Model Output Discussion 29th December - Into mid-Winter.

[fromey]

2 minutes ago, shotski said:

 

OMG thats a day old, how dare you post that in here. 

Is it, sorry!!I will get my coat!

[Gowon]

7 minutes ago, TEITS said:

Very different.

A N,ly via a Greenland high has a much better chance of verifying than an E,ly via a Scandi HP.  You get a lot less drama with a Greenland high i.e 2009, 2010 was relatively straightforward. An E,ly via a Scandi HP has been a nightmare to follow in the model output since I joined this forum.

The simple fact is the operationals with the exception of the UKMO have been rather erratic. So due to this the ensembles become even more unreliable. If the 06Z is repeated on the 12Z then even more ensembles will slowly follow. Bascially the ensembles lag behind the operationals when it comes to an E,ly.

Fine, but it would've been clearer if you had stated that in your earlier post

[snowwman]

14 minutes ago, fromey said:

I've just seen this, where would this sit within the models, if any where and what is it showing, it's for the 8th Jan

Intense height anomaly in the strat over Greenland. If that were to propagate downwards and directly, that would spell a Greenland block. However, there's a question as to whether the downwelling would be vertical, as the stratospheric and tropospheric vortices are often in different locations.

Edited December 31, 2016 by snowwman

[snowangel32]

Such a shame it would have been really special to see this forum talking about a true cold spell. Now the uncertainty is back and it's like Deja vu you know once the models start to agree on a UK high or a shortwave placement and phasing it's very unlikely to flip back. It seems if any model dosn't back cold weather in the UK that is always the correct one to back as it has picked up a slightly different signal we have seen it with all three the most Infamous being that ECM wich at the time Gfs never backed. I think now we have to look towards mid Jan hard not to be downbeat about the UK weather at present just rinse and repeat.

[Mucka]

I think looking at 2m temps within the ensembles and coming to the conclusion not much has changed would be to ignore what is in front of our eyes as far as snow chances go.

Even the GFS 06z shows the same cold at the surface but compared to yesterdays set for snow and cold uppers they are chalk and cheese.

The UKMO solution we all feared because it was so poor in comparison to GFS and ECM output now seems to be the new reality so let's not pretend the UKMO is suddenly wonderful now it has (seemingly) been proved correct.

The GFS 06z is pretty awful in comparison to previous runs, no need to sugar coat that. 

Fair to remind folk it is just one run so long as we don't bury our heads in the sand and pretend the output hasn't been trending that way lately.

Essentially we are looking as the pattern being forced East and being much flatter than ECM and GFS were originally modeling so any Northerlies are much tempered and glancing blows and the Northeasterly components with heights building toward Geenland have all bit disappeared.

Assuming there is no miracle flip back to what we had then the best we can hope for is glancing Northerlies and then hope the pattern is amplified enough to build heights toward Scandi in FI.

So as things stand we should get surface cold but snow chances will be very limited, especially in the West - as always it comes down to expectation.

If people had very low expectations then that isn't bad at all, if they had high expectations it is a big let down to what was potentially on offer.

It is really quite cruel how the only solution that prevent us getting a really nice cold spell always seems to be the correct one. but most cold and snow fan veterans have toughened to it to at least some extent.

 

All we needed was for the energy to our South not to develop and move up the Western flank of the Atlantic high when it does. That forces everything East and prevents Euro heights draining preventing the trough digging down and helping amplify the ridge behind and back the pattern West. It is as though some weather engineers have got around a table and worked out the only way to disrupt a cold weather pattern for us and executed it - it is that unlucky!

I guess all that said, it still means the trough could win the race with the low to be the dominant player but the output has only gone 1 way for the last 24h.

Currently I would say the chances of going back to the trough dropping over us and a strong Northerly and then NE are about 15%

Glancing Northerlies with surface cold about 85%

For FI I'd say about 20% chance of true cold pattern developing with HLB

65% chance of mixed with MLB remaining close to the UK

and 15% chance the Atlantic gets in proper with a reset.

That doesn't seem so bad on the face of it but I'm not going to pretend this mornings output hasn't all gone the wrong way for prolonged cold with with good snow chances.

Fingers crossed things go back the other way this evening and tomorrow but either way this saga is almost over, no doubt the next one (Easterly? Is around the corner)

 

 

Edited December 31, 2016 by Mucka

[Met4Cast]

The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent. 

Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame. 

[bluearmy]

4 minutes ago, Daniel Smith said:

The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent. 

Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame. 

I suspect the stats say different and it's our interpretation of what's in front of us that's perhaps the issue 

[shotski]

5 minutes ago, Daniel Smith said:

The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent. 

Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame. 

Probably worth just sticking with UKMO model for a more conservative view on things. 

[Spah1]

54 minutes ago, blizzard81 said:

Well, I have spent the last few hours trawling through the model output and reading this forum which by the way is by far the best weather forum out there. I have digested quite a lot (apart from bacon n egg and cheese cake) but I keep going back to the ecm day 7 op. Go on, have another look at it. It is a superb chart and the best thing is I usually find the ecm day 7 op charts are very accurate.

What are the chances of the northerly being modelled a few hundred miles further West though? Seems we'll just miss out again. 

[IDO]

4 minutes ago, bluearmy said:

I suspect the stats say different and it's our interpretation of what's in front of us that's perhaps the issue 

Not really, I have rarely seen such poor 10 day verification stats from ECM, with 0.1 even hit on one run; average close to 0.5. Pretty shocking of late:

[feb1991blizzard]

Just now, bluearmy said:

I suspect the stats say different and it's our interpretation of what's in front of us that's perhaps the issue 

Quite, and particularly with Easterlies, AT NO  POINT has any ensemble suite had more than 50% of members bringing an Easterly with proper frigid uppers into the UK. so its never been odds on.

[Methuselah]

22 minutes ago, TEITS said:

The Anomaly charts are even more of a waste of time than the ensembles.

Well, I'll certainly not be agreeing with that statement, TEITS...At least they're nae 'a waste of time' when there in the hands of those who know how to use them...

That doesn't include yours truly, BTW!

[snowwman]

8 minutes ago, Daniel Smith said:

The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent. 

Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame. 

The highly unusual patterns this Autumn/ winter is likely a big factor- it may be more difficult than usual for the models to accurately plot changes. Also means we shouldn't take as correct any model output which suggests mild just because that's what's often happened before.

[karyo]

22 minutes ago, snowwman said:

The highly unusual patterns this Autumn/ winter is likely a big factor- it may be more difficult than usual for the models to accurately plot changes. Also means we shouldn't take as correct any model output which suggests mild just because that's what's often happened before.

I firmly believe that the models are struggling to factor the record low ice (globally). This makes them more unreliable than usual.

On top of that the warm SSTs anomalies around Greenland encourage shortwave development which makes it difficult for high pressure to take control in that area. This is why the models show Greenland highs in FI that never materialise.

[LRD]

9 minutes ago, karyo said:

I firmly believe that the models are struggling to factor the record low ice (globally). This makes them more unreliable than usual.

On top of that the warm SSTs anomalies around Greenland encourage shortwave development which makes it difficult for high pressure to take control in that area. This is why the models show Greenland highs in FI that never materialise.

I thought warm SST's in that area encouraged high pressure? One of the things to look out for in terms of Atlantic SST's in the run up to winter is the tripole of 1) warm north Atlantic, 2) colder central Atlantic and 3) warm tropical Atlantic. It's something that Gav Partridge looks out for. Have I misunderstood something?

Edited December 31, 2016 by LRD

[Daniel*]

38 minutes ago, Daniel Smith said:

The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent. 

Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame. 

Not quite the GEFS and OP picked up the upcoming northerly for New Year's Day, 7-10 days out there was quite a strong convincing signal that far out, so thumbs up from me. 

[karyo]

1 minute ago, LRD said:

I thought warm SST's in that area encouraged high pressure? One of the things to look out for in terms of Atlantic SST's in the run up to winter is the tripole of 1) warm north Atlantic, colder central Atlantic and warm tropical Atlantic. It's something that Gav Partridge looks out for. Have I misunderstood something?

Well, we have the cold surface air of Greenland interacting with the warm waters around it. I think this causes shortwaves to develop and this is certainly what is happening again this year.

[karlos1983]

2 minutes ago, LRD said:

I thought warm SST's in that area encouraged high pressure? One of the things to look out for in terms of Atlantic SST's in the run up to winter is the tripole of 1) warm north Atlantic, 2) colder central Atlantic and 3) warm tropical Atlantic. It's something that Gav Partridge looks out for. Have I misunderstood something?

Warm seas and cold air feed storms not high pressure 

[LRD]

4 minutes ago, karlos1983 said:

Warm seas and cold air feed storms not high pressure 

I always though the Tripole that I described encouraged a negative NAO

Have I read this wrong then?

http://www.metoffice.gov.uk/learning/learn-about-the-weather/north-atlantic-oscillation

[karlos1983]

3 minutes ago, LRD said:

I always though the Tripole that I described encouraged a negative NAO

Have I read this wrong then?

http://www.metoffice.gov.uk/learning/learn-about-the-weather/north-atlantic-oscillation

Pass.....

But WAA going into artic regions will promote high pressure. That's for sure 

[snowbunting]

Perhaps the reliability issues are due to the perennial cold blob in the North Atlantic cutting off some of the warm water (energy) supply for fronts and depressions from the atlantic. Who knows!!!

[Polar Maritime]

Just discussion on what the 'current models' are showing please, There is a Winter thread open for all other musings. And the moan/banter thread..

Thanks please continue.

[chionomaniac]

One looks at this chart and the only thing one can see is the Iberian Low moving towards the NE.

But no, we see the trough reverse direction and head west. This has a significant effect as the high pressure block slips over the UK and prevents a straightfoward northerly setting up. So why has this occurred against what we would expect. The answer lies in the Jet stream pattern and if we look at that we can see why.

Here we have the unusual scenario of the returning arm of the Northern jet stream is stronger than the steering force of the weaker southern jet stream - hence the developing trough doesn't quite make it to Europe before heading back west. It would take a stronger southern arm to reverse the situation and it does not look like this is going to occur. This allows the ridge to slip back over the UK.

 

[Captain Shortwave]

Still no real resolution out at day 3 upstream

   

The UKMO dropping a deeper area of low heights underneath the high though both agree on the Azores low now at least.

To continue here, the UKMO day 4 from yesterday

Quite a bit different upstream, yesterdays UKMO had that low as one feature whilst we see two now with the upstream low much more significant.

All I can personally hope for is that it at least sharpens the ridge near the UK allow cold air to get a lot closer to us and not see the development of another Euro/Scandi high further on.

I am probably just straw clutching for something quick to develop. That said the day 4 UKMO would probably deliver scattered wintry showers down north sea coasts again though nothing spectacular.

Edited December 31, 2016 by Captain Shortwave

[LRD]

4 minutes ago, chionomaniac said:

 

Great explanation and this really does make you think 'what can go wrong, will go wrong' for UK cold and snow

Edited December 31, 2016 by Polar Maritime
To clear long quote.