In article ,
Graham writes:



This may be a case of forecast something often enough, then
when it eventually happens they can claim 100% accuracy?

My thoughts exactly, we get plenty of snow warnings through a
winter and most fall by the wayside but then one comes of and it's
what a great forecast.
People then soon forget about the previous warnings that
produced little or nothing, bit like next week I feel, at least here

Surely the purpose of warnings is to alert people to the /possibility/
that the event might occur in enough time for them to alter their plans
if that seems advisable. If a warning was only issued when the
probability was close to 100%, then you can bet that people would
complain about the occasions when severe conditions occurred without
sufficient warning.

If you click on the + to show the "warning assessment" on the page that
Col linked to, you will see that there is a matrix covering the range
of possible likelihoods and impacts (much like is often done for risk
assessments in the H&S field). Foe example, the risk of icy conditions
in the south tonight is shown as being at the third of the four
likelihood categories and the second of the four impact categories,
which rates a yellow warning.
--
John Hall

"Whenever people agree with me I always feel I must be wrong."
Oscar Wilde