Model Output Discussion - Christmas week and beyond

[trickydicky]

20 minutes ago, Eagle Eye said:

Atmospheric River = Plenty of moisture. Tail of an Atmospheric River = colder(for us that's the, I think Polar Maritime?). I've been saying it for a while now and the timing with this could potentially bring A LOT of snow to somewhere across Great Britain. As long as the Atmospheric River doesn't retreat back North then I think somewhere could see exactly what I've been talking about.

They're very underrated these Atmospheric Rivers although I don't remember one streaming across the Atlantic since I've joined here (well, in Winter anyway) and I think they're quite rare at this strength in the Atlantic. Just wish we got them as strong as California can get them, just look at the amount of snow that fell from one of them.

Ours isn't as strong as that but imagine if it was, maybe one day...

Is Atmospheric River not just another name for trailing fronts or pineapple express or whatever else? And is it not just what happened in November 2009 and December 2015? And rather than burying us in snow do they not tend to just drown the west of the UK?

Edited December 21, 2022 by trickydicky

[Drifter]

Things definitely happening out east. Day 7 UKMO

If you run the sequence, there’s definitely a brick wall appearing - if we went to day 10 I’d expect that area of HP to extend to Scandinavia. 

[Skullzrulerz]

52 minutes ago, Drifter said:

As ever, it would seem the GFS has led us up the garden path once again. 

Let's be honest here, the GFS was "mostly" on its own.

Despite the model uncertainty if you have just one model showing thing and a majority of models showing another then it's bound to be wrong in most cases.

Game over for winter? By no means it's not but I would give it a yellow card.

[Don]

5 minutes ago, Drifter said:

Things definitely happening out east. Day 7 UKMO

If you run the sequence, there’s definitely a brick wall appearing - if we went to day 10 I’d expect that area of HP to extend to Scandinavia. 

Could that also out pressure on the PV, too?

4 minutes ago, Skullzrulerz said:

Let's be honest here, the GFS was "mostly" on its own.

Despite the model uncertainty if you have just one model showing thing and a majority of models showing another then it's bound to be wrong in most cases.

Game over for winter? By no means it's not but I would give it a yellow card.

The Met Office 16-30 day offers hope for mid January, so something to cling on to!

[winterof79]

46 minutes ago, Mapantz said:

It's nothing to do with meteociel. 

It looks the same on other model viewers as well.

Fact remains it struggles with forecasting showery activity when all parameters are conducive as it showed during our recent cold spell.It was atrocious. 

[alexisj9]

1 hour ago, Don said:

I think the Euro heights may be the thorn in the side for this winter and (think) it was shown by many long range models in the lead up to winter?

I think we are about to watch them disappear. Already starting in the GFS 6z. Let's see what happens.

[Frosty.]

I never thought I would beg / pray for a NW’ly..ah well.. it is crime  innit!…honestly, this is just like this time last year (deja ..vavava.. va vu! ..when the mean imploded!..lightening has seemingly struck twice.. unfortunately?! …but we are slaves to what the models show, all the fancy talk (terminology) doesn’t mean diddly squat when the models pull the rug from under us?…however..it hasn’t happened yet so perhaps I’m being presumptuous?!..  

Edited December 21, 2022 by Frosty.

[bluearmy]

Looking at the NH, it’s possible that the current Alaskan ridge works around towards the Atlantic sector. The gfs run goes awry in week 2 as it introduces a low from near Bermuda into the mix which phases out west. Would have been a more interesting fi without that

Again fi gfs has high anoms over the Canadian sector 

the flatter mobile flow does also trend the euro high flatter too … more inclined to retrogress west or be suppressed se 

and as mentioned above, eyes on any Russian blocking 

Edited December 21, 2022 by bluearmy

[TSNWK]

2 minutes ago, Don said:

Could that also out pressure on the PV, 

11 minutes ago, Drifter said:

Things definitely happening out east. Day 7 UKMO

If you run the sequence, there’s definitely a brick wall appearing - if we went to day 10 I’d expect that area of HP to extend to Scandinavia. 

On what basis do you expect the high to back west ?

 

[Don]

1 minute ago, Frosty. said:

I never thought I would beg for a NW’ly..ah well.. it is crimbo innit!…honestly, this is just like this time last year when the mean imploded!..lightening has seemingly struck twice.. unfortunately! …but we are slaves to what the models show, all the fancy talk doesn’t mean diddly squat when the models pull the rug from under us?…however..it hasn’t happened yet so perhaps I’m being presumptuous!..  

Hopefully the models do not trend towards an exceptionally mild New Year like last year as well!  That really would be a kick!!

[bluearmy]

7 minutes ago, Don said:

Hopefully the models do not trend towards an exceptionally mild New Year like last year as well!  That really would be a kick!!

Surely that depends on the context of what looks likely to follow …..

[Drifter]

8 minutes ago, TSNWK said:

 

I didn’t say it would back west to impact us immediately. 
The trough is disrupting and filling over Scandinavia which would allow the Russian high to back west. 
We’d then have to wait for another round of disruption for to back westwards again. Discontinuous Retrogression, if we need another buzzword/phrase. 

[blizzard81]

A trend today to flatten Euro heights somewhat. This is giving more chances for polar north westerlies as we head towards the new year.

1 minute ago, blizzard81 said:

A trend today to flatten Euro heights somewhat. This is giving more chances for polar north westerlies as we head towards the new year.

A good example here.

[Frosty.]

23 minutes ago, Frosty. said:

I never thought I would beg / pray for a NW’ly..ah well.. it is crime innit!…honestly, this is just like this time last year (deja ..vavava.. va vu! ..when the mean imploded!..lightening has seemingly struck twice.. unfortunately?! …but we are slaves to what the models show, all the fancy talk (terminology) doesn’t mean diddly squat when the models pull the rug from under us?…however..it hasn’t happened yet so perhaps I’m being presumptuous?!..  

I meant crimbo!...sadly there isnt enough time to edit mistakes!..so sad.....merry christmas..hohoho

 

Edited December 21, 2022 by Frosty.

[Don]

14 minutes ago, bluearmy said:

Surely that depends on the context of what looks likely to follow …..

True but what followed last year/early this year wasn't up to much.

[blizzard81]

Looks like we will be cooler than the whole of the United States for New Year. Bet it's not often that happens.

[Mike Poole]

20 minutes ago, blizzard81 said:

A trend today to flatten Euro heights somewhat. This is giving more chances for polar north westerlies as we head towards the new year.

A good example here.

I think there is a new trend today, but the flattening of euro heights is a by-product of it, not the main point of interest.  What has struck me from the afternoon runs so far, and to be fair was evident from the extended clusters this morning (although I failed to comment on it at the time), is where has the upstream pattern gone?  UKMO T168, GFS & GEM T192:

Once the US storm remnants and other bits and pieces are out of the way, there isn’t anything else to come at us from a westerly direction, it looks very benign over the pond.  There is no sign of the trop PV setting up shop in a bad place.  You can see on this plot based on GFS 0z, T240 and T384, the position of the lowest, orange ellipse is squashed away from the USA by some margin, while the strat PV races away in pretty much a circle.

I think there is a good chance of weather from northwest or even north of northwest if this pattern persists, and at the time of year, this could be interesting.  Certainly not a return to standard +NAO zonal fayre, I would suggest, and at best, a visit from the vortex itself down the line?

Edited December 21, 2022 by Mike Poole

[Eagle Eye]

50 minutes ago, trickydicky said:

Is Atmospheric River not just another name for trailing fronts or pineapple express or whatever else? And is it not just what happened in November 2009 and December 2015? And rather than burying us in snow do they not tend to just drown the west of the UK?

Not really, it's a tight corridor of concentrated water vapour transport (that can be very long in length but its not that wide usually). The pineapple express is just an example of one really, it depends more on the initial state of at Atmosphere and what air source it mixes in with. In a large zonal system it does create that pineapple express but in something like this, if it times itself with the cold(ish) air then the potential for snowfall will arise with it. Its not really a weather system in itself, its simply a large transport of water over time in a narrow corridor.

Anyway, away from that and...

As @Mike Poole says, it's not a 'roaring' +NAO that seems to be setting up here just yet. It does initially connect up with the Trop and we get a slight +VE zonal state going into the New Year. Yet, it doesn't look to be really strong and I think the AAM becomes fairly significant here. If we can get a significant rebound of AAM then the Trop-Strat connect up probably won't be long enough to build itself strong. Instead, thermal Rossby transfer poleward from fairly unstable inertia in a 'marginal' situation like this should probably be enough to swing us back into a slightly -VE zonal anomaly state.

Edited December 21, 2022 by Eagle Eye

[Tim Bland]

1 hour ago, northwestsnow said:

I'd expect UKMO 120 to produce snow at moderate altitude ..

Providing the collapsing ridge hasn't killed off showers at this point..

Anyone know where to go (or have a link) for the UKMO precip charts ?

[northwestsnow]

4 minutes ago, Tim Bland said:

Anyone know where to go (or have a link) for the UKMO precip charts ?

I don't think they are available Tim

Edited December 21, 2022 by northwestsnow

[RhHh]

17 minutes ago, blizzard81 said:

Looks like we will be cooler than the whole of the United States for New Year. Bet it's not often that happens.

I thought that the US was heading into the freezer?

[blizzard81]

5 minutes ago, Mike Poole said:

I think there is a new trend today, but the flattening of euro heights is a by-product of it, not the main point of interest.  What has struck me from the afternoon runs so far, and to be fair was evident from the extended clusters this morning (although I failed to comment on it at the time), is where has the upstream pattern gone?  UKMO T168, GFS & GEM T192:

Once the US storm remnants and other bits and pieces are out of the way, there isn’t anything else to come at us from a westerly direction, it looks very benign over the pond.  There is no sign of the trop PV setting up shop in a bad place.  You can see on this plot based on GFS 0z, T240 and T384, the position of the lowest, orange ellipse is squashed away from the USA by some margin, while the strat PV races away in pretty much a circle.

I think there is a good chance of weather from northwest or even north of northwest if this pattern persists, and at the time of year, this could be interesting.  Certainly not a return to standard +NAO zonal fayre, I would suggest, and at best, a visit from the vortex itself down the line?

Absolutely, I noticed this too. I'm sure the US experienced similar benigness prior to our recent cold spell. This sluggishness over the US continent manifests itself with a resultant sluggish atlantic. This is certainly noteworthy and very positive for the UK as we approach deep mid Winter. Great timing!

[Tim Bland]

Just now, northwestsnow said:

I don't think they are available Tim

I’m sure I’ve seen them posted before . Perhaps they are behind a pay wall..or I imagined it

[Mike Poole]

7 minutes ago, Tim Bland said:

Anyone know where to go (or have a link) for the UKMO precip charts ?

Here, for the UK:

WWW.METEOCIEL.FR

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Meteociel propose de manière régulière le modèle à maille fine UKMO 0.1° du UK MetOffice (météo angaise) sur 5 zones (France, Nord-Ouest, Nord-Est, Sud-Ouest...

Edit, sorry that link doesn’t seem to work, go to UKMO page, click ‘UKMO HD 0.1 Pays’ and click UK flag.

Edited December 21, 2022 by Mike Poole

[Midlander]

Just now, Tim Bland said:

I’m sure I’ve seen them posted before . Perhaps they are behind a pay wall..or I imagined it

 

UKGUK chart

WWW.THEWEATHEROUTLOOK.COM

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UK Met Office global model is one of the leading numerical weather prediction models