Model Output Discussion

[Harsh Climate]

It's a bit marginal- but yes, somewhere would see severe snowfall on that chart. Probably a bit further north than you suggest with it falling as rain in the south.

Ye, shame the chances of this happening are very small

[mountain shadow]

I stand by what I said, it is a big wobble, the risk of this upcoming cold snap failing will increase due to the overall delay in tapping into the icy airmass. I think we have taken a step back since the 06z run.

What about the parallel run? Supposed to be new GFS which will handle short waves better then the op run which overdues things?

[Tim Bland]

The only positive if this run came off would be a short lived major snowfall for areas north of m4 and south of pennines. Paralel shows a topler i'm afraid. Lets hope ECM keeps the hope alive or I may have prematurely purchased a sledge today lol!

[Cecil Hogmanay Melchett]

Parallel shows the high toppling in early FI.

Watch the ecm suddenley jump back onboard.

[Mark Bayley]

Great GFS parallel

I don't think the GFS is all that bad. We still get the height rises to the north, unfortunately the cold is just delayed. At least it doesn't do what the parallel does in FI (which i highly doubt would happen!)

Lets see what the UKMO and the ECM come out with. A cold frosty spell is certain, cold snowy weather? Well its possible but not certain

Edited December 8, 2009 by mark bayley

[cooling climate]

It looks to me that the every shortwave and piece of vortex energy was thrown at the block

on the 06z GFS run and still we end up with a 1050 proper Greenland high.

The cold on this run is delayed by three days or so and is not quite as potent never the less

its still very cold and possibly exceptionally snowy.

The 06z operational may have overdone the lows etc going into the block and therefor I

think this run will come out on the milder side of the ensembles especially early on.

[snowmadchrisuk]

The only positive if this run came off would be a short lived major snowfall for areas north of m4 and south of pennines. Paralel shows a topler i'm afraid. Lets hope ECM keeps the hope alive or I may have prematurely purchased a sledge today lol!

I bet it does, Now gfs has decided to back down , ECM will come up with a belter of a run , it's all down to the model roller coaster im afraid .

[snowking]

I've got to say im suprised to come back to this sort of pessimism today, you didnt all go getting your hopes up that some of the Fi charts over the last 8 runs or so were definitely coming to fruition did you?

Two reasons for me as to why there shouldnt be this pessimism

1) MetO further outlook is shaping up quite nicely, im sure theres some people out there thinking hmmm it only says snow showers in the north and east....well the MetO are hardly going to be naive enough (unlike some of us here i fear) to try and predict a channel low 2 weeks away!

2) It will turn cold and dry! That is what has been progged all along. I've tried to keep my negative comments away from here as much as possible but some people really need to think back to november, and perhaps also the poor residents of cumbria who will be thankful for any sort of high pressure right about now - the fact that it will be a cool one with some long needed frosts and fog to cool the surface temps down a bit is a bonus. Classic example of this was last winter, thanks to the rather chilly spell before the snow arrived it settled rather easily quite widely

Also terrific news from the MJO as nick has pointed out.

I think perhaps everybody needs to take a step back from expecting a day after tomorrow type snow storm with every run and let us get the cool feed established initially - theres a whole winter ahead of us yet!

Kind Regards

Kris

[kold weather]

Saying that HD it hasn't moved closer to the ECM, the entire synoptic set-up is different but its far from moved closer, its just showing another possible evolution.

Long way to go yet guys but the GFS is a downgrade for the main part of the run but the synoptic evolution still looks pretty good to me!

Thats the key, the synoptic pattern...

Watch what the other models do with the shortwave between 96-120hrs, if it goes northwards then the 12z GFS will have back-up, if not then the 12z GFS maybe an outlier.

[karyo]

All eyes on the UKMO now...

[Geordiesnow]

If the parallel shows a shortlived easterly then that would suggest to me that nothing has changed and that the 06Z was OTT in it's set up. However it also shows that the set up can deliver if all the pieces fit together.

Unless you look at FI and believe it then you will find that any easterly on most runs has indeed been weak.

[NorthantsSnow]

What about the parallel run? Supposed to be new GFS which will handle short waves better then the op run which overdues things?

The parallel run gives us a brief but potent easterly shot before the high sinks and we get periods of cold zonality.

It's not a classic run by any means but would provide a significant snowfall event to Eastern Britain on the 17-18th.

[Shiny_Bottom_1]

Interesting that no-one seems to want to wait for the ensembles before making judgement

Whether ECM jumps on board or not, we have seen both situations occur.

I mentioned the other day that in the mid to long range it is an idea to watch correlation on the Air Pressure ensembles, which to be fair, have been quite scattered over the recent days.

[ChartViewer]

It looks to me that the every shortwave and piece of vortex energy was thrown at the block

on the 06z GFS run and still we end up with a 1050 proper Greenland high.

The cold on this run is delayed by three days or so and is not quite as potent never the less

its still very cold and possibly exceptionally snowy.

The 06z operational may have overdone the lows etc going into the block and therefor I

think this run will come out on the milder side of the ensembles especially early on.

Big big UKMO and Ecm tonight and 18z for that matter..However I have been trying to take a step

back, not look at every run on its own merit and try and compare like for like 12z to 12z etc...

What is completely mystifying to me is the 12z was the last of the 4 GFS Model runs to jump on board the Easterly train,

started being very progressive and now seems to have been the first to try to show a completely new

scenario....Which is why even at this stage things are still VERY much up in the air!

Regards

CV

Edited December 8, 2009 by ChartViewer

[weather eater]

Agreed KW.

The 12z operational is a big downgrade imo and has shifted to ecm a hell of a lot today.I had a feeling this was going to happen

so i cant say im too suprised.The pattern looks good for a spell of dry posibly frosty weather at times so

its not all bad.

I have to say hogwash, the 12z is certainly different from the 06z but its closer to that, than it is to the ECM 00z solution.

[kold weather]

As for the paralell...its a great run but it does really shunt the cold out the way very rapidly, but saying that we'd get another 1/2 Feb 2009 event on that run!

[Snowaddict]

Out to T+132, the 12Z GEFS Mean has the western flank of the main HP cell being advected into Greenland, with heights falling over Scandinavia.

By T+144, there is a mean easterly/northeasterly flow setting in over the British Isles.

Even if they are not great after this point, up to T+144, the mean ensemble agreement is excellent on the 12Z suite.

Edited December 8, 2009 by Snowaddict

[Hammer]

Gents, remember what the wise old posters say, don't follow every model run, unless you like rollercoaster of emotions.

It is far to easy to look at this GFS run, enter the word downgrade and be pessimistic then a whole flurry of similar posts detract from overall model outlook/trend.

The true talent is looking at what model run 06z, 12z etc is performing better at the moment and try to follow it.

For me the models are showing colder period coming up, the amount or frequenct of snow, is to worry about at a closer time.

[Mark Bayley]

When are the ECM and UKMO out?

UKMO is coming out now, ECM should be fully out by 19:00

[nick sussex]

So far this evening the gfs, gem and gme all disagree, the gem looks closer to earlier gfs runs.

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2009120812&field=Sea+Level+Pressure&hour=144hr

Still waiting on the ukmo but wouldn't be surprised if that's different too.

[weather eater]

As for the paralell...its a great run but it does really shunt the cold out the way very rapidly, but saying that we'd get another 1/2 Feb 2009 event on that run!

In terms of the parallel, the sinking high happens in FI and that will change several times over the next few days. The important bit is that it sticks with a similar evolution at the start of its run and develops an easterly; the rest is just so much pie in the sky.

[Snowaddict]

12Z GEFS Suite:

Excellent Control Run with a significant easterly by T+168 (Building blocks established firmly at T+132-T+144)

Rock solid support for an easterly/northeasterly evolution with a significant area of positive height anomolies cented to the far northwest of the British Isles.

Edited December 8, 2009 by Snowaddict

[Barb]

The thing people need to remember is that at this range we should be looking for POTENTIAL - looking at the big picture and looking at the trends and trying to find potential in them. If you pick a chart in FI and base all your hopes on it happening as showed then you will be dissapointed every time. It's the potential that matters and there is still LOADS of potential in these charts. Now if there's massive conclusive agreements among all the models for just 2-3 days away, THEN get excited. Til then, it's just trend and potential watching.

[NorthantsSnow]

Interesting that no-one seems to want to wait for the ensembles before making judgement

The ensembles mean less when there is a sudden gear change in the operationals IMO. There seems to be a delay in the OP run spotting something new and the ensembles reacting to it. If we have a few more operationals akin to tonight's 12z, then I would expect to see the ensembles follow suit soon after.

[Mark Bayley]

Well the GEFS ensembles are excellent!

Edited December 8, 2009 by mark bayley