On Sep 24, 8:50*pm, "Will Hand" wrote:
"Graham P Davis" wrote in ...





Richard Dixon wrote:

Paul Bartlett notwithstanding, do we have any resident people who
yearly attempt to do some pattern-matching with previous years ahead
of the forthcoming winter? If so, can we have your thoughts please?

No movement from the UCL guys for this winter (Adam Lea are you
reading?!) *http://climate.mssl.ucl.ac.uk/for_nao.html- nor the MO,
I'm always interested to see what ounce of useful information we can
get out of these forecasts.

I lost faith in pattern-matching as a long-range-forecasting tool in the
late autumn of 1963 I think it was. The monthly forecast mentioned a
particular year as having the best match for the month just ending. As it
was a fairly recent year I still had a vague memory of it and thought that
the weather had been completely different. I checked the monthly summary
concerned and found that one month was described as mild, dry and sunny,
whereas the other was said to have been cool, cloudy and wet. I said at
the
time that I didn't have much faith in the LRF for the coming month when
the
two matching months synoptic-wise were completely opposite weather-wise..
The
forecast, unsurprisingly, turned out to be totally wrong.

Hi Graham, I have never been a fan of it either. IIRC on TWO I criticised
Brian Gaze about it and I also disputed the value with Paul Bartlett on
here. My argument was that in a changing climate, pattern matching is futile
with nugatory value. Also what do you match? The atmosphere is a
3-dimensional fluid, so matching surface patterns or 500 mb charts will not
give the whole story. I accept there are teleconnections and important SST
anomalies that may give useful signals but that is as far as I would stretch
it. I have indeed used some of these myself in the past plus a few other
"indicators" with mixed results. Seasonal forecasting is incredibly
difficult, even getting the phase of the NAO is not easy, let alone weather
variations. I'm more than happy to see what the big professional
organisations put out and take an average!

Will
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Philip Eden has certainly done some Autumn-to-Winter pattern-matching
in the past which I've read with interest. I'm no great believer in
any winter forecasting which can't be backed by successful outcomes,
as you know; indeed I'm no believer in any forecasting that can't be
matched by outcomes, but Philip's pattern-matching seemed to provide a
rare example of some possibilities in this field. Sorry Philip, but I
can't provide links. Maybe you can elaborate.