On 11/06/11 09:00, Gavino wrote:
"Will wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?




Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

On Jun 11, 11:42*am, Adam Lea wrote:
On 11/06/11 09:00, Gavino wrote:

"Will *wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

"Adam Lea" wrote in message
...
On 11/06/11 09:00, Gavino wrote:
But the real lesson is that anyone who predicts the weather several
weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

OK, I was stretching the analogy a bit to make the point.
With some specialist knowledge, you can shorten the odds against you, just
as a seasoned stock-market analyst might occasionally come up with a good
tip.

But ultimately the chaotic nature of the underlying dynamics puts a limit on
how far out you can forecast with any degree of confidence.
I have yet to see any evidence that a 'successful' long-range forecast is
down to anything but luck.
Humans have an inbuilt tendency to be "fooled by randomness".
http://en.wikipedia.org/wiki/Fooled_by_Randomness

On Sat, 11 Jun 2011 14:19:26 +0200, Gavino wrote:

"Adam Lea" wrote in message
...
On 11/06/11 09:00, Gavino wrote:
But the real lesson is that anyone who predicts the weather several
weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him
for being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

OK, I was stretching the analogy a bit to make the point. With some
specialist knowledge, you can shorten the odds against you, just as a
seasoned stock-market analyst might occasionally come up with a good
tip.

But ultimately the chaotic nature of the underlying dynamics puts a
limit on how far out you can forecast with any degree of confidence. I
have yet to see any evidence that a 'successful' long-range forecast is
down to anything but luck.
Humans have an inbuilt tendency to be "fooled by randomness".
http://en.wikipedia.org/wiki/Fooled_by_Randomness

Long-range forecasting reminds me of the state of short-range forecasting
when I was a lot younger. Some days you'd count yourself lucky if you got
a 6-hour forecast right but, on others, the synoptic situation allowed
you to be confident on venturing out as far as three days. Come to think
of it, 6 hours would have been a bit optimistic. I recall issuing a
forecast which went tits up in 6 minutes.

My experience tells me that long-range forecasting was possible forty
years ago given well-defined starting conditions as long as the
forecaster didn't get too ambitious. SST anomalies would give a
statistically significant prognosis as to the following month's pressure
anomaly near Iceland but accuracy would tail off the further you moved
away from that area. So forecasts for the UK tended to be a bit flaky but
were of some use. Again, that depended on the SST pattern being strong -
a weak, flabby pattern was of little use.

Returning to the current time for an example, I'd say the SST pattern
points to pressure being lower than average east of Iceland and high near
and to the west of the Azores. All well and good, but how many variations
in pressure pattern over the UK will fit that scenario? The best bet is
for a cyclonic west- or north-west flow but it's not the only solution.

Broad-scale long-range forecasting is possible - and has been so for
decades - but customers and forecasters ought not to be greedy. Expecting
an accurate forecast for the UK is like someone who complains about the
daily forecast because it told of showers for southern England but his
garden in Bracknell didn't get a drop.

--
Graham Davis, Bracknell, Berks. E-mail: change boy to man
To consider the Earth the only populated world in infinite space is as
absurd as to assert that in an entire field sown with millet only one
grain will grow. - Metrodoros, 300BC

On 11/06/11 11:49, Dawlish wrote:
On Jun 11, 11:42 am, Adam wrote:
On 11/06/11 09:00, Gavino wrote:

"Will wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

http://www.tropicalstormrisk.com/doc...esetal2004.pdf
http://climate.mssl.ucl.ac.uk/docs/Q...unders2003.pdf
http://climate.mssl.ucl.ac.uk/docs/Q...unders2003.pdf
http://climate.mssl.ucl.ac.uk/docs/J...unders2008.pdf
http://www.tropicalstormrisk.com/docs/GlobalRe2004.pdf

using the criteria that "skill" means doing better than climatology over
the long term.

On Jun 11, 2:49*pm, Adam Lea wrote:
On 11/06/11 11:49, Dawlish wrote:





On Jun 11, 11:42 am, Adam *wrote:
On 11/06/11 09:00, Gavino wrote:

"Will * *wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts..

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

http://www.tropicalstormrisk.com/doc...obalRe2004.pdf

using the criteria that "skill" means doing better than climatology over
the long term.- Hide quoted text -

- Show quoted text -

Sorry Adam, forgot to say. When I "forecast" winters in the UK I only
use one variable; temperature. (rainfall, snowfall, storminess etc is
impossible, IMO). I've been right about 75%+ of the time since 1990
and I have forecasted "warmer than the long-term average" every year.
No flannel; I just use two things. Climatology, married to a UK
warming trend. Show me another forecaster that has that kind of level
of accuracy. *)) (notice the smiley)

Winter 2011-12 - warmer than average. You heard it here first! Easy
eh? *))

your variable is a crock of ****

On 11/06/2011 6:09 PM, Dawlish wrote:
- Show quoted text -

Sorry Adam, forgot to say. When I "forecast" winters in the UK I only
use one variable; temperature. (rainfall, snowfall, storminess etc is
impossible, IMO). I've been right about 75%+ of the time since 1990
and I have forecasted "warmer than the long-term average" every year.
No flannel; I just use two things. Climatology, married to a UK
warming trend. Show me another forecaster that has that kind of level
of accuracy. *)) (notice the smiley)

Winter 2011-12 - warmer than average. You heard it here first! Easy
eh? *))

On 11/06/11 18:09, Dawlish wrote:
On Jun 11, 2:49 pm, Adam wrote:
On 11/06/11 11:49, Dawlish wrote:





On Jun 11, 11:42 am, Adam wrote:
On 11/06/11 09:00, Gavino wrote:

"Will wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

http://www.tropicalstormrisk.com/doc...obalRe2004.pdf

using the criteria that "skill" means doing better than climatology over
the long term.- Hide quoted text -

- Show quoted text -

Sorry Adam, forgot to say. When I "forecast" winters in the UK I only
use one variable; temperature. (rainfall, snowfall, storminess etc is
impossible, IMO). I've been right about 75%+ of the time since 1990
and I have forecasted "warmer than the long-term average" every year.
No flannel; I just use two things. Climatology, married to a UK
warming trend. Show me another forecaster that has that kind of level
of accuracy. *)) (notice the smiley)

Winter 2011-12 - warmer than average. You heard it here first! Easy
eh? *))

That is what is known as a climatology forecast, or a "zero
intelligence" forecast. It is a benchmark against which seasonal
forecasts are judged, a forecast is skilful if it outperforms the
benchmark forecast over a significant number of forecasts.

Just to check, are you trying to claim all seasonal forecasts have no
skill or just UK seasonal forecasts?

On Jun 11, 10:29*pm, Adam Lea wrote:
On 11/06/11 18:09, Dawlish wrote:





On Jun 11, 2:49 pm, Adam *wrote:
On 11/06/11 11:49, Dawlish wrote:

On Jun 11, 11:42 am, Adam * *wrote:
On 11/06/11 09:00, Gavino wrote:

"Will * * *wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

http://www.tropicalstormrisk.com/doc...004.pdfhttp://....

using the criteria that "skill" means doing better than climatology over
the long term.- Hide quoted text -

- Show quoted text -

Sorry Adam, forgot to say. When I "forecast" winters in the UK I only
use one variable; temperature. (rainfall, snowfall, storminess etc is
impossible, IMO). I've been right about 75%+ of the time since 1990
and I have forecasted "warmer than the long-term average" every year.
No flannel; I just use two things. Climatology, married to a UK
warming trend. Show me another forecaster that has that kind of level
of accuracy. *)) (notice the smiley)

Winter 2011-12 - warmer than average. You heard it here first! Easy
eh? *))

That is what is known as a climatology forecast, or a "zero
intelligence" forecast. It is a benchmark against which seasonal
forecasts are judged, a forecast is skilful if it outperforms the
benchmark forecast over a significant number of forecasts.

Just to check, are you trying to claim all seasonal forecasts have no
skill or just UK seasonal forecasts?- Hide quoted text -

- Show quoted text -

I did say "notice the smiley" and I think you missed the inverted
commas Adam. *)) I'm very aware of what that "forecast" shows. No-
one, AFAIK has got anywhere near that benchmark during that time. If
they have, I'd love to know, as we would have found a forecasting holy
grail. It just illustrates that any forecast you read for this coming
winter (or any other season) does not deserve the credence some people
like to give them. Judge forecasters on their accuracy; not on their
forecasts.

On 12/06/11 07:15, Dawlish wrote:
On Jun 11, 10:29 pm, Adam wrote:
On 11/06/11 18:09, Dawlish wrote:





On Jun 11, 2:49 pm, Adam wrote:
On 11/06/11 11:49, Dawlish wrote:

On Jun 11, 11:42 am, Adam wrote:
On 11/06/11 09:00, Gavino wrote:

"Will wrote in message
...
OK I'm conceeding that it is highly likely that I will be totally wrong
about my indications for a hot and dry June

Kudos for admitting failure.
But the real lesson is that anyone who predicts the weather several weeks
ahead is never 'right' or 'wrong', merely 'lucky' or 'unlucky'.

If someone wins the football pools, no-one would think to praise him for
being a great forecaster.
Why should (long-range) weather forecasting be any different?

Because seasonal forecasting is conducted using physical/dynamical
relationships within the atmosphere, not guesswork. It is possible for
some seaonal forecasts to show skill when assessed over many forecasts.

Where Adam. Gavono's assessment is harsh and harsher than my view. I
feel that SSTs may provide a means of forecasting seasonally in the
future. They are already used by the MetO to predict the winter sign
of the NAO with reasonable hindsight accuracy, but that does not
predict our winter weather pattern well, unfortunately.

As I've asked many others, if you feel there is success in using
dynamics for long-term (seasonal) forecastuing then the research to
show that must exist. Simply show it to us, or you are just repeating
percieved wisdom - which I feel is not correct, as I have not seen the
research evidence. if you can show me it, I'll happily revise my
thinking. If it's not there; you and others must really revise yours.
*))

http://www.tropicalstormrisk.com/doc...004.pdfhttp://...

using the criteria that "skill" means doing better than climatology over
the long term.- Hide quoted text -

- Show quoted text -

Sorry Adam, forgot to say. When I "forecast" winters in the UK I only
use one variable; temperature. (rainfall, snowfall, storminess etc is
impossible, IMO). I've been right about 75%+ of the time since 1990
and I have forecasted "warmer than the long-term average" every year.
No flannel; I just use two things. Climatology, married to a UK
warming trend. Show me another forecaster that has that kind of level
of accuracy. *)) (notice the smiley)

Winter 2011-12 - warmer than average. You heard it here first! Easy
eh? *))

That is what is known as a climatology forecast, or a "zero
intelligence" forecast. It is a benchmark against which seasonal
forecasts are judged, a forecast is skilful if it outperforms the
benchmark forecast over a significant number of forecasts.

Just to check, are you trying to claim all seasonal forecasts have no
skill or just UK seasonal forecasts?- Hide quoted text -

- Show quoted text -

I did say "notice the smiley" and I think you missed the inverted
commas Adam. *)) I'm very aware of what that "forecast" shows. No-
one, AFAIK has got anywhere near that benchmark during that time. If
they have, I'd love to know, as we would have found a forecasting holy
grail. It just illustrates that any forecast you read for this coming
winter (or any other season) does not deserve the credence some people
like to give them. Judge forecasters on their accuracy; not on their
forecasts.

Well there is an easy way to check:

1. Take your "climatology married to a warming trend" as a benchmark
forecast (this is equivalent to a trend line of temperature against
year, is it not?).

2. Look up the Met Office (or anyone else's) winter forecasts going as
far back as possible.

3. Compute the squared error between the forecast anomaly and observed
anomaly for each year.

4. Compute the squared error between the benchmark forecast anomaly and
the observed anomaly for each year.

5. Compute the mean squared error for benchmark and operational
forecasts and from these, calculate the mean squared skill score (MSSS):

MSSS(%) = 100*sqrt(1-(MSE(f)/MSE(cl)))

where MSE(f) is the mean squared error of the operational forecast, and
MSE(cl) is the mean squared error of the benchmark climatology forecast.
A positive MSSS indicates the operation forecast is skilful over the
climatology forecast over the years assessed.

The mean squared skill score is recommended by the World Meteorological
Organisation for verification of deterministic seasonal forecasts.