Model output discussion - cold spell approaching?

[Cold Winter Night]

1 minute ago, IDO said:

The d8 gefs similar to the 06z with the main cluster mimicking the 06z op, a small cluster supports the op at the same time frame:

Hopefully it is not gfs randomness and we see this as a path forward in line with the 12z but atm it is not obvious?

Perhaps a small cluster that closely follows the Op, but there's a whole bunch of them that have the High more East than earlier today, so I'would say this is definitely in line with these 12Z upgrades.

The models must have eaten some good data today. Hopefully the ECM and its EPS shared that meal.

[IDO]

1 minute ago, Cold Winter Night said:

Perhaps a small cluster that closely follows the Op, but there's a whole bunch of them that have the High more East than earlier today, so I'would say this is definitely in line with these 12Z upgrades.

The models must have eaten some good data today. Hopefully the ECM and its EPS shared that meal.

Yes, it is certainly not a downgrade so positivity is the starting point. The control looks similar at d9:

That is always a good sign for me!

[Griff]

19 minutes ago, Griff said:

I'm wondering what the ECM will do next after latest gem, still rolling out. 

I'd say this might have some truth to it, and what might follow? 

 

14 minutes ago, Mike Poole said:

GEM is an absolute cracker, T222:

This model has shown some consistency in the run up to this, when the others have been all over the place, sure there have been the odd poor run, but it is possible that the model is really on to something too.

After the day I've had, this has lifted the spirits, fascinating stuff at the moment, what chance of a shift in the ECM? 

[Methuselah]

As much as love these T384 charts, there's always a bit of 'it's too good to be true' about them... Not that I wouldn't be jumping with joy, were they at T+12!

    

[Tim Bland]

Most have a chance of snow over the next few days and then there are plenty of juicy charts in FI...still very much in the game

[Chesil View]

Normal service is resumed on the GFS 12z . Gem has remained consistent throughout.

[Mike Poole]

2 minutes ago, Griff said:

 

After the day I've had, this has lifted the spirits, fascinating stuff at the moment, what chance of a shift in the ECM? 

One things for sure, we will be glued to it after 6pm!  Prime time model viewing!  Reckon this mornings runs were an aberation.  It can happen when there’s lots of uncertainty - chance of 6 or so models show the bad end of the uncertainty envelope on the same run?  1/64. We view them twice a day, so you’d expect it to happen about once a month.  

[swfc]

41 minutes ago, Griff said:

My eldest cat was put to sleep earlier, the model outlook went the same way over night, so given this is the model thread, I'm unashamedly loving this FI. Moaners to the other thread or regionals please. 

Sorry man, big loss int it

[Matt H]

An improved set of GEFS 12z ensembles this evening as the colder theme beyond the 21st is re-established with less scatter than the 06z suite.

[Tim Bland]

2 minutes ago, Frosty Winter said:

An improved set of GEFS 12z ensembles this evening as the colder theme beyond the 21st is re-established with less scatter than the 06z suite.

Massive improvement compared to the 06z set! (Below)  Looks like the ensembles are as fickle as the ops at the moment though! 

[Met4Cast]

6 minutes ago, Frosty Winter said:

An improved set of GEFS 12z ensembles this evening as the colder theme beyond the 21st is re-established with less scatter than the 06z suite.

Highlighting why it's important not to throw in the town and start screaming "winter is over" on the back of a couple of poorer runs. A marked improvement there with a much greater clustering towards colder solutions. 

Not that it means anything at that range, if an entire suite can be flip flopping as much as we're currently seeing there's not much point putting weight into them for either solution. 

To make things worse, models will now have to begin resolving a splitting lower SPV vortex, I'd expect things to get worse before they get better! 

[Hotspur62]

1 hour ago, Griff said:

Just for fun, this would be of no interest? 

And that is proof of how volatile and quickly things can change in a short space of time (hypothetically speaking of course)!

[Catacol]

23 minutes ago, Ali1977 said:

Yep, can’t beat chasing medium to FI charts!! Who needs ones that verify !!

Plenty of background signals pointing to a cold spell, I’m just enjoying the ride!! 

 

This is the way to try and be. I’m just back from work, and not had time to see if this image from Simon Lee has been posted elsewhere....but there isn’t much more we can hope for from broad seasonal trends than this. Assuming all these models can’t be wrong () at such short notice then we have 2 out of 3 months of winter with a -NAO, impacted by a SSW and setup for cold.

The only thing we need now is a bit of luck, and with a lot of luck we could yet cash in long term. Given what the seasonals offered us pre-winter no one here with a snowy persuasion should be unhappy. If we don’t land at least one decent widespread snow event from the hemisphere as it has developed since Xmas and looks likely to develop for the next 6 weeks or so we will be extremely unfortunate.

Bad luck happens of course. The U.K. gets plenty of it in winter it seems to me. Can such bad luck hold for the rest of January and February?

[Frosty.]

4 hours ago, Jon Snow said:

 i think there continues to be plenty of wintry / wintery potential during the next few weeks...so, I’m not giving up on snowy nirvana visiting our little island in the not too distant future!!

And, as if by magic the Gfs 12z operational shows just that!...keep the faith

[Purga]

LOL - down we go again

It's still very much in the balance, as it has been for days now: the MetOffice long ranger has given strong hints that the dividing line between mild and cold was likely to be somewhere over the country with the north colder and the south probably milder, with scope for significant snowfall in the transition zone.  The charts, for me, are just playing variations on that tune.

Plus, and importantly, the effects of the 1st wind reversal in the stratosphere are still playing out and the second SSW pulse hasn't happened yet.

The charts are still hinting at snowfall, starting tomorrow and at various points in the next week to ten days.

Trends in the models can change; trends in the ensembles change - as we all know.  Ensembles aren't a crystal ball: they do no more than test the stability of the model output; they cannot tell us what hasn't yet happened in the atmosphere. 

Keep the faith

 

[BLAST FROM THE PAST]

9 hours ago, BLAST FROM THE PAST said:

Certainly a change in how models are now projecting the way forward. All this the following morning or 2 when tweets from professionals get on board of an imminent PV split, v cold for NW Europe and UK etc etc.  So on that basis is it ‘just typical’ that the promised land of proper cold spell is getting taken away from us?  Or is this a model jitter to what’s happening with the PV of a split rather than displacement?.  And if it’s a jitter is the response going to head us away from deep cold or will they start adjusting to where they were showing nirvana a couple of days back.  

I know what’s on my mind...and usually the safer bet is the way to go

 

BFTP

 

So were we seeing ‘noise’ on the 00z?  I think we still have to wait and see as inter runs are a tad volatile now.

 

This afternoon first I looked at UKMO 12z and thought...that’s looking like heading into very cold territory.  Then GFS is sending us back into the freezer.  If, and it’s if, the developments we get  show as they are now up to t144 on 12zs then imo we are well in the game for a freeze...not so if it’s the 00z route.  

 

BFTP

Edited January 13, 2021 by BLAST FROM THE PAST

[snowking]

Firstly @Griff sorry to hear that and I hope the ECMWF has a little something in it to help cheer you up.

 

Onto less important things (and I think it is worth everyone keeping that in mind in the context of the wider world right now, it's just a bit of weather!) - if you remember back to my post from yesterday (which referenced posts from before then - meta or narcissistic, you decide), there's a reason I had referenced the 15th as a check in date for hopefully clearer resolution of the medium term prognosis. This is the day, and has been roughly forecast to be the day for some time now, that the split in the stratospheric vortex reaches it's highest point, at around 5mb:

And just to demonstrate this occurs all the way from the bottom up to this point, here's 70mb:

@bluearmy referenced this earlier too. I suspect modelling is chopping and changing as it tries to cope with the very complex dynamics brought about by this split. As Nick said, the expectation would be that around this time, LP would be struggling to move past the longitude of the split - in this instance this lines up quite nicely with the meridian. Don't be surprised to see further swings back and forth until this split is within the initialisation data at all levels the split is going to occur at.

The next watch date is then the 18th as everything tries to come back together - again expect some volatility between 15-18th as this occurs (though hopefully at least having the initial split into the initialisation data by this point should help with the volatility somewhat) as this occurs, shown below for those who prefer their picture books 

Admittedly these charts are now 24 hours out of date, so I could well be left with a lot of egg on my face in an hours time, but the progression from there onwards looks pretty favourable for us for keeping any westerly momentum away from the Atlantic, higher heights to our N and NW, and hopefully allowing colder air from Asia/Siberia to slowly trickle down towards us:

The point here is the trough should track slowly Eastwards over time, and the hope is it does so far enough East in the first place to allow us to sit on the colder side of the trough.

Unless things drastically change stratopsherically, it would be very surprising for us to end up tropospherically with anything that doesn't include higher heights to the N and NW, and a mean trough over us or to the East.

That's not to say it can't happen - something like tropical interference could interfere with that into the medium term, but without any other extraneous influences, be very suspicious of any runs dramatically lowering heights to our North/West

[Allseasons-Si]

@Griff,sorry to hear of your loss mate,you have my purest sympathy

as for the gfs,..what a run and here it is in motion.

500's/850's and iso/dam

certainly nothing marginal about this with -8's>-10 uppers and a dam of 510 in some places.

WE AWAIT THE ECM!!! to see if there is any more meat on the bones...

 

[Radiating Dendrite]

@Griff sorry to hear that! I'm sure she had a brilliant life with you and is up there trying to avoid going out in the snow!

[BLAST FROM THE PAST]

Here’s a punt.  ECM t72 0z

 

t96 12z ....post in a second but I think a sharper rigdge to west and more of a diving trough to our north...

 

BFTP

Edited January 13, 2021 by BLAST FROM THE PAST

[Tim Bland]

WOW talk about a shift south!! ECM has snow much further south at breakfast time and it’s cleared all by lunchtime ?! 

Edited January 13, 2021 by Tim Bland

[MKN]

1 minute ago, Vikos said:

Can someone explain me the actual mood here? Can't read 10+ pages now...

Yeah or Nai?

GFS is fine in its global patterns...

In summary im not even sure whats going to fall from the sky tomorrow (rain or snow) and that sums up everything the models are showing right now. Lots of uncertainty however there is a reasonable chance for spells of snow at various stages in the next two weeks. 

[Mucka]

Lots of talk about UKMO improvements but that is a very delicate balancing act having the phasing on W side of the ridge and hoping for enough undercut for the pattern to reamplify.

Most of the energy is not undercutting at 144 and next low is already phasing with the trough W of the ridge so IMO you would get energy going over the top and the pattern flattening.

That pattern 500 miles further W would be much better though.

Amazing how the models find another way to scupper blocking if they resolve another issue.

Let's just hope that low can stay cut off because the phasing either way puts us on a knife edge hence the mixed signals.

ECM 96 has it further N than GFS 12z but also further W so one cross, one tick, a coin toss and prayer.

[EML Network]

39 minutes ago, Purga said:

LOL - down we go again

It's still very much in the balance, as it has been for days now: the MetOffice long ranger has given strong hints that the dividing line between mild and cold was likely to be somewhere over the country with the north colder and the south probably milder, with scope for significant snowfall in the transition zone.  The charts, for me, are just playing variations on that tune.

Plus, and importantly, the effects of the 1st wind reversal in the stratosphere are still playing out and the second SSW pulse hasn't happened yet.

The charts are still hinting at snowfall, starting tomorrow and at various points in the next week to ten days.

Trends in the models can change; trends in the ensembles change - as we all know.  Ensembles aren't a crystal ball: they do no more than test the stability of the model output; they cannot tell us what hasn't yet happened in the atmosphere. 

Keep the faith

 

Well said. I had to laugh when I saw the 12z GFS Op run today and I really feel for all the relative newbies on here, the last few weeks output really has been a game of cat and mouse, I can imagine there a tonnes of cold and snow fans literally banging their heads against the wall, tearing out hair, crying into their coffee and jumping out and down with jubilation all at some point this week alone. 

On Monday we were hearing shouts of ''A cold spell is nailed'' followed yesterday and this morning by ''Ohh well there's always Feb'' and now it seems the were somewhere in between...the likely outcome ??? ...as per usual in the UK when we get a cold spell with a hint of Atlantic....is somewhere in between. 

It's always been the case of when we are looking at a cold spell with an Atlantic influence then a large amount of luck is indeed needed to see any meaningfull amounts of snow falling from the sky, especially so in the south. 

Uppers generally tend to get mixed out as pressure systems fill and stall becoming slow moving as it pushes against a block, when there is one.

from my years of model watching I only get excited when a true beast from the east is practically on our doorstep and even then as was the case recently it's not a guarantee. 

UKMO doesn't appear to me that it has any interest in producing a cold spell the +144 chart, all i'm seeing there is a conveyer belt of High pressure

to our south and low pressure systems barrelling through the country across the top of it.

 


No doubt there will be many more twists and turns in the days and weeks ahead and here's hoping you all get to see some snowfall over the next few weeks and months.

Edited January 13, 2021 by EML Network

[Griff]

Ecm 120 vs gem

Edit: probably too similar to gfsp for my liking 

Edited January 13, 2021 by Griff