In article
,
Dawlish writes:
On Dec 23, 11:12*pm, Dave Cornwell wrote:

----------------------------------------
You may be right but surely this does not meet your normally stipulated
model consistency criteria. There is absolutely no agreement from
January 2nd onwards in the ensembles so your normal advice would be to
ignore it.

It's about consistency and agreement between the 2 main models, for me
Dave and both have been rock solid out to T+240. They still are this
morning. I use the ensembles only as a check at 10 days, because the
spaghetti that you find there is not useful, on its own, for
forecasting.

If there is spaghetti at 10 days, then surely that indicates that the
operational run cannot be relied on. Having said which, the most recent
ECM ensemble mean pressure chart is actually in excellent agreement with
the operational run and is showing an unusually small degree of standard
deviation, especially in the vicinity of the UK.
--
John Hall
"The power of accurate observation is commonly called cynicism
by those who have not got it."
George Bernard Shaw

"John Hall" wrote in message
...

If there is spaghetti at 10 days, then surely that indicates that the
operational run cannot be relied on. Having said which, the most recent
ECM ensemble mean pressure chart is actually in excellent agreement with
the operational run and is showing an unusually small degree of standard
deviation, especially in the vicinity of the UK.

Yes John, the ensemble mean is always the best guide for synoptic type, even
at low likelihood. The perturbations (members) will give probability of
weather based on the initial conditions at the time.
Time-lagged ensembles are better (not seen publicly) as they give an
indication of numerical stability and consistency. Also ensembles from the
MetO (not seen publicly) and with GFS used in conjunction can also add
confidence or otherwise.

Oh for a single multi-model, time-lagged ensemble product :-)

Will
--

On Dec 24, 11:32*am, John Hall wrote:
In article
,

*Dawlish writes:
On Dec 23, 11:12*pm, Dave Cornwell wrote:

----------------------------------------
You may be right but surely this does not meet your normally stipulated
model consistency criteria. There is absolutely no agreement from
January 2nd onwards in the ensembles so your normal advice would be to
ignore it.

It's about consistency and agreement between the 2 main models, for me
Dave and both have been rock solid out to T+240. They still are this
morning. I use the ensembles only as a check at 10 days, because the
spaghetti that you find there is not useful, on its own, for
forecasting.

If there is spaghetti at 10 days, then surely that indicates that the
operational run cannot be relied on. Having said which, the most recent
ECM ensemble mean pressure chart is actually in excellent agreement with
the operational run and is showing an unusually small degree of standard
deviation, especially in the vicinity of the UK.
--
John Hall
* * * * * * *"The power of accurate observation is commonly called cynicism
* * * * * * * by those who have not got it."
* * * * * * * * * * * * * * * * * * * * * * * George Bernard Shaw

It is *highly* likely to change and the agreement you see now at 10
days is unlikely to be there at 9 days, or 8 days. It may be, of
course, but it is more likely to be a one-run wonder than it is
something to be relied on. That's why I require a day's operationals
and two models to judge consistency and agreement, John. It sounds
like the MetO forecasters do something similar with the time-lagged
ensembles........but then they give them to the tea boy to present to
the public, in the form of that dreadful 6-15 day forecast, which no-
one can trust at 10-days. There is no measure that tells you when an
ensemble can be trusted at 10 days and I'd love to see someone try to
forecast on a regular basis, and get it right with even reasonable
accuracy. I don't think it is possible. If it was, the MetO would use
it for 10-day forecasting and get the synoptic type correct, on a
basis, regular enough to judge accuracy and justify that accuracy to
their public. They don't. It's as simple as that.

I do wish the MetO would make their ensembles public - after all we do
pay for them - but whatever judgement they use is not accurate enough
to give the public any kind of consistent accuracy at 10 days. I also
wish that the MetO would give some indication of the confidence they
have in forecasts at that distance, but, sadly, they don't seem to set
store by them, for the public.

whats your dolmio day?

On 24/12/2011 9:17 AM, Dawlish wrote:
because the
spaghetti that you find there is not useful,

On Dec 24, 12:55*pm, Dawlish wrote:
On Dec 24, 11:32*am, John Hall wrote:





In article
,

*Dawlish writes:
On Dec 23, 11:12*pm, Dave Cornwell wrote:

----------------------------------------
You may be right but surely this does not meet your normally stipulated
model consistency criteria. There is absolutely no agreement from
January 2nd onwards in the ensembles so your normal advice would be to
ignore it.

It's about consistency and agreement between the 2 main models, for me
Dave and both have been rock solid out to T+240. They still are this
morning. I use the ensembles only as a check at 10 days, because the
spaghetti that you find there is not useful, on its own, for
forecasting.

If there is spaghetti at 10 days, then surely that indicates that the
operational run cannot be relied on. Having said which, the most recent
ECM ensemble mean pressure chart is actually in excellent agreement with
the operational run and is showing an unusually small degree of standard
deviation, especially in the vicinity of the UK.
--
John Hall
* * * * * * *"The power of accurate observation is commonly called cynicism
* * * * * * * by those who have not got it."
* * * * * * * * * * * * * * * * * * * * * * * George Bernard Shaw

It is *highly* likely to change and the agreement you see now at 10
days is unlikely to be there at 9 days, or 8 days. It may be, of
course, but it is more likely to be a one-run wonder than it is
something to be relied on. That's why I require a day's operationals
and two models to judge consistency and agreement, John. It sounds
like the MetO forecasters do something similar with the time-lagged
ensembles........but then they give them to the tea boy to present to
the public, in the form of that dreadful 6-15 day forecast, which no-
one can trust at 10-days. There is no measure that tells you when an
ensemble can be trusted at 10 days and I'd love to see someone try to
forecast on a regular basis, and get it right with even reasonable
accuracy. I don't think it is possible. If it was, the MetO would use
it for 10-day forecasting and get the synoptic type correct, on a
basis, regular enough to judge accuracy and justify that accuracy to
their public. They don't. It's as simple as that.

I do wish the MetO would make their ensembles public - after all we do
pay for them - but whatever judgement they use is not accurate enough
to give the public any kind of consistent accuracy at 10 days. I also
wish that the MetO would give some indication of the confidence they
have in forecasts at that distance, but, sadly, they don't seem to set
store by them, for the public.- Hide quoted text -

- Show quoted text -

And nothing now really shows this cold zonal scenario.

http://www.jp2webdesign.co.uk/two/ensembles/

what, like the one that went over your pig head and was dimissed as
fantasy?

On 25/12/2011 10:39 PM, Dawlish wrote:

And nothing now really shows this cold zonal scenario.

http://www.jp2webdesign.co.uk/two/ensembles/

On Dec 23, 7:48*pm, Dawlish wrote:
There's no end to it. This zonal spell of weather began around the
start of the last week in November and if this forecast proves
correct, the spell will be close to 6 weeks in length. The forecasts
of a cold December, that we had to endure from some quarters in early
November are now a distant, failed, memory. 2 months of the winter
left. It'll get cold and snow widely at some stage (probably) but
there's nothing, for most, on the 10-day horizon.

**At T240, on January 2nd 2012. the UK will still be under the
influence of zonal, Atlantic weather. Pressure will be higher to the
South of the UK than to the north. Temperatures will vary with the
position of the depressions which will continue to pass to the north
of Scotland - colder, with hill snow in their lee; mild and perhaps
very mild, as depressions approach. rainfall amounts will be above
average over the next 10 days, especially in the N and NW of Scotland,
where there will be occasional spells of gales. Frosts will be
confined to transient ridges and lowland snow will be absent, for
most**.

No blocking; very little chance of sledge weather for anyone living
below 250m. Sorry coldies, but you can do nothing about those
consistent charts.

Nothing that changes mymind on this one, 3 days in. If the charts stay
the same today, I may well extend this to the 5th. There seems no end
to this zonal spell, at present. It really is solidly consistent
across all models, not just the gfs and ECM.

On Dec 26, 11:28*am, Dawlish wrote:
On Dec 23, 7:48*pm, Dawlish wrote:





There's no end to it. This zonal spell of weather began around the
start of the last week in November and if this forecast proves
correct, the spell will be close to 6 weeks in length. The forecasts
of a cold December, that we had to endure from some quarters in early
November are now a distant, failed, memory. 2 months of the winter
left. It'll get cold and snow widely at some stage (probably) but
there's nothing, for most, on the 10-day horizon.

**At T240, on January 2nd 2012. the UK will still be under the
influence of zonal, Atlantic weather. Pressure will be higher to the
South of the UK than to the north. Temperatures will vary with the
position of the depressions which will continue to pass to the north
of Scotland - colder, with hill snow in their lee; mild and perhaps
very mild, as depressions approach. rainfall amounts will be above
average over the next 10 days, especially in the N and NW of Scotland,
where there will be occasional spells of gales. Frosts will be
confined to transient ridges and lowland snow will be absent, for
most**.

No blocking; very little chance of sledge weather for anyone living
below 250m. Sorry coldies, but you can do nothing about those
consistent charts.

Nothing that changes mymind on this one, 3 days in. If the charts stay
the same today, I may well extend this to the 5th. There seems no end
to this zonal spell, at present. It really is solidly consistent
across all models, not just the gfs and ECM.- Hide quoted text -

- Show quoted text -

gfs 12z keeps the zonal train on the tracks. See what the ECM shows.
The 12z operational showed a hint of rising pressure in mid-Atlantic
at 10-days, but with this ensemble set, I wouldn't trust it!

http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif

On Dec 26, 5:36*pm, Dawlish wrote:
On Dec 26, 11:28*am, Dawlish wrote:





On Dec 23, 7:48*pm, Dawlish wrote:

There's no end to it. This zonal spell of weather began around the
start of the last week in November and if this forecast proves
correct, the spell will be close to 6 weeks in length. The forecasts
of a cold December, that we had to endure from some quarters in early
November are now a distant, failed, memory. 2 months of the winter
left. It'll get cold and snow widely at some stage (probably) but
there's nothing, for most, on the 10-day horizon.

**At T240, on January 2nd 2012. the UK will still be under the
influence of zonal, Atlantic weather. Pressure will be higher to the
South of the UK than to the north. Temperatures will vary with the
position of the depressions which will continue to pass to the north
of Scotland - colder, with hill snow in their lee; mild and perhaps
very mild, as depressions approach. rainfall amounts will be above
average over the next 10 days, especially in the N and NW of Scotland,
where there will be occasional spells of gales. Frosts will be
confined to transient ridges and lowland snow will be absent, for
most**.

No blocking; very little chance of sledge weather for anyone living
below 250m. Sorry coldies, but you can do nothing about those
consistent charts.

Nothing that changes mymind on this one, 3 days in. If the charts stay
the same today, I may well extend this to the 5th. There seems no end
to this zonal spell, at present. It really is solidly consistent
across all models, not just the gfs and ECM.- Hide quoted text -

- Show quoted text -

gfs 12z keeps the zonal train on the tracks. See what the ECM shows.
The 12z operational showed a hint of rising pressure in mid-Atlantic
at 10-days, but with this ensemble set, I wouldn't trust it!

http://www.meteogroup.co.uk/meteo/ep...t6-london.gif- Hide quoted text -

- Show quoted text -

2 runs from the ECM showing more meridionality but no support
whatsoever from the gfs. No more than slight interest at present from
me and I think the depressions are more likely to roll the ridging out
of the way, so as to speak, tomorrow, but it ruins the model agreement
for a forecast.

http://www.wetterzentrale.de/pics/Recm2402.gif

On Dec 26, 9:17*pm, Dawlish wrote:
On Dec 26, 5:36*pm, Dawlish wrote:





On Dec 26, 11:28*am, Dawlish wrote:

On Dec 23, 7:48*pm, Dawlish wrote:

There's no end to it. This zonal spell of weather began around the
start of the last week in November and if this forecast proves
correct, the spell will be close to 6 weeks in length. The forecasts
of a cold December, that we had to endure from some quarters in early
November are now a distant, failed, memory. 2 months of the winter
left. It'll get cold and snow widely at some stage (probably) but
there's nothing, for most, on the 10-day horizon.

**At T240, on January 2nd 2012. the UK will still be under the
influence of zonal, Atlantic weather. Pressure will be higher to the
South of the UK than to the north. Temperatures will vary with the
position of the depressions which will continue to pass to the north
of Scotland - colder, with hill snow in their lee; mild and perhaps
very mild, as depressions approach. rainfall amounts will be above
average over the next 10 days, especially in the N and NW of Scotland,
where there will be occasional spells of gales. Frosts will be
confined to transient ridges and lowland snow will be absent, for
most**.

No blocking; very little chance of sledge weather for anyone living
below 250m. Sorry coldies, but you can do nothing about those
consistent charts.

Nothing that changes mymind on this one, 3 days in. If the charts stay
the same today, I may well extend this to the 5th. There seems no end
to this zonal spell, at present. It really is solidly consistent
across all models, not just the gfs and ECM.- Hide quoted text -

- Show quoted text -

gfs 12z keeps the zonal train on the tracks. See what the ECM shows.
The 12z operational showed a hint of rising pressure in mid-Atlantic
at 10-days, but with this ensemble set, I wouldn't trust it!

http://www.meteogroup.co.uk/meteo/ep...ondon.gif-Hide quoted text -

- Show quoted text -

2 runs from the ECM showing more meridionality but no support
whatsoever from the gfs. No more than slight interest at present from
me and I think the depressions are more likely to roll the ridging out
of the way, so as to speak, tomorrow, but it ruins the model agreement
for a forecast.

http://www.wetterzentrale.de/pics/Recm2402.gif- Hide quoted text -

- Show quoted text -

12z shows the same kind of chance of a slower-moving, more complex low
transferring east, to the north of the UK, with the potential to drag
down some colder air in its wake. That's 3 ECM runs showing more
meridionality, but the gfs just won't play ball! I do feel. however,
that the 12z gfs operational will be a rank mild outlier, like the 06z
was. Will's (2-day) cooler change of pattern will be on us on
Thursday. *)) I wonder if this ECM colder chance at 9/10 days is
tickling the coldies' fancy? It's not impossible that the end of the
first week in Jan will see some distinctly cooler weather.