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Model output discussion - into 2018

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Looking at the gfs day 8 and thinking about the eps mean anomoly countdown charts I put up earlier, the gfs isn't so far away in broad terms but it's so messy. the eps is made up of 50 runs at pretty well the same resolution as the gfs. no question that at day 8 the eps mean should be a better guide than gfs op. it won't take much for gfs to get to the other output and similarly, a.middle ground solution closer to the euros/gem should be fairly reachable. I'm not of the opinion (as Aaron) that a blend is bound to be a poor result. Some of the consistent models have to fidget a bit tomorrow - surely!

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4 minutes ago, northwestsnow said:

Thats likely because like myself they rate Gfs as a poor model.

 

Lol until it shows Easterlies for weeks from Kamchatka :)

Just jesting

BFTP

Edited by BLAST FROM THE PAST

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Just now, northwestsnow said:

Its a pile of junk.

And no im not saying that because its poor for cold.

I have watched NWP for years...

In fact i dont even know why i look at it.

I may not post in forums like this but I also have watched NWP for years and I can tell you as any other honest person on here would have to say the same that the GFS has had a better verification of certain situations in our locale in the past than the likes of the ECM and UKMO in the past (please forget the verification stats as they are not specific to the U.K.)

im not saying any model is right but to call one rubbish is short sighted! As you say if the GFS is so bad why is everyone waiting for it’s 4 runs it churns out daily? 

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This often seems to play out between the models when easterlies are involved. One model, GFS at the moment, puts coldies through the grinder run after run by showing a quick removal of the Scandi block, lack of appetite for an undercut and swift return to +NAO regime. This may well happen, but not, I feel, a quickly as the GFS operationals want to us to believe. It goes against several EC high res runs and accompanying EPS means which keep the block over Scandi much longer than the GFS ops suggest. Even the 12z GEFS mean isn't so quick on Scandi block removal either. Seems like we can't see in a Scandi high and easterly spell evolving in the model output without the drama of one model trying to break it down as quickly as it begun!

On another note, noticed Joe B was highlighting conflicting MJO phase signal, with convection wave over eastern Indian Ocean suggesting phase 3-4 progression, while there is also major convection near and east of the dateline giving a phase 8/1 look, kind of throws any reanalysis composite charts out the window for any particular phases and perhaps maybe giving conflicting pattern signals between the models.

Edited by Nick F

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2 minutes ago, nick sussex said:

Don't worry folks the love child of the ECM the ICON has improved from its 12hrs run! :D

 

Phew that's a relief nick, we really need the ICON on board don't we!:D...anyway, another great day / night's model viewing full of twists and turns..I'm sure tomorrow won't be any different but I really feel something very worthwhile for coldies is on the way..night all. 😉😯:cold-emoji: 

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7 minutes ago, January Snowstorm said:

The gfs if often rubbished not too sure why. In my view its as good as the others if not better. I do take the view though that it might be weak on picking out Easterlys 

One last comment from me. I have never in all my years on here heard so much talk about the GEM. Has it this week been promoted to a top 3 slot? Upto this week it rarely got a mention yet lately we're getting constant updates 😤

 Pretty certain if gfs was showing an easterly from the far reaches of Russia with -20 850s and the others had a mlb then you would have your ans.i still think a cold spell is on to a degree but its anyones guess what the nhp will be 7-10 days away!!!

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00z runs will make intetesting viewing...

Back to work for me..

 

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3 minutes ago, Quicksilver1989 said:

Hello

So a bit of a barmy model output discussion thread this evening and for the casual observer things can be confusing. So thought I’d chip in with my interpretations and try to be as objective as possible.

This is a very complex synoptic situation coming up. So far the following looks likely.

Saturday – coldish easterly progresses southwards across the UK Very cold in Scotland, less cold further south. Some snow showers on north-east coasts maybe getting further inland.

Sunday – High pressure over the UK very cold up north but settled. Less cold in the south due to stronger winds easterly winds with higher uppers.

Monday – Milder air pushing from the SE, however here is where things begin to get uncertain.

First thing to note is that the easterly is associated with notably mild uppers considering the circulation type. An explanation for this is partly the very mild air to our east and south. Just look at the global temperatures for example!

image.thumb.png.d224d1b1a3c6a10ca02fd57cb7212b83.png

The second is that some high pressure over the far east of Europe could bring warm air from Africa to Italy.

image.thumb.png.37cb5620dd4907ee6180b04e40a0965e.png

The above chart shows the synoptic situation for Monday and demonstrates why this pattern is so hard to forecast. Keeping the Scandi high in place is key.

What strikes me is how similar to last February this pattern is. If pressure to our far SE is too high then the easterly can actually turn very mild. February 2017 is a great example of this.
image.thumb.png.f2a01cc6125b806448ef6e1a67e61442.pngimage.thumb.png.b0623127cec458d7751882b563236a87.png   

However if the warm air from Africa moves further east the low pressure can bring in colder air as January 1996 shows.

image.thumb.png.763e4c243265d91c7fcb4d602226f389.png  image.thumb.png.7f0c6aa581e8e904ddf6266c95a220ec.png

However due to exceptionally warm temperatures to our east, it will take a while to import some really cold uppers (thanks climate change!). So we may need a lot of patience but the final chart shows that the Scandi high could at least allow some cold pooling to our far east as the final diagram shows. The winter has been very mild across Eurasia and Europe so far and the UK was very lucky to fall in the small pocket of cold during December. If we get cold air to our east that would be a great help.

image.thumb.png.87f97bd364b34fc3fc3f247d72b7d1a9.png

So overall a very difficult pattern to call. ECM/GEM could be right and so could the GFS 18z. A mild SE’ly transitioning to a mild southerly is a very plausible option so dismiss the GFS at your peril. It may not be what people want to hear but that is the way I see it.

Lets hope the Scandi high can persist and we finally see some cold pooling over the continent.

Excellent post and a fair summary there.

I feel that some people dismissing the GFS completely out of hand are setting themselves up for a fall. It makes no sense to dismiss the GFS at all considering it is a very viable (if somewhat low chance at present) option.

Edited by CreweCold

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7 minutes ago, northwestsnow said:

00z runs will make intetesting viewing...

Back to work for me..

 

Joking with you....just that if GFS showed easterlies from Far East of Russia....onto it.  That’s all.  Nights? Did continental shifts for 30 years...exhausting

 

BFTP

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Its poised on Ens and close up fluid dynamics until the US system bombs - that is as succint as I could say, the resulting nuances in either clustering or model consensus will not be readily resolved until the margins reduce.

The margins involved include the dissipation across our locale in the next 68 hrs of all the energy of the US system..

 

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1 hour ago, northwestsnow said:

Im not steve..

Its stubbornly useless and cannot resolve split jet energy.

It will be another day minimum..

This is your boss speaking.....get off your bloody phone and get back to work!

 

:crazy:

 

 

another fascinating day of model watching draws to a close...... Must admit though, I do get a kick out of people slagging off various model outputs, and others referring to model outputs as if they are sentient beings......back to the output itself, as the mighty Sherminator posted earlier, easterlies can fail at T24, so chicken counting is prohibited!....The Euro's are great for those of us with a fixation of brass monkey's but it can and might yet go horribly wrong (hopefully not though) 

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5 minutes ago, Purga said:

A couple of comments from John Hammond

"Strengthening signs now of major UK cold spell lasting through much of next week. Bitter easterly winds will be a feature but significant snow is less clear cut. Severe frost where winds fall lightest across north UK."

And regarding the GFS:

"Not yet and we shouldn’t discount it. But it’s looking less progressive than it did a day or so ago and edging towards a more blocked outcome in longer range. Enough evidence from other model output to suggest blocked, cold easterly is most probable next week."

From my POV the GFS is throwing up a different scenario every 6hrs so until this inconsistency resolves it's pretty useless to draw any firm conclusions except the comparisons with the more steady ECM/ UKMO outputs. :)

Sounds like John Hammond is setting himself up for a big fall too!!( oh the irony) !!

Night all...( those that are going to bed).

Edited by northwestsnow

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Over the last 24 hours or so we have seen constant strengthening of the modelled Scandinavian high , especially in the euros.

Ultimately I am encouraged by the timescale at which this is occurring - 120 hrs onwards. As this gets even nearer into the more reliable timeframes i think a significant spell of cold weather will materialise. It has the feel of a classic build up to a synoptic pattern that is quite so rare - the familiar story of its development. It differs from previous(poor) attempts since 2013 in that more robust heights over the scandi region are continually being modelled.

850 temps really only need a day or so of modelled upgrades to become much more noteworthy, it has happened. The failed easterly of Feb 2012 was an example of incredible promise then let down. I would not like to see modelled -10c to -15c modelled only to be let down. As long as things keep trending positiveley tomorrow then i think we will be surprised by what may start to show regarding depth of cold.

Finally: ECM 12z De Bilt ensembles really starting to show agreement on the type of frigid weather we are looking for.

 

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In the short term,yes I know there is a separate thread,but seems to be not many

Posting in there.

Saturday morning the GFS shows some snow through Northern England and into

Wales.

C.S. 

 

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Tomasz  Schafernaker in his week ahead video indicated that an easterly was coming and showed interestingly enough in the graphic that the high was to the north of the UK in a very helpful position for a cold easterly. Granted a graphic is not a chart, but I do believe that the BBC place a graphic’s content where they mean it to be.

 

I agree that the gfs output as it stands is plausible, particularly given the mild air over Southern Europe, but my experience of significant cold is that it really develops inside 24-48 hours of commencing. So I’m also prepared to believe that the gfs May come round to the other solutions.  I would come down on the cold side of the fence because I see blocks as being hard to shift, but I’m not completely convinced.

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Quick comparison with updated t+120 fax vs 12z EC +UKMO and 12z/18z GFS for 12z Monday 8th Jan. Fax and EC centre over southern N Sea, GFS definitely further east with the high centred over Sweden/Baltic Sea, is it wrong, maybe not, but on it's own.

20180103_2252.PPVO89.thumb.png.14addf018b214b4120512dc470b3ca76.png

12z EC and UKMO (T+120) for 12z Monday

ECMOPEU12_120_1.thumb.png.ff6e04e5cc8337a56adced41c678f817.pngUKMOPEU12_120_1.thumb.png.e7588e0c0149463a43527571d21d9037.png

12z and 18z GFS for 12z Monday

GFSOPEU12_120_1.thumb.png.f4a45da83921f876c89953f798c10c40.pngGFSOPEU12_120_1.thumb.png.f4a45da83921f876c89953f798c10c40.png

Looking at the 12z EC T2m for London, EC close to the mean 8th-11th as it continues the flow from points to the E, GFS warmer end of the spread, though EC colder end of spread towards end

ensemble-tt6-london.thumb.gif.ed13cd89a1442e6da72ccf6fc1ba3466.gif

Still not convinced of the GFS more progressive output of removing the Scandi high influence will be more likely to transpire ... for now.

 

GFSOPEU18_114_1.png

Edited by Nick F

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4 minutes ago, Steve Murr said:

Updated 18z NAVGEM

04C58E94-E041-44AB-B61E-C293FE88A76C.thumb.png.6920f9016b5958afc3ac7b88f4ddaae5.png

That's almost a carbon copy of the ECM . Interestingly it also phases both jets over the eastern USA developing more amplitude and helping to pull back the PV.

JMA upto T84hrs also looks fine.

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7 minutes ago, cheshire snow said:

In the short term,yes I know there is a separate thread,but seems to be not many

Posting in there.

Saturday morning the GFS shows some snow through Northern England and into

Wales.

C.S. 

 

Which model is that CS :)

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The highly regarded CMA model is more progressive than even the GFS. (not highly regarded, I've literally never heard of it)

CMA.thumb.png.3e72a61fa30ad524518acbbb2be364ec.png

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2 minutes ago, northwestsnow said:

Which model is that CS :)

The one you hate:D

C.S

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16 minutes ago, lorenzo said:

Its poised on Ens and close up fluid dynamics until the US system bombs - that is as succint as I could say, the resulting nuances in either clustering or model consensus will not be readily resolved until the margins reduce.

The margins involved include the dissipation across our locale in the next 68 hrs of all the energy of the US system..

 

Yes, the rapidly bombing Winter Storm Grayson grazing the east coast of US will certainly be throwing a lot of energy our way over next few days and is one of the main catalysts for the high to build close to / over northern Britain this weekend before drifting east. How much energy it throws into the upper levels could determine how strong the block becomes, which may not be handled properly perhaps by the models - perhaps a GFS weakness there?

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8 minutes ago, Steve Murr said:

Updated 18z NAVGEM

04C58E94-E041-44AB-B61E-C293FE88A76C.thumb.png.6920f9016b5958afc3ac7b88f4ddaae5.png

Nice chart Steve but I thought we only dragged NAVGEM in when we were in big trouble... :rofl:

It's been an intiguing winter so far and let's face it this signal for the oncoming blocked easterly has come out of nowhere (in relative terms) and despite (rather than because of) some known key drivers to the hemispheric circulation. An enjoyable ride ahead! :D

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