i would have thought its 40% chance of rain, but then again i guess they would throw a medium out there to claim being 50% right, 50% of the time

On 20/07/2017 20:57, Rod Speed wrote:
James Wilkinson Sword wrote
What do you believe weather forecasters mean when they say "40% chance
of rain"?

I know that they mean.
1) It will rain for 40% of the day.

Nope. Ours has both that daily number and a break down in 3 hour
blocks with that 40% appearing on at least one of the 3 hour blocks.
2) There's a 40% chance it will rain at some point.

Yep.
I googled it and apparently it depends on the forecaster?

Not here it doesn't.
1) and 2) are completely different meanings.

Sure.
This thread reminds me of my favourite weather forecast. "It may rain at
times in places" 100% accurate, but also 100% useless, in my opinion.

On Sat, 22 Jul 2017 10:37:02 Broadback wrote:

On 20/07/2017 20:57, Rod Speed wrote:
James Wilkinson Sword wrote
What do you believe weather forecasters mean when they say "40%
chance of rain"?
I know that they mean.
1) It will rain for 40% of the day.
Nope. Ours has both that daily number and a break down in 3 hour
blocks with that 40% appearing on at least one of the 3 hour blocks.
2) There's a 40% chance it will rain at some point.
Yep.
I googled it and apparently it depends on the forecaster?
Not here it doesn't.
1) and 2) are completely different meanings.
Sure.
This thread reminds me of my favourite weather forecast. "It may rain
at times in places" 100% accurate, but also 100% useless, in my opinion.

No, it's not 100% useless. It tells you that it might be a good idea to
take an umbrella with you, particularly if you're going for a walk.

David

--
David Rance writing from Caversham, Reading, UK