Model Output Discussion: 12Z (02/12/12) And On...

[Continental Climate]

Im going to be a bit of a stick in the mud and say that the only problem with this dream chart is that the truly brutal cold has to travel a lot further round the monstrous high in order to reach us http://www.meteociel.fr/modeles/ecmwf/runs/2012120212/ECH1-240.GIF?02-0!! Look at the size of that thing!!

[AWD]

Those last 3 frames of the ECM would provide the south with a respectable amount of snowfall.

The difficult bit is getting these charts into the reliable timeframe. Nice to see the GFS & ECM on course with the broad basics of things, and that's height rises to our NE.

[Isolated Frost]

I would also like the 850hPa temps to be 2 or 3c colder please!

Great synoptic from the ECM.

I think that is good enough for widespread snow showers on all east-facing coasts, and a very strong flow means that it should penetrate further inland-

[shotski]

Those last 3 frames of the ECM would provide the south with a respectable amount of snowfall.

The difficult bit is getting these charts into the reliable timeframe. Nice to see the GFS & ECM on course with the broad basics of things, and that's height rises to our NE.

Also the UKMO going for this with a strong block to our northeast

[ukpaul]

The ridge to Greenland would merge with the Scandi high giving an easterly.

In time the PV is expected to shift over to Siberia away from Canada allowing the Scandi high to retrogress to Greenland for a northerly. Shades of 2010.

I think, with the way things are set up, any GH earlier makes things more difficult down the line. Better to have something transitory brushing through south and east Greenland which then allows for the Scandi High which, retrogressing, will be more long lasting.

In the strat thread, with the current set up, there have been suggestions that Dec 20th and on could see the effect of what is currently happening. The ECM would be a really nice way of passing the time until then!

[bluearmy]

Cant believe i missed that run comng out. Anyway, whilst all of you are looking at that day 10 chart and thinking 'if only', i'm looking towards the urals and watching the A road from this mornings suite having been widened to a dual carriageway on the 12z op. lets hope it can be made into a motorway before the austerity measures of model verification cut it off!

I was a bit upset that steve missed it this morning. Hopefully he will spot it this evening.

[nick sussex]

Greenland High starting to set at 240h?

Yes that looks like the next step.

A Greenland high after an easterly is often a good sign that the cold is likely to be long lasting as the NH pattern is primed for more cold outbreaks in Europe.

[kold weather]

I'm afraid that's complete tosh Kold.

I presume you wouldn't see a cold spell coming from this chart either then

http://www.wetterzen...00119470118.gif

A long time ago but BIG differences between that and the UKMO.

1: Notice the angle of the low in the Atlantic, the fact is the flow is already going meridonal there, as evidenced by that small cutoff low and the lower heights down there. In the Atlantic on the 12z UKMO the heights are angled W-E in the Atlantic, thats a sure sign that the jet on that run is running flatter across the Atlantic.

2: The angle of that ridge in the Atlantic in 1947 is already showing a big hint of where it wants to go and importantly there is already a low down to its SW that is going to help prop it up. The ridging that is present on the UKMO is angled in such a way that the Atlantic is going to leave a little upper high probably near Greenland but with an unfavourable Atlantic (seemed to happen alot in the 1970s I notice)

It could evolve into a cold spell but its going the LONG way round and probably wouls lead to a watered down rather poor attempt. I can see a cold spell on the 1947 chart because there ARE hints there, the shape of the highs, the little features. On the UKMO run its a real long shot and requires a lot of luck for things to fall into place. That run WILL be one of its "milder" groupings that Ian mentioned earlier from the UKMO discussion.

See 12z ECM as a safer and stronger way of doing the job!

Edited December 2, 2012 by kold weather

[Tim Bland]

I'm surprised there's not much talk about the short term. Latest fax has front slipping south in 72 hrs time in sub 528 dam, could give a covering? Anyone see country fille? I know it's off topic but what were the pressure charts used for the end of the week?

http://www.meteociel.fr/modeles/ukmo2.php?ech=72&carte=2000

[cooling climate]

Intially no we won't see a GH. However if the E,ly does occur then in my opinion from mid month onwards we could see the block over Scandi transferring W towards Greenland as the PV backs further W.

I don't wish to ramp but we could be on the cusp of something very special developing here!!

Looking at the ECM t240 chart (which is excellent) you could easily see that happening

plus if the ECM went out another 3 days I think you would see a very strong easterly

airflow developing with widespread heavy snow showers being blown along on strong to

gale force eastery winds.

Excellent run.

[Ice BIast]

Great run from the ECM, and with the PV starting to weaken and edge away from greenland at T240, that high wouldn't be going anywhere, except perhaps up to greenland down the line.

My only criticism of the run is that if would be nice if there was a bigger cold pool to the east.

Edited December 2, 2012 by lce Blast

[Cloud 10]

The 12z ECM operational run is a good match for its earlier 00z ensemble mean at 240 hrs

which is very encouraging to see.

12z ecm.. 00z ens mean..

On the other hand,this is what the operational was predicting 10 days ago for today!

10 days ago.. today..

[Thundery wintry showers]

I have to admit that when I first saw this evening's UKMO 12Z run I had similar feelings to Kold, but when considering the way the pattern evolves, it was similar to how this morning's ECMWF 00Z evolved (as a couple of other members mentioned)- a rather more dicey evolution towards a potential return of cold wintry weather with the low pressure systems further north, but by no means a likely evolution into something mild.

In essence there are three low pressure systems to watch out for over the next week, all set to dive NW-SE, and their precise positioning will be critical for whether we pick up cold enough airmasses from the north, and eventually north-east, to bring widespread snowfall. The first of these lows comes in tomorrow, and will bring us a chilly northerly flow on Tuesday and Wednesday with some embedded troughs possibly sending wintry showers a fair way inland from the North Sea, albeit with marginal temperatures. I think this low is pretty much "finalised" and that any changes to the outlook up until Wednesday will now be minor.

The second low is set to come in during Thursday/Friday and this will probably generate some headaches due to being a fair way out. This will bring rain at low levels, perhaps with some snow on the eastern flank of the system, but again it may bring wintry showers into eastern areas in the northerly flow behind the system.

The real forecasters' headache though is the low pressure system for next weekend. This low is progged by both GFS and ECMWF to bring a northerly outbreak followed by a north-east to easterly type as the low retreats SE, and this would bring a mix of sunshine and showers with a wintry mix next to windward coasts and falling/lying snow inland, but if the low ends up further north (as shown by tonight's UKMO and this morning's ECMWF run) then snowy potential may be rather more limited and we may not see the sinker allowing the north-easterly type to establish with high pressure from Iceland across to Scandinavia.

Having discussed snow potential, also significant is the concern over future flooding resulting from active precipitation belts from the low pressure systems. On the whole, it doesn't look like there will be any excessive deluges over the coming week, but the second and third low pressure systems are associated with considerable uncertainty and so the possibility of the "at-risk" areas being hit by further persistent deluges cannot yet be ruled out.

[Isolated Frost]

I would also like the 850hPa temps to be 2 or 3c colder please!

Great synoptic from the ECM.

I think that is good enough for widespread snow showers on all east-facing coasts, and a very strong flow means that it should penetrate further inland-

[bluearmy]

I'm surprised there's not much talk about the short term. Latest fax has front slipping south in 72 hrs time in sub 528 dam, could give a covering?

And did you also notice the warm sector removed on the shortwave following ?

[Ice BIast]

The JMA certainly looks different to the ECM, but isn't bad by any means.

[bobbydog]

yes in 2 main points...

1) 'Poor run' as in a output run where after a certain timescale the output predicts implausible synoptic patterns when compared with most recent output snapshot i.e the output at, for example, T144 bares absolutely no relation to the predicted synoptic patters at T132, in essence, possible data errors lead the subsequent output 'up the garden path'

or, based on what we normally see in this thread

2) 'Poor run' as in an output run when the predicted synoptic pattern DOES NOT meet the requirements for the originating posters favourite type of weather!

unfortunately, 99.9% of the use of the word "poor" is for reason 2......

[Zenarcher]

Looks like Scotland and Northern England on Monday will see some snow and the country file forecasts back this up as well. Tuesday scattered showers around with some wintry ones in Northern Scotland and on Wednesday Eastern Scotland and North Eastern England may see some wintry showers. Thursday mainly dry but wet across the North and snow in the highlands. Friday mainly dry but a cold strong North Westerly wind that could give some wintry showers in parts of Southern Scotland and South East England.

Onto the models, they seem to have a better idea on these Atlantic lows and over the past 24 hours we have seen a better trend for mid December occur at the moment it's looking like a blocked cold trend which is great to see.

[Ice BIast]

I think that is good enough for widespread snow showers on all east-facing coasts

Not for where I live LOL. -8 uppers at least for snow here, possibly colder as its December and the seas are still warm. Despite this, the details aren't worth worrying about yet.

[cooling climate]

The ECM t240 chart really is something to look at. You have high pressure

covering an area from the tip of Greenland right round to almost the bering

straits.

I do remember reading somewhere that one of the reasons for the bitter winter

of 62/63 was the size of the Siberian high. Well this year considering we are

only into the beginning of December the Siberian high is simply humungus.

This really could be a winter to remember.

Edited December 2, 2012 by cooling climate

[stewfox]

Oh the ECM has changed it tune from the earlier run. The cold sets back in.

Its one run at 168 hours and I am sure its going to change its 'tune' again. The ones that say "your just too good to be true" seems to hardly ever verify.

I have also seen comments such as "models that are changing from run to run" thank god for that or we would have April pinned already .

My understanding is we have T144 fairly pinned and beyond that short wave developments making it harder to pin anything in stone.

I can watch to see if the LP pushing SE, post T144 thats what i will look for and treat operational runs at T240 as fun but hardly as others have said have they been spot on or even close.

[Jason H]

The ECM t240 chart really is something to look at. You have high pressure

covering an area from the tip of Greenland right round to almost the bering

straits.

I do remember reading somewhere that one of the reasons for the bitter winter

of 62/63 was the size of the Siberian high. Well this year considering we are

only into the beginning of December the Siberian high is simply humungus.

This really could be a winter to remember.

Wow rampaging ramping.

I know you're only commenting on one chart out at the edge of the suite, just hope that most other people reading this know that charts like this very rarely verify. Winters like 62/63 are more rare than hens teeth.

[Paul_1978]

On the other hand,this is what the operational was predicting 10 days ago for today!

And therein lies the lesson. Very sensible to point this out. We'll just have to keep our fingers crossed that these charts get nearer as the week progresses.

[Neilsouth]

Actually apologies it is slightly under the GFS last month when looking at the big three. ECM the leader by a way.

but as ever short term past performance is no indicator of future performance - the more reliable long term performance is bettter here.

Appology accepted, I thought the fact they put new computer system's in place or atleast worked on the modeling alot better it would improve?, why is it behind the GFS and ECM now?

[chionomaniac]

Appology accepted, I thought the fact they put new computer system's in place or atleast worked on the modeling alot better it would improve?, why is it behind the GFS and ECM now?

In running terms the ukmo has had 1 poor circuit around the track in the 10,000m.

That leaves the other 9600m where it is performing well.