Model output discussion 24/01/21

[Methuselah]

Looks as if maybe our first blow might be our 'appetiser'? Awaits the real deal, straight out of the northeast!

    

[Griff]

Does it? Can it? 

[MJB]

DEEP DEEP DEEP into FI

Have to also remember just how different the 0z and 6z were , its a variation of the cold theme from the East 

[TSNWK]

Dear Meteocile please stop GFS 12z - we like UKMO and would now like to move onto Para.

GFS is welcome this evening for a drink if it behaves

[Griff]

Back to gem, a lot going on, Atlantic might spoil? 

[Matt Jones]

Cold and snow is by no means a certainty here, this 12Z GFS just shows there are many options on the table later next week between more cold rain and very cold snowy weather from the east or NE. Still a long way to go and many more changes, fine lines here are going to make a big difference. Don't like the latest GFS run, UKMO good but no certainty it will maintain a cold snowy outlook post 144hrs. 288hrs and GFS puts us back where we started cold rain.

Edited January 29, 2021 by Matt Jones

[chris55]

Arome for tomorrow lunchtime. 

[Froze were the Days]

5 minutes ago, MJB said:

Snow piling in

I wouldn't trust those GFS precip type charts...not great 850 uppers towards the south coast/south east (barely gets below -5c)

[snowking]

Many reasons to be suspicious of this GFS 12z run. If we compare the Z500 anomalies to that of it's own 6z suite and the 0z EPS:

Note entirely outside of the envelope, but different enough with the angle of the troughing to make it suspcious.

Of course if we want an even easier way of seeing why it should be treated with caution, we can just compare it at the same time synoptically to its previous run:

A vast enough difference that I think it's wise for us to question the validity anything beyond Day 6 at the moment.

[Allseasons-Si]

The GEM is trying something else at prob amplifying another ridge upto Greenland at 186

the gfs was toying with this the other day sending a shortwave in the mix from S Greenland.

 

 

[BLAST FROM THE PAST]

Anyone else thinking we’re gonna get a relatively poor 12z set?...apart from UKMO which is very nice at t144

 

BFTP

[Snipper]

Are many actually considering the possible downgrades or should I warn the Samaritans?

[feb1991blizzard]

Just now, snowking said:

Many reasons to be suspicious of this GFS 12z run. If we compare the Z500 anomalies to that of it's own 6z suite and the 0z EPS:

Note entirely outside of the envelope, but different enough with the angle of the troughing to make it suspcious.

Of course if we want an even easier way of seeing why it should be treated with caution, we can just compare it at the same time synoptically to its previous run:

A vast enough difference that I think it's wise for us to question the validity anything beyond Day 6 at the moment.

Yes, use the ensemble means products at D10, its never going to get the pattern bang on of course when its averaged out randomness up to a point, but while it wont get the shortwave pattern correct it might give you an idea about where the ridge will setup.

[Griff]

2 minutes ago, Allseasons-si said:

The GEM is trying something else at prob amplifying another ridge upto Greenland at 186

the gfs was toying with this the other day sending a shortwave in the mix from S Greenland.

 

 

Does it open the door? 

To be fair it was cold on this run prior to this but what happens next? 

Edited January 29, 2021 by Griff

[TheJCInsights]

So, if there's anything I have learnt from reading the posts here over the years and never being brave enough to post, is that the GFS often blows up lows out of nowhere once you get into FI.

Surely the big low forming at +240 isn't likely and is just another classic GFS explosion?

Fantastic model watching!

[Anthony Burden]

 Charts continue to try and work out details for a week or so time,perhaps not so 

keen on Scandinavian high.Will of course look at ECM later,but feel nothing resolved 

untill weekend ie Sunday 12 z charts should give a more general idea.

[Snowman.]

Can we get the cold spell in first before we start talking about the break down please? 

We have these discussions every time a cold spell is shown, the models always try to break them down far too quickly and it ends up persisting much longer. Even are feeble attempt at an easterly new years time lasted 2 days longer than it was originally shown.

We know models struggle with trough disruption against weak heights, we've seen it a lot these part few days of models trying to figure it out. So if we add trough disruption to the GFS chart below we're suddenly looking at a very decent chart.

Shades of Jan 2013. 

GFS  vs actual chart 

[nick sussex]

I think to be blunt this is quite a downgrade from the 06 hrs run and this all stems from the day 6 and 7 output.

The disruption of energy is too south and not se . You need low pressure in northern Italy as this funnels a wider pool of colder air sw wards , it also impacts the longer term in sustaining the block in a favourable position for any Atlantic attack .

After a weekend at the Ritz we’re now back to the Premier Inn. The UKMO is equally uninspiring .

Hopefully the ECM can repair some of the damage . 

[Methuselah]

3 minutes ago, snowking said:

Many reasons to be suspicious of this GFS 12z run. If we compare the Z500 anomalies to that of it's own 6z suite and the 0z EPS:

Note entirely outside of the envelope, but different enough with the angle of the troughing to make it suspcious.

Of course if we want an even easier way of seeing why it should be treated with caution, we can just compare it at the same time synoptically to its previous run:

A vast enough difference that I think it's wise for us to question the validity anything beyond Day 6 at the moment.

I'm always suspicious, Kris... but, anywho, there'll be a lot of nervous teddies by the time the 18Zs roll out!

    

[Allseasons-Si]

8 minutes ago, Griff said:

Does it open the door? 

Yes,the door has opened up nicely,but a long way off and there is too many scenarios to pinpoint what is going to happen,lets get the trough digging further SE from 120 and go on from there.

 

Edited January 29, 2021 by Allseasons-si

[Griff]

Gem 240 says Hmmm not game over but come back later? 

Definitely poorer

[East_England_Stormchaser91]

GFS 12z I would be more than happy with. 

What I’m liking about this, is that it is teetering on the edge of the more reliable time frame, and possible small snow events before the main course a week later. 

The steps are certainly still heading in the right direction! Hopefully Lake effect type snow before February is out at least! 

[Griff]

Just now, Allseasons-si said:

Yes,she's opened up nicely

 

I'm genuinely stumped, does it go mild or very cold? 

[Cold Winter Night]

6 minutes ago, snowking said:

Many reasons to be suspicious of this GFS 12z run. If we compare the Z500 anomalies to that of it's own 6z suite and the 0z EPS:

Note entirely outside of the envelope, but different enough with the angle of the troughing to make it suspcious.

Of course if we want an even easier way of seeing why it should be treated with caution, we can just compare it at the same time synoptically to its previous run:

A vast enough difference that I think it's wise for us to question the validity anything beyond Day 6 at the moment.

Exactly. There is still a huge spread post day 6 and perhaps these successive GFS 6z - 12z runs help to show both ends of the envelope.

We'll have to await the GEFS anyway, perhaps this is just an outlier in an improved ensemble.

[MJB]

3 minutes ago, nick sussex said:

I think to be blunt this is quite a downgrade from the 06 hrs run and this all stems from the day 6 and 7 output.

The disruption of energy is too south and not se . You need low pressure in northern Italy as this funnels a wider pool of colder air sw wards , it also impacts the longer term in sustaining the block in a favourable position for any Atlantic attack .

After a weekend at the Ritz we’re now back to the Premier Inn. The UKMO is equally uninspiring .

Hopefully the ECM can repair some of the damage . 

Just to clarify when you say downgrade you are talking about the OP .

No one can make any judgement until the ENS are out .

Take the Control , there is more in the way of cold over the UK at this point than on the 6z , so is that an upgrade ?