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Looking at our holiday weather forecast and for the first week it shows a cloud with sun, rain and lightning.
Underneath it say 19% chance of rain. To me anything less than 50% means it’s unlikely to rain.
Am I right? Cheer up the Zip household.
81% chance of decent weather sounds good to me...
I've made bigger decisions on worse odds than that. Cheer up and enjoy the time off.
Yep, ideally you'd like the ole <5%, but the odds are in your favour.
If you're like family_oab, it took a week of 2% chance of rain in the Alps to persuade us not to carry waterproofs around...
You can take the family out of Scotland, but you can't take Scottish weather paranoia out if them....
Ooh i’d pack a kagoolie if I were you
as I understand it the way these numbers are usually reported is that they run a number of computer simulated forecasts, then it’s simply the proportion of models that suggest it will rain. It’s worth bearing in mind the the computer says it will rain if even it is a shower at 0300 for two minutes or if it is relentless rain for the whole day.
a 20% chance of rain (they aren’t usually as precise as 19) would mean that four out of five models got their prediction wrong if it did actually rain. That seems pretty unlikely but it ignores whether we trust one model/forecaster more than another, or how difficult the forecast was (location, time to forecast etc all make it harder). Imagine a forecast is a maths exam question and you have 5 students sitting the exam. If one gives a different answer from the rest are they the really smart kid who got the right answer when everyone else tripped up or are they the one kid who never gets that sort of question right? If you were the teacher you’d probably have a better feel that 20% because you know the prior performance - you can get similar confidence by watching how accurate your forecasting source is over a period of time.
“PoP (probability of precipitation ) = C x A where “C” = the confidence that precipitation will occur somewhere in the forecast area, and where “A” = the percent of the area that will receive measurable precipitation, if it occurs at all.”
so so it’s a partly how likely rain is and also how widespread the rain might be in the forecast area.
this time of year, i'd say a 20% chance of rain doesn't mean it'll rain 20% of the time.
it means you've got a 1/5 chance of getting caught in a downpour and getting soaked, but 4/5 chance of being 2 miles down the road in glorious sunshine all day.
Well I live in Manchester so anything less than 50% chance of rain just means 90% chance of continuous drizzle instead.
<10% - probably not going to rain.
20-50% - light drizzle, possibly actual rain
>50% - definite rain
Sorry for being a miserable sod. It's currently raining and I'm wet.
It’s worth bearing in mind the the computer says it will rain if even it is a shower at 0300 for two minutes or if it is relentless rain for the whole day.
That depends on how the raw forecast data is interpreted. Some forecasters will put a rain symbol on if it's >50%, others >20% and so on.
That's why a verbal forecast is better IMO, because they explain the nuance whilst looking at a big map.
19% chance of rain simply means that the hugely expensive forecasting system is saying that it might rain. Or may not. If they pay me huge amounts I can do the same.
It's a mistake to assume that a precise forecast is accurate.
The predicted 20% chance of rain yesterday equaled "pissed down all afternoon". This mornings 40% chance of rain has, so far, seen horizon to horizon blue skies.
Mr Fish, or his replacement, does not know his arse or his elbow.
* I know it doesn't work like that, but still.
If they pay me huge amounts I can do the same.
No, you can't tell how likely it is.
Also, it doesn't always say 20%. Sometimes it says 1% and sometimes 95%.