may have understood and use the chart below as an illustration. If I'm standing on the ground at 1000hPa, I'm looking up through the atmosphere to the top of the stratosphere at 0hPa. The chart shows the fluctuations of temperature at different heights above me. Somebody plese correct if I've got it wrong.

Irrespective of short term question marks and differences being resolved by the models, the outlook from the stratosphere continues to show sustained warming and wave breaking with latest Mountain Torque event probably due to produce yet another warming spike to maintain a disturbed vortex and repel any attempts by it to reform through February and beyond.

I think the UK will be very unlucky indeed not to see an end product in terms of cold at some time

Spot on!

I noted in another thread that some were a bit bamboozled by the terminology used in here - that goes for me too. I think I may have understood and use the chart below as an illustration. If I'm standing on the ground at 1000hPa, I'm looking up through the atmosphere to the top of the stratosphere at 0hPa. The chart shows the fluctuations of temperature at different heights above me. Somebody plese correct if I've got it wrong.

 

That's certainly my understanding of that chart. One clarification - it shows temperature anomalies not 'fluctuations', i.e. it shows warmer and colder points in the atmospheric 'column' between 60 and 90 degrees north.

From some way out the cusp period of end of January and the start of February has seemed the most likely time for this noticeable pattern change to show its hand. We still don't know exactly how things are going to change for the BI, or to what extent, but what it has already shown is that the stratosphere/troposphere interaction is a very prominent one in determining cold or mild weather potential.

Without the recent and ongoing large scale changes in the stratosphere we may as well have been praying for longer days and Spring as the only way to get out of interminable atlantic westerlies and frequent dark, wet and windy days

What we can be fairly confident about is that the stratosphere is very unlikely now to return to the state it has been, this side of the summer, and a final warming will surely be much earlier than last year

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=temps&alert=1&lng=eng  90N 30HPa coming back down and only forecast to rebound a bit in four days time. Not the surging event that some were hoping for maybe.

Sometimes there is a simple explanation for this. And in this case that is so. The warm stratospheric air is deflected away from the North Pole - south of 60N - by the shape of the vortex, before re-entering a day or so later to latitudes further north (E-P flux important here)

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ec.php?alert=1&level=30&forecast=all&lng=eng

 

Rest assured the stratosphere is driving NH events here.

 

Interesting tweet fro Matt Hugo a short time ago

Compare & contrast - Very important signs from the ECM in particular regarding the Polar Vortex into early Feb..

https://p.twimg.com/AjxOHM3CIAEirDy.jpg

https://twitter.com/#!/MattHugo81/status/161089572292403201/photo/1

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

That's a pretty good description of it, I must say.

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

That's a pretty good description of it, I must say.

The sustained process of destroying the polar votex continues to grow with every passing day. Looking to the ECM forcast now for yet another spike in temperatures. GFS stratosphere forecasts already indicating this, courtesy of the latest MT I have been speaking about

Meanwhile the next pulse of warming anomalies are making their way to the troposphere - and they underpin further the prospects for February with a new entrenched -AO/NAO pattern and strongly question any suggestion of attempts to return to zonality. Of all the options available as far as the UK is concerned, this is the least likely to occur. So easterly, then north/north easterly as blocking retrogresses to the NW?

The refreshed and newly updated ECM 32 dayer which has stayed consistent for several roll-outs now, looks very good value for money

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

That's a pretty good description of it, I must say.

The sustained process of destroying the polar votex continues to grow with every passing day. Looking to the ECM forcast now for yet another spike in temperatures. GFS stratosphere forecasts already indicating this, courtesy of the latest MT I have been speaking about

Meanwhile the next pulse of warming anomalies are making their way to the troposphere - and they underpin further the prospects for February with a new entrenched -AO/NAO pattern and strongly question any suggestion of attempts to return to zonality. Of all the options available as far as the UK is concerned, this is the least likely to occur. So easterly, then north/north easterly as blocking retrogresses to the NW?

The refreshed and newly updated ECM 32 dayer which has stayed consistent for several roll-outs now, looks very good value for money

Indeed

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

That's a pretty good description of it, I must say.

 

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

 

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

The sustained process of destroying the polar votex continues to grow with every passing day. Looking to the ECM forcast now for yet another spike in temperatures. GFS stratosphere forecasts already indicating this, courtesy of the latest MT I have been speaking about

Meanwhile the next pulse of warming anomalies are making their way to the troposphere - and they underpin further the prospects for February with a new entrenched -AO/NAO pattern and strongly question any suggestion of attempts to return to zonality. Of all the options available as far as the UK is concerned, this is the least likely to occur. So easterly, then north/north easterly as blocking retrogresses to the NW?

The refreshed and newly updated ECM 32 dayer which has stayed consistent for several roll-outs now, looks very good value for money

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

 

 

Ignore the 18z GFS at least everything in the stratosphere is looking good

Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling

That's a pretty good description of it, I must say.

 

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

 

I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.

We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.

The sustained process of destroying the polar votex continues to grow with every passing day. Looking to the ECM forcast now for yet another spike in temperatures. GFS stratosphere forecasts already indicating this, courtesy of the latest MT I have been speaking about

Meanwhile the next pulse of warming anomalies are making their way to the troposphere - and they underpin further the prospects for February with a new entrenched -AO/NAO pattern and strongly question any suggestion of attempts to return to zonality. Of all the options available as far as the UK is concerned, this is the least likely to occur. So easterly, then north/north easterly as blocking retrogresses to the NW?

The refreshed and newly updated ECM 32 dayer which has stayed consistent for several roll-outs now, looks very good value for money

 

The NAO can operate in disconnect to the AO, at least for a time, but as far as winter is concerned seasonal wavelengths dictate that this usually happens early in the season - late November and December. However during the second half of the winter there is an increased coupling of the two during January and most especially February.

However the key part of this is that the relationship cannot operate indefinitely de-coupled. Despite the gyrations and contrary signals coming from the models atm, that are leading people to believe what they are saying at face value, nothing has changed in terms of the outlook in terms of February for an entrenched -AO pattern in direct contrast to first half of the winter.

On that basis any suggestions by the models to over strengthen the northern arm of the jet should be taken (imo) with a pinch of salt. Especially kee jerk reactions to the ebbs and flows of daily model forecasts. It seems wiser to take an overview imo over a couple of days or so to get a wider picture.

The present complication in terms of jet energy to the north is a residual parcel of vortex close to the North Pole and the modelling of this has been chopping and changing for some time. But when seen in the context of the overall pattern and expectations of stratospheric forecasts this is not a long term situation with further downwelling of warmer layers expected through the first week of Feb that should further change, and improve the polar profile. I'm not sure that the models have read this signal yet properly.

Irrespective of what happens next week, easterly or not - that is why I am taking model projections into the new month with a pinch of salt.

Edit: chionomaniac on NW has given a much more technical answer to the overall situation than I ever could in my own simple lay language - but the gist is more or less the same in terms of the prognosis for February. As he states in terms of the vortex - longer term changes should be expected in the context of the present messy and uncertain situation