Model Output Discussion 18th Nov.2013-12z onwards.

[Cecil Hogmanay Melchett]

GFS ECM comparison for what is now just 138h

 

 

One of them is very wrong. 

GFS much flatter,well the 18z is at any rate.

[Tamara]

Early days... but this is as valid a model image as any other, even though this thread tends to focus on charts at 500 or 850.

 

Here is the Strat prediction for 1hPa - right at the top of the troposphere - for 10 days time.

 

 

Note the warming that is forecast to develop over our part of the NH.

 

This is the strongest predicted warming so far this autumn/winter - we cant see beyond 10 days but quite possible it may build further. It takes a week or more for something like this to propagate downwards towards the troposphere... but it may suggest the beginning of some kind of assault on the vortex.

 

If it turns out as forecast then currently it supports the idea of blocking in our locale. We could do with any vortex distortion at lower levels dragging that high pressure to our east or west... but without trying to use our crystal ball too much this is generally a good sign overall. I'm not knowledgeable enough yet to say more than this - but if we can get blocking enhanced in the latter half of the month with some reduction in the zonal wind speed aloft then our chances increase for sustained rather than transient cold.

I think we might have to be patient with durable higher latitude blocking for quite some time yet beyond these amplified atlantic ridges which are very welcome of course based on the limits of the overall pattern, but as a departure from the Friday evening ramping, this is a good post

[Iceaxecrampon]

Next weekend looks interesting I have been tracking the Seventh from the last weekend  - but you gotta love FI

 

 

 

 

Friday the 13th BTW if you buy into that sort of thing?

Edited November 29, 2013 by Iceaxecrampon

[Cloud 10]

The 18z is brewing a super-low which shouldn't be there!

 

http://modeles.meteociel.fr/modeles/gfs/runs/2013112918/gfs-0-138.png?18

[Cecil Hogmanay Melchett]

The jet is further north on 18z by a couple of hundred miles.Might prove to be critical on the snow stakes...

[Mucka]

The 18z is brewing a super-low which shouldn't be there!

 

http://modeles.meteociel.fr/modeles/gfs/runs/2013112918/gfs-0-138.png?18

 

 

 

 

 

 

 

If that verifies I will eat your hat. Laughable.

 

 

What sort of hat do you have by the way?

Edited November 29, 2013 by Mucka

[SMU]

erm, can you explain why you feel that will/may happen please. Both the 500mb charts show an upper trough over Scandinavia, and over the past few days there has been no sign of the upper high moving on them to where you suggest?

honest question

 

Evening All-  I will quote this post as its Shorter John-

 

This guide below is based on the energy going NORTH up the west of GH not SE across the atlantic as MAY still happen.........

 

Your quite right John the closed upper level low is plain to see at 144-

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/ECH1-144.GIF?29-0

 

However the ECM @ 144 is amplifying the jet & with that high comes trough disruption- so the closed low seperates & we get a piece of energy moving North- its JUST about a closed low, but equally could end up a shortwave feature-

The same goes if was moving ESE- a shallow system due to trough disruption.

 

So then onto Scandi- Am I Mad- I hear John shouting into his computer the upper level anomalies don't support it-

 

why isn't it a toppler V scandi ridge?

 

SIMPLE- Split energy & angle of flow.... If people are really looking to upskill on the models the key is to analize the ANGLE of flow & whether the flow is sinuous or split.

 

So we move onto the ECM 240- toppler???- NO CHANCE. Its a good chance but 'not quite there' where as I suspect the control rin is ( don't worry I will show you why)

 

ECM 240

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/ECH1-240.GIF?29-0

 

Now look at the jet ( & angle)

 

You will not that firstly its not the usual sinuous flow, with energy being spread out- The jet moving south through Scandi is enough to create a wave that would move south while the ridge continues to elongate on is northern flank- eventually that ridge elongates so much it becomes detached & can sit over Scandi in Situ-

The ECM 264 would probably see a UK- Scandi ridge with a slight continental flow-

 

HOWEVER ECM Control is rather better & MORE elongated- fortunately we see this in the CFS tonight-

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-0-258.png?06

 

If this popped up on the GFS or ECM all the calls would be toppler / sinker etc. but no..

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-4-258.png?06

Look at the angle of the JET - tilted SW NE & that horseshoe shape-

 

Roll on 2 days-

 

This is how it is in the transition-

 

& VIOLA

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-0-336.png?06

 

 

So this is what the ECM is trying to resolve today although at day 10 it will struggle-

 

Also the ENSEMBLE MEAN screams Scandi high-  but by the way it will be read people will think its a toppler-

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/EDH1-240.GIF?29-0

 

The suite of runs are 'trying' to push the energy of the top but that big blue hole over scandi will suddenly turn into high pressure just like that in a few days-

 

Remember that 'crappy' ECM mean from 3 days ago at 240 that lead to forecasts being built on that-

well that had no amplification built it- it was a toppler-

 

well now look at the ECM at 168

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/EDH1-168.GIF?29-0

 

All of a sudden things are near 'vertical' - as tommy cooper would say- just like that.......

 

 

S

Edited November 29, 2013 by Steve Murr

[East_England_Stormchaser91]

Still plenty of time for that low to go straight under that high. At the moment it is still well over the US, so we don't even know yet where the high will end up, let alone that pesky low that GFS is bringing forward stereotypically! 

More runs needed for sure.

[Tamara]

Its only the weather, and not a score card competition, do we have to have this combative male rutting with detached sentences and capital letters for emphasis? Model analysis is good - but can't it be restrained without machoism

Edited November 29, 2013 by Tamara תָּמָר

[Allseasons-Si]

 

 

 

What sort of hat do you have by the way?

 

 

A big straw clutching hat

 

 

as for the models,i would just like to comment on the 12z ECM 240 at face value(i know people have commented on this scenario)and also in FI,but it could be plausible IF it went right,here is my paint job if that 240 chart would come off

 

 

we could fetch a easterly if this ridge pushes further NE

 

i await another 24-48hrs to see if there is a trend there.

Edited November 29, 2013 by allseasons-si

[bluearmy]

Luv ya steve but drop the french!

Btw, the 18gfs shows what i meant re atlantic fronts meeting embedded cold air. Ian, are you there??

[Purga]

A bit more interest - and - uncertainty from the 18z

Marginal in the south but could develop into a decent frosty spell

 

-10C uppers into the SE

totally different to the 12z so who knows??

[garbagebags]

18z looks mighty flat Seems to be showing a very brief cold brought on only by the low, rather than any Atlantic ridging. Hope the ridging increases but the GFS has seemingly been overcooking Atlantic highs so far this season. Only to dowgrade them later.

 

I see heavy rain followed by freezing temps. Much like the other week.

Edited November 29, 2013 by garbagebags

[Cloud 10]

The new 120 hrs fax chart looks fairly sensible with the 528 dam line already into 

northern Scotland.

 

http://www.meteociel.fr/ukmo/fax/fax120s.gif?29-12

 

 

I doubt the gfs was weighted very heavily when it was created.

[Ali1977]

Beast from the east out the blue....

[Skyraker]

Evening All-  I will quote this post as its Shorter John-

 

This guide below is based on the energy going NORTH up the west of GH not SE across the atlantic as MAY still happen.........

 

Your quite right John the closed upper level low is plain to see at 144-

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/ECH1-144.GIF?29-0

 

However the ECM @ 144 is amplifying the jet & with that high comes trough disruption- so the closed low seperates & we get a piece of energy moving North- its JUST about a closed low, but equally could end up a shortwave feature-

The same goes if was moving ESE- a shallow system due to trough disruption.

 

So then onto Scandi- Am I Mad- I hear John shouting into his computer the upper level anomalies don't support it-

 

why isn't it a toppler V scandi ridge?

 

SIMPLE- Split energy & angle of flow.... If people are really looking to upskill on the models the key is to analize the ANGLE of flow & whether the flow is sinuous or split.

 

So we move onto the ECM 240- toppler???- NO CHANCE. Its a good chance but 'not quite there' where as I suspect the control rin is ( don't worry I will show you why)

 

ECM 240

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/ECH1-240.GIF?29-0

 

Now look at the jet ( & angle)

ECM240JET.jpg

 

You will not that firstly its not the usual sinuous flow, with energy being spread out- The jet moving south through Scandi is enough to create a wave that would move south while the ridge continues to elongate on is northern flank- eventually that ridge elongates so much it becomes detached & can sit over Scandi in Situ-

The ECM 264 would probably see a UK- Scandi ridge with a slight continental flow-

 

HOWEVER ECM Control is rather better & MORE elongated- fortunately we see this in the CFS tonight-

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-0-258.png?06

 

If this popped up on the GFS or ECM all the calls would be toppler / sinker etc. but no..

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-4-258.png?06

Look at the angle of the JET - tilted SW NE & that horseshoe shape-

 

Roll on 2 days-

CFS288.jpg

 

This is how it is in the transition-

 

& VIOLA

 

http://modeles.meteociel.fr/modeles/cfs/runs/2013112906/run1m/cfsnh-0-336.png?06

 

 

So this is what the ECM is trying to resolve today although at day 10 it will struggle-

 

Also the ENSEMBLE MEAN screams Scandi high-  but by the way it will be read people will think its a toppler-

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/EDH1-240.GIF?29-0

 

The suite of runs are 'trying' to push the energy of the top but that big blue hole over scandi will suddenly turn into high pressure just like that in a few days-

 

Remember that 'crappy' ECM mean from 3 days ago at 240 that lead to forecasts being built on that-

well that had no amplification built it- it was a toppler-

 

well now look at the ECM at 168

http://www.meteociel.fr/modeles/ecmwf/runs/2013112912/EDH1-168.GIF?29-0

 

All of a sudden things are near 'vertical' - as tommy cooper would say- just like that.......

 

 

S

 

 

 

Funnily enough.

 

[SnowObsessor90]

The GFS has defo gone to the pub tonight judging how FI looks to be shaping up

[nick sussex]

Jeez what a mess that GFS 18hrs run is, we get the low from hell and then the GFS goes onto develop what a few of us were talking about re a possible easterly as that dig of energy into the Atlantic helps kick the high ne.

 

This model soap opera is reaching Dallas proportions! You have to laugh, great fun is this but many members will be treated for nervous exhaustion by the time the cold arrives!

[SMU]

No rutting Tamara- just emphasising the point to people reading.

 

18z.

 

Energy separation & angle at 276 - classic scandi loading pattern

http://modeles.meteociel.fr/modeles/gfs/runs/2013112918/gfsnh-0-276.png?18

 

Viola!

http://modeles.meteociel.fr/modeles/gfs/runs/2013112918/gfsnh-0-324.png?18

 

http://modeles.meteociel.fr/modeles/gfs/runs/2013112918/gfsnh-1-324.png?18

 

The 18z couldn't have timed it better......

 

S

[Purga]

Snow showers for S Murr?

[bluearmy]

A messy 18z delivers copious amounts of snow as the uk straddles the polar front and then helps that scandi ridge drum beat a little louder still. Unlikely in the medium term but perhaps more plausible in the longer?

(Steve - its voila!)

Edited November 29, 2013 by bluearmy

[johnholmes]

from Steve

So then onto Scandi- Am I Mad- I hear John shouting into his computer the upper level anomalies don't support it-

no they don't and I am not sure anything else does unless one tries to 6th guess what the model is showing.

The anomaly charts, for what it is worth, are far from consistent, one accepts this at times with the ECMWF-GFS output, but not so much from NOAA. However their output tonight is hardly consistent with what they suggested 24 hours ago. That on both the 6-10 and 8-14 outlooks. When this happens then they are somewhat more use than a chocolate fireguard but not by much. What this does often indicate is that the 'signals' call them what you will further out are not consistent either. Indeed the whole model outputs seem so inclined to me, whether it be 96-144h, 240-384h on the synoptic models or looking at such as Stratosphere outputs, MJO etc. Makes the issue of predicting anything beyond day 3-5 an interesting and volatile exercise and anyone on here may get it right. Most of us will probably get it wrong but that is British weather for you. Come back the days prior to computers with seat of the pants forecasting using sensible maths and physics along with emperical rules for 24 sometimes as much as 48 hours ahead!

 

night night folks

Edited November 29, 2013 by johnholmes

[Skyraker]

Scandi High & slider @ 384.

 

They all seem to be getting to the same end product albeit by differeing routes.

 

I've never seen that before.

[johnholmes]

The new 120 hrs fax chart looks fairly sensible with the 528 dam line already into 

northern Scotland.

 

http://www.meteociel.fr/ukmo/fax/fax120s.gif?29-12

 

 

I doubt the gfs was weighted very heavily when it was created.

 

 

talking of 24-48 hour forecasting.

Whoever drew that 1000-500mb thickness 528DM line MID way between two fronts instead of close by one would have a serious problem explaining that to any instructor at the Met Office College!

Being specific, the area around 25w I think where the cold front becomes a warm front for a short length; the 528dm line crosses it into what is effectively a warm sector=really, explain that using the thickness equation please?

 

this is the simple bit before one starts to differentiate, integrate it and generally have fun!

 

The hydrostatic equation, in its simplified form, is -dp/dz = pg/RT

Edited November 29, 2013 by johnholmes

[East_England_Stormchaser91]

My days, look at that for a Scandi High. South and Eastern Coast event maybe if that comes off. French talcon powder type snow made in Paris!  

Edited November 29, 2013 by East_England_Stormchaser91