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Model Output Discussion 01/09/17


phil nw.

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
17 minutes ago, tight isobar said:

Lets take this to pm.

Hahaha- i think we'd probably just go round in circles :)

Lets stick to cold hunting :D

And hope for upgrades ..

TBF I should have wrote a warming globe in my opinion thinking about it, anyway ...i like EC 12Z ...its cold for the vast majority and has potential at day 10 for a reload, compared to last December its heaven :)

Edited by northwestsnow
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Hi everyone, I do not normally allow myself to get too involved in the run by run analysis, especially whilst they're being churned out - I leave that to the regulars for their comments, which are sometimes as variable as the model output or even more so! This is in no way a criticism and I enjoy reading many of the posts. I normally prefer my more balanced and thorough analysis. I must say, however, that today's 12z ECM is consistently much better than some have suggested. In general, most of our longer cold spells have brief milder or less cold blips. The November/December 2010 spell was split into two severe spells and a milder chunk in between.

What I am seeing in today's runs is an adjustment from the Arctic northerly to a quite probable easterly into week 2. The initial indications start at around T+168 to T+192. Obviously we cannot be sure that this will be the eventual evolution but there are various encouraging signals.This is what I have been looking (and hoping) for as I said in my long report this afternoon (on page 222). I'll explain what I'm on about with some of the charts:

ECM 12z charts:

                    T+168                                                    T+192                                                   T+216                                                   T+240

ECH1-168.GIF     ECH1-192.GIF     ECH1-216.GIF    ECH1-240.GIF

As the likes of @stevemurr and @nicksussex and several other regular posters keep telling us, it's a good idea to look upstream and not just in the immediate vicinity. At 168 we see the Atlantic heights sinking somewhat and heights also starting to fall over Greenland. This is more than compensated for with a strong build of heights over central Russia and into the Arctic.By 192 heights are building from Russian into Scandinavia. There are also signs of renewed heights building up into western Greenland - I do not believe that this is the dreaded west based -NAO setting up residence but just a part of the overall evolution. Shallow low heights are spreading south and west over Europe. The lower heights over eastern Greenland are beginning to shear off. By 216 this evolution continues with heights rising over most of Greenland. The Russian high continues to build strongly into Scandinavia. The lower heights which were over Greenland have been forced south-east over Iceland.This process continues nicely into 240. The low heights over Iceland are steadily sinking south-east into Europe with strong heights building to the east, the north-east, the north and the north-west from Russia into the Arctic, across Scandinavia and also in Greenland. This is an entirely possible (perhaps even probable) evolution and how many a decent cold spell has developed in the past. I hate to ramp this too much but it is not dissimilar to December 1962, December 1984, January 2009 and December 2010. Yes, we'll have to see on the next run if this trend continues. I feel that if there was a T+264 ECM chart it would show the low pressure completing its journey into central Europe and a strong Scandi high building behind with a long fetch easterly starting to assert itself and much colder air being dragged down into north-west Europe and the UK.

Just briefly, a look at a couple of the ECM 12z 850 charts:

                    T+168                                                   T+240

ECH0-168.GIF   ECH0-240.GIF

Some -8s starting to show up, with an area of -12s over Scandinavia and that wedge of milder air to our west is being steadily squeezed out. By 240 there is a decent pool of -8s and a lobe from Siberia is moving steadily south-west through north-west Russia heading towards Scandinavia and northern Europe with some -12s, -16s and even -20s upstream. 

Now I and the ECM may be wrong but this is my take on it right now. Fingers crossed that we see an evolution along these lines. I'll be interested to hear others comments on this and I'll be happy to exchange PMs so that we do not clogg up this thread too much. That's about the most bullish I've been for many years!

 

 

 

Edited by Guest
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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

ECM 240.

That low can only disrupt SE (It is already doing so) but in actuality it would disrupt more 216 to 240 IMO than shown against the Scandi ridge anyway.

It would take a little while to bring a cold flow back across the UK if it was as shown on 240 but all academic and the important signal is that the Atlantic remains blocked and any trough will have to drop from the North keeping the pattern amplified.

We have seen this modelled several times in various ways toward the end of the first week of Dec and it this trough I expect to open the floodgates to cold arctic air.

It won't be as simple as that of course and there are no guarantees but the basic synoptic of strong high pressure in the Atlantic/Greenland area and deep trough to E/NE is about as strong as possible as far a signals go at that range.

The only real development for me is the models playing with bringing a Scandi/Russian ridge or high into play later.

 

EDIT

Nice summary BB1962, you posted while I was typing but  seems we are on the same page.

 

Edited by Mucka
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Posted
  • Location: Milton Keynes
  • Location: Milton Keynes

ECM mean at 240 looks excellent - large negatively tilted ridge in the mid Atlantic. It is probably best to not keep reacting to every detail of the Op runs and talking about upgrades/downgrades etc. It looks like it will be blocked for the foreseeable future and the details past 4/5 days are currently unknown.

EDM1-240.thumb.gif.be42380d281762dae8894fd1cf843e4b.gif

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

ECH1-168.GIF?25-0 gfsnh-0-144.png?12   Yesterday:  gfsnh-0-168.png?12

Today has seen the emergence across most of the models (ICON an exception) of a desire to cut-off the low by the Azores, rather than keep it linked to the low heights over Canada to form a nice negatively-tilted trough extension. With that, the door opens for a ridge to surge across to the north of the cut-off low and retrogress the pattern - but the trouble is, there does not currently look to be enough amplification at least to begin with for this to do a good job for us. Unless we can get further amplification as per the ECM 12z to kick things back into a nicer position, we do run the risk of the ridge heading too far west and perhaps even setting up a negative NAO pattern - although probably not for very long given stratospheric events.

I have to wonder about that cut-off low, though, as they have a habit of not quite coming off. In that scenario we'd probably be back to the negatively tilted trough extension. I guess we'll find out before too long - within the next day or two's worth of runs. 

30 hPa stratospheric progression from the 12z GFS is akin to the 00z and the height rises now begin at around +216, so that's encouraging. The subsequent propagation up to 10 hPa is bound to see quite a bit of variation between the runs as the blocking patterns shift about.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
Just now, mulzy said:

Retrogression signal still shows up in the eps.

EDM1-168.GIF?25-0

EDM1-240.GIF?25-0

is it continuing in the extended eps though is the big question?

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL

Read into this what you will.

easterly looks unlikely, however brief.

pretty good agreement out to the 30th

33087BD5-E4C5-424C-80E5-7100D5A4A960.thumb.png.0001172947add58d0ccd7f2f3f6263a5.png

Edited by karlos1983
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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
4 minutes ago, feb1991blizzard said:

is it continuing in the extended eps though is the big question?

Yes, very much so, though at that range there is some dilution.  Better extended set than this morning but someone needs to check the clusters.

Edited by mulzy
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
Just now, mulzy said:

Yes, very much so, though at that range there is some dilution.  Better extended set than this morning but someone needs to check the clusters.

Thanks. will do when they come out at 1031 tonight, I have to say I didn't expect an upgrade looking at the 240 mean, I was thinking the best we could hope for is avoiding a downgrade but great news.

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Posted
  • Location: Lincs
  • Location: Lincs
6 minutes ago, feb1991blizzard said:

is it continuing in the extended eps though is the big question?

The signal on the EPS anomalies for a atlantic/Greenie high Is right at the top of the scale. if anything, its getting stronger than the last few EPS!

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Any coldie should be more than satisfied..delighted even with these Ecm 12z ensemble mean charts showing bitter winds from the arctic next week..worth a Boom!:bomb::bomb::D:cold-emoji: 

ECMAVGEU12_72_1.png

ECMAVGEU12_96_1.png

ECMAVGEU12_120_1.png

Edited by Frosty.
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Posted
  • Location: uxbridge middlesex(- also Bampton oxfordshire
  • Weather Preferences: blizzard conditions. ice days
  • Location: uxbridge middlesex(- also Bampton oxfordshire
13 minutes ago, Daniel* said:

 :shok:

22B258EE-9603-424B-B44B-F799C7DB55DE.thumb.jpeg.1aa1aecfb94449a50a670dac6dcb803d.jpeg

 

Thats some serious thermodynamics

Its an' assault on any re-charge of establishment @the pole...

Its a burnt spaghetti format' into the polar regions...

And wonderfully-via greenland.

Which opt's cold advection to us on an' almost perfect scale.....

Edited by tight isobar
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Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth
7 minutes ago, Summer Sun said:

Could you elaborate further?

A shock emoji and chart isn't really helpful for those members who don't understand those charts

Could you say please? Please and thank you? Thank you.:D

 

as I am sure you are aware summer sun. It is suggesting a lot of high pressure in the northern hemisphere and as such a lot of blocking. 

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
4 minutes ago, Ryerson said:

Do experienced members consider this to show genuine northern blocking, or a strong mid-latitude Atlantic ridge?

It shows a mid Atlantic ridge but significantly +ve anomalies over Greenland, its an ensemble mean at 312 hours though so considering some members of the suite are bound to be much flatter, guaranteed there will be a significant cluster which shows a stonking big persistent ridge over Greenland.

Edited by feb1991blizzard
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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
1 minute ago, That ECM said:

Could you say please? Please and thank you? Thank you.:D

 

as I am sure you are aware summer sun. It is suggesting a lot of high pressure in the northern hemisphere and as such a lot of blocking. 

Karlos likes this ....

yes im out of likes:unknw:

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
4 minutes ago, tight isobar said:

Thats some serious thermodynamics

Its an' assault on any re-charge of establishment @the pole...

Its a burnt spaghetti format' into the polar regions...

And wonderfully-via greenland.

Which opt's cold advection to us on an' almost perfect scale.....

I do admire your thespian musings but could you simplify it a touch thanks:D.So yes whether the atlantic high orientates itself to the north west or north east ecm earlier did show generally all roads lead to a cold set up. I think gp once said that a big change is a foot when big swings occur on all models in a short time frame.

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