Model output discussion - The run up to Christmas

[bluearmy]

Well that different mid range trop evolution led to a bottom up split in the spv later in the run ...... I’m off to bed but I’m sure there are some clever people on here who will work out what was different hemispherically on the 18z to cause that .....

[northwestsnow]

18 minutes ago, Allseasons-si said:

If anyone says the gfs 18z is rubbish,....then they need to go to .....

 

Absolutely!!

A frigid run... think some folk think they live in Moscow!!

[sheikhy]

The mean and control are fantastic at 204 hours!!high sliding into greenland and cold with maybe snow showers over the uk!!

[Allseasons-Si]

3 minutes ago, bobbydog said:

This... says we have a very good chance of something to look forward to... 

We are starting to see the split again.

 

[Met4Cast]

1 minute ago, Griff said:

This is a huge shift in your outlook from only a few days ago, I suspect the Christmas sherry has come out early?  

In all seriousness, great commentary, thank you. 

My outlook a few days ago was about the Xmas>New Year period, always favoured the Atlantic high rather than the GH that GFS was suggesting at the time - I've been excited about January's prospects for a little while now, and that's growing exponentially now! 

[Matt H]

5 minutes ago, Met4Cast said:

Beautiful 18z mean. Low slowly filling to the east, air getting colder with snow growing more & more likely as time goes on. 

I wouldn't worry about the lack of GH, that's the GFS being the GFS. I am fully confident that we'll see a resurgence of height come early January with a GH far more supported by tele-connective signals.

GWO orbit is currently moving through phase 2, this supports the Atlantic high we're seeing in the xmas>new year period before cycling through into phase 3 later, supportive of a Greenland lock. 

At the same time we've got a strong +EAMT event taking place. Come January, I can't see anything but blocked conditions with growing support for true Greenland blocking, and that's before we even begin taking into account a possible SSW in early Jan. 

Starting cold, turning colder.. and possibly turning colder again. We are in a very, very good position.

 

Thank you, the posts from the experienced members really have been superb recently. Thank you so much everyone, I truly appreciate it!

[ICE COLD]

1 minute ago, bluearmy said:

Well that different mid range trop evolution led to a bottom up split in the spv later in the run ...... I’m off to bed but I’m sure there are some clever people on here who will work out what was different hemispherically on the 18z to cause that .....

Don’t close your eyes yet Nick . Tell us more . Talk bout leave us on a cliffhanger

[Downburst]

8 minutes ago, Griff said:

FI seems to be predispositioned towards the blocking signal, but I often wonder how much they trend back towards climatology and seasonal forecasts in later stages? 

Probably been debated here countless times. 

I can answer that, they don’t. Have you read up on it? Put simply the base state is the actual base state, the sea surface temps world wide, the landmass temps outside variance in ENSO and the like, which is one or two degrees at most, but that aside as I only mention it as it will get a reply, the average is the most likely to occur, not because the bias is entered as a bias, but because it exists.

[Allseasons-Si]

4 minutes ago, bluearmy said:

Well that different mid range trop evolution led to a bottom up split in the spv later in the run ...... I’m off to bed but I’m sure there are some clever people on here who will work out what was different hemispherically on the 18z to cause that .....

Do you have any charts to back that up

[northwestsnow]

3 minutes ago, Met4Cast said:

My outlook a few days ago was about the Xmas>New Year period, always favoured the Atlantic high rather than the GH that GFS was suggesting at the time - I've been excited about January's prospects for a little while now, and that's growing exponentially now! 

thanks for your grounded contributions on here, they are appreciated.

[Matt H]

Control looks like a stonker compared to the operational run out to t216 so hopefully things are still on track. Night all!

[bluearmy]

2 minutes ago, ICE COLD said:

Don’t close your eyes yet Nick . Tell us more . Talk bout leave us on a cliffhanger

There’s nothing to tell. The spv  on that run splits and it does do earlier the lower down you go. So it must be a trop wave that’s responsible.  Compare 12z and 18z in the T144/T216 period and see where the differences are re NH amplification and then you’ll work out what ps needed to cause a split high up. 

oh - slp is quite high on that run over much of the U.K. early on in the new year ........just saying ......

[bluearmy]

2 minutes ago, Allseasons-si said:

Do you have any charts to back that up

Instant weather maps would show you 

[blizzard81]

Just now, Frosty Winter said:

Control looks like a stonker compared to the operational run out to t216 so hopefully things are still on track. Night all!

Indeed. The control rescued itself. The op is crud in the long run. Lets see what the morning brings. 

[Howie]

I feel like the operational picked up a signal for less of a west based  -NAO and then absolutely ran with it and went overboard

[Griff]

Just now, blizzard81 said:

Indeed. The control rescued itself. The op is crud in the long run. Lets see what the morning brings. 

We're looking at fi just for fun, whilst keeping an eye on trends though, right?  

Good night all! 

 

[northwestsnow]

Just now, blizzard81 said:

Indeed. The control rescued itself. The op is crud in the long run. Lets see what the morning brings. 

 

Its not crud in the long run?

These are typical nighttime temps long run...unless sub zero is crud?

[danthetan]

2 hours ago, Updated_Weather said:

This was Matt Hugo reply to MetO suggesting that high pressure was more likely around new year.. 

I mean I get they have to be cautious but lie about something that isn’t there? 

It could be a holding pattern before more amplification thats my guess. 

[Met4Cast]

6 minutes ago, northwestsnow said:

thanks for your grounded contributions on here, they are appreciated.

That's kind, thank you. We genuinely are entering into an interesting period of weather full of potential, I'm sure we'll see a few surprises popping up next under an unstable low pressure system with increasingly cold air feeding into the mix.

January is a loaded gun..

[Weathizard]

No west based NAO here, don’t come too Far East though....

 

-6 mean over parts of the country also out to day 10

[Allseasons-Si]

The mean is slightly further east at 240 than the 12z which is a good sign plus slightly more height's over the top.

 

[blizzard81]

2 minutes ago, northwestsnow said:

 

Its not crud in the long run?

These are typical nighttime temps long run...unless sub zero is crud?

I should have clarified. Crud in a northern hemisphere synoptic sense. Just one operational though. Like I said, lets see what the morning offers. 

[Uncertainty]

7 minutes ago, Allseasons-si said:

Do you have any charts to back that up

Here you go fellas

GEPS going for the split...

Only 3 EPS members don’t reverse...

GFS op flips back to a split...

The seasonals are on the ropes...

[Uncertainty]

Btw

That would be a beautiful chart for any operational run in the winter...

But it’s the mean!

Aaand it had a wobble at the key time frame!

Surely the other big models don’t back it up...

Not so fast! Eps shows a mean Icelandic high too!

 

The best month of model watching since Feb 2018, can we top it?

Edited December 23, 2020 by Uncertainy

[Jason M]

At day 10 and 11 the GEFS are pretty damn good. Some real promise in there which is good to see as it will help me stay cheerful as I watch the cold rain and sleet run down the window 

Some places will see rain, some snow and frankly no one can be confident exactly who gets what at this stage. I stick though to my thoughts though which is SE & EA are least favored for snow. Kent, Essex, Suffolk & Norfolk will probably end up with a sleet mix. Away from the obvious places like Welsh Hills & Pennines, the higher ground of central / southern England might be a good place to be with only modest elevation.