On Tue, 25 Jul 2017 22:01:30 +0100, Steve Walker wrote:

On 25/07/2017 19:18, James Wilkinson Sword wrote:
On Tue, 25 Jul 2017 11:55:29 +0100, whisky-dave
wrote:

On Thursday, 20 July 2017 20:38:25 UTC+1, James Wilkinson Sword wrote:
On Thu, 20 Jul 2017 16:08:28 +0100, NY wrote:

"James Wilkinson Sword" wrote in message
news What do you believe weather forecasters mean when they say "40%
chance of
rain"?

1) It will rain for 40% of the day.
2) There's a 40% chance it will rain at some point.

I googled it and apparently it depends on the forecaster? 1) and
2) are
completely different meanings.

Given that it includes the word "chance" (ie probability) I'd
interpret it
as the second meaning: if (hypothetically) you replayed the day
many times
(Groundhog Day!) then approx 40% of the occurrences of the day
would have
some rain.

Which is of no use to me whatsoever. Pouring with rain all day is
nothing like spitting for half an hour. Yet they don't distinguish
between the two.

How about showers or inteminant showers or heavy downfalls, storms.

Yes, those are more helpful. But "20% chance of rain" means nothing,

There should be a measurement where 0% means no rain at all, and 100%
means rain all day.

So what would 50% mean light showers for 50% of the day or heavy rain
50% of the day, and whayt would the other 50% be of the day be like ?

If there's only a % number it should be expressed as a percentage of
pouring all day.

But is 50% pouring all morning and dry all afternoon or alternating
between pouring and dry every hour?

Could be either, but those two are more similar than a 50% chance that it might give light showers for 10 minutes at some point during the day, which is what the current system allows for.

The weather app that I use on my phone

Ooooh! Snob! An app on one's phone eh? I run applications on my computer. I use my telephone for making telephone calls.

gives me a percentage chance of
rain for each hour of the day and a symbol next to it for bright
sunshine, partial sunshine, overcast, light rain, heavy rain, downpour
or thunderstorm.

Yeah right, we haven't invented forecasting that accurate. I'll stick to my barometer watch. It draws a graph of the next 12 hours, simply stating it'll get worse, a lot worse, better, a lot better, etc. Stick my head out the window, cloudy, graph says better later, I know the sun will come out. Graph says worse later, I know it'll rain.

--
Women are like a pack of cards... you need a heart to love them, diamonds to marry them, a club to kill them and a spade to bury them.