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#1494148 - 13/03/2019 19:39 So is it 50 or 80?
Graham M Offline
Weather Freak

Registered: 21/01/2002
Posts: 441
Loc: Boambee East near Coffs Harbou...

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#1494153 - 13/03/2019 20:28 Re: So is it 50 or 80? [Re: Graham M]
wilyms Offline
Weather Freak

Registered: 06/03/2013
Posts: 191
Loc: Roma, Qld

RTM / FAQ

http://www.bom.gov.au/NexGenFWS/rainfall-faq.shtml

Weather station site forecast (80%)

Larger area forecast (averaged across the area) 50%

And donít forget the number in mm is the 50% / 25% chance of at least that amount

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#1494156 - 13/03/2019 20:57 Re: So is it 50 or 80? [Re: wilyms]
Graham M Offline
Weather Freak

Registered: 21/01/2002
Posts: 441
Loc: Boambee East near Coffs Harbou...
That's an interesting theory. I couldn't find any verification on the link you provided, and indeed, in the examples they give, the two percentages match up.

Edit: I looked a little harder and found it. Still a bit confusing though, don't you think?


Edited by Graham M (13/03/2019 21:02)

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#1494162 - 13/03/2019 21:22 Re: So is it 50 or 80? [Re: Graham M]
wilyms Offline
Weather Freak

Registered: 06/03/2013
Posts: 191
Loc: Roma, Qld
I do agree - Itís definitely not the most intuitive system and explanation Iíve come across.

Ive been lucky enough to have it explained to me by a meteorologist in person so its now something i just remember.

Forecasting is a numbers (statistics) game and i think for the general public

Cloudy, shower or two

(Based on your example above) really might be enough

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#1494165 - 13/03/2019 21:33 Re: So is it 50 or 80? [Re: wilyms]
Graham M Offline
Weather Freak

Registered: 21/01/2002
Posts: 441
Loc: Boambee East near Coffs Harbou...
While I'm at it, another thing that I find misleading is the figures labelled "the day so far" on a number of BoM pages. Wouldn't one assume that this would mean since midnight? But all the figures (rain, max and min temps and max wind) all reset at different times ó midnight, 9 am and 6 pm. So for example if you look at the page at 7 pm you'll see the minimum temperature since 6 pm, hardly the "day so far".

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#1494331 - 14/03/2019 18:15 Re: So is it 50 or 80? [Re: Graham M]
retired weather man Offline
Meteorological Motor Mouth

Registered: 01/07/2007
Posts: 5161
Loc: Wynnum
That is why with my station here, using a mix of old time manual and some electronic gear, everything I report resets at 0900.

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#1494345 - 14/03/2019 18:35 Re: So is it 50 or 80? [Re: Graham M]
wet sky Offline
Weather Freak

Registered: 10/10/2015
Posts: 662
Loc: Fairfield, Brisbane
Also, how can there be a 80% chance of 0.2mm yet only a 50% chance of exceeding 0mm? Don't quite get that. Don't mind the percentages system though, it is more precise than saying 'maybe' or 'probably'.

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#1494511 - 15/03/2019 10:04 Re: So is it 50 or 80? [Re: retired weather man]
Graham M Offline
Weather Freak

Registered: 21/01/2002
Posts: 441
Loc: Boambee East near Coffs Harbou...
You're clearly a stickler for convention, RWM. Certain complications arise from the fact that a maximum temperature read at 9am is recorded against the day before, but the minimum is not ó which can create some peculiar anomalies on rare occasions. I opined on this matter seventeen years ago ó doesn't time fly?

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