Model Output Discussion 01/09/17

[festivalking]

More fascinating charts and scenarios. Two very differing scenarios with GFS/ECM in the one corner and UKMO in the other. Fight night part 2. Who's everyone' money on? Has to be a blended solution I reckon but how strong the blend. Anyone recall when UKMO backed down towards GFS.

What a great period of model watching we are living in

[feb1991blizzard]

Actually the ECM 240  mean is a very slight upgrade in terms of 850's, the -4c line is now Wirral / North Wales (ish) to London (ish), the 0z it was North of Liverpool to Suffolk, synoptically although some might say the ridge isn't as higher latitude so its a downgrade, I think shortly afterwards there would be a decent cluster which produces a snow event.

Edited November 26, 2017 by feb1991blizzard

[Guest]

MODEL VERIFICATION

There is always a lot of disagreement on here as to which model has performed better or worse compared to another. This has been strongly in evidence again today.  I know that verification charts are sometimes posted but I imagine I am not the only one who finds these difficult to read and compare. I remember when @Gibby used to produce his superb daily analysis (up to about 18 months ago, I believe) and he used to provide simple model verification statistics. I’m not sure if these are easily available.

Anyway, it occurred to me that we can do our own verification exercise whenever we want to and in a way we can all easily relate to. The Meteociel site provides archive records for the main models. So, I’m going to do a cross model comparison to today’s actual 12z chart. Then I’ll show each models’ chart for this time at Day 5 and at Day 10 (where available, as UKMO only goes to day 6 and NAVGEM to day 7/8).

Current Chart showing 1300 on November 26th ECM 12z T+0:

 

 

Day 5 T+120 Forecast Charts from 1300 on November 21st – all are 12z:

                  ECM                                                             GFS                                                           UKMO                                         

                                                      

                  GEM                                                         NAVGEM                                                        JMA

                                                    

 

Day 10 T+240 Charts from 1300 on November 16th – all are 12z:

                   ECM                                                            GFS                                                           GEM                                                            JMA

                                                         

Now we can all disagree upon which are the best and worst matches!  Remember most of the models flipped flopped all over the place from run to run, not just the FI charts. It may well have been the case that a particular model went off track on the 12z run only to nail it on their next run! I cannot go into ensemble charts and all the perturbations, that would take me all night and in any case, I could not find an archive link for the GEFS ensemble mean or any of their earlier run charts.

None of the Day 5 charts are too far from the current chart and in my view, perhaps JMA takes the prize with ECM a close second. Possibly the two USA models GFS and NAVGEM get the wooden spoon. .Not surprisingly, the Day 10 charts are much further away from the current position, in fact they fail quite abysmally and I do not feel any of them deserve a prize. This type of exercise could be done with just one model taking 10 of their runs for each day or even every single run for a certain period.

In future if an argument crops up on who performed well or badly, remember that the evidence is available!!! 

Edited November 26, 2017 by Guest
Correct typos

[Frosty.]

Hoping for cross model agreement on the Gfs 12z solution..I'm greedy!

Anyway, cold shot number 1 is locked and loaded so enjoy the northern / arctic chill after Monday.

Edited November 26, 2017 by Frosty.

[bluearmy]

5 minutes ago, Ryerson said:

I like extreme weather... but yeah the flooding and wind damage wasn't good.

Also, today's GEFS output is suggesting northern blocking isn't favoured.  Something is working against it, not just averaging of data.

But things change quickly, so...

What?

[Weather Observer]

I was planning to slip in quietly to open my winter account. But not much chance of that! Just to say that those ECM means are the best I as a coldie have seen for several winters past and we are technically only just entering that season. In some ways they remind me of December 1981, one model and too early to get carried away I know. ? Just enjoy the ride.

[Tracy Flick]

1 minute ago, bluearmy said:

What?

Well if this is the definition a northern block then it's a northern block.

night all

[Mucka]

1 hour ago, Daniel* said:

Folk are missing out what is in front of them. Is this eye candy? At day 2 a sight to behold after all this woeful muck of the last few years. The first wave of cold has been picked up very well. 

EDIT

I just got home and posted thebelow as I came across the post and responded to it before reading through the rest of the thread but see this has already been covered by BB1962. (That's twice in 2 days)

LOL

 

Agree with the eye candy and what is in front but not so sure about the models performing well.

None of them spotted the Atlantic ridge on the 27th until it was fairly close in (well within 10 days if memory serves. They have been all over the map since then with the placement of the ridge, amplification and sharpness of the trough.

TBF it has been quite a complex pattern but the look ahead to a possible sustained cold spell has less moving parts so they should have it resolved much quicker.

Edited November 26, 2017 by Mucka

[bobbydog]

12 minutes ago, bluearmy said:

What?

we also have backup from higher up.

the strat i mean, not some higher being...

that should have a big impact further down the line and will probably have knocker hiding in his woodshed....

[knocker]

The NOAA , GEFS and EPS anomalies this evening are not without interest., well IMO anyway, and certainly add some credence to the ecm det take this evening. And they are in pretty good agreement.

Upstream we have the elongated Siberian vortex and the Canadian lobe with an important trough orientated south east to NE N. America, There are also channels across the pole to the  east European ridge and the trough to the east of the UK that tracks south to southern Europe.

I mentioned the Canadian trough because it one of key players to the action downstream in the Atlantic  where we have a ridge in mid Atlantic orientated north west to strong positive anomalies south east of Greenland. There is a fair bit of energy running out of the eastern seaboard south of the trough which is split with one arm running around the ridge over southern Greenland  and down over the UK as a quite strong NW upper flow.

It will be interesting how the det runs sort the detail of this but it portends some quite unsettled wintry weather as systems swing south east into the trough.

The ext period is also not without interest either as the amplification increases , including upstream with strong ridging in western North America. Downstream the Atlantic ridge/European trough readjusts but still a north west/NN west flow over the UK so remaining unsettled with temps still below average. It goes with out saying the precise orientation of these two features is of paramount importance.

 

Edited November 26, 2017 by knocker

[Penrith Snow]

December 1981 began with high pressure over the UK which then pulled back into the Atlantic and joined up with a large Greenland High.

A low moving south east across England on the 8th ushered in bitterly cold northerly winds and the rest as they say is history.

Tonight's GFS shows a remarkably similar scenario as does ECM, lets hope history is repeating itself 36 years later 

Andy

[Cheshire Freeze]

4 minutes ago, bobbydog said:

we also have backup from higher up.

the strat i mean, not some higher being...

that should have a big impact further down the line and will probably have knocker hiding in his woodshed....

The stratospheric aspect was the missing part of the puzzle RE this winter as far as I was concerned...hence the reason for my negativity early doors. If we can see a warming through to the finish line then all options are on the table...

[tight isobar]

Well soon onto the 18z gfs   

And i promise to be a boring as poss-

In analysis!!!

[bobbydog]

1 minute ago, CreweCold said:

The stratospheric aspect was the missing part of the puzzle RE this winter as far as I was concerned...hence the reason for my negativity early doors. If we can see a warming through to the finish line then all options are on the table...

in the winter thread, we were drawing comparisons with 1962. that year had similar patterns and background signals to this year. it also had a minor warming in early december then a major one in january. as it stands, a minor warming will do and that seems to be on the cards. 

[lorenzo]

The 18z GFS is overdue one of it's reverse zonality specials, if it takes the idea of the 12z GFS and goes to the nth degree who knows.

We have - 

Atmosphere wanting to deliver huge negative AO

-NAO in the area where it has not been the default for a few yrs

A Solid eQBO following the blip in the QBO metronome

A Pacific not ruling the pattern one way or next

A three wave assault on a disconnected vortex and the best projections for Aleutian, Greenland waves for years.

The pacific conduit for wave driving seemingly on an endless wave train for wave driving into the strat.

Global AAM positioned to launch an EAMT.

Solar heading into the circle of death

vs Classic Vortex Intensification Period, Nina front loaded winter and poor strat analogs for displacement events of this nature.

 

All in - tremendous model viewing, and something we have not had to enjoy for a few years. Lets make the commentary on said viewing as cool as it can be..

[Summer Sun]

The ECM ens shows it turning colder from Tuesday through to the end of the week over the weekend it briefly turns less cold before another plunge of colder air into the 1st full week of December

London

Northern Scotland

[Methuselah]

Not usually one for making comparisons with previous years...but I do see some similarities this time: memories (almost invariably distorted by both memory loss and wishful thinking!) of the late Novembers of 1962, 1978, 1981, 1995, 2009, 2010 and 2012, keep repeatedly springing to mind...

I'm more certain now than I've ever been before.........that I'm finally losing it!

And, now, it's back to the GFS rollercoaster!

[swilliam]

Very clear trend on De bilt ensembles. Steady cool down this week then a notable warm up for a few days. this is then followed by a steady decrease again - remarkable support for this at this range with only a few members going differently (including control).

 

[carinthian]

3 hours ago, carinthian said:

Looking at the latest chart from UKMO, not good . Seems if it wants to take the Atlantic trough northwards away from the Azores. This can only lead to sinking of the high close to the West of British Isles. There will hopefully be a correction in later outputs to dig in the trough and undercut the high. This will be the best solution to retrogress the high polewards again and open up Northerlies again as mentioned in there medium range forecasts. Its a shame we have no access to these charts past 144t but I am sure this latest run at 144t does not fit in with the general consensus shown by the other models. The form horse this past few weeks has been the persistent lower heights near to the Azores and this has been a prominent factor of the blocking scenario.This latest run from UKMO wants to scupper that.

C

Following on from the above post, the UKMO extended chart at 168t seems to confirm a big difference compared the other 2 big models, GFS and ECM. The UKMO replaces the lower heights and builds the Azores high towards the British Isles with the Atlantic trough heading north. In stark contrast at the same time,GFS and ECM maintain the lower Azores heights with retrogressive high moving poleward. So will UKMO be the winner or loser against all odds .?

Edited November 26, 2017 by carinthian

[Daniel*]

No idea of late but a general pattern for the models success is indentifable. ECM top dog of course, the canadian model GEM (the black line) ought to be wheeled out more often, greater success at day 5 than GFS in many occasions. On rare occasions the canadian model has outperformed the ECM at day 5, however when it goes wrong.. it can be the worst of the bunch. Sadly nothing of UKMO but I sense it will just be knocking second.. 

 

[tight isobar]

36 minutes ago, bobbydog said:

we also have backup from higher up.

the strat i mean, not some higher being...

that should have a big impact further down the line and will probably have knocker hiding in his woodshed....

Great to have some humour/character alongside decent knowledge...

Im dying here???onto the 18z...

[terrier]

Not liking the look of the 18z so far 

[swilliam]

3 minutes ago, Daniel* said:

No idea of late but a general pattern for the models success is indentifable. ECM top dog of course, the canadian model GEM (the black line) ought to be wheeled out more often, greater success at day 5 than GFS in many occasions. On rare occasions the canadian model has outperformed the ECM at day 5, however when it goes wrong.. it can be the worst of the bunch. Sadly nothing of UKMO but I sense it will just be knocking second.. 

 

It says in the text UKMO was tied 4th (i.e behind theses three).

[Daniel*]

Just now, swilliam said:

It says in the text UKMO was tied 4th (i.e behind theses three).

Oh, I should have gone to Specsavers eh? Well there you go.  

[nick sussex]

This thread seems to have taken on a rather negative tone with some sniping.

Its like The Walking Dead where the humans (coldies ) start turning on each other instead of fighting the real enemy zombies ( mild mush )! 

Barring a few mildies who slipped through the vetting procedures we’re all on the same side!  

 

Edited November 26, 2017 by nick sussex