Model Output Discussion 25/11/2012 12Z onwards

[The Eagle]

Can't post images but if one looks at UKMO T72 to T120, a quite deep low gets squeezed to nothing and the ATlantic ridge moves north getting absorbed into the arctic HP. I have to say it looks not right and thus makes the ECM plausible and a worry re depth of cold and longevity.

BFTP

Yeah it's too neat and fragile almost. Does not take much of a leap of the imagination to see the LP to the southwest of GL getting through and flattening everything.

http://www.meteociel...20-21.GIF?25-18

Having said that there is still a chance so long as some model runs are backing the much colder blocked outcome. It's just less than 50/50 now. Every run critical now including 18z.

Edited November 25, 2012 by The Eagle

[Jonan92]

Its always interesting how we will always regard milder weather as somewhat more valid in terms of charts than colder weather. Yesterday we had the GFS vs the ECM and UKMO and the majority of minor models (even though it has been said many a time on here that these models are unreliable). And yet many cautioned people on "not ruling out" what this one chart was showing, despite its utter difference to the other models.

Skip forward to today and despite the fact that these same models are showing cold, and, particularly the UKMO, have been very consistent, many are happy to write off the cold spell and take the ECM as gospel. Now, I may have been looking at the wrong thread, but has the general trend over the past, oh I don't know, week or so been for colder than average weather? Why all of a sudden does an unprecedented switch that has emerged in the past number of hours mean it is undeniable fact and that all hopes of a nice cold spell, which is still on, btw, have evaporated?

Now, I know this might fall on deaf ears, but can we please not make overly sweeping statements like "bitter disappointment" and "its all over" BEFORE we see proper consistency from all models, you know, like the consistency that we have seen for cold weather in the last week or so.

Thanks.

People are trashing the cold spell of the next week, not the whole winter

[Chess01]

People need to chill . Yes most of the models show different but its only being today that they have being doing this. If they show the same in 2 days then be worried . I take it as just a wobble like the gfs has had nut these models are a day later . Just cant see it playing out the way most of the models are showing . Everythings to progresive and looks too easy to break down with the current conditions

[bradymk]

I might sound a bit repetitive here but even with the ECM and a few other models not on the cold side this evening, imo we still have the most important people on board at the moment and that is the professional people at the MetOffice. Plus countryfile forecast for end of the week showed the low not progressing eastwards so who knows what is going to happen to that low. A nervous 96 hours or so though. Hoping the fax charts stay with the raw output which i think they will but once again, more runs needed.

[shotski]

Can't post images but if one looks at UKMO T72 to T120, a quite deep low gets squeezed to nothing and the ATlantic ridge moves north getting absorbed into the arctic HP. I have to say it looks not right and thus makes the ECM plausible and a worry re depth of cold and longevity.

BFTP

Looking back the evolution from T96 to T120 just looks wrong as that deep low just gets zapped.

[Weather-history]

- incredible how the weather can make fools of us.

It certainly can, I mean some people only 3 years ago were saying northerly block was impossible during winter.

From what I can see with ECM is that it models a piece of the PV across the North Atlantic into Scandinavia. Will that happen? Well we will have to see.

[Methuselah]

Any chance of some model-discussion?

[Frosty.]

But the ECM does also have massive support, JMA now added to the list.

I agree with the previous post, we need to be prepared for a 'Crushing disappointment'

I'm very pleased I kept an open mind.

Yes but Dexter, there is also still a lot of support for a wintry outlook from gfs and ukmo model plus uk met office and several experts on here are still onboard. On balance, I still think we are in for a cold outlook but it looks like a bit of a wobbly start before the block makes a more definate move southwestwards towards next weekend, in the meantime, it will be trending cooler anyway with a cooler northerly flow and some showers which look more wintry in the east after midweek.

[weatherguy]

Anyone else remember those height anomaly charts posted a few days ago? That's why I'm sceptical about zonality. This attempt may fail, but blocking should soon re-establish itself, giving us another shot.

[Harsh Climate]

This is why the ECM at 144h will not be proven right, I put my bottom dollar on this! In a negative AO/NAO depressions sweep over the block not straight through them!!

The ECM tonight is a kin to a POSITIVE NAO/AO.

.

Anyone with an IQ above..... Say 2, know's that this isn't going to happen with an AO/NAO of -2/-3.

Look at the clumping in the perpetrations (AO/NAO), very good agreement.

http://www.cpc.ncep....a/nao.sprd2.gif

http://www.cpc.ncep....dex/ao.fcst.gif .

A smart man would look at the bigger picture, the 'telleconections' rather than a single run rolling out during pantomine hour

Edited November 25, 2012 by Harsh Climate

[Karl83]

Noob question here - As per the GFS, what would cause that Canadian Low to vanish? The block is strong?

[PubliusEnigma]

The JMA 12z has backed up the ECM and gone the same way,

[The PIT]

Waiting for the ECM to be trashed as an unreliable model. Deep FI showing a cool zonal flow which is better than nothing I suppose. Now if the other models latch onto this next run then you'll know it's picked something up. So more model watching in order.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

CPTEC still looking good

[Summer Sun]

Before we can begin to think about a cold spell there is some further heavy rain coming tomorrow for, North East England, North Wales, Devon, Yorkshire & Humberside with flooding likely for these parts

We are looking at 50mm to 70mm for parts of North Yorkshire, Hartlepool and Middlesbrough, with up-to 90mm for high ground in North wales 50mm to 70mm for lower parts, Devon could see a further 20mm in places

By later this evening the rain gets going in the west

Into tomorrow morning and it moves in to the north east and Yorkshire

By lunchtime its still in the same parts

By Monday night its still in the same areas but turning lighter

Into Tuesday theirs some respite for the flood hit areas with the rain moving away slowly but surely

By Wednesday its a much better picture with sunshine replacing the rain giving places a chance to dry out

By the weekend wintry showers are possible as things turn much colder

Edited November 25, 2012 by Gavin.

[MR EXTREMES]

funny that pressure on the gefs in greenland rises and falls twice theres plenty of scatter for lower pressure.

but in oslo pressure seems on the up so its not the be all of end all.

i could be wrong with what ive wrote but i still strongly believe cold will win out good to see north east and central eastern europe getting much colder.

http://www.netweather.tv/index.cgi?action=ensviewer;sess=

[Mark Neal.]

Noob question here - As per the GFS, what would cause that Canadian Low to vanish? The block is strong?

Also worth me asking; has the low developed yet or is there a high possibility that it doesn't at all, is it a vital cog in getting the cold conditions to us in the long term by having the waa heading upto towards Greenland, sorry if my question sounds stupid, just something i was wanting to know

[weather eater]

What would actually be surprising is if we get to the morning and the ECM, BOM, JMA, GEM AND NOGAPS are still supporting this evolution, now that would be a trend.

And can we skip the melodrama, try thinking of yourself as a pretty healthy, lifelong non-smoker who goes to the hospital to be told the lump in his neck is cancer, now that is a shattering experience, an evening of realising that your dreams of cold and snow may not be just around the corner is not a shattering experience or a crushing one either.

[swilliam]

I must say there are some rather silly posts on here tonight; talking about how can the ECM be so far out, saying it is a battle between ECM + minors agsinst GFS/UKMO and depending on the outcome one is right and the other wrong etc.

There are two basic solutions for the period t120-144. One is that we have extensive blocking to our N and a cold solution for a protracted period (i.e. GFS/UKMO). In this case the Canadian low goes N/NW up the W coast of Greenland and does not send enough energy eastwards to break the Atlantic ridge.

Eventually this minor remnant energy moves SE as a potenial slider.

The other is that the Canadian low sends energy eastwards and does not go up the W of Greenland - a small difference in positioning of this low.

This energy then breaks the link between the Atlantic ridge and the N blocking. The result of this is the Atlantic ridge falls over and the energy from, and substantial remnants of, the Candian low link up with euro low and we end up with mildsih westerly winds over us. Blocking and splitting vortex remain to the N but we loose the blocking in our immediate vicinity (only).

Thereafter there is the possibility of blocking reestablishing near to us.

The differences between these two solutions is very small and therefore marginal but the consequences for our weather >t144 is massive. So whichever way it goes (and no-one knows at present) does not mean one model got it hugely wrong or right - both options are quite plausibe at present - further small changes will determine which way it goes. These two solutions have been showing on the ensembles in the last few runs and on one or two of the GFS ops (when it was derided).

Some less hysterical or emotional posting would make this thread rather more enjoyable.

[Ian Brown]

Can't post images but if one looks at UKMO T72 to T120, a quite deep low gets squeezed to nothing and the ATlantic ridge moves north getting absorbed into the arctic HP. I have to say it looks not right and thus makes the ECM plausible and a worry re depth of cold and longevity.

BFTP

Yes, if you were asked to predict where it would go at about T72/96 you would go for the ECM route.

Obviously the METO have made their outlook which may be subject to a sudden reversal tomorrow. We need to see the ECM ensembles, but we already have ( I think) all the minor models on their side as well as some GFS ensemble members.

The real shame is that as I said it is an all or nothing, it is not as if it is failed Northerly or failed Easterly, where you can have another go a few days later; once the Arctic High has failed the Azores High has won, it's the nature of the beast.

[CHOCOBLUE]

Anybody got the times that the fax charts come out?

[Ian Brown]

This is why the ECM at 144h will not be proven right, I put my bottom dollar on this! In a negative AO/NAO depressions sweep over the block not straight through them!!

The ECM tonight is a kin to a POSITIVE NAO/AO.

.

Anyone with an IQ above..... Say 2, know's that this isn't going to happen with an AO/NAO of -2/-3.

Look at the clumping in the perpetrations (AO/NAO), very good agreement.

http://www.cpc.ncep....a/nao.sprd2.gif

http://www.cpc.ncep....dex/ao.fcst.gif .

A smart man would look at the bigger picture, the 'telleconections' rather than a single run rolling out during pantomine hour

The AO/NAO forecasts are only reflective of the general NWP. The models change then so do these.

[SMU]

Anybody got the times that the fax charts come out?

The UKMO will not follow the ECM with the 120 Fax chart- 99% sure of that

S

[Frosty.]

There has been a frankly ridiculous over reaction about the ecm, its only 1 op run, is the ukmo suddenly useless? and what about the uk met office update, will 1 ecm op run trash their outlook tomorrow?

[johnholmes]

Anyone else remember those height anomaly charts posted a few days ago? That's why I'm sceptical about zonality. This attempt may fail, but blocking should soon re-establish itself, giving us another shot.

see my pdf on page 10 post 189 a pile of 'em in there?