Model Output Discussion 1st January 2014-06z onwards.

[Ali1977]

So, will we start seeing signs of where this possible cold is coming from on the 12z, be nice to see an eastily start to show for more than 1 run...Every time we see a cold run, the next one wipes it out again!!

[The Northern Ramper]

So, will we start seeing signs of where this possible cold is coming from on the 12z, be nice to see an eastily start to show for more than 1 run...Every time we see a cold run, the next one wipes it out again!!

Which is why the more experienced members tell you not to follow each run.

[TSNWK]

Frustrating, around 150 mark there were some tentative heights starting to build over scandi, again presure over Europe scruppers any chance of energy heading southeast

[Ali1977]

High developed at 162 over Central Europe, hopefully that starts moving North now the Atlantic train has weakened!!

[gottolovethisweather]

For those wanting to know the latest, I haven't checked and don't especially trust the outputs at weekends when the added balloon data isn't up to the usual standards. Anyway, I did a post over here in the CSE & SW thread yesterday which tells you all you need to know I imagine, remember today's chart from the GFS some nine days painted this horror chart, it obviously knew something.

 

 

Hopefully the drier spell alluded to within the Stratosphere thread will arrive in time for the second two-thirds of January.

Edited January 4, 2014 by gottolovethisweather

[SMU]

http://www.meteociel.fr/ukmo/runs/2014010412/UN144-21.GIF?04-17

reasonable UKMO is the grand scheme of things-

 

The deep cold pool on its journey getting into Northern Europe & critically heights remaining east of Greenland-

 

The lows are beginning to slide SE which is indicative of a POSSIBLE wave of cold moving west @ 168

 

Finely poised for the UK in around 7-9 days time.

 

S

As for the progressive 12z GFS I just cant even be bothered to comment on it

Edited January 4, 2014 by Steve Murr

[chionomaniac]

I would strongly recommend following the ensembles over the next few days for the 8+ day output. Already we see on the GFS 12Z a change to the NE with slightly higher heights. The trend is growing....

[Cumulonimbus Tower]

The 06 gfs was a step away from the 00 gfs zonal express and the 12 gfs looks to be a further step away from an atlantic driven 06h gfs. It will be interesting to see where we are left after the other output this eve but i suspect it won't be as zonal and mild as we were this morning....

[Ali1977]

FI looking good, jet stream digging further and further south

Possible North Eastily on the way I think...FI though!!

Edited January 4, 2014 by Ali1977

[Panayiotis]

FI on the 12z will be good I think, not much of a vortex, low heading SE, on a negative tilt...

Edited January 4, 2014 by Panayiotis

[Grimsby Snow Lover]

FI on the 12z will be good I think, not much of a vortex, low heading SE, on a negative tilt...

When you say 'Not much of a vortex' what do you mean? I thought those purple colours indicate a strong vortex. I'm asking because I would like to know what to look for. Many thanks GSL

[Ali1977]

Close but no Cigar, be interesting to see if the Ens trend in this direction!!

[Biggin]

FI on the 12z will be good I think, not much of a vortex, low heading SE, on a negative tilt...

US still on lockdown ??

[weather eater]

As you were for most of this run with the Atlantic running out of puff and then in low res the GFS gives everyone a little tease of HLB before changing its mind and reverting to the zonal train which at least is more PM than recently.

[Panayiotis]

When you say 'Not much of a vortex' what do you mean? I thought those purple colours indicate a strong vortex. I'm asking because I would like to know what to look for. Many thanks GSL

Its fairly weak, a strong vortex will look like this:

Notice how much of it is over Greenland/Canada, whereas the 252hrs image has 'pieces' of it over Bering Sea/north of Scandi/Canada. Which leaves a small area over Iceland/SE Greenland where heights can build, and this is where the GFS 12z built them:

Edited January 4, 2014 by Panayiotis

[johnholmes]

For those wanting to know the latest, I haven't checked and don't especially trust the outputs at weekends when the added balloon data isn't up to the usual standards. Anyway, I did a post over here in the CSE & SW thread yesterday which tells you all you need to know I imagine, remember today's chart from the GFS some nine days painted this horror chart, it obviously knew something.

 

 

 

Hopefully the drier spell alluded to within the Stratosphere thread will arrive in time for the second two-thirds of January.

 

I think you comment about balloon data is rather misleading-who/where says is not up to it's usual standards. Do you mean quality or quantity? If there is any problem you will read it on the NOAA site-not seen any comment.

Edited January 4, 2014 by johnholmes

[SMU]

I would make this comment tonight - general model consistency out to 96-108 then a RAPID move to large scale variations in how the energy & ridging interact in the atlantic-

 

So whatever is presented today take it with a pinch of salt- especially the GFS !

 

Best run seems to be the GEM especially @ 150

 

http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&carte=1&mode=0&archive=0

 

however we do seem to be missing the key ingredient on all models- a trigger low diving SE.

 

S

[Captain Shortwave]

Seen enough of the GEFs, a lot more Scandi high solutions than previous runs (over half a dozen), but the remaining issue being that we can't get cold air heading westward towards the UK, Most runs with height like this have a left over ridge over the UK southwards which results in a westerly flow. Pretty similar to the GEM.

[Mucka]

I would make this comment tonight - general model consistency out to 96-108 then a RAPID move to large scale variations in how the energy & ridging interact in the atlantic-

 

So whatever is presented today take it with a pinch of salt- especially the GFS !

 

Best run seems to be the GEM especially @ 150

 

http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&carte=1&mode=0&archive=0

 

however we do seem to be missing the key ingredient on all models- a trigger low diving SE.

 

S

 

This may happen with a second bite at the cherry if the ridge can hold on as pressure will be lower to the South allowing for possible slider/undercut and I think there are hints of that across the output including GEM to a certain extent though it goes the long way round. Either way I think we will struggle to get an Easterly flow at the first attempt around day 5/6 unless the pattern gets backed west and we get a stronger ridge than currently modelled but if it holds on we could see the next low further South with WAA reinforcing it and the low sliding/undercutting.

 

GFS 12z ensembles are trending toward some form of high pressure to our North/Northeast rather the flatter pattern modelled previously. This probably won't be evident in the ensemble graphs but maybe in the mean pressure charts over the next few runs. Trending the right way anyway.

 

It would be nice to see some big upgrades and get some cold uppers from the NE in followed by a slider around day 5/6 which would bring snow for many but more likely we will need that second bite.

[fergieweather]

A pattern change therefore IS coming, but at this stage no one (including the MO) know exactly where we are heading post mid month, as I'm sure Ian F would confirm despite his very encouraging recent post re Mogreps. Let's just wait and see what the next few days bring, but I still see no reason not to view the 2nd half of winter in a much more positive light for cold.

Correct: timing and outcome uncertain. Just to also stress the 30d colder possibility is not based on the nearer-term MOGREPS signal (on another product).

[weather eater]

I would strongly recommend following the ensembles over the next few days for the 8+ day output. Already we see on the GFS 12Z a change to the NE with slightly higher heights. The trend is growing....

I have to say C with all respect, people have been following the Ens since late autumn and they have offered no more in the way of guidance than simply following the operational’s and using a little knowledge and some common sense, they chop, change and trend this way and that in much the same way, which is not surprising as they come from the same data, just tweaked. If over the years I had a tenner for every time this thread had been advised that the Ens would cast some light on the way ahead, only for the Ens to show nothing of the sort, I'd have accumulated a large pile of cash by now. The main problem for all modelling, is that the starting data is constantly changing, the Ens are supposed to help with that fact, but what you end up with is Bertie Bots every flavour of jelly bean, with little idea of which one isn’t poisoned, thus people on this thread just go with whatever most suits their preference, usually cold in winter because that’s what most of us are looking for. In terms of the tweaking there must be a set criteria for the way each perturbation is set, so with every new run with its change in data a corresponding pre-set change must be made to each ensemble run, therefore an ensemble spread can only be of real use when analysing the run that they were derived from, trying to put them in the context of several runs over several days in an attempt to look for trends is fraught with even more problems than attempting to find a trend in just the operational’s, this is because the greater number of perturbations the greater spread of possible outcomes, in other words spotting the correct trend can become like looking for a needle in a haystack, especially given that the chaotic nature of climate means that even when something looks to have wide support it still has a massive chance of not being the correct trend, in other words you may have a good cluster of members supporting a similar evolution but a single member with no support could conceivably be the correct call. I hope this make sense it does to me at least LOL

Edited January 4, 2014 by weather eater

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=188&y=177 (South West England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=312&y=141 (South-East England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=267&y=2 (Northern England)

 

The number of colder runs has increased fairly notably on the GEFS 12z, however as many have pointed out, the 850 temps do not reveal the real fact of the matter that there are many more runs which introduce blocking to our North East but do not quite advect the cold uppers westward. A great improvement indeed

Edited January 4, 2014 by Joe Levy

[gottolovethisweather]

I think you comment about balloon data is rather misleading-who/where says is not up to it's usual standards. Do you mean quality or quantity? If there is any problem you will read it on the NOAA site-not seen any comment.

 

There is a link somewhere on the NOAA site posted on netweather within the archives which suggests fewer balloons are released during the weekend period, hence I'm a believer in weekend runs having more wobbles than would be otherwise anticipated. Whether a few less observations have enough impact on the entire GEFS suite for example, would be up for debate. Back to the model discussion we better go, otherwise both of us will be in trouble, John. PM me for a chat if you wish.

Edited January 4, 2014 by gottolovethisweather

[phil nw.]

Continuing signs of a weakening jet as we look through the high resolution part of the 12z.

 

compare 06hrs with 192hrs.along with height anomalies-images from extra

 

 

 

signs of the split flow as it comes across the Atlantic as heights show up to our east.

A better looking GFS mean at T240hrs indicating those continental heights.

 

Nothing dramatic yet but if the 12z is considered a progressive run then these are promising indications that our current Atlantic pattern may be on the wane after next week.Small steps and all that.

 

 

[SMU]

http://modeles.meteociel.fr/modeles/reana/2001/archivesnh-2001-2-2-0-0.png

 

lets hope we don't end up here- unless you live in Shetland!S