Stratosphere Temperature Watch 2015/2016

[chionomaniac]

3 hours ago, CreweCold said:

My question is will it come too late in the season to benefit us? I know most questions can't be answered as it's showing over two weeks away but what are the 'gut' feelings over how this should impact the trop?

I don't think that it is too late to benefit us - but I am very wary of how we may get any benefit should a SSW occur. 

Displacement SSW's vary somewhat in intensity. (check out Martineau's site). We may have a displacement SSW where the vortex is pushed off the pole - loses intensity for a while but soon recovers and gains strength. Or we could see a SSW where the tilting of the warming and strength of the warming induces a complete collapse of the vortex. In this case the vortex has to rebuild itself from scratch once the temperature have dropped again. My feeling at this point is let's just get a SSW under our belts first before estimating how it will affect the trop.

[fergieweather]

3 hours ago, feb1991blizzard said:

Yes I thought that myself, whats slightly concerning is the met office have dropped their 'Further cold spells possible' line from the end of their 30 dayer, you would think if they think an SSW is possible that they would mention the chance of colder weather, they cant think an SSW is likely because at this range surely they wouldn't actually commit to an SSW actually occurring but either not propagating down the atmosphere far enough or the ridges and troughs setting up in the 'wrong' place for cold to occur

If and when ECMWF and GloSea5 show a clear, unambiguous signal of warming below 30hPa, then it'll certainly garner greater focus/interest.

[chionomaniac]

Further to Ian's post - we know as of yesterday that the EPS showed a significant 10hPa warming as of yesterday at day 15 - but this was not as strong as the GEFS and is far too far away for any confidence to be introduced into any met forecasts.

But the signs of a warming were there - so this may change. It doesn't stop us discussing the possibilities - but it will the METO ( or at least publicly)

 

[fergieweather]

4 minutes ago, chionomaniac said:

Further to Ian's post - we know as of yesterday that the EPS showed a significant 10hPa warming as of yesterday at day 15 - but this was not as strong as the GEFS and is far too far away for any confidence to be introduced into any met forecasts.

But the signs of a warming were there - so this may change. It doesn't stop us discussing the possibilities - but it will the METO ( or at least publicly)

 

absolutely agree, Chiono!

[feb1991blizzard]

27 minutes ago, fergieweather said:

If and when ECMWF and GloSea5 show a clear, unambiguous signal of warming below 30hPa, then it'll certainly garner greater focus/interest.

Thanks Ian, I certainly wasn't trying to pre-empt or tell the MO how to do their job, sorry if it did come across that way, its just that because we don't have access to a lot of data but they (MO) are a world wide respected organisation, i will always try to tie the 30 dayer in with extended model forecasts and try to read between the lines, particularly in winter wrt possible strat warmings, thanks for your updates.

[fergieweather]

1 hour ago, feb1991blizzard said:

Thanks Ian, I certainly wasn't trying to pre-empt or tell the MO how to do their job, sorry if it did come across that way, its just that because we don't have access to a lot of data but they (MO) are a world wide respected organisation, i will always try to tie the 30 dayer in with extended model forecasts and try to read between the lines, particularly in winter wrt possible strat warmings, thanks for your updates.

No, no worries and it wasn't perceived that way! In any event, I'm not here to defend UKMO forecast wording. However, realistically they'd probably only discuss strong SSW signals in e.g. blogs, rather than a generic text forecast for general public.

[feb1991blizzard]

Just now, fergieweather said:

No, no worries and it wasn't perceived that way! In any event, I'm not here to defend UKMO forecast wording. However, realistically they'd probably only discuss strong SSW signals in e.g. blogs, rather than a generic text forecast for general public.

Thanks Ian.

[fergieweather]

29 minutes ago, feb1991blizzard said:

Thanks Ian.

JMA considered a more superior strat guide than GFS, incidentally :-)

[Recretos]

new day, new runs. Luckily, the trend is still here. 

 

 

 

Edit:

have i heard someone say JMA?

Edited January 12, 2016 by Recretos

[John (Netherlands)]

http://www.aer.com/science-research/climate-weather/arctic-oscillation

According to Cohen SSW likely......

"The models are now coming into better consensus for a stronger pulse of energy transfer beginning next week that is predicted to initiate a sudden stratospheric warming (SSW) at the end of the month"

Of course we will have to wait and see what the consequences will be for the weather in Western Europe.

[Paul123]

2 hours ago, John (Netherlands) said:

http://www.aer.com/science-research/climate-weather/arctic-oscillation

According to Cohen SSW likely......

"The models are now coming into better consensus for a stronger pulse of energy transfer beginning next week that is predicted to initiate a sudden stratospheric warming (SSW) at the end of the month"

Of course we will have to wait and see what the consequences will be for the weather in Western Europe.

Thank you John, for posting this update from Cohen.

I would like to add some images from his blog, to make matters clear. Firstly the observed and predicted dailly vertical component of the WAFz, say the vertical energy transport over the polar region. This will increase significantly towards the end of the month.

.

The impact of the increased vertical energy input from the troposphere to the stratosphere is seen in figure 8. This warming should, according to Cohen, lead to a SSW.

The warming of the stratosphere is being accompagnied by a cooling of the polar troposphere (see below, the picture of the mean polar cap height), causing a rise of the AO. Initially this will cause a warming of the temperatures of Western Europe, some time after the SSW a cooling trend is to be expected.

 

 

Quote from Cohen:

'Therefore we are more confident that a troposphere-stratosphere-troposphere coupling event is underway (Cohen et al. 2007).   The current strong negative AO is a tropospheric precursor that will initiate a strong burst of vertical energy transfer from the troposphere into the stratosphere the last week of January as seen in the vertical wave activity flux (WAFz) plot (Figure 7).  More recent model runs have trended stronger with this energy burst and are indicating this energy burst will be of sufficient amplitude to initiate a SSW during the last week of January.  And as can see from Figure 8, a dramatic warming of temperatures is now predicted at the Pole the fourth week of January as much warmer air floods in from Siberia.   As we have discussed previously in the blog, the vertical transfer of energy from the troposphere to the stratosphere warms the polar cap heights in the polar stratosphere and forces a negative AO trend in the stratosphere.  And for the first time this cold season, the models are predicting the cold polar cap geopotential height anomalies (PCH) or the strong polar vortex in the stratosphere to be erased (Figure 9). However the energy burst forces the opposite in the troposphere resulting in a cooling polar cap height and a positive AO trend, which can be seen with a weakening of the warm PCH in the troposphere.  However following the SSW, the associated circulation anomalies of positive geopotential height anomalies and warm temperatures over the Arctic and negative geopotential height anomalies and cold temperatures in the mid-latitudes propagate down from the stratosphere to the troposphere.' 

 

Edited January 12, 2016 by Paul123

[Katrine Basso]

I have just seen this on Twitter today: SSW being shown on the GFS map.

 

 

[Glacier Point]

I would go along with Cohen's view on a temporary bounce in the AO as a precursor to the early stages of warming being programmed now widely across NWP. Think of at as a Tsunami. The seas get withdrawn prior to the wave breaking onshore as the tropopause is depressed over the Arctic and lifted around the edge of the polar region. That bounce may actually be from -6SD to -2SD, enough though to send the GFS into a tailspin.

Today's EPS and GEM ensembles dropping strong hints of mid latitude highs being in position from day 10 onwards, and lowering of pressure over the Arctic. How long will they stay there though, that's the key question ?

[Ruben Amsterdam]

9 minutes ago, Katrine Estella said:

I have just seen this on Twitter today: SSW being shown on the GFS map.

 

 

If this is the map shown along with it, it does not show a technical SSW  

[Gazza H]

"heart warming" looking 30hpa chart 

[Ruben Amsterdam]

06z close to a technical? 

[BLAST FROM THE PAST]

15 minutes ago, Gazza H said:

"heart warming" looking 30hpa chart 

Is that showing the PV getting shifted to Siberia?  Got to admit I haven't cottoned on to what the graphs in here show

 

BFTP

[Gazza H]

24 minutes ago, BLAST FROM THE PAST said:

Is that showing the PV getting shifted to Siberia?  Got to admit I haven't cottoned on to what the graphs in here show

 

BFTP

to be honest I'm just looking to see the vortex shifted significantly of its axis , i'm uncertain as to what differences it makes to the trop weather on our shores depending on which way it gets shifted, maybe @Recretos or @lorenzo could shed some light on this? 

[Recretos]

We will talk about trop implications when there will be time for it.  But one thing is certain, and that is that we could see some uncertainty and confusion in the models when doing the possible coupling. i will take the tropospheric FI with a big grain of salt. 

GEFS is now going below 10m/s in the U-mean U-wind section, just like GFS. So we kinda have a unique look here at a super agreement between the operational and the ENS. 

 

 

And in the flesh.

 

 

Edited January 12, 2016 by Recretos

[Glacier Point]

Andrej - are you able to plot previous GEFS means on top of your zonal winds graph so we can keep a check on how the individual GEFS runs are progressing this ?

Thanks

[Recretos]

Well, I actually have an issue with that, since the axis are not the same. But will try to get around it a different way.

EDIT: So here is Excel

  

P.S.

I would also plot GEM ENS, but am out of time. i would tho say that care must be taken when dealing with GEM ENS for the strat since it has a very low model top of only 10mb. Especially need to take care when doing possible coupling, since it can easily undershoot the intensity. 

Edited January 12, 2016 by Recretos

[bluearmy]

Andre - I suspect you could spend your time doing much more productive stuff than plotting the GEM ens which don't top out high enough.  We are v lucky to have your output on here to see. 

[northwestsnow]

I am waaaaaaay out of my depth here but would that reduction in zonal winds would be a sign of the PV weakening?

Thats some reduction on GEFS!!

[Force7]

8 hours ago, Glacier Point said:

11 hours ago, Glacier Point said:

I would go along with Cohen's view on a temporary bounce in the AO as a precursor to the early stages of warming being programmed now widely across NWP. Think of at as a Tsunami. The seas get withdrawn prior to the wave breaking onshore as the tropopause is depressed over the Arctic and lifted around the edge of the polar region. That bounce may actually be from -6SD to -2SD, enough though to send the GFS into a tailspin.

Today's EPS and GEM ensembles dropping strong hints of mid latitude highs being in position from day 10 onwards, and lowering of pressure over the Arctic. How long will they stay there though, that's the key question ?

Hi Stewart, I was just wondering about your "torpedo" and how it would interact with the "temporary bounce in the AO" if it happens. Could you give us your thoughts please? thanks

Edited January 12, 2016 by Force7

[bluearmy]

14 minutes ago, northwestsnow said:

I am waaaaaaay out of my depth here but would that reduction in zonal winds would be a sign of the PV weakening?

Thats some reduction on GEFS!!

That's exactly what it shows NWS

it looks like the strat vortex will be displaced to the Asian side of the NH, if GFS and ens data verifies.