Model Output Discussion - Into the new year

[Tim Bland]

GFS looks further north than 12z...

[AWD]

I'm not one for taking PPN charts seriously, so just for fun, the GFS 18z puts the West Country right in the firing line Wednesday evening;

[Harsh Climate]

18z now has central southern England and Kent in sweetspot Wednesday now, impossible to nail down anytime soon lol

Edited December 28, 2020 by Harsh Climate

[Mark Neal.]

GFS 18z for what its worth is further north than its recents runs.. but not as north as the ECM.

 

 

[snowice]

1 minute ago, AWD said:

I'm not one for taking PPN charts seriously, so just for fun, the GFS 18z puts the West Country right in the firing line Wednesday evening;

Very like icon

[kold weather]

The 18z GFS is pretty close to bang on the mean position of most of the models. Good to see both the GFS and ICON shift a little northwards though to come more inline with what the ECM has been showing today.

Will have to see what the other runs do down the line with it tonight. Should they show broadly the same on the 00z run then confidence will increase in a snow event for Wales and southern half of England, though where the northern extent is remains to be seen.

The good news is it looks like an evening/overnight event, which will help tip it towards being less marginal and better chance of settling.

[Jarrow Posh]

A lot is being made of the possible snow in the south on Weds night into Thursday but my eyes couldn't help but notice the larger area of precipitation moving in off the North Sea and covering a large swathe of Northern England shown here on the ICON 18z.

[Matt H]

Just now, Jarrow Posh said:

A lot is being made of the possible snow in the south on Weds night into Thursday but my eyes couldn't help but notice the larger area of precipitation moving in off the North Sea and covering a large swathe of Northern England shown here on the ICON 18z.

I think that’s the IMBY perspective working its magic to be honest, especially for me at least.

[JamesL]

Seems many of the models put south and SE Wales in the firing line on Wednesday. Looks like the Heads of the Valleys could be esp prone 

[kold weather]

3 minutes ago, Jarrow Posh said:

A lot is being made of the possible snow in the south on Weds night into Thursday but my eyes couldn't help but notice the larger area of precipitation moving in off the North Sea and covering a large swathe of Northern England shown here on the ICON 18z.

Yep also being shown on the 18z GFS as well:

It'll probably usher in some more marginal air behind it however based on what I can see.

Still definitely a decent shot at snow in the north from this feature, though way too early to tell of track and maybe partly dependent on the LP that swings across the south first.

Both suggest 5-10cms possibly for some areas in the north, less as it comes further SW and gets more marginal.

Edited December 28, 2020 by kold weather

[Man With Beard]

Quick look at individual ECM ensembles for D10

Number of ensembles that go zonal = 1 out of 51

Number of ensembles likely to prolong the cold = Most of them 

Number of ensembles likely to produce a snow event at D10 or shortly before/after = Plenty 

Number of ensembles that might end the cold by stalling to the SW = A few, maybe 6 out of 51?

So the signal remains very much to prolong cold well into week 2

[Tim Bland]

GEM is probably half way house between ECM and the models like Euro 4 / UKV.  GFS only gives about 3cm in the far south. ECM had 17cm. 

[BLAST FROM THE PAST]

This is why WIB (Richard) shouldn’t be vilified....he knows his stuff. 
 

That is close to a sinker

But look at the sharpening of the trough to the SW of this high...it suggests propping and retrograde 

 

 

BFTP 

Edited December 28, 2020 by BLAST FROM THE PAST

[Allseasons-Si]

7 minutes ago, Man With Beard said:

Quick look at individual ECM ensembles for D10

Number of ensembles that go zonal = 1 out of 51

Number of ensembles likely to prolong the cold = Most of them 

Number of ensembles likely to produce a snow event at D10 or shortly before/after = Plenty 

Number of ensembles that might end the cold by stalling to the SW = A few, maybe 6 out of 51?

So the signal remains very much to prolong cold well into week 2

Trendsetter,...SORRY couldn't resist...

...but a fab summery

Edited December 28, 2020 by Allseasons-si
typo

[Griff]

Sorry to disturb, steady as she goes... 

[Man With Beard]

Wednesday feels a very long way off, but plenty to keep an eye on just in the next 24 hours! Widespread dusting of snow across much of England by midnight tomorrow according to latest ARPEGE

[snowice]

4 minutes ago, BLAST FROM THE PAST said:

This is why WIB (Richard) shouldn’t be vilified....he knows his stuff. 
 

That is close to a sinker

bear with me

 

 

24hours later it heads north west so it's not going to topple.

Edited December 28, 2020 by snowice

[Allseasons-Si]

6 minutes ago, BLAST FROM THE PAST said:

This is why WIB (Richard) shouldn’t be vilified....he knows his stuff. 
 

That is close to a sinker

bear with me

 

 

That is not sinking BFTP

 

Edited December 28, 2020 by Allseasons-si

[Captain Shortwave]

So trends today, well perhaps gaining soe momentum on the possible trajectory once the low heights over or just east of the UK begin to sink deeper into Europe.

ECM day 6 vs GFS

         

Similar ideas, just slight differences in regards to how the ridging pans out. Essentially we have an Atlantic ridge and also heights over Russia. The trough over us should fill and allow winds to back more towards the east. However differences occur in regards to whether that are of lower heights becomes fully cut off. Anyway the retrograde signal remains strong and the area of weakness where low heights could move south out of the arctic is likely to be towards Scandinavia, especially if the Atlantic high is allow to re-amplify and move further north.

In the shorter term, there are a sizable number of potential events that are cropping up now. Not only the system mentioned previously that could affect more south western areas, but also some troughs or occlusions that run in off the north sea.

 

Edited December 28, 2020 by Captain Shortwave

[Matt H]

5 minutes ago, BLAST FROM THE PAST said:

This is why WIB (Richard) shouldn’t be vilified....he knows his stuff. 
 

That is close to a sinker

bear with me

 

 

Are you watching the run upside down? 

[Mark Neal.]

10 minutes ago, Man With Beard said:

Wednesday feels a very long way off, but plenty to keep an eye on just in the next 24 hours! Widespread dusting of snow across much of England by midnight tomorrow according to latest ARPEGE

Yep makes more of the low pressure in the NW, moving through Wales and into SW before clearing Central Southern parts.  You also have a secondary feature which moves down from the NE, from the North Sea. Weakening as it heads south. 

Edited December 28, 2020 by Mark Neal.
Added Gif

[kold weather]

I think what BFTP is trying to say is that in many a normal situation that set-up would indeed topple, but that with the set-up sloft as it is its going to retrograde to some extent up towards Iceland/Greenland.

This run is a little colder aloft due to more of a high pressure influence. A more conservative evolution and probably more believable than the 12z GFS which was rapid!

Time for another Cillit Bang run!

Edited December 28, 2020 by kold weather

[BLAST FROM THE PAST]

1 minute ago, Frosty Winter said:

Are you watching the run upside down? 

Read the full post...and don’t hide behind the fact that the HP is further south.  It’s to show the dangers here...nit the outcome as we don’t know 

 

BFTP

[Ice Day]

Pub run out to 174.  What. A. Chart.

 

[BLAST FROM THE PAST]

1 minute ago, kold weather said:

I think what BFTP is trying to say is that in many a normal situation that set-up would indeed topple, but that with the set-up sloft as it is its going to retrograde to some extent up towards Iceland/Greenland.

This run is a little colder aloft due to more of a high pressure influence. A more conservative evolution and probably more believable than the 12z GFS which was rapid!

Time for another Cillit Bang run!

Thanks KW...exactly right

BFTP