Model output discussion - 5th December 2016 - Into Winter we go

[Singularity]

Just now, feb1991blizzard said:

You've just illustrated the best pattern you can get IMO, a wave 2 split from pacific through to atlantic straight through Greenland, IF that type of pattern downwells, you've got a decent chance of at least a 2 week bitter cold spell as there's only one place the high will topple to after GL and that's Scandinavia.

Absolutely, I'm amazed nobody spotted it before I did, it's not even Friday night when drinking is an excuse - perhaps people saw the ECM 12z and took to the booze a day sooner .

Mid-afternoon tomorrow, I'll be staring at the H-W MJO plot and willing it with all my heart to show EC ens. moving toward GEFS with the tropical signal.

[Frosty.]

Tonight's Ecm 12z ensemble mean shows a changeable outlook with the best of the fine weather to be found further s / se and the most unsettled conditions further n / w.

Edited December 8, 2016 by Frosty.

[bobbydog]

5 minutes ago, CreweCold said:

Ooops Sorry! 

No, more the point about the WAA at the time. 'I don't think you quite understand the effects going forward of this' i.e WAA and Greenland high fail. It's why I reacted so glumly to the downgrade of that general synoptic as it was obvious that it would have had a significant weakening effect on the vortex going forward had it happened. However, people seemed to refuse to acknowledge the importance of that first very important step en route to a cold first month of winter.

To be fair, it did concern me a little that we never had a full SSW modelled. It was always just out of reach. I did think that a major displacement was enough though (which we did have) as often this is almost as good. In this case, apparently not. On a positive note though, it has caused enough disruption to put us in the situation we are in- huge uncertainty. It really doesn't mean 'winter's over'  - by a long shot!

[Cheshire Freeze]

Just now, bobbydog said:

To be fair, it did concern me a little that we never had a full SSW modelled. It was always just out of reach. I did think that a major displacement was enough though (which we did have) as often this is almost as good. In this case, apparently not. On a positive note though, it has caused enough disruption to put us in the situation we are in- huge uncertainty. It really doesn't mean 'winter's over'  - by a long shot!

No winter not over but we've sure been dealt a set back with how things played out through the second half of November. For the record, we were close to a SSW and would have had one had that last week of November Greenland block not failed! We were a gnats whisker away from the point of no return but all crumbled pretty quickly once that block failed to materialise. It had knock on effects all over the show.

[SMU]

23 minutes ago, Singularity said:

In an ideal world...

Quick doodle on the GFS 12z at 30 hPa which shows very nicely the classical response to MJO 6-7-8 type forcing.

The + symbols indicate where heights would increase (with trop. following suit), and - where they'd decrease (again, trop. following suit).

The 10 hPa stratospheric vortex isn't going to propagate down in a hurry with that sort of thing going on. Seeing an increase in zonal winds at 30 hPa and assuming that it's propagating down is too simplistic; the vortex stretches out across the pole ahead of the (probable) split, so the zonal winds increase despite the vortex actually undergoing increasingly extreme distortion.

Edit: I must of course stress that the pace of events is open to variation; anything up to 3 days quicker or a week slower seems viable to me.

 

19 minutes ago, feb1991blizzard said:

You've just illustrated the best pattern you can get IMO, a wave 2 split from pacific through to atlantic straight through Greenland, IF that type of pattern downwells, you've got a decent chance of at least a 2 week bitter cold spell as there's only one place the high will topple to after GL and that's Scandinavia.

Otherwise known as a wave 2 SSW- & to date all known W2 SSWs have split the vortex-

Singularity you have posted the day 16 chart that actually shows a canadian warming event starting which would decelerate the zonal wind- problem is your saying it would stop propergation- its already missed the boat by then, you have 16 days of acceleration before that.

Its pretty clear a SSW is needed asap, hopefully a W2 one as well.

If the chart was in some sort of timeframe pre day 8 then if would have some credibility but taken in isolation its a long long way out to assume that a wave 2 SSW is coming ( as nice as it looks & of course it would be perfect timing )

 

 

S

Edited December 8, 2016 by Steve Murr

[Nouska]

This is the FIM forecast so will be a bit different in the modelling of the strat to the one a couple of posts up. Note the difference in the wind speed between 10mb and 25mb. Shame there are no more layers to look at but it could be useful to monitor whether the very high speed winds are propagating down.

10mb    25mb

http://fim.noaa.gov/FIM/Welcome.cgi?dsKey=fim_jet&domain=201&run_time=08+Dec+2016+-+12Z

[feb1991blizzard]

Just now, Singularity said:

Absolutely, I'm amazed nobody spotted it before I did, it's not even Friday night when drinking is an excuse - perhaps people saw the ECM 12z and took to the booze a day sooner .

Mid-afternoon tomorrow, I'll be staring at the H-W MJO plot and willing it with all my heart to show EC ens. moving toward GEFS with the tropical signal.

That's a wave break as well so surely by the time its hit the buffer (somewhere between 10mb and 30mb presumably as it couldn't possibly go all the way up) and rebounded, that's quite a decent length of time, ive been looking at the unusual warming from the American sector lately, I usually follow the strat on every run but kind of gave up the last few after the vortex sat on top of the pole in the mid strat for a few FI runs a couple of days ago.

[feb1991blizzard]

7 minutes ago, Steve Murr said:

 

Otherwise known as a wave 2 SSW- & to date all known W2 SSWs have split the vortex-

Singularity you have posted the day 16 chart that actually shows a canadian warming event starting which would decelerate the zonal wind- problem is your saying it would stop propergation- its already missed the boat by then, you have 16 days of acceleration before that.

Its pretty clear a SSW is needed asap, hopefully a W2 one as well.

If the chart was in some sort of timeframe pre day 8 then if would have some credibility but taken in isolation its a long long way out to assume that a wave 2 SSW is coming ( as nice as it looks & of course it would be perfect timing )

 

 

S

Yes true, not confident of it actually occurring, as stated a while ago, the GFS has been useless when predicting favourable strat synoptics since the big success of Jan 13 but been much more accurate when downgrading them.

[Singularity]

10 minutes ago, Steve Murr said:

 

Otherwise known as a wave 2 SSW- & to date all known W2 SSWs have split the vortex-

Singularity you have posted the day 16 chart that actually shows a canadian warming event starting which would decelerate the zonal wind- problem is your saying it would stop propergation- its already missed the boat by then, you have 16 days of acceleration before that.

Its pretty clear a SSW is needed asap, hopefully a W2 one as well.

If the chart was in some sort of timeframe pre day 8 then if would have some credibility but taken in isolation its a long long way out to assume that a wave 2 SSW is coming ( as nice as it looks & of course it would be perfect timing )

 

 

S

Acceleration where? At 30 hPa I've just explained. In the troposphere is related mostly (or entirely - but I think the very lowest levels of the strat. are in sync?) to energy transfers within - hence it looks increasingly likely to be short-lived.

Chart is at +16 days and subject to usual potential overly-fast/energetic errors, but it ties in with the tropical outlook which is trending the right way this time instead of wrong, which combined with disconnect between upper/lower strat. layers (I'm sticking with that, can we agree to disagree for the time being?), so - IMO - reasons to be more hopeful this time around in that delays in arrival don't necessarily mean missing the boat. Or at least, we have a wider margin for error, perhaps much wider.

Edited December 8, 2016 by Singularity

[bluearmy]

What about day 11 on the mean as opposed to day 15 on the op?  The temps don't mimic both sides but heights are encouraging 

 

Or the ECM op at 50 hpa day 10

Edited December 8, 2016 by bluearmy

[SMU]

12 minutes ago, Singularity said:

Acceleration where? At 30 hPa I've just explained. In the troposphere is related mostly (or entirely - but I think the very lowest levels of the strat. are in sync?) to energy transfers within - hence it looks increasingly likely to be short-lived.

Chart is at +16 days and subject to usual potential overly-fast/energetic errors, but it ties in with the tropical outlook which is trending the right way this time instead of wrong, which combined with disconnect between upper/lower strat. layers (I'm sticking with that, can we agree to disagree for the time being?), so - IMO - reasons to be more hopeful this time around in that delays in arrival don't necessarily mean missing the boat. Or at least, we have a wider margin for error, perhaps much wider.

I wasnt neccasarily in total disagreement- just the 10HPA & 30HPA s now as both alligned to a steady uptick ( 10HPA since Nov end ) so if the warming lands on 24 Dec then there will already have been a month of increase at the highest levels - tapering off the further down you go -

so yes / no depending what level you look at it may or may not be shortlived - what that also means is if the warming did land on 24th & it was of decent NAM magnitude the propergation window to reversal is ~ 10days so based on that the second week of Jan is currently our best case scenario for any substantial HLB driven cold -

best

S

[Singularity]

5 minutes ago, bluearmy said:

What about day 11 on the mean as opposed to day 15 on the op?  The temps don't mimic both sides heights are encouraging 

More reliable of course 

I used GFS because it was a more satisfying illustration. Hence 'In an ideal world' which I perhaps should have put in bold to reduce instances of taking it as a prediction of what will actually come to pass without much doubt.

Anyway - encouraging signals tonight once you look past the det. runs with their foibles. 

[nick sussex]

The GFS 18hrs run is desperately trying to cut another shortwave se like it did earlier but this time further west!

[Singularity]

1 minute ago, Steve Murr said:

I wasnt neccasarily in total disagreement- just the 10HPA & 30HPA s now as both alligned to a steady uptick ( 10HPA since Nov end ) so if the warming lands on 24 Dec then there will already have been a month of increase at the highest levels - tapering off the further down you go -

so yes / no depending what level you look at it may or may not be shortlived - what that also means is if the warming did land on 24th & it was of decent NAM magnitude the propergation window to reversal is ~ 10days so based on that the second week of Jan is currently our best case scenario for any substantial HLB driven cold -

best

S

I see where you're coming from, and I'm happy to leave our discussion there for today - it's been good chatting this evening 

First half of Jan does look the most promising period within view, later Dec depends on how well tropical forcing behaves; phase 6-7-8 is known to correspond to height rises NW of the UK irrespective of stratospheric events. So we have possible troposphere-led chances followed by stronger potential stratosphere-led chances. There are worse positions to be in just one week into Dec 

[SMU]

27 minutes ago, feb1991blizzard said:

Yes true, not confident of it actually occurring, as stated a while ago, the GFS has been useless when predicting favourable strat synoptics since the big success of Jan 13 but been much more accurate when downgrading them.

http://www.meteo.mcgill.ca/~pmartineau/updated_graphs/svw_anim/all_gif/2009_01_29[/IMG]

this is what we want !!

Edited December 8, 2016 by Steve Murr

[knocker]

20 minutes ago, bluearmy said:

What about day 11 on the mean as opposed to day 15 on the op?  The temps don't mimic both sides but heights are encouraging 

 

Or the ECM op at 50 hpa day 10

Or even the 100mb seeing as this is now the lower Strat thread

 

Edited December 8, 2016 by knocker

[nick sussex]

Its amazing just how many times in the last few weeks we've had pressure rising ne from the UK and yet have been unable to get a single undercut.

[feb1991blizzard]

8 minutes ago, Steve Murr said:

http://www.meteo.mcgill.ca/~pmartineau/updated_graphs/svw_anim/all_gif/2009_01_29[/IMG]

this is what we want !!

Yes,  I posted one of the charts the other day on the strat thread, that's an absolute belter, although I had a Murr feb 1996 special happen to me - no word of a lie, there was 8 inches to a foot of snow 6 miles from me and I got sleety flurries for 18 hours and no accumulations.

[bluearmy]

2 minutes ago, nick sussex said:

Its amazing just how many times in the last few weeks we've had pressure rising ne from the UK and yet have been unable to get a single undercut.

Euro heights have proved too persistent nick. Most of us agree that euro heights are as important as HLB. Infact, some would say more important .................

[nick sussex]

2 minutes ago, bluearmy said:

Euro heights have proved too persistent nick. Most of us agree that euro heights are as important as HLB. Infact, some would say more important .................

True but its the lack of amplification upstream at the crucial moment which has been a big problem. I've found the recent weeks much more frustrating than last year because there was no hope last year, this year so far it seems like we've missed a couple of open goals and managed to sky the ball into the stands.

[Nick F]

9 minutes ago, Steve Murr said:

http://www.meteo.mcgill.ca/~pmartineau/updated_graphs/svw_anim/all_gif/2009_01_29[/IMG]

this is what we want !!

And there was a westerly QBO that winter as now too.

18z GFS op, only thing of note so far is that the high close enough to east later next week to allow a continental flow bringing slightly chillier conditions towards the east - maxes of 6-7C across eastern England next Thursday

 

[karlos1983]

GFS(P) 12z sends the PV packing from Canada,  most of it anyway. 

[SMU]

13 minutes ago, Nick F said:

And there was a westerly QBO that winter as now too.

18z GFS op, only thing of note so far is that the high close enough to east later next week to allow a continental flow bringing slightly chillier conditions towards the east - maxes of 6-7C across eastern England next Thursday

 

Yep & the only Novemeber in the Merra data with surpressed zonal figures - at the moment its running like a total replica !

[Ravelin]

2 minutes ago, Nick F said:

18z GFS op, only thing of note so far is that the high close enough to east later next week to allow a continental flow bringing slightly chillier conditions towards the east - maxes of 6-7C across eastern England next Thursday

 

Out to t198 so far and it's almost identical to the 12z run. A level of run to run consistency I don't think we've seen for days. Which of course means that we'll wake up tomorrow to the 0z run being completely different. 

[booferking]

GFS More amplified day 9 Eastern seaboard.

Edited December 8, 2016 by booferking