Model Output Discussion - Into November 2019

[booferking]

Some strat warming on 12z.

[Ali1977]

2 minutes ago, northwestsnow said:

Just need this chart to countdown to T0 now

For those of wanting cold foggy/frosty weather GFS 12z delivers beautifully...

Usual caveat being it is but one GFS operational of course..

And look at this, that’s come to fruition quickly . That’s a great HP over Scandy, add in a poss SSW and you could have something quite Special last week Nov!! 

[tight isobar]

Yeah..layer warmth @Eurasia..

And an-operantional stomping latter frames..

 

Tbh..tricky to think of better dynamics...as we roll forward!!!

Edited November 4, 2019 by tight isobar

[Methuselah]

Well, the 12Z Operational certainly ends with a degree of stonkeriety...We could be on the cusp of something special???!!!

   

A slow, steady and relentless descent into winter...for a change?

[Ali1977]

The FI mean on GEFS is great, heights over Greenland and pretty much nil PV - as a mean how often would you get this mid Nov ???

 

[Tamara]

16 minutes ago, JON SNOW said:

and it's great to read that the longer term signal has flipped from mild / mushy to colder / below average..all the right boxes are being ticked in the run up to winter!!

Just a one-off summary before disappearing once more..

 I freely admit I have no interest whatsoever in attempting to fit patterns to preferred outcomes, despite my own preferences which much more closely align these days in terms of this thread at the opposite time of the year - so this approach will be in stark contrast to the overwhelming one adopted in this thread and likely disregarded due its later conclusions

I have only done a bit of speed reading through most of the posts on this thread, and the majority of them are rooted in my honest opinion within confirmation bias circles anyway. But despite so many claims to the contrary, this is in truth a very typical late autumn low angular momentum driven pattern that features an anomalously amplified wavelength as dictated by a strong NE Pacific ridge leading the downstream configuration of ridge/trough/ridge/trough

These low momentum phases in autumn are often punctuated by an intra seasonal higher phase tropical cycle which augments the underlying natural downstream Atlantic ridge profile that the default La Nina type circulation imprints. Forget the actual ENSO base state here - it is the tropical/extra tropical circulation that the atmosphere is adopting to the base state that matters in terms of wind-flow inertia to determine the jet stream behaviour -  and it remains likely in my opinion that a Nina type disconnect will persist through at least the first half of the winter

So the current intraseasonal phase tropical signal is attempting to pass the Pacific over the coming period and this is providing an added boost to the amplified ridge/trough profile. Much of the seasonal modelling is in excellent agreement with this signature for November, so a continuation of trough disruption likely to continue this side of the Atlantic for a while yet based on the meridional aspect to the wavelength. The CANSIPS, as one of the various majority of models in agreement with the longer term evolution of the pattern is a very close matching example indeed of what is advertized to persist well throughout November

 

As the tropical signal ultimately heads back towards the Indian Ocean following this period, and returns alignment to the default circulation, the period beyond this looks accordingly highly susceptible to a renewed collapse of angular momentum and occurring very conceivably at the same time as  the seasonal wavelength change occurs as November progresses closer and into December. Such a  renewed drop in momentum implies increased energy returning to the polar jet and re-alignment of sub tropical ridging as trade winds re-dominate the Pacific.

With this in mind, and with the the stratospheric vortex uptick to over 40 m/s prior to upcoming temporary (relative) reduction in speed - it means that the November planetary wave poleward momentum providing some perturbing of the tropopause has to be taken into context of longer term angular momentum trends related to the tropical cycle - and also related to the transition of the QBO which is still within its transition phase to easterly. This transition unlikely to complete till late winter. On that basis its hard, at present at least, to see how a disconnect will sustain beyond the tropospheric support available over the coming few weeks and this in my opinion would point in such circumstances to an elevated chance of quite a pattern change during December

I am very aware that this suggestion will not be taken seriously, but the context of a chilly November therefore, has (in my opinion anyway) to be treated in sensible perspective and *shouldn't * be extrapolated forward into winter as part of the huge bias preference in this audience. Similar principle to warm late Springs that often are featured as part of low angular momentum wavelength regimes - but, with a few exceptions, more often than not give way in accordance with summer wavelength changes  to cooler and more unsettled summer patterns

If a warm May was in progress, I would be enjoying it, but still cautious of prospects beyond this time -, so as far as I am concerned the same applies to below average Novembers( for those enjoying that if its your thing) and the portents for winter.

And yes, before the usual response(s)  appear, I am perfectly aware of all the arctic feedbacks that are chattered endlessly in these threads every year with cast iron guarantee and which always are supposed to lead to the *big one*  - but these still require a conducive tropospheric/stratospheric pathway to engage them and in turn provide a sustainable pattern to make it snow...

I am not a forecaster,  and don't pretend to be able to second guess the weather - but continue to differ from the popular bias view and can see support for the seasonal modelling suggestions of a milder much more south westerly driven type ultimately taking over heading into/or during  the early part of the winter.  The seasonal models can be wrong, and will surely be wrong again at sometime - but that doesn't mean they are always wrong and especially when it is clear to see from a bias free diagnostic approach that less appealing solutions are indeed also possible than the one most want to fit to suit their preference.

Those *other*solutions  might entail a NW/SE type of split, with reduced air frost risk and the wettest and windiest weather transferring accordingly away from more southern parts and some hope perhaps for some quieter drier weather here after so much rain this autumn - and at least for the benefit of a very small minority of those who visit this thread, also a much welcomed chance to reduce heating bills at least during the day.

With that in mind, the CANSIPS model closely reproduce this prevailing thinking with the seasonal wavelength change showing a much less amplified Pacific/Atlantic ridging regime during December - and a European downstream ridge replacing the disrupted trough. At present at least, most of the other main models have close variations on this same theme

Time of course as always will tell. The winter as a whole of course remains anyone's guess 

Best wishes for the remainder of 2019 and for the start of 2020 . A very few of us will wait as patiently as possible for Spring and the longer days spending more time outside once again..

 

[Allseasons-Si]

The gem gives us a straight easterly although the uppers could do with being a tad lower but from a conti-sourced dryer air could produce the odd snow grain or a full on snow making machine

a good afternoon of model outputs so far,come on ecm.

[ICE COLD]

I’m late to the party on the 12z so haven’t read through but the GFS 12z is another brilliant run and that warming is even stronger and moving closer . Sorry if it’s already been posted .

[knocker]

The key features of the ext mean GEFS are the strong TPV northern Canada and the quite intense European ridge into the eastern Arctic. Thus still a strong westerly upper flow exiting the eastern seaboard but diverging mid Atlantic courtesy of the ridge and the UK trough which is now over Iberia, The surface analysis remains tricky with temps around average

Edited November 4, 2019 by knocker

[Mike Poole]

ECM out to T144:

I think the air is probably not cold enough for snow (bit early yet anyway) from that for most, especially in the south.  I'm slightly interested in where the really cold air is here, seems to be strung on an east west line across the NH which looks quite odd, not sure if this result of the disrupted trop vortex, or indeed the partial cause of it.  

Edited November 4, 2019 by Mike Poole

[knocker]

As noted earlier the strong jet whips another upper low east for next weekend before it noticeable hits the buffers An overview wet and windy

.

 

Edited November 4, 2019 by knocker

[blizzard81]

Just to illustrate how the tpv over north east Canada was over estimated. The ecm day 10 chart from the Friday 12z for 11th November compared to today's day 7 chart for the same date. 

[Methuselah]

I think that the GEFS 12Z ensembles add a bit of perspective to our excitement: the operational run is one of the coldest in the pack...

   

    

It might be cold bias, but let's hope it's not -- the warmer ensemble-members haven't had much success, of late?

Edited November 4, 2019 by Ed Stone

[January Snowstorm]

Well there's not much comment on the ecm I suppose because it doesn't show much promise compared to gfs

Knocker makes a good point tbh the news isn't potential snow it's cold and wet with flooding become more and more likely

[MATTWOLVES 3]

Yes Pete, the op was most definitely on the colder side of things. Don't no what to make of the ECM, high pressure to the West and East of us, but not much in the way of cold air to tap into, I think it must be having one of its evening happy hour moments! But without wanting to sound cold bias.... God forbid me of all people doing that!! I do like the GEM 12Z tonight... Lovely little Estly with a nice bit of cold pool to boot. 

[northwestsnow]

1 minute ago, January Snowstorm said:

Well there's not much comment on the ecm I suppose because it doesn't show much promise compared to gfs

Knocker makes a good point tbh the news isn't potential snow it's cold and wet with flooding become more and more likely

EC looks OK to me JS...

Looks to be becoming blocked later on..

Thats all i want at the moment, as others have said,  little chance of snow away from the higher hills in early November..

I would be content with a cold dry set up..

[bluearmy]

14 minutes ago, northwestsnow said:

EC looks OK to me JS...

Looks to be becoming blocked later on..

Thats all i want at the moment, as others have said,  little chance of snow away from the higher hills in early November..

I would be content with a cold dry set up..

no point getting hung up on wintry nirvana sypntoics in mid November that lead to miserable greyness and cold rain - the NH profile remains promising (on many levels)  as we head towards winter proper 

[SMU]

14 minutes ago, bluearmy said:

no point getting hung up on wintry nirvana sypntoics in mid November that lead to miserable greyness and cold rain - the NH profile remains promising (on many levels)  as we head towards winter proper 

Yes - as we settle in to the current runs the Euros & GFS paint a mix of rain / Wind & depending on the tracks of the shallow systems some snow as well.

The Easterlies look great synoptically but at this stage dont quite carry the weight of the deep cold required for Early / Mid November...

There is still the caveat that at day 5 what the GFS / Euro blend portray in terms of a slider could sharpen up a bit more to become a little more wintry...

Background wise GFS mean for the 13th -3.5 AO

ECM operational slap bang along that line

The JMA

Meteociel - Modèle numérique japonais JMA

WWW.METEOCIEL.FR

---

Meteociel propose les cartes du modèle déterministe japonais JMA

is a run tonight that broad brush is the same as ECM however the macro synoptics drive cold over the UK rather than cool air from the ESE

Edited November 4, 2019 by Steve Murr

[Frosty.]

My take on the GEFS 12z mean is temperatures gradually dipping below average this week, especially at the weekend and early next week with the coldest potential further north and it looks unsettled to varying degrees throughout so plenty of rain and wind and I would imagine some snowfalls on northern hills / mountains at times and overnight frosts during the quieter interludes.

Edited November 4, 2019 by JON SNOW

[feb1991blizzard]

Last weeks EC46 was poor, lets hope for better luck tonight.

Mind you it could well be a prelude to an SSW.

Edited November 4, 2019 by feb1991blizzard

[tinybill]

lets  see  what  the pub run  come  up with later

[MATTWOLVES 3]

15 minutes ago, feb1991blizzard said:

Last weeks EC46 was poor, lets hope for better luck tonight.

Mind you it could well be a prelude to an SSW.

Last weeks EC46 may have been poor Feb!!! But the EC46 was poor for the whole of last winter... So much so... That I decided to save the money I was paying to view it!!! I've saved that much now... I can afford a skiing holiday in the alps!!! Joking aside... I feel there could be a big turnaround in the coming weeks from these long range models.... There is a lot of confusion and contradiction going on with some of them presently.... 

Edited November 4, 2019 by Mattwolves

[Ali1977]

10 days means from both the GFS then ECM below. ECM looks better with regards less PV, with heights north of Iceland, The GFS day 16 mean looked better than the GFS day 10 mean - so I’m punting if the ECM were to go to day 16 like the GFS, the ENS would be even more impressive in the NH!! Total punt of course!! 
In short - ECM looks great and no doubt some very blocked NHs  in the suite!!  

Edited November 4, 2019 by Ali1977

[Mike Poole]

FWIW the JMA probably the most likely to deliver a flake or two, or maybe more, here at T192:

Didn't know JMA did strat charts, but some forcing on the vortex as early as T192:

Very interesting to read @Tamara thoughts above.  Couple of thoughts, re the idea of lower AAM as per La Niña atmospheric setup, could the Indian Ocean Dipole as mentioned as a reason for the +NAO forecast in the MO contingency planners forecast, be contributing factor here?  A strongly positive IOD adds easterly winds at the equator, so seems to support.  (Usual caveat, I can't claim to fully understand this area so maybe barking up wrong tree!)

Second thought, like I was saying the other day when a new probabilistic model shows results that echoes the others, it doesn't actually change the probability of cold or mild, I think most of us now have factored in that there is a certain weight of evidence against a cold winter, Tamara's post backs that up.  

However, in my mind, weight must be given also to the arguments about what is seen here and now in models regarding both the trop and strat, and persistence of a -NAO regime, and the extreme solar minimum, which I believe the science is lacking a bit on.  If the coldies get nothing this year i.e a 2013/14, I will eat my pants.  But the fact that we're up against it, makes the jackpot sweeter when it lands!  Going to be great model watching as winter proper is now fast approaching...

Edited November 4, 2019 by Mike Poole

[Ali1977]

4 minutes ago, Mattwolves said:

Last weeks EC46 may have been poor Feb!!! But the EC46 was poor for the whole of last year... So much so... That I decided to save the money I was paying to view it!!! I've saved that much now... I can afford a skiing holiday in the alps!!! Joking aside... I feel there could be a big turnaround in the coming weeks from these long range models.... There is a lot of confusion and contradiction going on with some of them presently.... 

I’m hoping the JAMSTEC long range has it nailed, others to follow that!!

Edited November 4, 2019 by Ali1977