Model Output Discussion 01/09/17

[Paul_1978]

2 minutes ago, BLAST FROM THE PAST said:

12z GFS is incredible.  I think though there is a fair bit of tinkering to be had yet...... but a pretty darn cold last 3rd of Nov is definitely the favourite here whichever form.....I hope so ?

 

BFTP

Agreed. 12z couldn't be any more different to the 06z. Puzzling but interesting..... Puts everyone on tenterhooks this model watching doesn't it!

[ICE COLD]

Can't believe there's no one posting these

[EML Network]

Well it was just a matter of time before we saw charts such as the 12z GFS run today, you know when a cold spell is more likely than not when things start ''upgrading'' closer to the time frame, rather than the other way around, i guess it's more a firming up. 

I recall saying earlier this week that I preferred the GFS evolution as opposed to the ECM as it kept us in the game as today's 12z GFS run highlights that perfectly, with just about anywhere having a chance of some pre Winter snowfall IF IT CAME OFF as modelled. 

Lets not forget that we're still in Autumn here !!

The timestamp above is post 200+ so needless to say taken with a lorry load of salt, however, it's a chart loaded with possibilities and pretty much all of them favour some form of cold evolution thereafter. 

Things are shaping up quite nicely and I can't recall when we last had a cold November and it would be interesting to see some sort of analog showing winters that followed a cold November and how they panned out. 

Great charts over the past few days and everything I am seeing bares all the hallmarks of a solid and dare I say even prolonged cold spell looming

[SteveB]

It's great to see like..... but it's sure to look different later on the 18z, 0z, 6z, 12z if you catch my drift.

[bluearmy]

I suspect that most charts post day 6 will be viewed with some scepticism after that ukmo run. 

Even if ecm throws out a stellar suite that ukmo will be gnawing away at the back of our minds .......

[Mucka]

The lack of excitement for 12z GFS is probably twofold.

firstly it is just another possible solution and one of many but perhaps more likely is the lack of deep cold upper air so that although the synoptic pattern is an impressive winter pattern, at this time of year it may not be enough to bring snow to low levels.

Personally I am with the camp that states get the blocking in first and worry about the cold uppers next and then finally potential snowfall.

Edited November 10, 2017 by Mucka

[Singularity]

06z:   12z:   

Well, GEM just went from horror show to near-nirvana from the 00z to the 12z, so it seems uncertainty is sky-high right now. Makes me less concerned about the UKMO 12z, but less jubilant over the GFS 12z or this GEM 12z for that matter. 

[SMU]

Afternoon All

So the other day when I put a bit of commentary on the changing phase of the AO the key note was the abrupt change in the polar field- an almost full reversal of polarity over 60N-90N

Within the models we have the usual stable polar cell working alongside the unstable volatile ferrell cell ( mid lattitude ) - in a positive AO phase there isnt to much overlap however when we head deep into negativity - you have a steep unstable change curve across the polar cell overlapping the instability of the ferrell-

This is when Entropy / Volatility is at its highest so the longwave pattern which overlaps both is subject to frequent changes & revisions even in the 144-240 arena & the shortwave pattern is also even more volatile in the 96-144 timeline

With that in mind I still forecast the GFS & the notion that that big low will go through the block into Scandi is going to be wrong & rather the energy will go under the block allowing for some sort of ridge out of France over the UK & alligned more Northerly towards Scandi-

If this notion is correct then my chosen model for the afternoon is the UKMO 12z which is having none of the GFS antics-

This difference mainly impacts the way the pressure fields are alligned over western Europe when the Canadian & Arctic High try to allign together across the pole--

If that forecast does come true forget about the Northerly as it will be replaced by a southerly possibly swinging Easterly later as the high pressure migrates into the x2 parent highs.

Sadly i have next to no eggs in the GFS basket tonight similar to the forecast yesterday ( but I have left one there as a token gesture ! )

UKMO > GFS .. ( less we forget Mar 13 )

S

just a PS if you have been since the start even back when the GFS was the AVN & even in more recent examples when you have a split jet the GFS bias always adds more energy to the northern arm & thats what its doing tonight forcing the trough over the top / through where UKMO is southern stream focussed.... 

Edited November 10, 2017 by Steve Murr

[Don]

14 minutes ago, bluearmy said:

I suspect that most charts post day 6 will be viewed with some scepticism after that ukmo run. 

Even if ecm throws out a stellar suite that ukmo will be gnawing away at the back of our minds .......

Yes, it's always a concern when the UKMO goes against the GFS and ECM.

[tight isobar]

There will 99/100 be a wrong en' in main three ops' ukmo-gfs-ecm.

And no doubt about it ones soon to be shown. Atm the ukmo is the odd one out with regards-evolution.

Ecm 12z is up next/soon and with 12z theres no lack-nor catch up.

So lets see who she sides with short/medium term!!!

[mulzy]

6 minutes ago, Don said:

Yes, it's always a concern when the UKMO goes against the GFS and ECM.

Indeed - the German ICON model (not sure how good this model is?) follows UKMO...

 

[northwestsnow]

Ok i cant post updated charts after numerous attempts.

I dont see the issue with the UKMO 144- it looks dry and cold, and imho the uk high will be moving north towards the GIN  soonafter.

 

Edited November 10, 2017 by northwestsnow

[karlos1983]

The only thing that made viewing the GFS even better than it was, is that I got to watch it roll out in the pub with a beer. BANK!  Let’s hope the ECM has that Friday feeling 

Edited November 10, 2017 by karlos1983

[BlakeyWeather]

Back to the here and now, Monday morning looking very cold for northern and western areas with a widespread hard frost. Could we see our first -10c in the frost hollows of Scotland?

[northwestsnow]

3 minutes ago, BlakeyWeather said:

Back to the here and now, Monday morning looking very cold for northern and western areas with a widespread hard frost. Could we see our first -10c in the frost hollows of Scotland?

Wonderful chart, enough to warm the cockles of every coldie on Net weather.

UKMO looks cold too.

Faith is restored this evening.

[Singularity]

41 minutes ago, Steve Murr said:

Afternoon All

So the other day when I put a bit of commentary on the changing phase of the AO the key note was the abrupt change in the polar field- an almost full reversal of polarity over 60N-90N

Within the models we have the usual stable polar cell working alongside the unstable volatile ferrell cell ( mid lattitude ) - in a positive AO phase there isnt to much overlap however when we head deep into negativity - you have a steep unstable change curve across the polar cell overlapping the instability of the ferrell-

This is when Entropy / Volatility is at its highest so the longwave pattern which overlaps both is subject to frequent changes & revisions even in the 144-240 arena & the shortwave pattern is also even more volatile in the 96-144 timeline

With that in mind I still forecast the GFS & the notion that that big low will go through the block into Scandi is going to be wrong & rather the energy will go under the block allowing for some sort of ridge out of France over the UK & alligned more Northerly towards Scandi-

If this notion is correct then my chosen model for the afternoon is the UKMO 12z which is having none of the GFS antics-

This difference mainly impacts the way the pressure fields are alligned over western Europe when the Canadian & Arctic High try to allign together across the pole--

If that forecast does come true forget about the Northerly as it will be replaced by a southerly possibly swinging Easterly later as the high pressure migrates into the x2 parent highs.

Sadly i have next to no eggs in the GFS basket tonight similar to the forecast yesterday ( but I have left one there as a token gesture ! )

UKMO > GFS .. ( less we forget Mar 13 )

S

just a PS if you have been since the start even back when the GFS was the AVN & even in more recent examples when you have a split jet the GFS bias always adds more energy to the northern arm & thats what its doing tonight forcing the trough over the top / through where UKMO is southern stream focussed.... 

 

You've not been at the controls of the ICON model have you Mr. Murr? 

[Paul]

Please can we keep it to model discussion in this thread, head over to the winter thread if you want to chat more generally about the weather prospects during the upcoming winter. 

 

[The PIT]

GFS seems in a bullish mood in keeping things generally on the cold side so lets see what ecm comes up with.

[tight isobar]

London ens.

850's...

Some very notable cold showing later november!!!!

 

12z

Edited November 10, 2017 by tight isobar

[northwestsnow]

4 minutes ago, tight isobar said:

London ens.

850's...

Some very notable cold showing later november!!!!

 

12z

Tremendous set of ensembles!!

[SMU]

ECM 144 slap bang half way house inbetween UKMO / GFS

[tight isobar]

Gfs-ecm-ukmo..

@144..

Not hard to spot the odd one out...

Lets see where rest of run goes ec-12z...

Gfs

Ecm

Ukmo

Edited November 10, 2017 by tight isobar

[mpkio2]

Hello all once again!

Just returned from hand therapy session to find my page with 20+ new posts - must be good 12z suite this afternoon - I thought. ..

And sure enough....

12z GFS 10/11 t162:

12z ECM 10/11 t168:

12z GEM 10/11 t162:

12z UKMO 10/11 t144:

Just wanted to add to @Steve Murr earlier post regarding "model volatility" in output - this always happens, as Steve points out, in these kind of complex, atmospheric changing situations; especially heading into a negative AO phase, the models finding it difficult in how ridging in the Atlantic, Arctic high will interact with the fledging Polar Vortex and how the outcome Polar Volticies will behave (re be positioned and affect mid-lats). It's quite a lot for a computer model to predict!

Regarding the UKMO 12z t144 - looks good to me!   Look at the bigger picture - its just pinned for the low to head SE as the high builds over Scandi and connect to the ridging growing over Greenland. The Low is negative tilted which will allow for it to go under any high that builds in the GIN corridor.

Also, I think its best we get to where the models start to form ridging or HLB and how fast or slow the low that comes of America around the 16th November - the models are struggling at this point, because they can't fathom how it will affect the NWP, which is why we are seeing many different outcomes post this point!  Look above and see how this is illustrated above with how each model structures that low sitting to the west of the UK!!

To summerise, not bad 12z suite this afternoon! The theme/trend is still there (Blocking in/around Arctic), which is good if you want cold weather! So, expect different outcomes post Day 5 period and beyond - let's get to where the blocking starts to form, then we can worry where we will get the cold and snow from.

P.S. ECM, don't let us down now! *Hides behind sofa*

Edit - Not bad 12z ECM up to t168! Halfway between GFS/UKMO. Think its to "blob" like to head under any block though....*Waits and sees*

~mpkio2~

 

Edited November 10, 2017 by mpkio2

[SMU]

Ec 168 -Scandi ridge up she goes- Atlantic stuck over uk & will struggle with much more easterly progression-

GFS at same point into benelux with trough- UKMO would be well hung back... ( awaiting ukmo 168 )

S

[tight isobar]

 "Trouble uploading snapshots"..

Run of the day coming up??!!. 

Complete scandinavian height settlment..

Partial grenny high...

And vortex with no formed definition???