comp.john wrote:
On 2009-12-07, John Hall wrote:
The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

I think they are the 20 ensembly members, basically 20 different runs.
If they all follow the same line then confidence is higher. e.g.:
http://www.wetterzentrale.de/pics/senspanel2401.html
This shows 20 versions of the same day....
All others can be found he
http://www.wetterzentrale.de/topkarten/fsenseur.html

--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

In article ,
comp.john writes:
On 2009-12-07, John Hall wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

Good question. Hopefully someone else will know, as I don't have a clue.
--
John Hall "[It was] so steep that at intervals the street broke into steps,
like a person breaking into giggles or hiccups, and then resumed
its sober climb, until it had another fit of steps."
Ursula K Le Guin "The Beginning Place"

On Mon, 07 Dec 2009 22:04:40 +0000, John Hall wrote:

In article ,
comp.john writes:
On 2009-12-07, John Hall wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

Good question. Hopefully someone else will know, as I don't have a clue.

I've always assumed that they're simply a guide to which perturbation is
shown in which colour.

--
Bewdley, Worcs. ~90m asl.

On Dec 7, 11:42*pm, David Buttery wrote:
On Mon, 07 Dec 2009 22:04:40 +0000, John Hall wrote:
In article ,
*comp.john writes:
On 2009-12-07, John Hall wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

Good question. Hopefully someone else will know, as I don't have a clue..

I've always assumed that they're simply a guide to which perturbation is
shown in which colour.

--
Bewdley, Worcs. ~90m asl.

Yes, as far as I know. It's so you can identify which run is which.

"Martin Rowley" wrote ...
"comp.john" wrote in message
...
On 2009-12-07, John Hall wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the
chart?

... tags identifying the individual perturbation outcome depicted on
the composite plume. P=0 is the first perturbation, P=1 is the
second and so on. The colours match the individual (thin) lines on
the chart. Useful if you're trying to identify clustering of the
members of the plume-set.

.... I should have added that for each main time-step of the ensemble
run, a set of 'postage stamps' will be available. They're called that
because they look like a sheet of stamps you might see in a post
office.

Usually (based on the EC output), for the main VT times, each 'postage
stamp' sheet will show the 'operational' run mslp pattern, the
'control' run mslp pattern, and for each perturbation, the model's
idea of what the mslp pattern would be that produced that individual
outcome.

So, the analyst would look as these data - and want, say to
investigate why P16 was markedly colder than the rest, and view the
mslp (and perhaps other diagnostics) that are attached to that
particular outcome.

We don't (AFAIK) see these on the open 'web', so in a sense the
coloured 'P' lines/numbers aren't of high relevance.

Martin.


--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

On 8 Dec, 12:03, "Martin Rowley"
wrote:
"Martin Rowley" wrote ...





"comp.john" wrote in message
...
On 2009-12-07, John Hall wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the
chart?
... tags identifying the individual perturbation outcome depicted on
the composite plume. P=0 is the first perturbation, P=1 is the
second and so on. The colours match the individual (thin) lines on
the chart. Useful if you're trying to identify clustering of the
members of the plume-set.

... I should have added that for each main time-step of the ensemble
run, a set of 'postage stamps' will be available. They're called that
because they look like a sheet of stamps you might see in a post
office.

Usually (based on the EC output), for the main VT times, each 'postage
stamp' sheet will show the 'operational' run mslp pattern, the
'control' run mslp pattern, and for each perturbation, the model's
idea of what the mslp pattern would be that produced that individual
outcome.

So, the analyst would look as these data - and want, say to
investigate why P16 was markedly colder than the rest, and view the
mslp (and perhaps other diagnostics) that are attached to that
particular outcome.

We don't (AFAIK) see these on the open 'web', so in a sense the
coloured 'P' lines/numbers aren't of high relevance.

Martin.

--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N * Long: 01.88W
NGR: SU 082 023- Hide quoted text -

- Show quoted text -

I'm still not convinced the cold next week is going to be anymore than
sleet, with any snow quickly melting on the ground, well at least at
my neck of the woods :-(

Obviously at longer range gfs goes off at a tangent, but I'm not
really taking then serious atm.

Keith (Southend)

Martin Rowley wrote:

"Martin Rowley" wrote ...
"comp.john" wrote in message
... On 2009-12-07, John Hall
wrote:

The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

... tags identifying the individual perturbation outcome depicted on the
composite plume. P=0 is the first perturbation, P=1 is the second and so
on. The colours match the individual (thin) lines on the chart. Useful if
you're trying to identify clustering of the members of the plume-set.

... I should have added that for each main time-step of the ensemble run, a
set of 'postage stamps' will be available. They're called that because they
look like a sheet of stamps you might see in a post office.

Usually (based on the EC output), for the main VT times, each 'postage stamp'
sheet will show the 'operational' run mslp pattern, the 'control' run mslp
pattern, and for each perturbation, the model's idea of what the mslp pattern
would be that produced that individual outcome.

So, the analyst would look as these data - and want, say to investigate why
P16 was markedly colder than the rest, and view the mslp (and perhaps other
diagnostics) that are attached to that particular outcome.

We don't (AFAIK) see these on the open 'web', so in a sense the coloured 'P'
lines/numbers aren't of high relevance.

Martin.


The GFES 'postage stamp' sheets are available at

http://www.netweather.tv/index.cgi?a...wer;type=panel

They are in 6-hourly time-steps out to T+384.


Norman

On 2009-12-08, Martin Rowley
wrote:

[...]

cool, that's easy to follow. Thanks for the explanation.

--
comp.john

In article ,
Jon O'Rourke writes:
"comp.john" wrote in message
...

How does 850mb temp correspond with surface temp at this time of year?
is -5 @ 850mb 0C at the surface?
-- comp.john

It's not really the best guide for surface temperatures as the boundary
layer conditions at this time of year can heavily modify a direct
adiabatic translation. However, to give you some idea, when 850mb
temperatures were around -4 around a week ago daytime surface
temperatures were in the +4 to +6 ballpark.

And the long-term mean 850mb for this time of year is about -1, as shown
by the white line on the GFS ensemble temperatures. The mean maximum
surface temperature at this time of year would be about 8, again
indicating a difference between the 850mb level and the surface of about
8 degrees on average.
--
John Hall "[It was] so steep that at intervals the street broke into steps,
like a person breaking into giggles or hiccups, and then resumed
its sober climb, until it had another fit of steps."
Ursula K Le Guin "The Beginning Place"

On Dec 8, 12:03*pm, "Martin Rowley"
wrote:
"Martin Rowley" wrote ...

So, the analyst would look as these data - and want, say to
investigate why P16 was markedly colder than the rest, and view the
mslp (and perhaps other diagnostics) that are attached to that
particular outcome.

We don't (AFAIK) see these on the open 'web', so in a sense the
coloured 'P' lines/numbers aren't of high relevance.

We do - as well as the "postage stamps" Norman mentioned, you can see
each GFS ensemble member in detail at Meteociel.

http://www.meteociel.com/modeles/gefs_cartes.php

Click the numbers +1 to +20 where it says "Perturbations", or "Moy"
for the ensemble mean.