According to the BBC Countryfile .

December was 0.3c above the 1960 - 1990 average.

"codge" wrote in message
...
According to the BBC Countryfile .

December was 0.3c above the 1960 - 1990 average.




Which made your CET forecast only 0.2C out I believe so close enough to make
no difference.
However, when are the WMO and Met Office going to start using the 1971-2000
figures?

Victor

And what ever happened to Codge's 'I will NEVER' post on any other weather
discussion forum )

On Sun, 4 Jan 2004 12:28:49 -0000, "Victor West"
wrote:

"codge" wrote in message
...
According to the BBC Countryfile .

December was 0.3c above the 1960 - 1990 average.

Which made your CET forecast only 0.2C out I believe so close enough to make
no difference.
However, when are the WMO and Met Office going to start using the 1971-2000
figures?

I don't understand this, the Met Office have the 1971-2000 averages
and it's up on on their website (apart from the mapped averages).
http://www.meto.gov.uk/climate/uk/averages/index.html

OK, so the WMO are a bit slow on this - but why use out of date
averages when talking to the UK public about the UK? Seems plain daft
to me.

--
Dave

OK, so the WMO are a bit slow on this - but why use out of date
averages when talking to the UK public about the UK? Seems plain daft
to me.

Stoopid question-why use 30 yr averages.Why not extend the reference period decadally as new data
becomes available?

--
regards,
david
(add 17 to waghorne to reply)

In article ,
Waghorn writes:
OK, so the WMO are a bit slow on this - but why use out of date
averages when talking to the UK public about the UK? Seems plain daft
to me.

Stoopid question-why use 30 yr averages.Why not extend the reference period decadally as new data
becomes available?

Because our climate isn't constant. There therefore has to be a
trade-off between having a period long enough to iron out most of the
year on year random variations but one short enough to be representative
of the current climate. Presumably it has been decided that 30 years is
a reasonable compromise.
--
John Hall
"If a man will begin with certainties, he shall end in doubts;
but if he will be content to begin with doubts,
he shall end in certainties." Francis Bacon (1561-1626)

"John Hall" wrote in message
...
In article ,
Waghorn writes:
OK, so the WMO are a bit slow on this - but why use out of date
averages when talking to the UK public about the UK? Seems plain daft
to me.

Stoopid question-why use 30 yr averages.Why not extend the reference
period decadally as new data
becomes available?

Because our climate isn't constant. There therefore has to be a
trade-off between having a period long enough to iron out most of the
year on year random variations but one short enough to be
representative
of the current climate. Presumably it has been decided that 30 years
is
a reasonable compromise.

.... the following are extracted from the entry against 'Normal' in the
1939 edition of the Meteorological Glossary:

"Normal: the name given to the average value over a period of years of
any meteorological element .....
In the British Isles the present standard period for rainfall normals is
the 35 years 1881-1915; for sunshine and temperature, normals are
calculated for 30-year periods and are revised every 5 years. The period
1901-30 was adopted by the International Meteorological Organisation at
Warsaw in 1935 as a standard period for climatological normals. "

I believe that the WMO (IMO successor) then decided that the 'normals'
should be updated every 10 years.

Martin.

However, when are the WMO and Met Office going to start using the 1971-2000
figures?

I don't understand this, the Met Office have the 1971-2000 averages
and it's up on on their website (apart from the mapped averages).
http://www.meto.gov.uk/climate/uk

Dave, True, the MO have added some 1971-2000 averages for a sample of
locations, but that is not the same as saying that they use it operationally -
they do not; climatic anomalies are all in relation to 1961-90. When most
others use 1971-2000 - including COL - It really does invite media
misrepresentation (through confusion).

Julian
Julian Mayes, West Molesey, Surrey.

On Sun, 4 Jan 2004 15:00:19 +0000, John Hall wrote in


In article ,
Waghorn writes:
OK, so the WMO are a bit slow on this - but why use out of date
averages when talking to the UK public about the UK? Seems plain daft
to me.

Stoopid question-why use 30 yr averages.Why not extend the reference period decadally as new data
becomes available?

Because our climate isn't constant. There therefore has to be a
trade-off between having a period long enough to iron out most of the
year on year random variations but one short enough to be representative
of the current climate. Presumably it has been decided that 30 years is
a reasonable compromise.

This thread had me thinking back to my student days, as I was sure the
number 30 had statistical significance. It plays a part in the concepts of
sample and population means, and standard deviations of same, IIRC.
Statistical work is best undertaken on samples of 30 numbers or more. In
the case of climate - more than 30 would hide the continuous changes we
know exist. So 30 is, as John writes, a compromise - allowing rigorous
analysis but not too long as to hide change.

The confidence in a mean and SD when n30 (in relation to the population
values) is quite low compared with n=30.

--
Mike 55.13°N 6.69°W Coleraine posted to uk.sci.weather 04/01/2004 18:20:19 UTC
My aurora images here http://www.mtullett.plus.com/29a-oct and
http://www.mtullett.plus.com/20-nov/

The confidence in a mean and SD when n30 (in relation to the population
values) is quite low compared with n=30.

Doesn't the variability come into it as well as the population size.
My recollection (without looking it up so it might be wrong!) is that the
confidence level is derived using Student's t values from tables. These vary
with population size but after about n=10 the value for 95% confidence (most
commonly used) is approx = mean +/- 2* SD.

Dave