Model output discussion - 1st December onwards

[Ali1977]

Just forget about the "bin it" and see what the next run says....Nit picking at posts is why people like Tamara left the forum, let's hope Ian F is still about!!

[Mair Snaw]

1 minute ago, *Sub*Zero* said:

Suppose the person who said 'bin it' saw where the run was going and they don't really like cold weather, so that would maybe explain why they said it? You have to look at both sides of the coin, although I think Iceaxecrampon does like cold weather and was merely saying 'bin it' as that particular chart posted was showing a long draw southerly from Spain. 

so maybe an explanation as to why it should be put in the bin might of helped... im not trying to have a pop at anybody but you can see how confusing them 2 post could be for a newer member...... anyway lets move on to the up coming pub run....

[Polar Maritime]

Lets get back to discussing the models at hand please.

Im sure we will see many more wild swings in the charts out in the extended period over the next few days,  Enjoyable model watching for the Christmas period.

[Mair Snaw]

5 minutes ago, Ali1977 said:

Just forget about the "bin it" and see what the next run says....Nit picking at posts is why people like Tamara left the forum, let's hope Ian F is still about!!

im not  Nit picking just stating that this thread is not helped by one post saying Bin the run then the very next saying Epic cold for the exact same chart.... if me questioning a post is a problem for others then maybe its time i left the forum as well..... i only asked a simple question about 2 confusing posts...

 

[Polar Maritime]

Right, Thats that then.. Lets please move on in a friendly manner thanks.

Edited December 20, 2015 by Polar Maritime

[cornish snow]

8 minutes ago, Ali1977 said:

Just forget about the "bin it" and see what the next run says....Nit picking at posts is why people like Tamara left the forum, let's hope Ian F is still about!!

Agreed.LOL, this forum is priceless.2 hours from now it will be all change again. 

The 384hr chart is epic,would love to see it happen,but it's chip paper unfortunately.

[Iceaxecrampon]

Bit of clarification.

Wasn't "binning" the whole model run just the sudden absurdity of the LP at T+231.

Hopefully it wont materialise.

[mulzy]

While we await the 18z GFS, the ECM De Bilt ensembles shows that the 12z operational was among the more progressive runs.

http://projects.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=12

However, the cluster of cold runs has diminished from the 00z set.

Edited December 20, 2015 by mulzy

[Weather Observer]

I have always been interested in weather and l like to think I have a feel for what the charts are suggesting without knowing where the weather is actually going. The charts do not suggest a cold spell  anyday soon. I can remember cold spells developing between Christmas and year end  in average Decembers but I cannot recall any early relief from the unrelenting warm south- westerly pattern that we appear locked into now. I think patience will be needed.

 

 

[Methuselah]

Welcome to Netweather, Weathervane...Always remember this: we all get a tad over-excited from time-to-time.

[SMU]

Evening All

So the ECM ensembles are in & paint the picture that the operational ( & Annoyingly the control ) were fairly significant outliers for Debilt ( to the tune of around 6c in the latter stages ) - The 12Z ECM has had a reputation before to be very over progressive so its certainly not over yet-

Infact, being here over the last 10 years has seen this type of scenario modelled countless times - A high ridging North through the UK aligning Northwards & heading the core towards Western Norway - with a deep upper air cold pool dropping into Central / Northern Europe- & the hope it aligns westwards towards the UK-

At this stage its important to point out with 100% confidence that despite all the computing power we have or the past / present climatic & stratospheric data we have - no one can forecast whats actually going to become of the prediction at day 10- will it be a scandi High or will it be a flatter Euro / Sceuro High - the background signals aren't great with a beast of a northern jet this year- but sudden change unaided by the stratosphere is virtually impossible to forecast.

There of course have been some spectacular fails in the last 10 years, one day going to bed seeing the -15c isotherm over the UK at t120 to find it stuck over Germany the next evening at T96, also those Bitter Easterlies slowly morphing to dry Chilly South Easterlies has been a repeat offender over the years-

However less we forget the stunning model accuracy of December 2010, to the 2 week Easterlies of 2005 & the snow wipeout for the south / East in 2009 , so mixed in with the Epic fails have been some success....

Statistically you would hope at best we would be 50/50 on verification - however its more like 80/20 fail rate - even that could be generous....

So here we go again for another battle of the models for accuracy, one tip to look for if we are going to get a High pressure in the right locale is the alignment of the first bout of Vertical advection heading North from the UK-

We need 0 degrees - to really a max of 15 degrees positive , ( remember the landing zone needs to be West coast of Norway - so past 20 degrees we have missed the boat- also a bit of negative tilt is ok, up to 15/20 degrees the other way is fine....)

The GEM was a peach in this stakes

http://modeles.meteociel.fr/modeles/gem/runs/2015122012/gemnh-0-198.png?12

So if we are going to get this Winter off the ground this projection of a significant wave 1 profile attacking the vortex needs to deliver ( in a big way ) to start the domino effect down the line For January-

If we miss the boat here & get to day 10 building another big Euro block we could be 6 weeks down of winter before think about the next possible pattern change.....- lets hope so

 

S

Edited December 20, 2015 by THE CHOSEN ONE

[Methuselah]

I've always thought it was the GFS that was 'over progressive', Steve. And also, shouldn't we recall the ECM's disasters (all the models have them)...December 2012 was perhaps the finest example?

[chionomaniac]

The only saving grace may be that if we gat a Scandi high - and the EPS do still back this days 11-15 (though drifting eastwards), is, that combined with the N Pacific profile then we see a strong classic precursor profile for an SSW 20 days after that.

 

Garfinkel paper http://www.eps.jhu.edu/~cig4/GHetal10.pdf

Edited December 20, 2015 by chionomaniac

[peborant]

48 minutes ago, Ali1977 said:

Just forget about the "bin it" and see what the next run says....

That is, I am afraid, the thrill and the punishment of being a weather aficionado, especially if you're a coldie in the Northern Hemisphere's Mi(l)d Atlantic Gap. This geographical area I just made up would encomprise from Gibraltar to southern bits of Scandinavia all the way into the border of Germany and Poland, probably a tad further east. Areas that, due to ocean modification, are less prone to any sustained periods with lying snow on the ground according to data from NOAA, the number of days of snow falling and settling decreasing the closer you are to the Atlantic. 

Therefore we cannot expect big cold set-ups every year as we do happen to be in a mild part of the world, thanks to the ration of raging lows we endure every other day in the British Isles, i.e. being on the Jet Stream's pathway. It's not easy -maybe these days?- for it to move further down into southern France / northern Iberia / Italy / Balcans, which is what we really do need for cold to establish itself over central and northern Europe. 

It now looks as this might just happen but I am sure 18z-06z will slightly modify the outcome as these things always go, but it is undeniable that the trend has been there on the past few runs and it is worth keeping a -keen!- eye on it. Worst comes to worst here we will always scrap some snaw on top o'the hill off some rancid westerly! But oh boy wouldn't be a -15 or less be nice? 

Easterlies can be epic and this year might be one to watch out for them to be directed towards us as that Anticyclone is misbehaving so much. It clearly wants to stay and develop badly wherever it chooses to go as it already has done in Italy and Iberia and now it looks as it could be headed to more favourable parts for us in terms of cold, i.e. Scandinavia. 

We will certainly see what happens. 

Edited December 20, 2015 by peborant

[SMU]

5 minutes ago, Ed Stone said:

I've always thought it was the GFS that was 'over progressive', Steve. And also, shouldn't we recall the ECM's disasters (all the models have them)...December 2012 was perhaps the finest example?

yep it usually is as well-

But I remember the 2010 secondary cold spell & a more recent one where the ECM 12z just went very progressive- only to revert to the right solution back on the 00z...

 

S

[Methuselah]

1 minute ago, THE CHOSEN ONE said:

yep it usually is as well-

But I remember the 2010 secondary cold spell & a more recent one where the ECM 12z just went very progressive- only to revert to the right solution back on the 00z...

 

S

Just a quick question, Steve: if the models are indeed 'over progressive', how come it's so very often the 'stellar runs' that fail to materialize, whilst those predicting mild mush usually come to fruition? And I love snow as much as anyone here!

[SMU]

6 minutes ago, Ed Stone said:

Just a quick question, Steve: if the models are indeed 'over progressive', how come it's so very often the 'stellar runs' that fail to materialize, whilst those predicting mild mush usually come to fruition? And I love snow as much as anyone here!

 

well I suppose you have a point there-  I guess for clarity, all the decent cold spells that have actually landed more often than not the models have been over progressive with the atlantic jet to start with -( so as we get closer towards T0 be get a better ridge in Scandi ) & of course the always brush the scandi high aside far to quickly-

so If you are coming from a position of - this modelling scenario is 100% going to end in a cold spell then the models do appear to be progressive, however maybe we could take the more realistic approach ( seeing as we fail more often that not ) & assume the models are not being progressive enough .... then wait for the inevitable failure......

depends if your glass is half full or empty !

S

PS the 18z has alignment over the UK at 168 of about 5 degrees- so that fits in the box of should be successful....

Edited December 20, 2015 by THE CHOSEN ONE

[NorthernRab]

Being incredibly IMBY here, but wintry conditions certainly look a possibility for the Big Day here in Scotland based on tonight's ECM and GFS. The tracking of that small stormy feature could lead to some surprising Christmas snowfall for some although it's looking quite mild for those in the south. The slight shifts between the 12z and 18z runs shows that there could be some surprises.

Boxing Day looks particularly interesting as cold air digging south clashes with moist warmer air.

Edited December 20, 2015 by NorthernRab

[Methuselah]

I agree with much of that. Come to think of it, most of the cold spells that occurred when I was a nipper (late 1880s) did take the forecasters rather by surprise...So, when it does take a turn for the better, it often takes us all by surprise...

[Nick F]

Not sure why some are resigned to the 12z EC det. being the way forward now, after all,  the EPS mean still has a stinking ridge north through Scandi = a lot more amplification than the det.

12z GEFS AO and NAO graph has the mean trending neutral or negative in early Jan.

When we start seeing these big swings in the medium range, don't immediately assume the poorer evolution will be the done deal, rather it could be the sign of a pattern change and the model high res runs overcompensating in different directions with each run.

Not saying that 12z EC isn't correct, rather that it is too early to jump to conclusions.

Edited December 20, 2015 by Nick F

[SMU]

 

Well that's about as vertical as it gets ( think 2010 west of Greenland tip )

That should be a slam dunk easterly.......

[Captain Shortwave]

In the near term we still remain mild, but maybe just a straw clutch in terms of the big day.

We see a cold front clear east during Christmas eve with a clear night for many, so we might get a frost in favoured spots. Even in the south.

The pressure build from Christmas day onwards to me looks to be a rather long path to a proper cold spell as we would need to see changes occur hemispherically which wouldn't result in the jet stream blowing the high away in the meantime.

The axis on the trough does not look as good on the 18z compared to the 12z at least.

Though it does improve later on

So a mild end to the year on this run with winds between the south and south west, this could offer some drier and brighter weather if we can pull in some drier air (albeit still on the mild side).

The two most likely outcomes again are the mild south to south west flow with rain in the north and west or a continental flow with the high closer to the UK after Christmas. I would probably put a proper cold Scandi high at around 5% chance (10% if I am visited by 3 ghosts during the night :P). But heck it is more likely than a northerly....

I guess as a start, the ECM ens do start to develop low heights over the eastern Med in association with the plunge of cold air through  western Russia during the period between Christmas and New Year.

We really need to see this progress westwards without seeing the high slide away east at the same time. GEFs never really develop this as of yet. A lot of work needed yet but at least there are some signs that we could see something more wintry as opposed to the scraps in the north and damn naff all down south.

Edited December 20, 2015 by Captain Shortwave

[feb1991blizzard]

Beautifully aligned ridge slicing through the PV on the 18z.

[feb1991blizzard]

We need that shortwave just being ejected to dig SE as far as possible.

[Ali1977]

Those alpine resorts will be hoping by New Year winter may arrive looking at the GFS!! They need the change in set up  desperately !!