In message , Anne Burgess
writes
Thanks Jon.

But if that is the case, there is no need to have the red map
for Sunday - it could just have been left green until Monday.
There's such a thing as 'crying wolf' and if the Met Office
overdoes the incidence of warnings of sever weather which
doesn't then happen, people won't believe them, and won't take
notice when they ought to.

Anne


Some very uncomplimentary remarks about weather forecasting at the golf
club here this morning. It was the second round of the Club Championship
and yesterday there had been fears that today might be a washout, on the
basis of the severe weather warning that was current yesterday. The
fears proved totally unfounded as there hasn't been a drop of rain.

At 11 p.m. last night I looked at the Heathrow long TAF valid
0000z-2400z today. It predicted moderate rain 0600z-1300z with a 30
percent probability of heavy rain 0600z-1200z. A bit pessimistic in view
of the actual weather this morning :-(

Over the past couple of years or so I reckon that out of all the
occasions on which there was an early warning of severe weather for this
part of the country the severe weather has actually occurred on less
than 10 percent of the occasions. Typically in the early warnings the
probability of disruption due to severe weather in this area is given as
somewhere in the range 30-60 percent, sometimes a little less than that
and sometimes a bit more. For those probabilities to verify it would
suggest that the severe weather should actually occur on something like
40-50 percent of occasions on which the early warnings are issued. If
the severe weather actually occurs on less than 10 percent of the
occasions, as I believe to be the case in this part of the world, then
it would appear that there is a significant systematic
overly-pessimistic bias in the warnings. Either the models appear to be
overcooking it or those issuing the warnings are adding a "cover the
backside" factor.

Anne's point about crying wolf too often is very well made.

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles 85m a.s.l.
England