Model Output Discussion - 30th November onwards

[Yarmy]

I have not got access to the ECM postage stamps and probably not allowed to post tweets so i am rehashing what Matt Hugo said re the ECM Members.

 

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At T240 only 7 out of 51 support a Scandi High/Easterly. (This ties in with the ECM mean at the same time.)

 

However by D11-D15 27 members now support the Scandi/easterly.

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So ECM seeing a settled period with a SW flow but their long term trends towards heights in the NE/N. See if any of the other models go that way.

 

I think the ECM postage stamps have been withdrawn from public consumption. Someone correct me if I'm wrong.

 

I recall last year 41 of the 51 supported the Easterly at a much closer timeframe. We aren't going to go through all this again, are we? 

[Weather Boy]

The unfortunate realisation this morning that this severe cold spell with uppers below -10 has once again been watered down considerately , deep cold for one day , we should learn massive lessons from this , and those chasing deep cold at 240z on the ECM should think realistically if it's actually gonna happen ?The models still haven't got it right for 4 days time , so the chance of them getting it right for 10 days time is very very slim .Everyone backing the ECM but in reality it's backed right off the cold weather , it's gone from 4 days cold spell , to one day , the snow will be in Scotland , and maybe through western areas , with a few through the Cheshire gap , but nothing to get excited about .The gfs has been to progressive as always , but the ECM has been far to amplified .I think the scandi ridge will set up shop , but if I had to make a shout I would say we will be too far west , and more likely to have extremely mild southerly winds rather than cold easterlies .I hope I'm wrong I really do , I love snow as much as anyone but I'm not gonna be unrealistic again , and previous years Iv had my snow blinkers on all winter only to be let down time and again so to save disappointment it's best to look realistically at the models .

 

I don't follow every run, or even get close, TBH, as often it's only necessary to look at these posts to get a picture.  However, I think that some of the posts regarding the ECM are harsh.  It was never solidly behind anything other than a brief cold snap, which is what is going to happen.  It briefly toyed with a longer cold spell and/or reload, but that's what models do, take ideas and maybe drop them after a bit if at long range.  If it had been rock solid behind a long cold spell and then dropped it at T48 then fair enough to crtiicise, but not at the kind of range it was postulating a longer cold spell.

 

I don't see that what the ECM has modelled is a million miles away from what now looks to be nailed on i.e. a brief northerly blast, except for the odd run or two, which is fair enough.  It seems to me that people latched on to some speculative runs which were never cast in stone and now are disappointed when it hasn't happened i.e hopecasted.

 

I also think it scientifically wrong to draw an inference from the ECM's so-called failure on this northerly to therefore assume that it is wrong on a longer term Easterly.  Even assuming it was wrong on scenario A doesn't mean it's wrong in picking up on a trend in scenerio B a week later.  At the moment, the easterly appears to be poorly supported and therefore probably won't happen.  However, if it doesn't happen, I don't see it is right to criticise the ECM for playing with an idea at some 10 days out before saying no after all.  That's what models do: model.

 

More generally, with the polar vortex as it is, we are going to do very well to get anything sustained over the next fortnight or so.  As TEITS says, a Scandi high is our only hope.  The jury is out on that, but for my money, at the moment it's looking unlikely.

[BLAST FROM THE PAST]

i believe a ridge to our east will be place come/during 3rd week of Dec but how far n or s? An advancing scandi I'm against at this stage but so much is uncertain, look how problematic this weekend is being.

 

 

BFTP

[shedhead]

 

 

i believe a ridge to our east will be place come/during 3rd week of Dec but how far n or s? An advancing scandi I'm against at this stage but so much is uncertain, look how problematic this weekend is being.

 

 

BFTP

Hi Blast....can I ask what you consider to be problematic about this weekend?

Edited December 2, 2013 by shedhead

[snowking]

I have not got access to the ECM postage stamps and probably not allowed to post tweets so i am rehashing what Matt Hugo said re the ECM Members.

 

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"At T240 only 7 out of 51 support a Scandi High/Easterly". (This ties in with the ECM mean at the same time.)

 

"However by D11-D15 27 members now support the Scandi/easterly".

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So ECM seeing a settled period with a SW flow but their long term trends towards heights in the NE/N. See if any of the other models go that way.

Indeed.

 

12 day mean 500mb anomaly:

 

 

However with the split in the ensembles the mean flow remains a Westerly for now:

 

 

But with a virtually 50/50 split in the ensembles at present I wouldn't read too much in to those means at present.

 

Just briefly the obvious trend for the 10-15 day period from last week was for the main thrust tropospheric vortex switch from Siberia/Scandinavia towards the Canadian/Greenland sector. We can still see these changes in motion (this time in the 5-10 day period) from the ensemble means:

 

Day 3:

 

 

Day 9:

 

 

Now whilst I mentioned in a previous post that this was the reason for the certainty that the upcoming Northerly would be a short-lived one with little prospect for height rises towards Greenland for the 10-15 day period (from last week), this of course does not rule out the possibility of height rises towards Scandinavia. The difficulty now comes in the modelling of how much of any influence from the vortex gets left across the Scandinavian sector. The theme from forecast models over the past 18 months or so has been generally for early runs to under-estimate how much of the 'vortex energy' remains, and that would be my biggest note of caution. Admittedly that observation was generally true last winter of the Greenland sector as opposed to Scandinavia, but the same caution should be applied.

 

For this reason I would expect to see some further 50/50 splits and some flip-flopping of both deterministic and ensemble modelling for the next few days on this situation. Anyone making a call at this stage for where the high pressure will end up beyond day 10, from the model data available to us, is rather brave.

 

SK

[Man With Beard]

Beggining to lose a bit of faith in the ECM now. That's twice in a short period that's it's been off the mark, now it's going for a Scandi High, and we are not far off a year since it failed big time on an easterly. I will be waiting for UKMO to join that party before I even begin to get interested.

Yes the ECM has become the model of broken dreams, a few years ago it was the GFS but that mantle has switched! Although all of the models are making a bit of a mess of northerlies at the moment. Countless times they get shifted 300 miles east somewhere between T90 and T150, with wind directions altering up to 30 degrees anticlockwise. However, I can't ever remember even one westward correction, can anyone? It seems systematic and, sadly, I think the ECM is now the worst culprit.

[IDO]

The GFS 06z run has the northerly out of the UK by Friday afternoon:

 

 So a very brief northerly wind for the south.

[forecaster]

 

The 850's rise but whether surface temperatures respond remains to be seen

 

I would expect that for anywhere away from coastal west Wales, Cornwall, Ireland and N Scotland it will be a light continental drift for Sunday and Monday at least, with temperatures remaining low. "Concern" though because the 850hPa temperature rises from approximately -10C on Friday to +5C early the next week. This sort of rapid warming at the top of the boundary layer makes me think there'll be a very strong inversion. If stratocumulus forms there, it could persist. We could still get a few days of cold sunny weather though.

[nick sussex]

Yes the ECM has become the model of broken dreams, a few years ago it was the GFS but that mantle has switched! Although all of the models are making a bit of a mess of northerlies at the moment. Countless times they get shifted 300 miles east somewhere between T90 and T150, with wind directions altering up to 30 degrees anticlockwise. However, I can't ever remember even one westward correction, can anyone? It seems systematic and, sadly, I think the ECM is now the worst culprit.

Good post, the main reason IMO is the lack of a proper Greenland high, I'd always view any northerly without that as liable to be watered down. The GFS used to be the main culprit with overdoing the cold and longevity but in recent years the ECM has had a bias upstream with over amplification.Normally northerly topplers come by a deep low across the eastern USA running ne towards western Greenland developing a temporary ridge over Greenland , this projected one never had that much amplification.My general rule re northerlies without a proper Greenland block is whatever the models show expect a 36-48 hour max northerly before the flow is cut off.I've always been much more interested in what comes after the northerly as that will likely set the pattern for much of December.More extended cold given the expected PV set up really has to come from the east or ne, anything from the north or nw longer term ie Greenland block is a non-starter for the timebeing.

[shedhead]

Yes the ECM has become the model of broken dreams, a few years ago it was the GFS but that mantle has switched! Although all of the models are making a bit of a mess of northerlies at the moment. Countless times they get shifted 300 miles east somewhere between T90 and T150, with wind directions altering up to 30 degrees anticlockwise. However, I can't ever remember even one westward correction, can anyone? It seems systematic and, sadly, I think the ECM is now the worst culprit.

I think most westward corrections (and to be fair they are a bit like rocking horse poo) tend to occur inside T+48hrs. At T+144hrs and beyond they can be as far as 1000 miles out, several N'erlies over the years that have been progged to plunge across UK a week hence have ultimately gone across Finland and into the Baltic states.  Of course not all prove to be this inaccurate and the odd one can and has delivered a direct hit as indicated at T+144hrs, but anyone looking at projected N'erlies or E'erlies at that range and assuming they will verify as shown will end up disappointed more times than not imo.

Edited December 2, 2013 by shedhead

[Frosty.]

Short sharp cold snap is all the mods have been showing but it's better than no cold snap and northern scotland could be on course for severe wintry weather with gale force nnw'ly arctic air and frequent heavy snow showers according to the mods. :-)

[shedhead]

The GFS 06z run has the northerly out of the UK by Friday afternoon:

 

gfs-0-102.png  So a very brief northerly wind for the south.

Indeed, the speed at which GFS wants to eject the cold appears to be gathering pace on every run...hard to see a westward correct/delay at this stage it must be said.

[legritter]

Good moaning all ,The models in my opinion will always have a hard time getting even the general pressure pattern right out at 8/10 days .theres going to be times when its fairly right but more not .as i said yesterday i dont quite buy into a large pressure rise in the Scandy area quite yet ,But hey Presto its there on the modells .so if its going to happen we need to see several more runs before we can start Dreaming of what Could be .As for this thurs/Sat we could see some surprises i still feel .,Gfs is churning out now and i.v no idea what its showing as i would lose my Post if i looked ,Learning slowly on computer but enjoying NET Weather ,best forum around ,cheers all ,

[UV-RAY]

I warned about the eastward corrections in the regional threads on Friday and my concerns were proven right. not that it takes a weather guru to come up with the obvious really.

 

As for chasing phantom easterlies I think I'll pass on that one for now as we all know just how even more difficult these are to model than a northerly. My punt is for heights to remain in central Europe with us in a flow from the West/SW and then the high to slowly sink SE.

[Frosty.]

At this rate it will be over before it begins if that makes sense.

[BLAST FROM THE PAST]

 

 

 

Hi Blast....can I ask what you consider to be problematic about this weekend?

 

Was it going to be clean or issues around southern tip of Greenland affecting depth and longevity of cold blast.  Issues with models resolving the outcome. It doesn't seem there was an eastward bias this time.  The 06z totally waters it down to northern parts only really affected....for LRF purposes I'm ok with that.

 

BFTP

Edited December 2, 2013 by BLAST FROM THE PAST

[shedhead]

The 06 GFS remains bullish about sucking up air from south of the Canaries come this time next week and it's hard to see it franking or even mildly supporting ECM's Scandi HP immediately thereafter.

 

IF this set up does develop, some record breaking high Dec temps may well come under threat later next week....almost from the sublime to the ridiculous...

 

 

 

 

Edited December 2, 2013 by shedhead

[snowangel32]

At this rate it will be over before it begins if that makes sense.

Yep the eastward trend continues and we still have 4 days to go at this rate even Scotland are in danger of losing there snow in my area its more of a half day cold breeze now than a cold snap what a turn around

[shedhead]

Was it going to be clean or issues around southern tip of Greenland affecting depth and longevity of cold blast.  Issues with models resolving the outcome. It doesn't seem there was an eastward bias this time.  The 06z totally waters it down to northern parts only really affected....for LRF purposes I'm ok with that.

 

BFTP

Tks Blast, see what you meant now.

[Ian Brown]

The 06 GFS remains bullish about sucking up air from south of the Canaries come this time next week and it's hard to see it franking or even mildly supporting ECM's Scandi HP immediately thereafter.

 

IF this set up does develop, some record breaking high Dec temps may well come under threat later next week....almost from the sublime to the ridiculous...

 

 

 

 

 

Yes some December records could be broken certainly in Ireland if this comes off, also potentially quite wet out West too.

[Yarmy]

Well, we sort of get there in the end:

 

 

(Yes, I know this will not happen)

[shedhead]

Well, we sort of get there in the end:

 

 

(Yes, I know this will not happen)

I looks rather more plausible that ECM's current evolution though...at least the route to it anyway.

[Yarmy]

I looks rather more plausible that ECM's current evolution though...at least the route to it anyway.

 

Yes, if only. It would make for an epic run up to Christmas. (Insert wistful sigh smiley here).

[Ian Brown]

I warned about the eastward corrections in the regional threads on Friday and my concerns were proven right. not that it takes a weather guru to come up with the obvious really.

 

As for chasing phantom easterlies I think I'll pass on that one for now as we all know just how even more difficult these are to model than a northerly. My punt is for heights to remain in central Europe with us in a flow from the West/SW and then the high to slowly sink SE.

 

Yes I certainly think that is likely to be the case, will be interesting to see the METO update later today and see if they mention very mild conditions towards the end of the 6-15 dayer.

 

Chasing easterlies is a very long game from a starting point of HP over France.

[Frosty.]

The 06 GFS remains bullish about sucking up air from south of the Canaries come this time next week and it's hard to see it franking or even mildly supporting ECM's Scandi HP immediately thereafter.

 

IF this set up does develop, some record breaking high Dec temps may well come under threat later next week....almost from the sublime to the ridiculous...

 

 

 

 

The Gfs, on balance has more chance of being wrong about the outlook than the Ecm...it's not over yet shed...well it's not begun either but that's beside the point, the Ecm 00z ens mean is still showing a strong arctic blast on friday and saturday am further east..the fat lady is not singing yet, hopefully she will be kept backstage and then sent home in a cab

Edited December 2, 2013 by Frosty.