"xmetman" wrote in message
...
My memories as an observer on a wet day or night shift, were of hourly
observations where I reported total hourly rainfall typically in the range
0.2 to 2 mm per hour. Admittedly my memory isn't fantastic, but nowadays if
it rains (and I know I live in Devon now) it pours!
I do have an automatic weather station to watch rainfall intensities which
might skew things, but as an observer we always had the tipping bucket
gauge that gave off an audible click in the office as the counter updated,
so it's not that I'm any more attentive than I was back then. Don't get me
wrong, there were many occasions in showers or thunderstorms when you could
report closer to 10 mm in a single hour, and I don't think the frequency of
those events has changed. It's the other slow-moving frontal events I am
thinking of, when instead of reporting several hours of slight (0.6 mm/hr)
occasionally moderate rain (0.6 to 3.9 mm/hr), and perhaps an hour of
heavier rain (=4.0 mm/hr) as the front passed through, but in recent years
all you just seem to get is a succession of hours of heavy rain.
Perhaps it's that I'm finally coming to terms (after 12 years) with how
rain falls in this part of the country and it's just taken me a long time
to notice it!
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Yes you must be.
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Anyway here is my best guess of rainfall accumulations across the UK for
yesterday 0700 and today at 0645 UTC (13/14 August 2015). I must say the
total is spot on for here in mid-Devon. There is a sharp line running down
through the British Isles marking the extent of the rain, and it also
captures a number of drier pockets in East Anglia, West Wales and Central
southern England. see http://wp.me/p3yVic-1hS
===================
Haytor is 51mm. How are you estimating your totals Bruce. Surely you are not
assuming dwell times for the whole of the radar return? E.g if you have
quarterly reports then if you use a dwell time of 0.25 hours then you will
normally over-estimate. We found that out in the Nowcasting department way
back in the 90s when you were in the Office. Better to use 5 minute or even
1 minute radar data but there are more sophisticated algorithms that look at
the standard deviation of returns over the whole period and essentially fit
an accumulation model to the data. Yours is an excellent poor man's
representation of the data and does give a quick overview but I'm worried
that your readers wil take it as gospel when it could be so much better? Do
you reference your methodology anywhere?
Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
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