Hunt For Cold: Model Discussion - Heading Into Christmas

[northwestsnow]

1 minute ago, sebastiaan1973 said:

Very bad NH-profile with a postive AO. According to the study beneath, a downwelling will take place if the AO is negative on the date of SSW.

Predictability of downward propagation of major sudden stratospheric warmings Alexey Yu. Karpechko,et al 

Yes looking at the EC day10 while there are hints of the HP across Southern spain moderating there is also a whacking big +AO signature across the Pole..

 

[nick sussex]

The ECM showed some promise with the shortwave cutting back sw towards Denmark between day 7 and 8 but just too much energy upstream stops any further ne progression of the high .

The key thing is the Pacific shortwave development which is still in the early stages , we need to squeeze out more amplitude in that to amplify the Canadian high as it approaches the Great Lakes  . This will downstream impact the Atlantic troughing , that lobe of the PV over ne Canada will then be pulled further nw .

This then effects the shortwave near Denmark which will respond to more upstream amplitude by cutting back closer to the UK.

I wouldn’t normally be highlighting this chance but we’ve arrived at the buffet and there’s not much left barring some economy sausage rolls and stale coleslaw .

The poached salmon has long gone .

There’s a small chance we could see a bit more northwards movement in the high if the upstream pattern can develop a bit more amplitude .

Edited December 22, 2018 by nick sussex

[Mike Poole]

Interesting to see where the FV3 goes from the interesting position here T222, and then strat  chart:

We will need at some point to get some indication of  how quickly any strat signal is downwelled to our weather down here.  An earlier run, think GFS or FV3 6z.? This happened quite quickly.

Edited December 22, 2018 by Mike Poole

[northwestsnow]

Sensational developments in the strat thread!! EC shows a big split of the PV..

[Mike Poole]

Can  anyone else see HM  the Queen in yellow in this one, FV3 12z T204:

? 

Interesting run. If annoyingly slow to roll out....

[nick sussex]

40 minutes ago, sebastiaan1973 said:

 According to the study beneath, a downwelling will take place if the AO is negative on the date of SSW. More details in the stratosphere topic.

Important is 100 hPa till 300 hPa! (first i was mistaken and thought it was at 1000 hPa, sorry folks  

Predictability of downward propagation of major sudden stratospheric warmings Alexey Yu. Karpechko,et al 

It’s a little confusing Sebastian . I’ve read several papers on the downwellling . The base state of the AO does indeed effect the response . Sometimes the papers aren’t totally clear as to whether the importance is during the warming or the actual reversal itself.

The general rule is the more energy you have to play with the stronger the response , so AO neutral or plus more likely to downwell.

Which sort of makes sense if we think of the PV as explosives  and the SSW as a trigger  , less explosives  less response .

Although the outputs aren’t great no professional forecaster can say how quick the response might be . Or if there’ll be a QTR. 

 

[bluearmy]

6 minutes ago, northwestsnow said:

Sensational developments in the strat thread!! EC shows a big split of the PV..

It’s hardly sensational.... it’s simply consistent with its previous output .....

[northwestsnow]

1 minute ago, bluearmy said:

It’s hardly sensational.... it’s simply consistent with its previous output .....

Its significantly better than GFS so for me its brilliant news

[bluearmy]

The spread at day 10 says the uk retains the high heights with v low uncertainty..

Edited December 22, 2018 by bluearmy

[Singularity]

Remember that study that found strong UK high heights during SSW initialisation to be a big factor in whether NW Europe and the UK experience markedly colder than usual conditions as part of the response... it’s looking very good from that perspective .

[biggreyface]

13 minutes ago, Mike Poole said:

Can  anyone else see HM  the Queen in yellow in this one, FV3 12z T204:

? 

Interesting run. If annoyingly slow to roll out....

Yes I can see it but it’s not Elizabeth it’s Victoria that’s got to be a sign of a Victorian type winter ahea

[stodge]

Evening all

Onwards with the roller coaster it seems. The main model output still not yet factoring the stratospheric events but it's not surprising with the warming barely underway and still a couple of days off its peak.

I get the sense however there is some movement - the option of building a Scandinavian HP seems to be receding in favour of keeping the HP to the west or north west and allowing Arctic incursions as the main trough (and a lobe of the weakened vortex) to drop into Scandinavia. I imagine heights to the North West and a raging northerly in January will probably be cold enough for most. If the HP is kept well out to the west we might see the trough drop down right over us (shades of December 2010) and I imagine most people on here would be happy with that.

Watching the stratospheric modelling is fascinating - GFS seems to go less for a split than a shearing of the PV and what comes out at T+384 is a smaller, warmer and weakened PV (no -90c raging PV to start 2019). Looking at the 12Z Parallel and OP (which look very similar) the forecast sees this shredding of the PV rather than a full split so instead of two distinct intact PV segments you get a single weaker vortex - I don't know how that will play out and clearly the EC isn't seeing that.

For now, the immediate outlook looks benign for most with the weather not seemingly getting in the way of Christmas and New Year events.

[stodge]

9 minutes ago, Singularity said:

Remember that study that found strong UK high heights during SSW initialisation to be a big factor in whether NW Europe and the UK experience markedly colder than usual conditions as part of the response... it’s looking very good from that perspective .

As an aside I'm also struck by the difference in 10HPA temperatures between the stratosphere this time last year and now. By early 2018 it was still showing values of -84c and below at its core - the early 2019 value is scheduled to be -68c which is quite a difference, much warmer and much weaker.

[feb1991blizzard]

31 minutes ago, bluearmy said:

It’s hardly sensational.... it’s simply consistent with its previous output .....

Its a tiny bit wider which i will take, as long as it keeps trending that way day by day.

[Mike Poole]

6 minutes ago, stodge said:

As an aside I'm also struck by the difference in 10HPA temperatures between the stratosphere this time last year and now. By early 2018 it was still showing values of -84c and below at its core - the early 2019 value is scheduled to be -68c which is quite a difference, much warmer and much weaker.

Yes, after the SSW has done it's damaged fully but before then, the chance of the coldest strat temps in our neck of the woods for some time, here Christmas day

Some could see nacreous clouds, although not in the south probably!

Then, mediocre weather.

Then, cold and copious snow.

Then...

[Captain Shortwave]

      

As others have said, it is strange to say that the pattern is nailed at a week 2 range, but on this instance the signal for a UK high to end the year looks odds on, still there will be variation and once we remove any flow off the Atlantic (Be it under light and variable winds or a flow off the continent) then the temperatures will fall away with frost and fog under clear skies.  

[MR EXTREMES]

2 hours ago, Stuie W said:

The EC basically sends the vortex back to a location I think i have seen before...

But this is before the split so I wouldn't worry look at the cold so close to the UK.

So theme is settled high frost fog for starters.

Then it's very possible heights will edge ever further north east or north west.

Either way it's unlikely the models are 100 percent cent nailed could be further south so it's nowhere near a done deal.

What is a done deal is heights are established over Christmas period that will do for now.

Remember my start date for judgement day is the 7th January possibly few days later.

 

[bobbydog]

Just had a thought... @Glacier Point 's "torpedo" is still out there somewhere.... unexploded....

Sudden Stratospheric Warming?...

 

[snowfish1]

So where do things stand guys. Are we now looking at mid January and when will the cool looking charts start to appear.  By that I mean the ones that might come to fruition as opposed to the potential ones!!    Merry Christmas everyone from a NW Student https://tse2.mm.bing.net/th?id=OGC.a8e9c009b6740d7ac0aa53798647794d&pid=Api&rurl=https%3a%2f%2fmedia.giphy.com%2fmedia%2fvmNvy0UQd8e76%2fgiphy.gif&ehk=NIJDDshaO1k6ZsYiGghNOA

[karlos1983]

21 minutes ago, bobbydog said:

Just had a thought... @Glacier Point 's "torpedo" is still out there somewhere.... unexploded....

Sudden Stratospheric Warming?...

 

LOL just spat my beer out didn’t want to waste it until we had a solar minimum I reckon  

Inbound 

I still can’t get my head around how the ECM ant GFS are so far apart in the strat! Hopefully it torpedos the GFS server at the same time 

 

[Mizzle]

1 hour ago, Mike Poole said:

Can  anyone else see HM  the Queen in yellow in this one, FV3 12z T204:

? 

Interesting run. If annoyingly slow to roll out....

I see a dodgy looking HM looking NE & Queen Victoria looking W.

[abruzzi spur]

29 minutes ago, bobbydog said:

Just had a thought... @Glacier Point 's "torpedo" is still out there somewhere.... unexploded....

Sudden Stratospheric Warming?...

 

I remember the predicted torpedo from a few winters back.  I guess like many weather predictions it didn't quite pan out.  Hopefully it's not still in orbit with an increasingly dodgy fuse.  Maybe best next time to say something like 'chance of a change to something more wintry next week'

 

[ITSY]

The control is a thing of beauty! 

 

[Ravelin]

GFS 850s for my location, 0z then 18z.

 

That's some change in the mean in FI in the space of a day, and 6z & 12z neatly trended down between the two above. Could easily change back at that range, but promising all the same. 

[GeordieX9v]

Not the worst +204 I've ever seen coming from the Para