Model Output Discussion 5/12/2012 18Z onwards - the one after THAT ECM

[Frosty.]

The experts have no confidence of next week's pattern

They must have some confidence because the evidence is overwhelming for a very wintry outlook and we are now entering the semi reliable timeframe. Excellent model output from the 00z, a much colder outlook is nailed but the issues to resolve will be who gets most snow from all this, we will all have severe frosts.

[joggs]

It will be very interesting which ever way it goes re the weather, and what timing the met office goes with it or against it.For what the models are showing atm they must think there are doubts about the situation or dont want to end up with egg on their face, which you cant blame them. But been 4/5 days off i would of thought more detail would be shown either way. And thats not me having a go at the met o JH.

[BLAST FROM THE PAST]

There is a major fly in the ointment developing, and that is the LP developing over the low countries/Germany. This happened before and prevented the coldest air advecting west. I see this development overnight as a concern as it will cut the block off and leave the door open to attacks from the SW.

BFTP

[Ice BIast]

So great runs this morning. However, comparing the ECM to yesterdays 12Z, the high over western Russia is further south, which means that any easterly would be sourced from a more SErly direction. Also, the troughing over Europe is getting modelled further North every run, and we don't want it to be any further north than it is as it would prevent an Easterly airflow and also disrupt the Scandi high.

Edited December 6, 2012 by lce Blast

[Iceberg]

The experts will have confidence in some aspects of next week, i.e bloody cold and an easterly, but they wont have any detail as to precipitation and feature locations.

This is a light hearted comment, i don't think we should be paying a great deal of attention to flies too far off in the distance as this will change massively , lows coming up to hit the south is always a welcome possibility imo and we have to remember that i cant remember a time when the models havent been too quick to break down a cold spell such as the one forecasted. I would always add 48 hrs on to any breakdown shown(not that one is with any consistence or ens support.

sorry to add, the meto are quite rightly concentrating all press and efforts tot he weather over the next 2 days which could cause real problems, anything for next week will be left until after this has been done, simply so the message isnt confused.

[Paul_1978]

We are often told not to look further than T+144.

This morning everything looks good until at least T+192. Everything after that subject to change, and maybe for the better.

That'll do me.

[Frosty.]

I have seen enough evidence from the 00z and previously to safely say we are going to have a very cold blocked outlook, and it's bitterly cold this morning as well infact, the outlook appears to be getting snowier than earlier thought.

[Mark Bayley]

I have seen enough evidence from the 00z and previously to safely say we are going to have a very cold blocked outlook, and it's bitterly cold this morning as well infact, the outlook appears to be getting snowier than earlier thought.

I agree, ensemble means are definitely firming up on height rises over Greenland with the PV transferring into the Siberia region. Although they do show an increasing risk of attack from the South West, not always a bad thing though, especially if it turns out like the GEFS control run!

(12z)

http://www.meteociel...&carte=0&mode=0

In the medium term the cold remains, with some great snow potential, especially on the later stages of the ECM

Edited December 6, 2012 by Mark Bayley

[Continental Climate]

So a downgrade from the ECM this morning!!! But hey wasnt it always going to be? No way could it have bettered last nites 12z and in terms of downgrades its certainly not colossal!! We still have an easterly flow from 96 http://www.wetterzen...ics/Recm961.gif!! until 192 http://www.wetterzen...cs/Recm1921.gif!! Who is to say that it will even breakdown at all at 216 or 240 as that is deep into fi!!

Lets just get the easterly in place first people lets concentrate between 72 and 120 and worry about the breakdown later!! I personally think that as the vortex displaces to the siberian sector this will give greater likelihood of greenie rises which will pull down much colder air than we can tap into at present, so loads to look forward to folks!!

GFS also has blocking to our north pretty much throughout the run which is a bit special!!

UKMO is also better

Edited December 6, 2012 by Continental Climate

[Captain Shortwave]

Good runs again, actually something did catch my eye for tomorrow morning, looks like there is a chance of a short(ish) spell of heavy snow running down the north sea which looks to affect East Anglia and possibly the london area during the morning rush hour.

Also you know the met are having difficulty when the bbc don't update their five day forecasts (monday aka day 5 still has the estimates up), I see this as a good sign as well if this cold spell was supposed to be short lived and not that bad then i'm sure the met office would punt for it. There is obviously something very nasty which could happen in their minds so care must be used as to forecast snowmagedden would be unwise if the charts go tits up.

[nick sussex]

As that wonderful old Etta James song goes At Last.........

At last we have operational model agreement on the shortwave, thereafter the ECM looks very similar to yesterday mornings 00hrs with an Atlantic attack from the sw.

Of course the detail of its later output will change but it produces synoptics similar to what you see over in the eastern USA with those Nor'easters.

A Major Winter Event would brew with the ECM as that low tracks ne, milder air to the se igniting lots of energy so some unbelievable snow totals on the western flank.

However that was just for fun, it probably isn't going to show the same thing tonight!

All the models look like they will want to bring in some form of Atlantic attack but the angle of approach is uncertain.

Overall then good agreement on the shortwave, lots of uncertainty afterwards.

[chionomaniac]

"Final piece of crucial wisdom in MR guidance just issued from Exeter: "...confidence in developments from Monday onwards remains very low....". Having seen their full analysis this caveat sentence is, rest assured, well founded: they're leaning towards EC with latest modifications but let's see where the next few EC runs take us to offer better continuity on some critical nuances Exeter highlight versus UKMO-GM and MOGREPS.

That was from Ian Fergusson late last night. The experts have no confidence of next week's pattern, so even though the models have been showing consistency, they obviously have data that suggests this is not cut and dry. It was suggested that the weekend may be the earliest they use "Easterly" in their media output. We are gonna have to look for trends in the next 48 hours and at the moment we need ECM to stay on track for their next four runs and not waver like GFS. Thats not to say that even if the Easterly is a short affair, what follows would eventually not be cold as well.

I read that completely differently, ido. They are favouring the ECM but are exercising caution - rightly so in their position. And the nuances with the ukmo run may be less of an issue this morning.

[chionomaniac]

Looking at the GFS 00Z 850 ensembles there are only two members not 'on board' the cold train.

And the op is one of the milder options in FI

Edited December 6, 2012 by chionomaniac

[TEITS]

Pleased to say little change overall from the model output.

The intial E,ly looks very likely now but what type of E,ly remains unsolved. I see two options, one LP remains to the S of the UK and tracks E along the Med maintaining a bitter cold, convective E,ly or the other option is LP moves NE from the SW and possibly brings a big snow event.

One possible outcome in the longer term is shown on the GEFS control and follows what the likes of CH, GP have been suggesting.

The PV moving into Siberia continues to be suggested by the models which makes the GEFS control a plausible outlook.

Overall plenty to be excited about this morning.

[Iceberg]

thats pretty much how i read it chino as well, when the gfs ens members hit their lower res they start popping like pop corn upwards, but only a few at a time.

No real confidence in any of the solutions as each one probably developsa different low pressure system but totally expected a few of them out of 20 will want to introduce the atlantic influence(too quickly) after 200+

When we see even a a small cluster of the ens trying to follow a similar pattern, i'll sit up and take note.

[EML Network]

A word of caution among the excitement, the UKMO (which let's face it, NEVER wants to give us a nice chart at + 144) doesn't look all that good to me.... it could be a lot worse and It does have potential, but if that Low Pressure system retrogrades NW instead of W , we would end up being back in cold zonality before an Easterly ever gets the chance to even get going

UKMO + 144

[nick sussex]

I certainly would be cautious in reading too much into the output once the PV starts moving back to Siberia, this is likely to cause chaos in the models.

[bradymk]

My run of the 00z's goes to the GFS control. The PV moving into Siberia after the easterly with lots of snow throughout the run. GH sets up once the PV is in Siberia and this is what I really hope and think could happen following the easterly. Maybe a slight atlantic influence for a time.

[Nick F]

There is a major fly in the ointment developing, and that is the LP developing over the low countries/Germany. This happened before and prevented the coldest air advecting west. I see this development overnight as a concern as it will cut the block off and leave the door open to attacks from the SW.

BFTP

I don't see it as a fly in the ointment, in fact, I think it would help in producing snowfall as the associated fronts drift west towards the UK.

Looking at the 500mb level on the 00z ECM, I can see a upper low/cold pool spreading west across the UK and NW Europe, This will hopefully keep an attack from the SW at bay across SW Europe.

All in all, overall theme is for blocking to develop to our N/NE and for cold air to advect west across the UK, how cold the uppers get still to be decided and how much precip and how marginal it will be wrt snow/rain still TBA.

[Rob K]

Based on GFS FI trends over the past couple of runs I could actually see a Dec 2010 style event later in the month with a big Greenland High and the PV dropping down over us. Given that hadn't happened in 55 years before 2010, to have it occur again after two years would be pretty rare, but the general pattern certainly makes it possible.

In he meantime, ECM on the face of it may look like a downgrade but those charts would bury much of the country in snow.

[Wilxy]

Its going to be a intresting day model wise, the trend overnight, has shown the block slightly further west, but the low decides to come NW instead of W over germany, something to watch out for today.

Edited December 6, 2012 by TomW

[Snowy Easterlies]

http://www.meteociel...1-144.GIF?06-12

Edited December 6, 2012 by Snowy Easterlies

[JCP]

A word of caution among the excitement, the UKMO (which let's face it, NEVER wants to give us a nice chart at + 144) doesn't look all that good to me.... it could be a lot worse and It does have potential, but if that Low Pressure system retrogrades NW instead of W , we would end up being back in cold zonality before an Easterly ever gets the chance to even get going

UKMO + 144

That's the GEM though ?

[Frosty.]

The Gfs 00z looks fantastic for a very wintry spell until well into FI and increasingly snowy, early in the cold spell it looks like snow showers would be mostly coastal but some would spread inland but it would be very cold with persistent frosts and a high windchill as that easterly has a sharp cutting edge, as pressure falls, we would have a potent mix of unstable air and increased snowfalls, later in FI turns milder and messy but some incredible cold being bottled up to the north and i'm not concerned about what an op run shows at T+300 onwards.

The models have a general grasp on next week but lots more fine tuning to come.

[chionomaniac]

Hi all - I think that in between the model runs we should all try and keep on topic and the thread relevent - obviously during the runs like last nights ECM we will cut some slack - but otherwise please keep on topic.

Thanks.