Stratosphere and Polar Vortex Watch

[ArHu3]

37 minutes ago, bluearmy said:

You need to work out how to get the correct attachment to show without clicking arhu!  Otherwise, peeps will be confused! 

The forum needs to sort that out because when composing it displays correctly and sometimes it can be unexpected as this image seems to have come from a date stamped link. The workaround is very cumbersome on mobile (requiring locally downloading the image and then uploading again) 

[chionomaniac]

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

[northwestsnow]

2 minutes ago, chionomaniac said:

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

No you are not the only C im sure..

 

[Katrine Basso]

I have heard that there could be another stratospheric warming event coming soon.

[feb1991blizzard]

18 minutes ago, chionomaniac said:

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

I would agree about the initial split, this chart to me looks indicative of an continental flow, it is struggling to downwell though, perhaps it might just be taking its time though and perhaps that's why the long range forecasts are now talking last week Jan not mid Jan, I have been worried about this for a while though, it has never looked like the best SSW i have ever seen and was hoping you would come on and say i was talking rubbish but seems you have the same concern.

[shaky]

46 minutes ago, northwestsnow said:

No you are not the only C im sure..

 

Personally i just think the best we gona get out of this ssw is a long period off cold frosty weather if that aswell!!problem is i would av taken that if it was november or start of december but not anymore with winter tickin down!!

[phil nw.]

Plenty of talk about the split at 10hPa but as I posted the other day the reversal of zw are struggling to downwell below 20hPa at 60n.

To my untrained eye this suggests still some low heights to our north at 500hPa. 

Not yet a clear cut outcome to me. 

[Singularity]

1 hour ago, chionomaniac said:

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

My understanding is that the westerlies should at the very least be displaced some way south of normal in any case, and that the tropical cycle should help place some HLB where we'd like it. Recipe for battleground events IMO.

That being said, I'm seeing such a wide range of interpretations from different expert minds at the moment that the situation is giving me quite the headache! There's a lot we're going to learn from this event, as a scientific community.

 

Edit: Surely it's the N. American sector rather than Atlantic sector for that residual vortex at 10 hPa?  That gives more room for ridging N and NNW of the UK.

Edited January 2, 2019 by Singularity
Only Human After All

[Blessed Weather]

1 hour ago, chionomaniac said:

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

The fascinating thing about this SSW is the timing with other teleconnections cycles and how they will interact, and thus the final outcome for surface weather, especially for our small island, over the coming weeks. Of particular significance will be the MJO Phase 7 and also the GWO cycle that will see a significant East Asia Mountain Torque (EAMT) event over the coming days (shown to have a significant impact on the SPV; the research paper is here: https://atmos.washington.edu/~david/White_etal_GRL_submitted2.pdf).

The models will struggle with all these variables and the ensembles are the ones to watch for pointers.

These annotated charts courtesy of Matt Hugo (Twitter @matthugo81):

[Singularity]

Having looked below 10 hPa instead - I can see that the vortex split isn't ideal in the early stages, with the 'western' residual being closer to the N. Atlantic sector than at 10 hPa, but as we head toward mid-month, the indications are that the split at these levels will widen further, as opposed to the vortex coming back together, thanks to troposphere-stratosphere interaction driven by the tropical cycle - much as Malcolm has just referred to in timely fashion .

So the 'western' residual moves across Canada and, with the tropical cycle continuing to help out, we most likely see interaction between poleward ridges from the N. Atlantic and Arctic Highs. Of the morning operational runs, GFS was almost at that point as of D16 and ECM was getting close as of D10 (some trough deepening to our NW D8-D9 but already coming apart at the seams D10).

Edited January 2, 2019 by Singularity

[chionomaniac]

2 hours ago, Singularity said:

My understanding is that the westerlies should at the very least be displaced some way south of normal in any case, and that the tropical cycle should help place some HLB where we'd like it. Recipe for battleground events IMO.

That being said, I'm seeing such a wide range of interpretations from different expert minds at the moment that the situation is giving me quite the headache! There's a lot we're going to learn from this event, as a scientific community.

 

Edit: Surely it's the N. American sector rather than Atlantic sector for that residual vortex at 10 hPa?  That gives more room for ridging N and NNW of the UK.

 

2 hours ago, Blessed Weather said:

The fascinating thing about this SSW is the timing with other teleconnections cycles and how they will interact, and thus the final outcome for surface weather, especially for our small island, over the coming weeks. Of particular significance will be the MJO Phase 7 and also the GWO cycle that will see a significant East Asia Mountain Torque (EAMT) event over the coming days (shown to have a significant impact on the SPV; the research paper is here: https://atmos.washington.edu/~david/White_etal_GRL_submitted2.pdf).

The models will struggle with all these variables and the ensembles are the ones to watch for pointers.

These annotated charts courtesy of Matt Hugo (Twitter @matthugo81):

 

2 hours ago, Singularity said:

Having looked below 10 hPa instead - I can see that the vortex split isn't ideal in the early stages, with the 'western' residual being closer to the N. Atlantic sector than at 10 hPa, but as we head toward mid-month, the indications are that the split at these levels will widen further, as opposed to the vortex coming back together, thanks to troposphere-stratosphere interaction driven by the tropical cycle - much as Malcolm has just referred to in timely fashion .

So the 'western' residual moves across Canada and, with the tropical cycle continuing to help out, we most likely see interaction between poleward ridges from the N. Atlantic and Arctic Highs. Of the morning operational runs, GFS was almost at that point as of D16 and ECM was getting close as of D10 (some trough deepening to our NW D8-D9 but already coming apart at the seams D10).

Happy new year guys. I am very much of the opinion that we are going to need tropical help in assisting us in getting the maximum trop  benefits following the SSW. For me it was always going to come down to ultimately the location and severity of the split and I am not looking past day 10 in the output currently because of how the models handle downwelling SSW effects. But  no cream here for days 10 -15 unless the vortex residual position moves away completely. 

There has almost been a social media 'celebration' of the SSW without proper acknowledgement of how this one will affect us here in the UK. As a phenomenon I love the dynamics of a SSW and we could see a classic SSW without the UK benefiting here. I hope not, so lets keep an eye on the day 10 residual vortex position throughout all the levels of the stratosphere.

[mountain shadow]

4 hours ago, chionomaniac said:

I wonder am I the only one who isn't overly excited that the dynamics and downwelling of the SSW and subsequent split are not looking favourable for the UK? The split at 10hPA keeps the residual vortices over the Atlantic and Eurasian sector before rejoining and even with the strongest tilting that I can imagine, there is a strong possibility of some kind of westerly flow over our sector unless these daughters can 'do one' and bugger off elsewhere!

Good call Chiono. It appears the Met Office have pushed out any SSW impacts until month end now. The tropical impacts seem muted to me, the MJO is not exactly high amplitude for example.

Edited January 2, 2019 by mountain shadow

[bluearmy]

1 minute ago, mountain shadow said:

Good call Chiono. It appears the Met Office have pushed out any SSW impacts until month end now. The tropical impacts seem muted to me, the MJO is not exactly high amplitude for example.

Gefs bc has dropped its v high amplitude but it still does a decent amp circuit in phase 7 which should be good for me Europe

awaiting ec MJO update for today 

[mountain shadow]

1 minute ago, bluearmy said:

Gefs bc has dropped its v high amplitude but it still does a decent amp circuit in phase 7 which should be good for me Europe

awaiting ec MJO update for today 

Hi Blue, it was the ECM MJO I was referring too. I don't tend to take much notice of GFS products especially when they're at such variance to the ECM.

[bluearmy]

8 minutes ago, chionomaniac said:

 

 

Happy new year guys. I am very much of the opinion that we are going to need tropical help in assisting us in getting the maximum trop  benefits following the SSW. For me it was always going to come down to ultimately the location and severity of the split and I am not looking past day 10 in the output currently because of how the models handle downwelling SSW effects. But  no cream here for days 10 -15 unless the vortex residual position moves away completely. 

There has almost been a social media 'celebration' of the SSW without proper acknowledgement of how this one will affect us here in the UK. As a phenomenon I love the dynamics of a SSW and we could see a classic SSW without the UK benefiting here. I hope not, so lets keep an eye on the day 10 residual vortex position throughout all the levels of the stratosphere.

Are we not looking at a reasonably strong jet displaced into Europe with the arctic ridge poking down to suppress it south ??

ec’s new monthly must be imminent - last run had the mean storm track a bit too far north through central uk whereas ukmo looked further south, especially the further we go. 

[bluearmy]

2 minutes ago, mountain shadow said:

Hi Blue, it was the ECM MJO I was referring too. I don't tend to take much notice of GFS products especially when they're at such variance to the ECM.

Fair enough although thus far this season, the gefs hasn’t done a terrible job with ec being too low amplitude and having to correct higher and longer 

[Interitus]

The 06z GFS para has really gone off on one, here are u1060 of the last 3 runs, the 06z has it's lowest of it's runs I've seen so far, -15.5 at T384 -

The 850 mb zonal wind at 60°N is forecast to fall to -8.0 m/s at one point - this is lower than anything in the NCEP R2 reanalysis from Jan 1979 - Dec 2014 (struggling for more data with the government shutdown). The lowest in that period was -7.9 m/s from 09/02/85 - yes there was a notable SSW beforehand but over a month earlier. Interesting how the AO doesn't match this zonal wind especially well - the CPC AO value was -3.44 (NAO -1.06) whilst three weeks earlier on 19/01/85 the record lowest AO of -6.23 was recorded (NAO -1.64) with a 850 60°N wind of -6 m/s.

Meantime, the reduction of wave propagation by the easterly flow allows the 1 mb wind to get back up to 40 m/s, quite some wind shear as it only reaches 4.5 m/s at 3 mb

(Damn NaNs spoil plot!)

[bluearmy]

24 minutes ago, Interitus said:

The 06z GFS para has really gone off on one, here are u1060 of the last 3 runs, the 06z has it's lowest of it's runs I've seen so far, -15.5 at T384 -

The 850 mb zonal wind at 60°N is forecast to fall to -8.0 m/s at one point - this is lower than anything in the NCEP R2 reanalysis from Jan 1979 - Dec 2014 (struggling for more data with the government shutdown). The lowest in that period was -7.9 m/s from 09/02/85 - yes there was a notable SSW beforehand but over a month earlier. Interesting how the AO doesn't match this zonal wind especially well - the CPC AO value was -3.44 (NAO -1.06) whilst three weeks earlier on 19/01/85 the record lowest AO of -6.23 was recorded (NAO -1.64) with a 850 60°N wind of -6 m/s.

Meantime, the reduction of wave propagation by the easterly flow allows the 1 mb wind to get back up to 40 m/s, quite some wind shear as it only reaches 4.5 m/s at 3 mb

(Damn NaNs spoil plot!)

yesterday's ec 12z had quite a shear at the top aswell

[Singularity]

I must say that MO alteration is surprising to me; I can't see any modelling evidence to support anything later than 21st for a marked change, this being at the extreme end based on the tropical propagation being exceptionally slow (relative to historical precedent). Though I suppose one could just about classify the final 10 days as being late January so perhaps I'm being surprised over nothing much after all .

Still, I feel like more than a day or two beyond the midpoint in the month would be very unlucky given the ingredients at hand.

 

@chionomaniac Happy New Year to you too thanks (and to everyone else for that matter!). I agree that the SSW has been given way to much 'weight' relative to the other factors which, given that the split doesn't look optimal in the initial stages for NW Europe and the UK, are about as important as they could be.

Edited January 2, 2019 by Singularity

[bluearmy]

8 minutes ago, Singularity said:

I must say that MO alteration is surprising to me; I can't see any modelling evidence to support anything later than 21st for a marked change, this being at the extreme end based on the tropical propagation being exceptionally slow (relative to historical precedent). Though I suppose one could just about classify the final 10 days as being late January so perhaps I'm being surprised over nothing much after all .

Still, I feel like more than a day or two beyond the midpoint in the month would be very unlucky given the ingredients at hand.

 

@chionomaniac Happy New Year to you too thanks (and to everyone else for that matter!). I agree that the SSW has been given way to much 'weight' relative to the other factors which, given that the split doesn't look optimal in the initial stages for NW Europe and the UK, are about as important as they could be.

Do you have access to MOGREPS/GLOSEA ???

the extended eps are flatter for two runs now - perhaps they are now closer to in house models - these take us to mid month and any transition period would be around 5/7 days taking us to pretty well the last week of the month !  maybe the putting back is causing them to lose confidence in a change ….

[SLEETY]

so your writing off the chance of much colder weather later in jan on the 2nd of january lol

[Singularity]

8 minutes ago, bluearmy said:

Do you have access to MOGREPS/GLOSEA ???

the extended eps are flatter for two runs now - perhaps they are now closer to in house models - these take us to mid month and any transition period would be around 5/7 days taking us to pretty well the last week of the month !  maybe the putting back is causing them to lose confidence in a change ….

Oops - sadly not and I've seen your reports on the EPS trending flatter - I meant modelling of the MJO, AAM and such within the more reliable range, from which I extrapolate forward. 

Yes I expect EPS and MOGREPS/GLOSEA are converging but given questionable amplitude of MJO from EPS, I'm hesitant to place much faith in that at the moment.

Incidentally, in my experience the MO rarely factor an anticipation of different MJO behaviour to that being modelled into their outlooks. Perhaps because that way they minimise possible accountability if the outlook proves inaccurate? I've long wondered about it.

 

Not sure what the transition period you refer to is - doesn't the N. Atlantic - N. European pattern tend to chug along until a sufficient poleward ridge & -ve AO combination occurs to abruptly change the regime? Admittedly the historical examples aren't very numerous...

Edited January 2, 2019 by Singularity

[Nick F]

Saw this 10 hPa chart for 17/01 from 00z EPS on Twitter this morning which has the split with two daughter vortices, but Canadian vortex stronger than Euro, which would through coupling with the trop would not provide the best pattern for Atlantic blocking as per EPS mslp chart on the right for same timeframe ... may correspond similarly with MOGREPS / GLoSEA and with the MO forecast for westerly spell mid-month and cold/wintry flip delayed later this month.

However, before we all reach for the cheap Christmas whisky the inlaws gave, 15 days away even in the strat and certainly trop is a tall ask to verify, the downwelling is still a great unknown, plus the models yet to pick up the lag effects of MJO moving into colder phases coming 7 days, which will help create a more meridional pattern over NAO region. 

[Weather-history]

 

[Dorsetbred]

Reading the thread title, is it worth bringing it up to date at least even if a new thread isn't started...Stratosphere temperature watch 2017/18!