Model output discussion - 5th December 2016 - Into Winter we go

[booferking]

15 minutes ago, radiohead said:

06Z GFS (P) is out. And it's disappointing.

Lets see what the 12z have to say hopefully good for us coldies.

[shotski]

20 minutes ago, iapennell said:

The Circumpolar Vortex is strong (higher up into the Stratosphere, it's very strong); that means there is a likelihood that those models building upper heights towards northwards towards Greenland for the New Year will have to modify/downgrade them before we get to this time: Any folk hoping for a full-on Arctic blast may be disappointed. 

That's not to say we might not get a day or two of north-westerlies behind the deeper depressions, these could certainly bring snow to high ground and a frosty night in the following ridge of high-pressure. All the best for Christmas.

Surely the models have been programmed to take into account what's happening in the upper Strat ? Otherwise their not worth their salt. 

[phil nw.]

Let's see what the 12z runs bring but for any decent cold there needs to be stronger ridging in the Atlantic.

The earlier runs still had the jet running over the top-gefs

so this limits the northward ridging-we need to see the jet split with more going south for a better high.Still with a majority of the gefs clusterings going for some form of Atlantic high around new year there's still plenty of mileage in this evolution.

 

Edited December 23, 2016 by phil nw.

[northwestsnow]

43 minutes ago, radiohead said:

06Z GFS (P) is out. And it's disappointing.

Its also a complete waste of time, not because it doesnt show cold but every time it has its been wrong!

[damianslaw]

The trend over the past 2 days to something perhaps colder as we head into New Year continues in today's models, all thanks to a shift in the PV lobe which is forecast to move westwards deeper into NE canada, away from Greenland which in turn enables heights to rise over the western atlantic seaboard, with a downstream trough over NW russia, hence we quickly revert back to a highly amplified flow, with less energy in the jestream allowing ridging to build northwards in our vicinity early next week, propped up by lower heights over SE europe.

The route to a mid altantic high seems very plausible, but far from certain just yet. I think it will be a tall order to get a greenland high, mainly due to the strength and position of the PV, but there is a window which will allow heights to ridge sufficiently close to south greenland to probably pull down a cold northerly shot, indeed the evolution would be ripe for a cold NW/N pattern as we enter the New Year, with trough action heading into scandi with the ridge to our west moving back and forth - a cold pattern, another plausible set up would be for the ridge to sink south and build in to scandi. All conjecture.

In the meantime, a very changeable 2-3 days ahead, lots going on, tomorrow calmer but cold in Scotland chance of some snow down to modest levels, a brief warm sector over christmas day, then a plunge of cold uppers come Boxing Day, indeed a white boxing day could be on the cards for parts of Scotland, settling down 27/28 some frost for England and Wales. A real mixed bag, a white new year would make for a very topsy turvy christmas - new year week indeed, one of the most varied in a long time, reminiscent perhaps of 2003.. Lets see.

 

[booferking]

You have to lol at it really its just are luck in this island blink and you will miss the northerly..

[radiohead]

A lot less amplification on the 12Z GFS...

[radiohead]

12Z GEM offers up something a bit colder.

[Chris K]

From around T+150 you can see how the High pressure is pushed and topples towards the UK on the GFS 12Z op, resulting in a chilly NW feed before what looks like may join into that smelly mass of heights to our South and Europe again (or sit close-by). It does not try to edge up to Greenland or suitably position itself to hold off a flatter, stronger Jet. I've seen enough and await to see how it sits with the ens and what ECM conjures up later.

Edited December 23, 2016 by Chris K

[Banbury]

Missing out this time

[Frost HoIIow]

3 minutes ago, Banbury said:

Missing out this time

More like every time!

[booferking]

1 minute ago, Banbury said:

Missing out this time

When do we actually hit the target oh thats right always away in the fi one run but same old same.

[BLAST FROM THE PAST]

17 minutes ago, booferking said:

You have to lol at it really its just are luck in this island blink and you will miss the northerly..

There is nothing to suggest that a strong ridge would be in place for NY to produce a strong Greenie HP.  I think a MLB block will probably settle across us with GFS and the rest following suit.  This winter is going to be frustrating no fear!  Still no HLB Signal likely until possibly mid Jan onwards.....and even that now I'm wary of

 

BFTP

 

BFTP

[bluearmy]

The 06z was less amplified over the eastern seaboard than the 00z and the 12z is even moreso. Less amplification there and less WAA driven towards Greenland. 

The combination of evolutions in different parts of the NH needed to drive the amplified ridge do not come together on the 12z and the flatter solution results. 

the 06z GEFS did look rather more mobile week 2 so its not unexpected that the following op might be so too. the fact that the gem manages to amplify fairly well despite the trough sharpening up off the east of N America rather than over the east is a good sign for coldies but I susupect the polar high placement and subsequent big aleutian ridge  helps out that run later on. 

The ukmo at day 6 looks like it will amplify fairly well eastern states. The upcoming ECM op awaited with interest, especially as the gfsp was again flatter than the normal run. 

[BLAST FROM THE PAST]

14 minutes ago, radiohead said:

12Z GEM offers up something a bit colder.

Look where the core of the heights are...south of Iceland.....that is a non longevity scenario. Would be nice to get that though wouldn't it

 

BFTP

Edited December 23, 2016 by BLAST FROM THE PAST

[phil nw.]

The trend for the Atlantic high  to develop around day 8 is still there but it continues to be modeled at around 50/55N and without sufficient ridging the flow for us will be just something from the north Atlantic rather than any Arctic source.

We can see the difference in the jet flow compared to the earlier run

12z                                                                  06z

It's a while away before this will be resolved and a look at the clusters later will show if the trend towards a better ridge as shown earlier today is maintained.

Either way the Atlantic looks like quietening down again with some frosts and possibly fog after the holiday period with a period of mid-latitude blocking-i think we have been here before.

 

 

Edited December 23, 2016 by phil nw.

[frosty ground]

7 minutes ago, BLAST FROM THE PAST said:

Look where the core of the heights are...south of Iceland.....that is a non longevity scenario. Would be nice to get that though wouldn't it

 

BFTP

At no point has longevity been on the cards.... it has looked like a toppler from the start and the only debatable points are how far West will the high will Ridge north how far north and how quick it will collapse.

[bluearmy]

9 minutes ago, BLAST FROM THE PAST said:

Look where the core of the heights are...south of Iceland.....that is a non longevity scenario. Would be nice to get that though wouldn't it

 

BFTP

I think griceland is the best we can hope for unless everything just falls right which it rarely does. 

the eps say mid Atlantic ridge with the propensity to pulse north but as knocker mentioned earlier, it's the behaviour of the scrussian trough and how it backs sw which is important for nw Europe and potential cold. 

[Methuselah]

Agreed, Phil...Even this morning's opening shot (the one that went in off the post) barely grazed the side-netting, on the 12Z...A temporary blip in the overall pattern, perhaps...The Chinese Year of The Slug?

[knocker]

Another key difference between the 06 and 12 is the intensity and position of the cut off upper low and the phasing of the trough that has nipped east and phased in with the eastern trough.. it can now amplify NE.

Edited December 23, 2016 by knocker

[Stuie]

24 minutes ago, phil nw. said:

The trend for the Atlantic high  to develop around day 8 is still there but it continues to be modeled at around 50/55N and without sufficient ridging the flow for us will be just something from the north Atlantic rather than any Arctic source.

We can see the difference in the jet flow compared to the earlier run

12z                                                                  06z

It's a while away before this will be resolved and a look at the clusters later will show if the trend towards a better ridge as shown earlier today is maintained.

Either way the Atlantic looks like quietening down again with some frosts and possibly fog after the holiday period with a period of mid-latitude blocking-i think we have been here before.

 

 

Glad you mentioned Phil, you probably saw my post abut the JS yesterday, MAJOR player in anything that is to evolve.

Edited December 23, 2016 by Stuie W
Wrong name!

[stewfox]

4 minutes ago, knocker said:

Another key difference between the 06 and 12 is the intensity and position of the cut off upper low and the phasing of the trough that has nipped east and phased in with the eastern trough.. it can now amplify NE.

A friend of mine, wants to know is that good or bad ?

[Ali1977]

Ok so the Op wasn't as good, but I'd say the ENS are much better and  most have a good first few days of new year and show lots of that word "potential"

[knocker]

1 minute ago, stewfox said:

A friend of mine, wants to know is that good or bad ?

Well you can tell your friend that's impossible to answer because it's entirely subjective.

[IDO]

This morning's runs highlighted the split clustering, temporary height rise -v- UK high -v- mix; from the D8-9 stage. I expect the GEFS will maintain this split and it may take some runs before being resolved as it seems quite complex, revolving around shortwave features rather than the usual long wave drivers. 

Lots of cold air to tap into with the right setup, but this far away we can only look for trends and for me there has been no eureka moment yet, so still all three scenarios on the table.

In the shorter term dry for most next week and likely feeling cool despite the anomalous high uppers:

Still below average temps look like the watching brief as we start the New Year.