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.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/temps.gif

Warming of the strat to 30hPa is now approaching its peak, set to fall back down from Monday, looking to briefly dip below averag a couple of days later before starting to rise again as some more of the continued warmer than average atmosphere at 10hPa makes itself known at 30hPa.

Lets hope that the upturn at the end turns out to be the start of another notable warming.

The upcoming drop from the current peak at the 30hpa level will serve to knock the warming lower down to assist with weakening the polar vortex before another round of wave breaking and warming brings support to sustain the weakening of the vortex towards the end of the month. This, as I see it, in turn should help promote a more signifcant development towards HLB as we get into February and beyond

Very interesting output this morning:

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

10hPa levels remain elevated, which is something I have never seen in previous years, plus 30hPa levels show a drop followed by another uptic are forecast.

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.

Quite. Anyone who hasn't noticed the change in synoptics recently hasn't been following things very closely 😉. Whether we get a decent cold spell out of this change is still open to question though..

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

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.

Quite. Anyone who hasn't noticed the change in synoptics recently hasn't been following things very closely 😉. Whether we get a decent cold spell out of this change is still open to question though..

Unfortunately the PV HAS now become a single big Low.

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

No it hasn't.

http://images.meteociel.fr/im/5294/gfsnh-2012011600-0-6_tzz8.png

The stratosphere forecasts appear to be showing what we want to see in terms of assistance of propagation of the warming of the upper layers. That rise, fall, and indicated rise again f.e at the 30hpa level, as well as favourable flux and flux direction, is an important part of the assistance that will keep moving the warming upper layers downwards to affect the troposphere and the vortex in the way needed to create northern blocking. The upper level of the stratosphere is now consistently warm - so there is a pipeline of attack now available for downward propagation to attack the vortex. Pockets of cooling are actually assisting that process - as long as the top of the stratosphere stays uniformly warm as it has been for a little while now

As I continue to see it and repeat - February still shows promise as the lifeblood is drained from that vortex by this sustained and ongoing process

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/temps.gif 

That repeated 30hPa warming was lost yesterday but has returned today. That means that there is some uncertainty in the strat. forecast for 9-10 days from now, which means that model FI is going to be showing more wild changes in the near future. Look at the GFS 06z which has the Atlantic winning a battle against a Scandi High only to then throw an Arctic High down towards the UK in deep FI which throws the Atlantic aside in an entertaining fashion. All good fun to watch!

NSSC, your vision for the rest of this winter always brings a smile to my face, I sure hope you are right!

That repeated 30hPa warming was lost yesterday but has returned today. That means that there is some uncertainty in the strat. forecast for 9-10 days from now, which means that model FI is going to be showing more wild changes in the near future. Look at the GFS 06z which has the Atlantic winning a battle against a Scandi High only to then throw an Arctic High down towards the UK in deep FI which throws the Atlantic aside in an entertaining fashion. All good fun to watch!

NSSC, your vision for the rest of this winter always brings a smile to my face, I sure hope you are right!

Well we all know that on this small island there are lots of things in the grand open spaces of the Northern Hemisphere that need to go right for us to land any potential cold air that comes out of the arctic, but best imo to take the glass half full approach with this, whilst being realistic at the same time

Like with the troposphere models, the best thing I've found to do, is to try and anticipate the trend rather than individual daily movements - that fall yesterday at the 30hpa level looked rather ominous when taken in isolation and not taking into account the bigger picture. But the background factors seem conduisive for a warming period in the stratosphere now after the long period of cold polar stratospheric westerly conditions that, by no coincidence, has been one large factor in producing the long string of above average months we have seen in such a mild autumn and winter thus far

It could well be the case that there will be people complaining about cold blocking patterns come March/April when attentions turn towards wanting warmer weather and Spring like conditions. Quite ironic that would be after waiting so long for it to happen

The PV still looks pretty solid to me.

The PV still looks pretty solid to me.

You keep saying this, it's rather difficult to understand why?

Here it is at the end of the year.

http://images.meteociel.fr/im/635/gfsnh-2011123100-0-6_wgu8.png

Here it is today.

http://images.meteociel.fr/im/8406/gfsnh-2012011606-0-6_img8.png

I'm afraid this is, so far, a classic 'jam tomorrow' mild winter. What will the rest of the winter bring? Beyond T144 I've little idea - and I'm not sure anyone knows much better than that, stratosphere watch or not..

I'm afraid this is, so far, a classic 'jam tomorrow' mild winter. What will the rest of the winter bring? Beyond T144 I've little idea - and I'm not sure anyone knows much better than that, stratosphere watch or not..

None of us can that be sure, no.

However we can look at factors in the stratosphere that have prevailed for some time and that have directly had an influence on our unseasonal winter so far, but are now changing and evolving in a quite different direction. And from those changes, we can make suggestions and form opinions as to what the conequences of those changes might be and where it may all lead.

There have been 'jam tomorrow' winters. Some of those have delivered the fruit though, and become classic British winters in the sense of meeting the old folklore saying of 'as the days grow longer, the cold gets stronger' There are ingredients in place, as discussed already, that can meet that criteria. However we wait to see if the British Isles as a small part of the NH that these changes will influence, can be a direct beneficiary (if you like cold weather) to those changes

An SSW would make the case easier to judge. We have been close to one, and one may well still occur yet in view of the trend. However, even if one doesn't occur the steady pressure exerted as described above by a log jam of warm anomalies at the top of the stratosphere has to go somewhere at some stage. Thus the current indications of cooling and warming ebbing and flowing as described above is a good way to get things moving. A bit like a digestive system where food on food often, um, makes nature take her course further down

I'm afraid this is, so far, a classic 'jam tomorrow' mild winter. What will the rest of the winter bring? Beyond T144 I've little idea - and I'm not sure anyone knows much better than that, stratosphere watch or not..

None of us can that be sure, no.

However we can look at factors in the stratosphere that have prevailed for some time and that have directly had an influence on our unseasonal winter so far, but are now changing and evolving in a quite different direction. And from those changes, we can make suggestions and form opinions as to what the conequences of those changes might be and where it may all lead.

There have been 'jam tomorrow' winters. Some of those have delivered the fruit though, and become classic British winters in the sense of meeting the old folklore saying of 'as the days grow longer, the cold gets stronger' There are ingredients in place, as discussed already, that can meet that criteria. However we wait to see if the British Isles as a small part of the NH that these changes will influence, can be a direct beneficiary (if you like cold weather) to those changes

An SSW would make the case easier to judge. We have been close to one, and one may well still occur yet in view of the trend. However, even if one doesn't occur the steady pressure exerted as described above by a log jam of warm anomalies at the top of the stratosphere has to go somewhere at some stage. Thus the current indications of cooling and warming ebbing and flowing as described above is a good way to get things moving. A bit like a digestive system where food on food often, um, makes nature take her course further down

Unusual to see Dev in the "glass half empty" camp

IMO nothing has really changed as we look towards early February simply because its still 2 weeks away.

I'm afraid this is, so far, a classic 'jam tomorrow' mild winter. What will the rest of the winter bring? Beyond T144 I've little idea - and I'm not sure anyone knows much better than that, stratosphere watch or not..

None of us can that be sure, no.

However we can look at factors in the stratosphere that have prevailed for some time and that have directly had an influence on our unseasonal winter so far, but are now changing and evolving in a quite different direction. And from those changes, we can make suggestions and form opinions as to what the conequences of those changes might be and where it may all lead.

There have been 'jam tomorrow' winters. Some of those have delivered the fruit though, and become classic British winters in the sense of meeting the old folklore saying of 'as the days grow longer, the cold gets stronger' There are ingredients in place, as discussed already, that can meet that criteria. However we wait to see if the British Isles as a small part of the NH that these changes will influence, can be a direct beneficiary (if you like cold weather) to those changes

An SSW would make the case easier to judge. We have been close to one, and one may well still occur yet in view of the trend. However, even if one doesn't occur the steady pressure exerted as described above by a log jam of warm anomalies at the top of the stratosphere has to go somewhere at some stage. Thus the current indications of cooling and warming ebbing and flowing as described above is a good way to get things moving. A bit like a digestive system where food on food often, um, makes nature take her course further down

IMO nothing has really changed as we look towards early February simply because its still 2 weeks away.

Yep, agreed

Current session of strat. warming at its zenith now:

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

Cheers Matt for the update

the Ec32 could well be on the line with the projections for the AO forecast more agreeament between the members then the previous ones

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

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

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.

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.