Thread: All over now!
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Old January 29th 04, 08:36 PM posted to uk.sci.weather
Norman Lynagh Norman Lynagh is offline
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First recorded activity by Weather-Banter: Dec 2003
Posts: 208
Default All over now!

In message , Col
writes

"Chris" wrote in message
...
Well, that's THAT particular example of overhyped nonsense over and done
with. We DID have a little bit of snow, it DID get a tad colder for a time,
and the usual disruption and chaos HAS ensued. It's winter and this is the
U.K. - only to be expected, really. Perhaps now we can all get back to
normal again.


Although it was the media that did the hyping, not the Met Office.
Their advance warning of severe weather conditions issued last
weekend was correct, indicating the most severe conditions in
northern and eastern areas and snowfall up to 15cms.
Nearer the time their risk disruption maps correlated very well
with the severity of the weather in those particular areas.

I'm not sure what everybody else thinks but I think the Met Office
played this one as well as could reasonably be expected given
the uncertainties.

Col


I agree that within any reasonable accuracy limits the medium range
predictions from the Met Office were pretty good. Where I might add a
note of criticism (constructive, I hope) is that only one side of the
coin was presented. Quite rightly, the Met Office advance warnings gave
notice of the potential for severe weather. Percentage probabilities
were given for widespread disruption. Implicit in such warnings is that
these conditions may not occur, particularly where the probability is
less than 40 percent, but this is never stated explicitly in the
warnings. It might be helpful if the warnings also stated explicitly
what is likely to happen if the severe weather does not occur.

Also, the warnings tend to emphasis the most severe condition. I cannot
remember the precise texts of the warnings but they often use phrases
such as

"accumulations up to 15 cm may occur"

That figure of 15 cm is, typically, the only one that appears and that
is what is picked up by the media. Much better IMHO is to be more
explicit and say something along the lines of (example only):

"Accumulations will be very variable. Many areas will see
2-5 cm
but in NW and SW England and western Wales accumulations
will be negligible. Over the hills and coasts of
Yorkshire and
Lincolnshire accumulations will be greater and may reach
10-15 cm
locally".

A forecast needs to contain very good "signposting". If the forecaster
thinks that Buckinghamshire is likely to get an accumulation of 2 cm
that's what the man on the Buckingham omnibus needs to hear, not that
"accumulations up to 15 cm may occur".

Communicating the forecast in a meaningful way to the user is often a
more difficult task than getting the forecast right.

Max temp here today only 2.9c. The snow melted quite a bit in the sun
but very little melting in the shade. Still more than a 50 percent cover
of about 1 cm this evening. Freezing hard now with the temp down to -2c

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles
England