Winter Model Discussion - The Hunt For Cold -12z 14/12/12

[Frosty.]

This may be be a little of topic Frosty but what your currents for the overall winter? starting to get feelings of deja vu?

A zonal mixture of mild and cold until at least mid jan but you should be asking someone like chio or gp about that. The stratospheric warming could mean a cold blocked pattern from around mid to late jan into feb but then a lot depends on where the blocking sets up, a warming strat alone won't guarantee a freeze for the uk even through jan/feb.

[Anti-Mild]

As I said in a post a couple of days ago, the state of the atmosphere is unusual to say the least, particularly wrt the computer age. As such, I expect the models to struggle hugely most of the winter. It may be that we will end up with a mild Christmas, but with FI being no further than +120, and given that we have had some correction south and west, I wouldn't be at all surprised to see further adjustments in that direction. It wouldn't take a huge adjustment to bring in colder air by the end of the week.

[The Eagle]

GME 72hrs. It's irritating how close we are really.

Edited December 17, 2012 by The Eagle

[nick sussex]

Interesting GME at 72hrs! stronger ridge to the ne and trough disruption occuring at that time.

Its only one of the smaller models but certainly welcome.

Lol, Eagle you must be a fan of the GME like me! If that output is replicated across the bigger models this place might start getting a little busier!

Edited December 17, 2012 by nick sussex

[OldMetMan]

I am continuing to be bemused by the bewildering variations in model output! Also, with each day it seems the reliable forecast time frame is shrinking!

The plain fact is, we have a cold air block just to our NE so inevitably approaching fronts are going to occlude and trough E or SE. This is one aspect which all the models seem to be having trouble with.

Furthermore, the jet is still below 50N and the northern stream is virtually non-existent, quite unusual. With this configuration, it's common in my experience for approaching LPs to not gain much latitude and to spiral off NW in the Atlantic and elongate as I said above by troughing. Also, each subsequent LP tends to do this ever further south as the cold block holds its ground.

One other factor that is, in my opinion not be properly addressed by the models is that the depth of cold air gradually creeping westwards is increasing with 498dm thicknesses starting to appear over Russia.This does not suggest it's will be going anywhere in a hurry!

I am most unimpressed by the model runs so far today because the synoptic development forecast from where we currently are simply does not look realistic, even in the fairly near term for reasons given above. So I'll see what later runs come up with. But it still makes for fascinating model watching!

[IDO]

Do you really think that's it's wise to make any kind of prediction for more than 72 hours in the future? Given the ongoing severe fluctuations in the model outputs only a fool would try and predict the weather for Christmas Day and beyond (it's still 8 days away you know).

When posters refer to an easterly around the 22nd they don't mean Siberian winds sweeping the nation and a deep freeze. In this case its a couple of days at best colder flow that will favour high lands and northern areas. The GEFS highlights this:

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=6&ville=Londres&runpara=0

About 33% of members go with sub-zero 850s but they are all only temporary (to degrees), before returning to average temps. Over 60% say no to the low drawing in a colder flow. Not one run by GFS recently has had any sustained cold, conversely the Atlantic breaks through each time.

Nothing is written in stone and weather can shift quickly, but nothing supportive at the moment and from past experience these synoptics can be a recurring nightmare for cold lovers.

[Buzz]

Yes I do, i'm not going to say it's looking cold because it's clearly not. I'm only saying what the models are showing and i'm not expecting anyone to like what i'm saying for obvious reasons but unless there is a major change, we are on course for a milder spell from later this week and well into next week.

I think that you're desperately trying to convince yourself (and others) that it will be mild to avoid any disappointment if the weather turns out that way. I should say at this point that I don't care if it's mild or cold, i just find model watching fascinating. However, as already mentioned, anyone who thinks that what the models are showing 8 days away is 'right' is .......... foolish.

Maybe it will be mild.

Maybe not.

However, uncomfortable as it may be for some, fence sitting is the best option at this stage.

[The Eagle]

Interesting GME at 72hrs! stronger ridge to the ne and trough disruption occuring at that time.

Its only one of the smaller models but certainly welcome.

Lol, Eagle you must be a fan of the GME like me! If that output is replicated across the bigger models this place might start getting a little busier!

Not sure we would get a direct undercut from there but it seems to be more the way we need to go and it's better than the 00z. Pitty there is no 96hrs anymore. It would be interesting to see. A slightly more positive run. I'd hope to see something a bit better from the 12z GFS and UKMO.

Also note across the models how the strength of the Iberian ridge is being chipped away bit by bit. Hope to see this continue but time is getting tight!

Edited December 17, 2012 by The Eagle

[Methuselah]

Maybe a chance of some wet snow, for a short while on Tuesday, as that front approaches from the SW?

[Frosty.]

I am most unimpressed by the model runs so far today because the synoptic development forecast from where we currently are simply does not look realistic, even in the fairly near term for reasons given above. So I'll see what later runs come up with. But it still makes for fascinating model watching!

So am I, but the metoffice with all the extra forecasting tools at their disposal are gunning for a mild or very mild spell for most of the uk apart from maybe the far north of scotland before and during christmas and unfortunately, the gfs 6z and ecm 00z concur, anything cold is in FI as usual. If the models do a massive turnaround I will be as happy as everyone else on here but I think straight talking and being realistic is better than hopecasting and missleading anyone.

I think that you're desperately trying to convince yourself (and others) that it will be mild to avoid any disappointment if the weather turns out that way. I should say at this point that I don't care if it's mild or cold, i just find model watching fascinating. However, as already mentioned, anyone who thinks that what the models are showing 8 days away is 'right' is .......... foolish.

Maybe it will be mild.

Maybe not.

However, uncomfortable as it may be for some, fence sitting is the best option at this stage.

No i'm being unbiased and trying to convey what the majority of the models are showing at this moment, and it's now within the range to speculate as christmas is getting very close.

[TEITS]

This is the area you want to keep an eye on.

Ideally the deeper this develops and the further S the better.

[LomondSnowstorm]

Laughable differences between the NAE and the GFS at +48:

NAE:

GFS:

[The Eagle]

96hrs is interesting. How close is this?

[snow drift]

T96 and it is very similar . With little going South of us.It is at this point when the cold backs East on previous runs and I see no reason why it won't again, sadly. Edited December 17, 2012 by snow drift

[Shunter]

96hrs is interesting. How close is this?

Just another 150 mile shift west and a lot of the UK is in for a cold shock on friday.

[-uksnow-]

T96 and it is very similar . With little going South of us.

Thats this mornings 6z for the 23rd, not T96...

[TEITS]

Looking at that NAE I feel we would see SW tracking further S than the GFS is suggesting.

Just looked at the GEFS members for my location and an increase in the number of colder runs.

http://cdn.nwstatic.co.uk/ensimages/ens.20121217/06/t850Cambridgeshire.png

Crazy difference at this timeframe.

[LomondSnowstorm]

T96 and it is very similar . With little going South of us.

That's the 6Z, looks quite a bit better on the 12Z:

[Tim Bland]

Does anyone know if the long range forecasts mentioned by Matt Hugo (EUROSIP / ECM 32 dayer etc) take into consideration Statosperic tempreatures and the effects on the PV?

PS have to laugh at the difference between the NAE and GFS at just 48hrs out. We really are no futher forward than we were 10 years ago when it comes to medium / long range forecasting

[nick sussex]

The GFS has a worser start but then flattens the Azores high more and this could still go either way especially as we may see another shortwave ejected. This drama still has some way to run.

Really we can't take anymore! just decide models please. Could be some major drama about to ensue!

If you get the shortwave energy splitting cleanly then something good may happen!

Edited December 17, 2012 by nick sussex

[TEITS]

Crazy difference between the 06/12Z.

http://modeles.meteo...fs-0-114.png?12

Someone go and squash that bloody Iberian HP!

Edited December 17, 2012 by THE EYE IN THE SKY

[The Eagle]

This is close to undercutting here

Good run so far. Leaves options.

[-uksnow-]

The differences between the 06 and 12z at just 114 are stark

12z...

06z

Much better 12z imo.

[BurwellWeatherWatch]

Looking at that NAE I feel we would see SW tracking further S than the GFS is suggesting.

Just looked at the GEFS members for my location and an increase in the number of colder runs.

http://cdn.nwstatic....bridgeshire.png

Crazy difference at this timeframe.

That's insane - at around day 5, 850s range from -7/8 to +10/11, and it doesn't seem to be one rogue run in either direction: have you ever seen that sort of spread within the so-called reliable timeframe/?

[Ian Brown]

Well this is rather different, the shortwave is ejected more SE, and HP is trying desperately to extend Westward from Scandinavia. But we still have that Iberian High preventing a better outcome.