Stratosphere Temperature Watch 2012/2013

[AWD]

And whilst we enjoy all the lovely blocking showing up in the NWP output, we have the Strat going into the freezer;

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html

[Eskimo]

And whilst we enjoy all the lovely blocking showing up in the NWP output, we have the Strat going into the freezer;

http://ds.data.jma.g...e/pole30_n.html

Although clutching at straws...a SSW will send that sky high at any time.

[Duane S.]

It does seem to me that most of GP's confidence over this is as much about the timing of certain events as in the events themselves.

If this pans out as expected for the start of December it will appear to have been very much in the face of adversity (very cold strat, lack of ozone etc), thereafter more things seem to go our way? If that makes sense.

[chionomaniac]

Following this through..

The 1st wave 2 attack is now registering for the 20 day lag centred on 30th November. GFS 06z showing a massive ridge penetrating the Arctic at 30 hPa.

The possibly modification of the angle of ridge showing up at the end of the GFS run:

If we were right about the wave 2 activity (and so far this looks like an extremely good call and therefore excellent 'tool' added to our kit bag), then no reason to suggest that the continued disruption of the vortex throughout December will take place (possibly with a reduced level of 'forcing' as the +AAM signal diminishes a touch).

That in itself sets an interesting prospect - further tropospheric feed back and development of Aleutian low in response to hemispheric realignment - more wave 1 activity (vortex displacement) into January ?

For a while earlier in the month I was a little bit concerned that we would not get the increase in wave activity and hence my more guarded start of December outlook. Luckily the increase in wave 2 activity is now occurring - but not quick enough to save my Canadian Warming November forecast!

Even though we are seeing a desperately cold stratosphere we are saved somewhat by the tropospheric led PV splitting waves.

In today's cpc forecast upto day 10 we see that if the wave is strong enough and other conditions are ripe, then we see a split right up to the 30 hPa level.

In 2010 I remember emphasising that split vortices up to this level were no transient affairs - they are big vortex events with dramatic tropospheric consequences - normally cold spilling south.

Well we are not quite fully there yet compared to 2010. Firstly, we have yet to see the split come into a timeframe that the ECM can show and that leads to secondly, the split has only been seen out in GFS FI that can hardly be decreed as reliable.

When we see any strat vortex splitting modelled consistently by both the ECM and the GFS in a semi reliable timeframe then we will have more confidence in any tropospheric solution offered. Until that point then the modelling is likely to jump around tropospherically.

Moving on, one of the consequences that we may see from the increase in wave activity is a warming of the stratsosphere. This again appears to be somewhat tropospherically led.

At 70hPa at T+240 we see a warming as significant as we see a cooling at 10 hPa

This again will act as a barrier against the upper strat cooling . GP has often mentioned upwelling and downwelling phases in the stratosphere - it would appear that any downwelling (blue arrow) phase has yet to reach the troposphere and could very well be disrupted (red arrow) by the increase in wave activity before it does.

All of this disruption long term bodes well for the stratosphere later into winter. With the downwelling strat zonal anomalies being disrupted before they reach the troposphere and this likely to have a rebound effect stratospherically, we are now on the watch out for possible warming to occur.

And finally, yet agian the latest 12Z GFS forecast has shown another split and warming in FI up to 10 hPa.

Now we just want to see the ECM on board!

[bluearmy]

do we know if there is an ecm run that goes out to two weeks on the strat ? clearly there isnt one that we can see but i wonder if there is anything tied into the control run perhaps ? and if there isnt, there bloody well should be !

[snowking]

do we know if there is an ecm run that goes out to two weeks on the strat ? clearly there isnt one that we can see but i wonder if there is anything tied into the control run perhaps ? and if there isnt, there bloody well should be !

Just had a look at the data I've got access to, unfortunately nothing that high up on there. Best I've got is 200mb heights on the deterministic run out to 240. Whether that data is accessible to either Matt/Ian would be interesting to know.

Due an update of the ECM32 in the morning (last control run was available at 11pm the night before so might get lucky with a sneak at the control run later tonight

SK

[BLAST FROM THE PAST]

If the SH event we have experienced this year as we did in 2002 brings similar stratos effect or responses in troposhere then I am really interested and encouraged. Dec 2002 and indeed winter 02/3 was such a nearly winter with great blocking but never getting it there for us. Now with other factors now in different cycle could we be in for a stormer? I rule nothing out and recent developments are adding som spice IMO as I don't see any PV dominating the winter but a winter of 85/6 is the general gist of my thoughts.....but am up for adjustment!!!!

BFTP

[Gael_Force]

do we know if there is an ecm run that goes out to two weeks on the strat ? clearly there isnt one that we can see but i wonder if there is anything tied into the control run perhaps ? and if there isnt, there bloody well should be !

I think the new Met office long range model has the capability to model very high in the atmosphere. Don't know how often it is run though.

GloSea4 uses a computer model which simulates winds, humidity and temperatures on an approximately 150km-spaced grid of points at a range of vertical heights from the surface to beyond the stratosphere which is why it is able to represent SSWs more realistically.

http://www.iop.org/news/12/sep/page_57337.html

[Dave Kightley]

Did someone say charts like this are the start of a C.W?

[bluearmy]

Impressive ecm charts for day 10 yesterday with a split all the way up to 10 hpa and renewed wave 2 appearing mid strat at the end of the run.

[chionomaniac]

Impressive ecm charts for day 10 yesterday with a split all the way up to 10 hpa and renewed wave 2 appearing mid strat at the end of the run.

Yes ECM on board

[MattH]

Yabba-dabba-do, this will do!....

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf30f240.gif

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf50f240.gif (very similar to GFS Det now)

Wave 1 and Wave 2 re-developing with time;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha1_f216.gif

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif

Some positive signs becoming evident on the ECMWF now which clearly match/support what the GFS has been showing for days. The temp wave 1/2 are showing some interesting developments but as would be expected, as yet, the zonal mean state (temps) are yet to show any signs of warming.

The ECMWF 32 day update overnight as well maintains the signal for northern blocking through the 2nd week of December now with temperatures clearly becoming generally below average by a number of degrees. Without question, this excellent model, has nailed this situation down weeks in advance in terms of the broader change in synoptic pattern. However, what it now shows, is a return to more zonal conditions towards and beyond mid-December which is a concern. The +ve height anoms to the N and NW of the UK disappear by the 4th week of the run and are replaced by lower than average pressure anoms to the W and SW of the UK with temperatures recovering back to nearer average given a more unsettled theme.

Clearly this needs monitoring, as despite some promising signs from within the models regarding the stratosphere, in my opinion, after a period of northern blocking a return to more unsettled and potentially zonal conditions for a while mid-December seems reasonable, but then potentially turning colder again later in the month.

For now though, looks promising to me.

Matt.

[sebastiaan1973]

Thanks Matt. I don't bother about 3-4 weeks ahead in EC32; first see if it is a trend, in more than just 1 run and two it's to far in my opinion to be reliable.

[Terminal Moraine]

The ECMWF 32 day update overnight as well maintains the signal for northern blocking through the 2nd week of December now with temperatures clearly becoming generally below average by a number of degrees. Without question, this excellent model, has nailed this situation down weeks in advance in terms of the broader change in synoptic pattern. However, what it now shows, is a return to more zonal conditions towards and beyond mid-December which is a concern. The +ve height anoms to the N and NW of the UK disappear by the 4th week of the run and are replaced by lower than average pressure anoms to the W and SW of the UK with temperatures recovering back to nearer average given a more unsettled theme.

Clearly this needs monitoring, as despite some promising signs from within the models regarding the stratosphere, in my opinion, after a period of northern blocking a return to more unsettled and potentially zonal conditions for a while mid-December seems reasonable, but then potentially turning colder again later in the month.

For now though, looks promising to me.

Matt.

I'd regard this potential cold spell followed by a milder zonal spell as a positive rather than a concern as in my experience, and before, the coldest winters all began with short forays of anticyclonic cold followed by milder zonal spells before the persistent cold arrived. This also ties in quite nicely with Roger J Smith's forecast, and the preliminary thoughts of G.P, as to how the winter is likely to evolve.

The winters of 1947, 1963 and 1979 all began in this way so one would imagine that there would be some common factor, either stratospherically or within the general circulation, or both, which leads to periods of cold interspersed with mild early in the winter and more sustained cold later.

Colin Finch did some interesting work on this in the early 1980s and came up with a rule which I can't quote verbatim without looking it up but the essence of which was, that if southern England experienced a period of 5 consecutive days with a maximum temperature below 3.5c between the 7th and 16th of December then the winter as a whole was likely to be cold or very cold; this certainly had a high success rate over the period studied and it's time I stopped before I wander completely off topic.

[Suemoo]

Good morning, Sorry but I am a weather thicky and really dont understand any of these charts... in plain English does this mean that we are about to get the worse winter for a 100 years xxx

[lorenzo]

Any odds on a December SSW ????

[Glacier Point]

sneaky peak from the winter forecast for vortex projection Jan and Feb..

a solid signal for ridge towards Canada. Everything this year seems to be happening quicker.. the reaching of minimum stratospheric temps for example. Wouldn't be surprised to see this taking root in December and this I think is the axis of the winter stratosphere.

[Paul]

Good morning, Sorry but I am a weather thicky and really dont understand any of these charts... in plain English does this mean that we are about to get the worse winter for a 100 years xxx

Welcome Sue, in plain English it means that there's an increasing likelihood of cold weather into December

[memories of 63]

I'd regard this potential cold spell followed by a milder zonal spell as a positive rather than a concern as in my experience, and before, the coldest winters all began with short forays of anticyclonic cold followed by milder zonal spells before the persistent cold arrived. This also ties in quite nicely with Roger J Smith's forecast, and the preliminary thoughts of G.P, as to how the winter is likely to evolve.

The winters of 1947, 1963 and 1979 all began in this way so one would imagine that there would be some common factor, either stratospherically or within the general circulation, or both, which leads to periods of cold interspersed with mild early in the winter and more sustained cold later.

Colin Finch did some interesting work on this in the early 1980s and came up with a rule which I can't quote verbatim without looking it up but the essence of which was, that if southern England experienced a period of 5 consecutive days with a maximum temperature below 3.5c between the 7th and 16th of December then the winter as a whole was likely to be cold or very cold; this certainly had a high success rate over the period studied and it's time I stopped before I wander completely off topic.

Any chance of a link to Roger's forecast?

[Tom Quintavalle]

I'd regard this potential cold spell followed by a milder zonal spell as a positive rather than a concern as in my experience, and before, the coldest winters all began with short forays of anticyclonic cold followed by milder zonal spells before the persistent cold arrived. This also ties in quite nicely with Roger J Smith's forecast, and the preliminary thoughts of G.P, as to how the winter is likely to evolve.

The winters of 1947, 1963 and 1979 all began in this way so one would imagine that there would be some common factor, either stratospherically or within the general circulation, or both, which leads to periods of cold interspersed with mild early in the winter and more sustained cold later.

Colin Finch did some interesting work on this in the early 1980s and came up with a rule which I can't quote verbatim without looking it up but the essence of which was, that if southern England experienced a period of 5 consecutive days with a maximum temperature below 3.5c between the 7th and 16th of December then the winter as a whole was likely to be cold or very cold; this certainly had a high success rate over the period studied and it's time I stopped before I wander completely off topic.

Hi TM,

I remember conversing with you before regarding Colin Finch and December temps. As you state, his work concluded that when southern parts of the country record that sort of temperature regime during December (cant remember the exact dates), the likelihood of further cold spells during the rest of winter was pretty high.

To achieve that kind of temperature regime for southern Britain during December would almost certainly require some sort of high latitude blocking with a flow perhaps between N and E, other than perhaps a cold inversion high. His findings suggested that high latitude blocking would then be more frequent than usual, during the rest of winter, with resultant colder than normal spells.

Regards,

Tom.

[dallas]

Thanks for that info Terminal Moraine ref Colin Finch, something I shall look out for. I do realize though that if it does not occur it wont neccessary not be cold this winter anyway. Was there a % rate of its success? Thanks

Edited November 20, 2012 by dallas

[Northern Sky]

Yes ECM on board

I get a little confused regarding lag times involved with different kinds of warming. Am I right in thinking that the warming being shown at day 10 on the GFS and now the ECM would potentially affect the trop sometime around mid/late Dec, or is the type of warming shown likely to result in something more immidiate?

Thanks,

NS

[Catacol]

sneaky peak from the winter forecast for vortex projection Jan and Feb..

a solid signal for ridge towards Canada. Everything this year seems to be happening quicker.. the reaching of minimum stratospheric temps for example. Wouldn't be surprised to see this taking root in December and this I think is the axis of the winter stratosphere.

An increasingly west based NAO then come Feb? Hmmm - best hope for some intrusion from the Beast then...

On a "help me" please note GP - you said in an earlier post that a west based NAO was not a problem in Dec but could be a problem in Feb. I understand the potential synoptics of a western based NAO but am a bit puzzled by the month vs month distinction. Can you elaborate a bit?

Edited November 20, 2012 by Catacol_Highlander

[Gael_Force]

I'd regard this potential cold spell followed by a milder zonal spell as a positive rather than a concern as in my experience, and before, the coldest winters all began with short forays of anticyclonic cold followed by milder zonal spells before the persistent cold arrived. This also ties in quite nicely with Roger J Smith's forecast, and the preliminary thoughts of G.P, as to how the winter is likely to evolve.

The winters of 1947, 1963 and 1979 all began in this way so one would imagine that there would be some common factor, either stratospherically or within the general circulation, or both, which leads to periods of cold interspersed with mild early in the winter and more sustained cold later.

Colin Finch did some interesting work on this in the early 1980s and came up with a rule which I can't quote verbatim without looking it up but the essence of which was, that if southern England experienced a period of 5 consecutive days with a maximum temperature below 3.5c between the 7th and 16th of December then the winter as a whole was likely to be cold or very cold; this certainly had a high success rate over the period studied and it's time I stopped before I wander completely off topic.

Winter 62/63 and 78/79 began with a Canadian warming (anybody got data for 46/47)

In my root around for information I found this old thesis - nice clear explanation of the processes involved for someone, like me, new to the subject.

http://www.dtic.mil/dtic/tr/fulltext/u2/a227731.pdf

[chionomaniac]

I get a little confused regarding lag times involved with different kinds of warming. Am I right in thinking that the warming being shown at day 10 on the GFS and now the ECM would potentially affect the trop sometime around mid/late Dec, or is the type of warming shown likely to result in something more immidiate?

Thanks,

NS

This warming is definitely something for later on in winter - I am more concerned with the upcoming split, presently.