Will Hand wrote:

"Graham P Davis" wrote in message
...
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
--


I pattern match months by wetness/dryness, warmth/cold, relative to the
30 average. I can honestly say, although I try month after month, I can
never find two consecutive months that correspond from one year to
another. My base data goes back to 1960. And of cause it would only be
for my location, so as an example August comes up as dry, but we know
what the rest of the Country was like! In fact just looking at
August/September 2003 match, so do I then say October will be cold
followed by an average to mild winter? Actually, that may be so ;-)

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