Nick Whitelegg wrote in message ...
Dave Ludlow wrote in message
The BBC TV forecasts late on Friday evening certainly got it right - I
remember groaning when I realised that Saturday afternoon and evening
were probably a write-off for the outdoor activities I had planned.


I've just seen the radar animation for this "event" and I'm very
puzzled. In the northwest and north Midlands, the rain band was much
narrower and more fragmented, and less intense - despite lower
pressure up there. They got what I would have expected from the
pressure charts.

The rain seemed to intensify as it moved southeast into higher
pressure, and to my amazement the most intense area was actually west
of where I was, over Dorset, Somerset etc, where the pressure was
around 1024mb - I certainly expected the southwest and western Wessex
to have a dry day. Only Cornwall was out of the rain. A most bizarre
event - I have to admit that due to the vagueness of published
forecasts I normally go on the charts and am normally right but this
time was wrong :-(

As an aside, the times when my own chart-based forecasts are most
often wrong a

a) Cold fronts bringing in northerlies. I generally expect it to chuck
it down but frequently these pass through with almost no rain at all,
at most light showers, even with relatively low pressure.

b) Cold fronts bringing in westerlies after a hot spell, again these
are often associated with very little rain - I frequently expect
thunder out of these.

Nick

Nick, man cannot live by pressure and fronts alone. That is why we have NWP
models and satellite images. Rain occurs due to moist air being lifted high
enough to permit saturation and growth of precipitation particles. Pressure by
itself has nothing to do with that process. In fact pressure should be viewed as
a *result* of moist dynamical and thermodynamic processes. Have you thought
about the possibility that if it hadn't rained then pressure could well have
been higher ?

Will.
--

" A cup is most useful when empty "
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