Model Output Discussion - 31/10/2014 and Beyond

[gottolovethisweather]

Apart from a couple of odd cold runs the ENS concensus is for above average and unsettled conditions to perpetuate for the foreseeable future

We could scrape the odd ground frost if we're lucky and pressure seems to be rising through the medium term.

 

Agreed Purga, the near term is of no interest to us coldies (including you here?) but the mid to longer-term most definitely IS.  The charts you have chosen to illustrate your view, although valid, aren't of much use in determining the broader picture of where we're heading and I would remind all readers on the dangers of using one run in isolation. 

 

In fact, the consistency over the general model suites over the last three days for the potential cooler, to dare I say it much colder spell come next weekend for all is very NOTEWORTHY. 

 

I would advise everyone to keep looking at the bigger picture and whilst not losing sight of the nearer term, to bear in the mind the possibilities of changes upstream by the end of next week.  

Edited November 9, 2014 by gottolovethisweather

[Bobby]

Those touting a strengthening vortex would do well to pop into the strat thread and read Snowking's excellent post.

Basically there are expectations of an early season SSW during which time the AO would likely go positive. As he says, panic will ensue and "winters over" posts will be flying around. I would assume the vortex would appear to reform.

However,after this event (should it happen) the AO would go deeply negative and potentially last for several weeks.

Then we're in business...

 

A good post but I can't see talk of a SSW or a deeply -AO but a warming and neutral, negative AO..

 

Besides, predict a stratospheric warming, then predict blocking out of that, then predict where the blocking will fall, and then predict whether that shortwave spoiler around Iceland will scupper things or not, then lastly make sure those dewpoints are right for snow to lower levels. If only getting us into "business" was that easy and straightforward!

Edited November 9, 2014 by Bobby

[bobbydog]

A good post but I can't see talk of a SSW or a deeply -AO but a warming and neutral, negative AO..

 

Besides, predict a stratospheric warming, then predict blocking out of that, then predict where the blocking will fall, and then predict whether that shortwave spoiler around Iceland will scupper things or not, then lastly make sure those dewpoints are right for snow to lower levels. If only getting us into "business" was that easy and straightforward!

Its all in Snowking's post. Read both of the quotes from Cohen.

Anyway, we better leave it there, we're going OT....

[Tamara]

  >. thus, with all said thus far about the upstream pattern, a good template is in place for the persistence of an atlantic upper trough continuing to disrupt towards the UK well into this month, carving out an early season -NAO signature.. whilst important window dressing also occurs on our side of the pole that we hope to see sustained and eventually back Siberian cold westwards in the months to come.

 

Extensive Eurasian snow cover further promotes upper polar vortex segment sticking over central Siberia and teleconnects to establishment feedback of High pressure anomalies above it over the polar field. In this way the SST/Atmospheric feedback dovetails with the Eurasian feedback process to perpetuate sustained Rossby wave breaking trigger mechanisms to ensure that the vortex remains unstable and increases the likelihood of HLB further establishing though the rest of this month and into winter.>  

 

With the jetstream disrupting over and to the west/south west of us and still some residual lag warmth from a very warm autumn so far still to be mixed out, we best be prepared for plenty of unpalatable wet weather continuing in both the near term and probably intermittently in the few weeks to come. I wouldn't expect anything especially cold for a while yet. But who really cares at this early stage? In view of the progression of the bigger hemispheric pattern, then short term pain very conceivably holds long term gain>

 Snippets of last post for continuity purposes

 

5 days and 31 fast and furious pages of assessment and expectation later... -  little has essentially changed at all from the previous summary, much as anticipated. So all that is required is a brief-ish, at least by my standards, few (ish) words.

 

There is model disagreement at the time of typing regarding tropospheric solutions to wave 1 and (?) 2 activity. However, we should not expect the atlantic profile to improve sufficiently just yet, and the recent Fantasy Island -NAO modelling and Greenland High building of the ECM looks too premature imo.  

 

Both the strat/trop charts are currently being perused by many members in hope of fastrack to a properly cold spell !!  Refecting the sentiments of the highlighted post once more however, I think that expectations need to be managed beyond the strong wave 1 activity which is advertised by all models in terms of the heights modelling over the NE Quadrant of our hemisphere. In terms of feedback and background factors it looks however (thankfully) too early for predicted wave 2 activity (as documented by the ECM currently) . Those hints by the Euro, especially,of fledling early season cold pooling rooted up over Siberia attempting to back too far west are very likely too progressive.

 

On this basis the ECM once again looks culpable of over amplifying the atlantic pattern.

 

It might not be of interest and flavour for the thread (and it certainly is far from my own cup of tea!) but we have to endure further unsettled cyclonic conditions with more disruption from rainfall, principally, in the days ahead as further lows bleed out and disrupt from the section of upper vortex over Canada - the likely absence of wave 2 activity (for the time being) ensuring that this segment of vortex doesn't weaken and consequently prevents the height rises to our NW to improve the atlantic profile and provide true undercut

 

What the wave 1 activity will do however is back the unsettled weather slightly further west, so more eastern parts, at least dry up somewhat after some unsettled days ahead - but of much more interest and pleasure it will ensure that the aforementioned window dressing (for further down the line) continues unabated to our NE.

 

The pattern looks to cycle, wash, spin, and repeat. Although I agree the GFS is prone to an eastwards bias of patterns, in contrast to the over amplifying errors of the ECM I do think that it is best to be prepared for some less than enjoyable model watching with suggestions of a fairly mild NW/SE split , temporarily, after the current period of model watching interest finishes.

 

But don't fret . The next time around the SAI/ wave breaing -AO feedbacks will be stronger with greater repercussions hemispherically. It is common for a long period of AO phase dominancy (this season negative!) to be preceded by an opposite spike as zonal wind profiles with the polar field are re-shuffled. The AO/NAO lose their seasonal disconnect as we plough onwards into and through winter. Cold pooling to our NE will deepen and more extensive westwards and southwards. Over the coming month or so, resurgent tranches of wave activity are likely to draw deeper blood from the polar vortex that we increasingly pick up the scent

 

At the risk of posting a 'jam tomorrow' post - better then, than now, for sure

 

Edit: *sufficient* wave 2 activity - the point being made is that it looks far too negligible to create upper height rises over Greenland to back any properly cold air west.this early in the season

Edited November 9, 2014 by Tamara תָּמָר

[IDO]

Its all in Snowking's post. Read both of the quotes from Cohen.

Anyway, we better leave it there, we're going OT....

 

Yes the high anomalous flow in the Pacific Region is an essential prerequisite for a Polar Split and we look like we are going to get lucky there, with Nuri doing its worst. However the impact on the models of this possibility will not be in the charts at the moment, even in GEFS FI. So at the moment it is just tropospheric developments. No one is denying when a SSW (split or displacement) occurs that the surface/500hpa setup will not be relevant as the strat. will define the top down effect.

 

However it is still worthwhile seeing the current pattern and how it develops and it is clear the early season mid-lat cold pooling is more than likely to pass by the UK. The reason I say that is that the upper cold pools are trending towards  a very blocked flow so for example the US will get reload after reload, so by T300 according to the Parallel the US is still within this cold upper pool:

 

T30:   T300: 

 

The UK stays in a relative warm(er) sector and it is only in the latter stages that the drift from the US cold pool seeps across the Atlantic and we get some washed out cooler uppers:

 

 

 

This is why I am rather sceptical of the ECM charts leading to any sort of UK cold from this current trop led PV disruption. It would be remarkable if we could squeeze some cold out of this forecast wave pattern; a lot of luck needed? Though the GEFS suggesting that around D14 the upper pattern becomes more fluid, but by then the meridional flow has slackened and any colder air looks more transient in nature.

 

Lets hope when the strat led pattern change happens the blocks will be a bit more helpful for UK cold.

[Joe Levy]

Good afternoon everyone

 

Not that I understand the terminology too well, so correct me if I am wrong, but the GFS is coming out and at 120 hours the Northern hemisphere profile is looking very good from a perspective of northern blocking. I believe that is some wave 2 action there but please correct me if that is wrong! I get the general gist of things but I tend to fail to use the correct terms...

 

EDIT - talk about an apologetic post...

Edited November 9, 2014 by Joe Levy

[SMU]

GFS about to join the party....

Its about time - only 3 days late. Its finally resolved the energy seperation off the east coast of US at 126

Cmon UKMO-

S

[Winter Cold]

That looks like a big improvement from GFS to me? Its moving towards ECM?

 

We have a better push of heights (green) into Greenland and it looks like the low near us is seperating as Nick Sussex said it needed to?

Edited November 9, 2014 by Winter Cold

[shaky]

Much better heights across Greenland on the gfs 12z!!here we go again!!just clueless!!

[Joe Levy]

This is a very good setup synoptically on the GFS, but as of yet we don't have the cold uppers. However, getting the setup in place first is far more important based on previous winters here...

[Barry12]

If anything the GFS has stronger heights over Greenland than the ECM at days 4-6.

 

 

 

 

Edited November 9, 2014 by Barry95

[shaky]

At least the gfs has attempted to come to the party!!the bloomin ukmo doesn't wana come on board at all over the past few days!!

[Snowy L]

We have that vortex lobe near Svalbard attempting to move South as with the ECM., definite upgrade on the 12z.

 

http://www.wetterzentrale.de/pics/Rtavn1681.gif

 

Get the block set up first in the next 5-10 days and then this low pushing south can provide some cold uppers from fay 15 onwards. There's still loads to play for.

Edited November 9, 2014 by Snowy L

[IDO]

The GFS Parallel in line with the 06z output at D6:

 

   

 

Not seeing it getting close to the ECM output from there. In fact moving in the other direction!

 

D8:   

[nick sussex]

The UKMO is an improvement on the earlier 00hrs although it still keeps low heights near Svalbard, the GFS does clear that troughing allowing the ridge to back west, the GFS P though isn't as good.

 

I think theres to more to back the ECM trend than go against that so not a bad start to the evening from a coldies perspective.

[shaky]

Gfs parallel aint doing itself any favours!!its been just as inconsistent as the gfs over the last few days where as ecm has been rock solid!!gfs 12z goes ecm way and now we gota hope ecm continuous where it left off on the 00z!!

[IDO]

ECM on its own tonight as both GEM and UKMO closer to GFS at D6: 

 

 

[shaky]

Oh my days thats quite an improvement on the ukmo!!at the moment ecm is trumping it!!!

[Cloud 10]

GFS about to join the party....

Its about time - only 3 days late. Its finally resolved the energy seperation off the east coast of US at 126

Cmon UKMO-

S

 

Yes,a typical lurch from the GFS over the last couple of days towards the ECM.

 

120hrs today..  2 days ago..

[radiohead]

ECM on its own tonight as both GEM and UKMO closer to GFS at D6: 

 

UN144-21.GIF  gemnh-0-150.png

 

Sadly not the first time that's happened. ECM led us up the garden path big time on two occasions in 2012.

 

It's always very tempting to view the solution we want to see as the correct one in these situations. Human nature!

 

Still pretty interesting charts for November, and we are dealing with stuff in the FI range so I doubt we've seen the end of the evolution of this pattern change, for good or for bad!

 

Looking forward to the 12Z ECM...popcorn at the ready?   

[SMU]

Ukmo is fab !!!!

Someone post the UKMO 144 & the identical nov 2010 chart!!!

[Summer Sun]

GFS P shows the high drifting closer towards us by d10 as a result we get some southerly winds

 

The weekend and early next week sees SE'ly winds

 

 

By d10 we see southerly winds

 

 

D12 continues with the milder air especially in the south as high pressure remains

 

 

So a cooler spell over next weekend and into the following week looks to have good support this afternoon what happens by d10 is anyone's guess really we've got the GFS P southerly and the ECM easterly.........

[Mair Snaw]

How is the ECM out on its own?? The 12z GFS has just taken a huge step towards it...now if the GFS had stuck to its guns and had none of it then the ECM would be out on its own...UKMO also looks to be heading toward the ECM aswell...but not as much as the GFS but then im sure it was last to get in on the act Jan Feb and March 2013...

[bobbydog]

Ukmo is fab !!!!

Someone post the UKMO 144 & the identical nov 2010 chart!!!

 

this one?

 

 

 

and this one?

 

 

erm no..... this one?

 

Edited November 9, 2014 by bobbydog

[IDO]

Ukmo is fab !!!!

Someone post the UKMO 144 & the identical nov 2010 chart!!!

 

 

...  

How is the ECM out on its own?? The 12z GFS has just taken a huge step towards it...now if the GFS had stuck to its guns and had none of it then the ECM would be out on its own...UKMO also looks to be heading toward the ECM aswell...but not as much as the GFS but then im sure it was last to get in on the act Jan Feb and March 2013...

 

 

Thats the GFS op you are using which won't exist in a few weeks. I am looking at the Parallel now for guidance.