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

[karlos1983]

4 minutes ago, Timbo said:

i have a feeling that over the next few days the models will move more towards a proper Scandy High, this then allowing a cold pool to develop and move Westwards into the South of the UK

East Anglia could be seeing a proper white Xmas with frequent snow showers.

Watch this space and watch a turn around in the models starting tomorrow  

That's a bold call Timbo, but then we've seen a few of them historically by members (who have got it very wrong),  so I see no reason why you shouldn't have a punt 

heres hoping you've nailed it 

Edited December 10, 2016 by karlos1983

[bluearmy]

Steve, the  Berlin charts show the zonal flow at 60N pretty consistent over the next 10 days. the increase above 10hpa really not working down. There is an uptick at day 10 at 10hpa but unknown if that would work its way down as yet. certainly a lack of any reversal  through the NH  north of 40 but no great uptick of zonal flow below 15 hpa as yet. 

[Tamara]

2 hours ago, ManiaMuse said:

+1

As a lurker who doesn't understand most of the technical posts but still enjoys reading them anyway to get an idea of which way things may be swinging, it's getting really annoying having to sift through all the petty bickering and overly optimistic/pessimistic one liners that don't add anything to the thread.

 

+2.  I expect many more as well

Its one of those times when its hard to keep adding new information as we are stuck in something of a rut at the moment, which in itself is a statement of the obvious

However, what is clear is that this winter is already looking like one where a route to a cold pattern, this side of the pole requires the following to happen

1) Return to tropical/extra tropical feedbacks that characterised a lot of the autumn - which links to:

2) A +ve atmospheric angular state which provides a tropospheric amplification mechanism to promote wave breaking into the stratosphere alongside both the feedbacks from the SCE (Snow cover extent below 60N) and the Kara sea negative ice anomaly which enhance the Siberian High, amplify the Jetstream in the troposphere, weaken the polar vortex and destabilise (warm) the stratosphere

Without an atmospheric circulation that is conducive to downstream amplification, then the Siberian feedbacks are neutralised. This, through the type of low angular momentum pattern  we have started heading into which favours strengthened, flatter polar jet, steepened gradient created through cold air out of Canada/US > Western Atlantic and inability to amplify northwards any downstream heights in the European sector.

The current steep descent in relative angular momentum says more about the significant extent of the atmosphere/ocean disconnect that has existed through much of the autumn than it does about how far AAM itself might actually fall.

To illustrate that perspective, look at the previous steep drop on that chart shortly after the middle part of November - this was echoed by a previous large scale high amplitude Global Wind Oscillation Phase 8/0 (and back to 4) orbit .... and also coincided with the last unsettled westerly spell (incorporating Storm Angus) on 20 November.

If we consider that the models are programming another ramp up of energy in the Atlantic according to another low(er) AAM phase,, then I think it is significant that the long wave pattern has adjusted westwards(discontinuous retrogression) compared to November - and the storms and their secondary developments struggling to extend as far eastwards.

Assuming the atmospheric cycle can rebound again in terms of angular momentum and a return of the GWO to Phase 4/5, at the same time as the above Eurasian feedbacks seasonally beat a stronger drum imprinting stratospheric warming, then its not too difficult to see that height rises to the North and North East are quite conceivable as we head further towards and into January  - naturally helped by seasonal wavelengths adjusting the synoptic pattern favourably for us

We know that wQBO acts against the constructive feedbacks mentioned above through strengthening the stratospheric vortex, but we also know from other similar ENSO years that a stratospheric upper/lower disconnect is quite possible - especially where there are strong Eurasian feedbacks to assist this.

At present the tropical signals continue to frustrate timing of another uptick in AAM an re-amplifying the pattern - and something of an enigma persists in terms of all the signals either contradicting or cancelling each other out.  

But as can be seen, all the reasoning behind the stand-off(s) as discussed are not negative, looking ahead, by any means.  A switch back to a "constructive" tropical signal (in simple terms one that works in tandem with the ocean/atmosphere disconnect that helped assist the -AO profile ^^ appearing in the autumn) will still make a significant difference to the present highly underwhelming synoptic patterns by NWP - but I suspect that signal, if it is to come, now much more likely to come into the extended period radar.

The "make or break" often mentioned on this thread, for me at least, effectively depends on an end to the current "destructive" interference ending sooner rather than later - so the type of virtuous cycle described above can provide a lot more to smile about as we get closer and closer to the end of 2016. Those are the facts, that is where the hope lies that luck changes accordingly. Especially as the dominant Annular Mode (whichever way) couples much more tightly by January

 

Edited December 10, 2016 by Tamara

[Mucka]

1 hour ago, Nouska said:

If you look at the last ECM46 ensemble mean chart (Christmas week) for 500-1000 thickness - you can see why models are having such difficulties in solution. Such a narrow corridor between quite extreme thickness values and just tiny oscillations in the pattern give very different outcomes as surface conditions.

It could be some time before this is resolved.

For sure but it isn't just the detail, within the ensembles we are seeing swings from Atlantic dominance to dominant blocking not an ebb flow to where the trough/block sets up. 

Op and control have been a little more consistent but that consistency hasn't really lasted beyond 2 or 3 runs as yet and again I don't mean detail (wouldn't expect that at those ranges) I am talking longwave pattern overall. 

[Scandinavian High.]

14 minutes ago, Timbo said:

i have a feeling that over the next few days the models will move more towards a proper Scandy High, this then allowing a cold pool to develop and move Westwards into the South of the UK

East Anglia could be seeing a proper white Xmas with frequent snow showers.

Watch this space and watch a turn around in the models starting tomorrow  

You must have a  Crystal  Ball then  I just checked meto there going with a backtrack in models with very cold temperatures and blizzards hit south east England next weekend.

[SMU]

27 minutes ago, bluearmy said:

Steve, the  Berlin charts show the zonal flow at 60N pretty consistent over the next 10 days. the increase above 10hpa really not working down. There is an uptick at day 10 at 10hpa but unknown if that would work its way down as yet. certainly a lack of any reversal  through the NH  north of 40 but no great uptick of zonal flow below 15 hpa as yet. 

Hi mate

its slow but remember its scaled at 10M/S & @ 60N there isnt a huge range

check out the lower levels going slowly from 20 towards 30- a 'moderate' increase...

[Mucka]

49 minutes ago, bluearmy said:

Can we talk about anomalies

a high anomaly north of the uk needs to be intense to represent a proper area of high heights as standard climatology has fairly low heights in that area. Conversely, a weak looking high anomoly south of the uk could easily represent white high heights as we would usually find quite high heights to reside there.

looking at the CFS chart above, the high anomoly is north of the uk and this then weakens as we head south into Europe. The reality of this would be a fairly large area of highish heights spread from e Greenland down to se Europe. tough to say exactly where it's strongest at 500hpa but what's certain is that it wont be that large an area come verification. Coldies would want to see it further north and non existent further south allowing a flow east of south and strong enough to advect cold west. The circular shape of most intense variation from normal could offer a clue as to where it may be favoured but we have no idea of if the ridge will extend west towards greeny or se into Europe.  as ever, the heights over Europe are IMO critical to chances of deep cold and snowfall. 

Mucka, not sure I see the GEFS flip flopping that much. They are moving the position of most intense anomoly around but the broad theme is blocked around w Europe. 

Is it though?

And many others show blocking UK or Atlantic not Sceuro blocking.

If you check like for like 00z and 06z Blue it is very clear 06z are much flatter than the 00z and the 00z actually had a lot more HLB rather than just Sceuro high.

Sure the overall predominant theme may be +ve anomaly NW Europe, hence my thoughts on how Xmas may play out, but the swings in the ensembles are very evident and where any positive height anomalies set up far more volatile than seems to being suggested in the posts I am responding to.

I'm pretty confident 12z will swing back again toward 00z suit but we will see.

Edited December 10, 2016 by Mucka

[Daniel*]

Far too much shifting in the output, for one to have an idea how things will unravel at day 6/7 at a stretch. The 18z from last night did bring in some very cold continental air into E - which is plausible, a marked drop in 850mb temps & theta-E, sub 10c for parts of SE/EA now that is properly cold. All down to the orientation of the high, small changes, will have have a large effect, on the surface conditions. I've seen in winters gone, how a strong signal fade, not that we've particularly seen that, and then reemerge within t72-96 with a vengeance. A frustrating time of model watching, but surely the Devils spine is going to break soon, or a sacrifice indeed may be needed, any volunteers?

[nick sussex]

I'm wondering whether there might be another opportunity to get the high further north and also whether there might be some changes towards day 8 to 10.

This centres around a change in output upstream from both the ECM/GFS its in relation to a shortwave which briefly amplifies over the eastern USA,which helps to develop that ridge ahead,as this shortwave travels east it phases with the PV lobe this then helps to pull some of that away from southern Greenland. If you follow the ECM from T168hrs you can see that occur; unfortunately the amplification doesn't last long but just something to keep an eye on.

 

 

[mulzy]

GFS 6z parallel gives us hope of a SE drift at day 7.  Not a million miles away from last night's 18z.  Lower pressure to the west of Italy helping to advect the colder air east...

Edited December 10, 2016 by mulzy

[Nick L]

Numerous posts discussing White Christmases have been moved to the White Christmas thread (because, funnily enough, they're off topic)

Is it REALLY that hard to stay on topic?

[Scandinavian High.]

28 minutes ago, mulzy said:

GFS 6z parallel gives us hope of a SE drift at day 7.  Not a million miles away from last night's 18z.  Lower pressure to the west of Italy helping to advect the colder air east...

Hi where can I view GFS parallel can't see to find on net weather thanks.

[bobbydog]

2 minutes ago, abbie123 said:

Hi where can I view GFS parallel can't see to find on net weather thanks.

Here you go-

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=6&runpara=1&carte=1

[Ali1977]

Day 4 and high over Scandy looking stronger and slightly further North 

[Scandinavian High.]

10 minutes ago, bobbydog said:

Here you go-

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=6&runpara=1&carte=1

Thank you

[radiohead]

Looking at the 12Z GFS rolling out....Is that low sliding.....?

 

 

Edited December 10, 2016 by radiohead

[karlos1983]

That's quite a difference 12z to 06z 

Small window of opportunity for favourable corrections now! But stranger things have happened!

Edited December 10, 2016 by karlos1983

[Mucka]

Something for the weekend sir/madam?

Not quite but things that make you go, "hmmmm"

[feb1991blizzard]

3 minutes ago, radiohead said:

Looking at the 12Z GFS rolling out....Is that low sliding.....?

 

 

Its a better run and a tiny bit of energy sent south but if it doesn't re-phase it looks like it will still fill so no better in 8 or 9 day range, whether it delivers in FI remains to be seen.

Edited December 10, 2016 by feb1991blizzard

[feb1991blizzard]

Hang on!!!   -  might be better than I thought, just enough energy sent south to keep the run alive.

[radiohead]

UKMO has the low further south and east than the GFS at T120 too.

 

 

 

[Pembroke Dangler]

http://www.wetterzentrale.de/de/topkarten.aspx?map=2&model=gfs&var=1&run=12&time=135&lid=OP&h=0&tr=3#mapref

we need the high over scandi to be further north and I would expect the trough disruption would be better but more positive than the earlier runs 

[radiohead]

12Z GFS was a step in an interesting direction even though sliding low eventually failed on this run. GEFS will be interesting.

[Cheshire Freeze]

Just now, radiohead said:

12Z GFS was a step in an interesting direction even though sliding low eventually failed on this run. GEFS will be interesting.

FI will be interesting. The best FI synoptics have tended to follow the slightly more amplified closer time frames.

[Summer Sun]

Next week could end on a rather windy note if UKMO is correct