Model Output Discussion - 18z - 25th Nov onward

[karlos1983]

This run looks better to me so far, the HP in the Atlantic looks to be further west at +114, to my very untrained eye, and more of an easterly earlier?

[Matty M]

looks like GFS is struggling as to know what to do with that LP, worryingly it is intensifying it and keeping it static currently. On the plus side we got a better easterly forming at +114.

Hi, we want the Newfoundland Low to be intense as this will deflect it northwards into west Greenland which will advect warm air north which will enhance our Greenland High/ Arctic High

[karlos1983]

Hi, we want the Newfoundland Low to be intense as this will deflect it northwards into west Greenland which will advect warm air north which will enhance our Greenland High/ Arctic High

Thanks for explaining that Matty M, all these little comments are really helping me understand the Models, and maybe one day, get a better grip of what they may actually do, or when they may be losing the plot a bit. Very nervous to start commenting, as I'm miles away from some of the guys commenting in here in terms of knowledge.

[SMU]

Morning All -

A longer update in a moment- however until then-

The 06z NOGAPS trending to almost identical as the UKMO

S

[Jonan92]

Nogaps

[offerman]

Guy`s , I think the problem is all these cold runs keep getting pushed back, for the last 3 weeks many inc myself have been saying cold,snow on the way, but realistically it is to far out as is the case now, the previous deep cold would of hit us by now accoring to older charts but to many delays and uncertainty is happening, really we need to look at no more than 3 days out i reckon, any longer than that and its just pie in the sky.

No matter how powerful computer are/get, they will NEVER predict the weather AIMHO of course.

[TEITS]

Ok thanks.

I'm learning! from one set of models I still find it bizarre how one post can read 'Atlantic domination' and yet another 'cold still on the way'

I know it's discussion but for me that's extreme conflict and couldn't be more opposite

Let's make it clear before members jump on me, I am in no way shape or form dissing Gibby's posts- he is excellent.

All I am trying to establish is how his summary can reading 'Atlantic' and another senior member read 'cold and look east' when we are all looking at the same run

With regards to the Atlantic returning this doesn't always mean mild/rain. At the moment that could occur but another option is LP aligned NW-SE due to blocking being more influencial. If this happens then with the cold air that is likely to be across the UK then anyone on the NE flank of the LP is likely to see snow and remain cold. Once this clears SE the rest of the UK would turn colder.

When we have model disagreements I don't tend to stick with one model but view all outputs and try and find a mean. I also use my experience of following the models for many years because you do tend to find the models really struggle with any form of blocking to our N/NE.

[Hammer]

Up to T90 it certainly appears more favourable for later cold, however from then on between T105 and T150 it does rather seem like the model admits everything becomes a little messy and it doesn't know way forward. From my point of view this would tell me we should consider the output in the later range from the models, but we have to get a better consistency on what is happening up to T90 first.

Getting colder it would seem, as to whether this becomes colder with snow and deeper cold, then we may be some time from knowing.

[Weather Boy]

Guy`s , I think the problem is all these cold runs keep getting pushed back, for the last 3 weeks many inc myself have been saying cold,snow on the way, but realistically it is to far out as is the case now, the previous deep cold would of hit us by now accoring to older charts but to many delays and uncertainty is happening, really we need to look at no more than 3 days out i reckon, any longer than that and its just pie in the sky.

No matter how powerful computer are/get, they will NEVER predict the weather AIMHO of course.

Whilst pushing back in time often happens with models, on this occasion, that is simply not true. It is and has always been c. 30 November/1 December from the first occasion when it was hinted at in the depths of FI.

On a wider note, IIRC the models suddenly doing a reversal and tailspin and then reversing so that they end up swapping output is exactly what happened in December 2010. These synoptic situations are unusual compared to the Atlantic train, so presumably do not have the same experience of handling it and therefore do "struggle" to the extent that a computer occasionally getting it wrong can be called struggling.

[Met4Cast]

06z sticks with pushing the energy Eastwards from that low instead of Northwards. It seems to be GFS & ECM V UKMO.

In the past, whenever UKMO has showed something less cold whilst the ECM and GFS were showing cold, the UKMO model was right. Lets hope that the UKMO has this! If not, it's going to go down as one of the biggest model c*ck ups in history I think!

[The Northern Ramper]

So we have the ukmo rock solid with every run, some of the minor models mirroring what the ukmo is showing and the ECM and latest Gfs backtracking from their low ploughing east through Greenland and smashing the block.

An interesting 24 hours model watching for sure.

[TEITS]

NOGAPS backs the UKMO with a very impressive run.

The pendulum keeps swinging but so far today the pendulum has swung back to cold. Will this continue on the 12ZS??

[Zakos]

GFS 06z is an improvement

I still think it is far from clear as to what will happen. It does look likely that the Atlantic will put up a fight, but the block is also looking quite strong.

I think perhaps these conflicting signals are causing problems for the models.

While the conditions over the Uk changes massively on each run, the big picture is still looking great; with a strongly negative AO.

Edited November 26, 2012 by Zakos

[danm]

With regards to the Atlantic returning this doesn't always mean mild/rain. At the moment that could occur but another option is LP aligned NW-SE due to blocking being more influencial. If this happens then with the cold air that is likely to be across the UK then anyone on the NE flank of the LP is likely to see snow and remain cold. Once this clears SE the rest of the UK would turn colder.

When we have model disagreements I don't tend to stick with one model but view all outputs and try and find a mean. I also use my experience of following the models for many years because you do tend to find the models really struggle with any form of blocking to our N/NE.

Agree with this. During the Feb 2012 cold snap that affected the SE/East Anglia, what gave us the heavy snowfall was a low pressure system moving east and interacting with the cold air over the east of the UK, stalling and giving 6 inches of snow.

As TEITS says, a low pressure system aligned in a NW-SE angle wouldn't result in your traditional Atlantic attack.

[Ian Brown]

The 06z goes the same way as the 0z, a strongly positive NAO developing.

[london-snow]

06z has that low heading e-ne at 162+ we must see that stay north and drift north - north west to put us in a favorable position. Its been said before but this afternoons runs are going to be crucial as we are now within a reliable period with regards to that lp which holds the key at the moment.

Edited November 26, 2012 by london-snow

[fromey]

06z sticks with pushing the energy Eastwards from that low instead of Northwards. It seems to be GFS & ECM V UKMO.

In the past, whenever UKMO has showed something less cold whilst the ECM and GFS were showing cold, the UKMO model was right. Lets hope that the UKMO has this! If not, it's going to go down as one of the biggest model c*ck ups in history I think!

GFS 06z is an improvement

I still think it is far from clear as to what will happen. It does look likely that the Atlantic will put up a fight, but the block is also looking quite strong.

I think perhaps these conflicting signals are causing problems for the models.

While the conditions over the Uk changes massively on each run, the big picture is still looking great; with a strongly negative AO.

.

Confused.com

[BOMBHEADS]

is the GFS pushing back the progression eastwards of the LP in to the less reliable time frame each run? would that suggest that it really can't predict what path it's going to take? or am i just cluching at straws.

[snowmadchrisuk]

.

Confused.com

The 6z is an improvement because of the fact the block holds for longer and rebuffs the first SW , it is a big Improvement up to +120 and that has got to be nearing FI in this situation . (Well it is FI as we have other Models showing a different solution .)Interesting week coming up on the Models thats for sure.

Edited November 26, 2012 by snowmadchrisuk

[Buzz]

The 06z goes the same way as the 0z, a strongly positive NAO developing.

That really depends which model you follow doesn't it Ian.

[Liam J]

GFS sticking by it's guns and lending the ECM, GEM, CFS etc good support in bringing the energy eastwards over the Atlantic, the UKMO has support from the NOGAPS - not something i'd like to brag about!

Those saying that the 6z is an improvement are incorrect and misleading to others trying to learn here, at face value the whole pattern has flattened out with a full on Atlantic attack.

The fun and games continue another day!

Edited November 26, 2012 by Liam J

[WhiteFox]

06z sticks with pushing the energy Eastwards from that low instead of Northwards. It seems to be GFS & ECM V UKMO.

In the past, whenever UKMO has showed something less cold whilst the ECM and GFS were showing cold, the UKMO model was right. Lets hope that the UKMO has this! If not, it's going to go down as one of the biggest model c*ck ups in history I think!

Until the next one... It's simply not true. There is a signal in the vast volumes of data to indicate that some energy may seep through what is not a particularly strong block. The difference between the block holding and breaking is very small, but the results after that have big differences.

To rephrase your post above, on the occasions when the UKMO was right, does this mean that the ECM and GFS were the biggest c*ck ups in history? Hyperbole always seems to increase exponentially during times such as these!

[Hammer]

0z and 6z GFS show significant difference on the track of the low near Greenland. The later output seems somewhat messy. But in that even in 6 hours a model can handle the LP very differently, it does rather illustrate in times like this with blocking, we can't really look to much further than the earlier timeframes. Once we get any sort of consistency in the earlier part, this will increase confidence as to what will happen next.

[Interitus]

Whilst pushing back in time often happens with models, on this occasion, that is simply not true. It is and has always been c. 30 November/1 December from the first occasion when it was hinted at in the depths of FI.

On a wider note, IIRC the models suddenly doing a reversal and tailspin and then reversing so that they end up swapping output is exactly what happened in December 2010. These synoptic situations are unusual compared to the Atlantic train, so presumably do not have the same experience of handling it and therefore do "struggle" to the extent that a computer occasionally getting it wrong can be called struggling.

No, Offerman is actually correct, the first hints at cold in FI were forecast from this weekend onwards as the archive charts on meteociel so helpfully show - these are from 08/11 for example -

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=204&code=0&mode=0&heure=0&jour=8&mois=11&annee=2012&archive=1

[offerman]

Daniel WMD, Spot on bud.