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Paul

Model output discussion - into 2018

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The London T2’s aren’t spectacular considering we are looking at a broadly continental flow. Certainly clusters looking pretty parky but nothing sustained on the majority - I wasn’t particularly taken by the suite from a wintry POV actually 

Cold - yes but how cold and for how long .....

 

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4 minutes ago, warrenb said:

I don't think the GFS can override the La Nina pattern, and is purely going with it.

It cannot split the jet effectively in these set ups, it never has been able too and probably never will.

Occasionally  it gets this correct but not because it is a tactical genius and has trumped the rest. It gets it correct because on occasion the weather matches its default pattern. Think of it as weather roulette with the GFS going for 0 each spin.

This was my train of thought when I upset the GFS supporters club.

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6 minutes ago, Ramp said:

It cannot split the jet effectively in these set ups, it never has been able too and probably never will.

Occasionally  it gets this correct but not because it is a tactical genius and has trumped the rest. It gets it correct because on occasion the weather matches its default pattern. Think of it as weather roulette with the GFS going for 0 each spin.

This was my train of thought when I upset the GFS supporters club.

I dunno, Ramp...The way I see things, each and every model can 'split the jet', 'deconstruct the front', or 'eject the energy' to their hearts' content - but, it'll make not one iota of difference to the weather, however...?:D

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I think people are being a little harsh on the GFS. Sure, in these situations it's absolute cannon fodder, time and time again we've seen how it's struggled to deal with split flows and one of it's flaws is that it consistently underestimates blocking.

Knowing the flaws and pros of each model is what makes the difference between a good model analysts and a bad one. Steve Murr is often spot on when predicting what the models will do/where they will head so I'd follow his lead.

That's not to say we should completely discount it's output, but knowing where it struggles makes it easier to make an educated guess on what's likely.

FYI, ECM used to have a bias for over-amplifying, not sure if that's still evident though, haven't seen that much of it this year.

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1 minute ago, Danny* said:

I think people are being a little harsh on the GFS. Sure, in these situations it's absolute cannon fodder, time and time again we've seen how it's struggled to deal with split flows and one of it's flaws is that it consistently underestimates blocking.

Knowing the flaws and pros of each model is what makes the difference between a good model analysts and a bad one. Steve Murr is often spot on when predicting what the models will do/where they will head so I'd follow his lead.

That's not to say we should completely discount it's output, but knowing where it struggles makes it easier to make an educated guess on what's likely.

FYI, ECM used to have a bias for over-amplifying, not sure if that's still evident though, haven't seen that much of it this year.

BA pointed out to me yesterday that the bias on the ECM was muted.

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10 minutes ago, bluearmy said:

The London T2’s aren’t spectacular considering we are looking at a broadly continental flow. Certainly clusters looking pretty parky but nothing sustained on the majority - I wasn’t particularly taken by the suite from a wintry POV actually 

Cold - yes but how cold and for how long .....

 

I have to second this at present. We are at risk of overanalysing things at such a range which is Cold Spell 101 in terms of mistakes (and the sort of thing many of us would be cautioning others about) - but if we want to take things at absolute face value right now, minus the GEM, things look chilly and dry to me right now.

Fortunately there is still plenty of water (or ice) to flow under the bridge before we get to the secondary phase of the upcoming evolution (hopefully - as long as the GFS isn't going to play late scrooge on us) and if we start to get some undercutting of energy then things could get interesting further down the line. But in the realistic timeframe, things look a little more seasonal, and certainly synoptically things looks spectacular in comparison to recent winters, but there's nothing in the shorter term which especially excites me just yet.

But as alluded to a few days ago by Chio, and re-iterated again a few posts up by Catacol, the tropospheric pattern certainly conducive of something more exciting stratospherically in terms of Wave 2:

ECH1-144.GIF?03-12

Which will hopefully serve us well as the season goes on

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Not often driven to post here, but I see a lot of commentary which doesn't fit the evidential body. 

Although ECM and GEM ops runs consistently churn out a Scandi high of some form which adverts cold upper air, we know from clusters that ECM is split. 

The GFS suite by contrast virtually unanimously rejects the ECM op offerings, as do MetO, as do many ECM ensemble members. 

It seems to me that some people have been heavily and irrationally influenced by certain ops runs, probably because they show what we want to see. 

Consequently every GFS run is dismissed as faulty, or moving to ECM. This has been the story for days.

ECM and GEM ops may be right of course, but it seems to me most likely, based on the body of evidence, that they'll be wrong and we'll end up with a form of GFS sinking high to the south east. 

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1 hour ago, feb1991blizzard said:

This still screams battleground to me rather than big convective -10c uppers Easterly.

Or both? :) you never know!

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So as Snowking, GP and Blue army have pointed out my point about these being "fur coat and no knickers synoptics (at the moment) holds true. Things can of course change for the better down the line we are after all in the very early stages atm. and at least we're not at the end of feb and hanging our hats on this.

Edited by Broadmayne blizzard

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15 minutes ago, tight isobar said:

Gfs london ens...6z

😉

Screenshot_2018-01-03-12-22-47.png

Whats so good about them!!seems as though it hardly touches the -10 line now!!

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2 minutes ago, Broadmayne blizzard said:

So as Snowking, GP and Blue army have pointed out my point about these being "fur coat and no knickers synoptics (at the moment) holds true. Things can of course change for the better down the line we are after all in the very early stages atm. and at least we're not at the end of feb and hanging our hats on this.

The old mantra rings true here.  Get the pattern that we want established first......worry about precipitation afterwards.

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18 minutes ago, Tamara said:

The 'transitional' stage 4 GWO would deliver angular momentum sufficiently elevated against the base la Nina state to ensure enough downstream amplification and resultant split flow to be as closely ratioed as possible to orientate and hold the Scandi High in place for long enough so there is actually time for the stratospheric pathway feedbacks to prime themselves. AS well of course to extend the initial cold spell.

At the moment, we do not have 100% confidence this is going to happen - and hence why some WDT updates this week will give the guidance we need. Especially because differences still remain between the GEFS and other models on upstream tropical forcing - and as you know this has ramification for the broad-scale synoptic pattern.

Yep - 100% behind that. Broad scale macro forcings set the scene for microscopic scale pattern analysis. And the fascination for this winter's various evolutions continues.

@Glacier Point - are we not already GWO 2 into 3? Leaving aside schiraldi plot bias... and accepting that this chart is already 4 days old and subject to change - is it not indicative of an orbit heading to 4? 

Latest 90 Days GWO

Mountain Torque also elevated sufficiently over New Year period to help sustain AAM prior to next rise in frictionals?

Mountain Torque

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Allowing for a 10 day cycle in MT, we're probably at low point on a micro oscillation there Alistair - would tend to be supported by current GFS analysis and tropical forcing centred in the Indian Ocean.

gfsgwo.thumb.jpg.eb75ab2c72c10085f20c4cc08a36eee2.jpg

It's not until 9th January pattern looks vaguely +AAM over East Asia into the Pacific, and even then backend of week 2 into week 3 is when the tropical forcing signature becomes wholly supportive of a phase 4 transition. So if you buy into that GFS forecast dip (large -ve zonal wind anomaly forecast around 15-20N - annoyingly just out of range of Hovmoller plots to understand where this is occurring), a phase 2-3-2-1-2 type evolution looks in play for the next 10-14 day period.

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14 minutes ago, shaky said:

Whats so good about them!!seems as though it hardly touches the -10 line now!!

I didnt suggest they looked good...especialy in compare to 00z set!

The wink face was just for post purpose!

Anyway..in the overall scheme ; we have a lot to unfold over the next 24/48 hrs,-especialy where the gfs is concerned!!!

Edit..although there 'hardly completely drab-either....

12z will be more knowing.

Edited by tight isobar

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26 minutes ago, Borei said:

ECM and GEM ops may be right of course, but it seems to me most likely, based on the body of evidence, that they'll be wrong and we'll end up with a form of GFS sinking high to the south east. 

Or we could end up with a form of ecm/gem where the ridge isn’t as amplified north and sinks very gradually once the WAA pulses subside as the Atlantic pushes more ne and less se 

anything that doesn’t deliver a wintry nirvana will be labelled a GFS victory. It would be nothing of the sort. We have been banging on for days now that none of the op models will be right more than 6/7 days out. The gfs/gefs are moving closer to the other output - slowly but surely. But the other output will move a little towards a less cold solution - certainly the ops will. 

i always feel that the day 8 ens mean are a good fit for direction of travel - especially if eps and gefs are anomoly agreed.

Could this be one of those occasions where the ens play catch up to the post day 7/8 ops, day by day? Coldies would certainly hope so ! 

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10 minutes ago, Dennis said:

it would be nice :)

5.gif

Can you explain what this chart means please thank you .:)

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1 minute ago, abbie123 said:

Can you explain what this chart means please thank you .:)

It’s the Canadian ens mean anomolies for T192

 

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10 minutes ago, Dennis said:

it would be nice :)

5.gif

Hi Dennis could you put a bit more meat on the above to a numpty like me i have not the faintest idea what that chart is showing looks like something my six year old brings back from school.Not having a go just trying to learn.

Thanks

C.S

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19 minutes ago, Glacier Point said:

Allowing for a 10 day cycle in MT, we're probably at low point on a micro oscillation there Alistair - would tend to be supported by current GFS analysis and tropical forcing centred in the Indian Ocean.

gfsgwo.thumb.jpg.eb75ab2c72c10085f20c4cc08a36eee2.jpg

It's not until 9th January pattern looks vaguely +AAM over East Asia into the Pacific, and even then backend of week 2 into week 3 is when the tropical forcing signature becomes wholly supportive of a phase 4 transition. So if you buy into that GFS forecast dip (large -ve zonal wind anomaly forecast around 15-20N - annoyingly just out of range of Hovmoller plots to understand where this is occurring), a phase 2-3-2-1-2 type evolution looks in play for the next 10-14 day period.

Interesting. I will follow this carefully as it is a great moment to learn about lags and momentum trends up against NWP modelling. Given MT peak prior to NY I had assumed we would have AAM in the system prior to 9th Jan from it... and given amplitude of MJO currently and overall calculated tendency remaining weakly positive that we might sustain the orbit through to 4 without a temporary retreat through 1 - 2.

glcalctend.sig.90day.gif

 

However in all this I am significantly less experienced than many others... so will take a "watch and learn" perspective on it!

 

 

Edited by Catacol

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3 minutes ago, abbie123 said:

Can you explain what this chart means please thank you .:)

It shows higher than normal heights over Scandinavia and lower than normal heights to our south, with winds coming from an easterly direction.

Drawn with Crayons :D

Edited by karlos1983

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10 minutes ago, tight isobar said:

I didnt suggest they looked good...especialy in compare to 00z set!

The wink face was just for post purpose!

Anyway..in the overall scheme ; we have a lot to unfold over the next 24/48 hrs,-especialy where the gfs is concerned!!!

Edit..although there 'hardly completely drab-either....

12z will be more knowing.

Actually let me correct myself buddy!after taking a look at them again it seems the op and control are on the milder end and there are plenty more colder options between 120 amd 144 hours!!could be a good evening for us buddy!!

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