On Jun 27, 10:28*pm, Richard Dixon wrote:
On 27 June, 22:11, "Dave Cornwell"

wrote:
I see the flash warnings for most of central England have now shrunk to the
blob on the radar around and just to the North of London. Certainly appears
to have been where the height of the activity was today. My daughter
reported violent storms with torrential rain and pea sized hail from around
the Finsbury Park area.

Hopefully examples of this show
a) how horribly difficult convective warnings are to put out .

They are not difficult to put out; that's the easy bit, all that has
to happen is the trigger of a threshold i.e. the forecasters have to
believe, through their experience, that something will have x% chance
of occurring. The difficult bit is actually getting the warnings
correct by the outcome of an event happening in a particular area -
that's the difficult bit, especially in convective situations.

I would think the MetO have more chance of getting their heatwave
warnings correct, as it is far easier to forecast temperatures above a
threshold, that it is to forecast rainfall above a threshold. I would
have far more belief in a temperature forecast than I would have in a
convective forecast for my area (and my area is NOT the whole of
Devon!!). The MetO is not yet capable of forecasting convective events
accurately, at any distance greater than a very short time (for which
you could better use a freely available weather radar and watch the
sky as to when to move your BBQ indoors, or abandon the beach), either
in terms of 1. location, 2. intensity of rainfall, or 3. duration of
rainfall. Again, that is not a criticism, the tools are simply not
there to do that with good accuracy, it's just a fact.

MetO forecasters are some of the best in the world, but accurate
forecsating of those 3 perameters in these events would be beyond
almost anyone (forecasting of convective events in the mid-west of
America may provide the exception to "anyone". Maybe the threat to
life from tornados forces more resources and a higher level of skill -
just a thought). Yesterday's too wide severe weather warning, that
you've referred to, shows that yet again. There have been a number of
other examples already this year.

I must say, I do think the post mortem explanations are a good idea,
though.