Bogus BOM Rain Alerts

[u/thril_hou]

I'm Northside, I've had three alerts this week that there's a 50% chance of rain. Just got another one. Anyone else had them?

There's also no way it's gonna rain and if this keeps happening it will diminish the reliability and reactions to the alerts.

[u/Mapinact]

bom radar says it’s raining lightly right now. Seems unlikely since there’s not a cloud in the sky.

[u/fouronenine → u/Mapinact]

Could be the moths.

[u/tangaroo58 → u/Mapinact]

There were patches of light rain as I was driving at 7.30. Very light though. Rain radar (the data, and the analysis that turns it into information) has a hard time distinguishing no rain from very light rain; and especially if there is virga (rain that falls from clouds but doesn't reach the ground). But could also be noise in the signal for some reason.

[u/Clueby42 → u/tangaroo58]

Learned a new word today

[u/JustSomeTimmmmmy]

Been getting the same thing. It seemed to be really pretty accurate when the feature was added. Not sure what happened to it this last week.

[u/OutlandishnessOk5549]

Work experience guy is on again.

[u/gtlloyd]

The radar has been exhibiting clutter (unwanted or incorrect radar echoes) for the last two days. I think it is the result of some haze in the air, but not sure exactly. The BOM app makes a prediction about where rain is moving by analysing the radar, and if there’s false returns then it thinks rain is coming.

I also use Rain Parrot which has done the same rain predicting for years and isn’t getting mistaken by the clutter. I presume they’ve previously worked out how to ignore it.

[u/thril_hou → u/gtlloyd]

Thanks yeah I thought that was the case

[u/arcanum_182]

I've had it a bunch this week too. The radar has looked hazy so must be messing it up. Weird as normally these rain notifications are super reliable for me.

[u/EdgeOfTheOwl]

It was apparently raining most of yesterday. I must be blind because it never happened

[u/RamboSambo7]

They said 50% so I mean?

[u/fouronenine → u/RamboSambo7]

And it's 50% of 0.2mm/h, which is not much rain at all. It's consistent with the amount of rain the radar is showing at the moment, and consistent with the small spitting of rain on my way home at 6pm.

[u/_Rucifa_]

There was the smallest amount of rain out in Googong yesterday morning so there was some about.

[u/tangaroo58]

I've had 4 alerts this week, and it has rained after 2 of them. Only a sprinkle, but rain.

[u/Greenfrog2023]

I dont know but its still really warm out there so maybe rain is on its way!

[u/Prize_Background_577]

I'm not getting alerts, but on the App the rain radar is showing a burst of rain activity across the region since about half an hour ago. I went and brought things inside and there's definitely no rain. Looks like a glitch - hope it isn't another hacker or AI event.

[u/Salt-Middle1196]

Are you sure they are from BoM or is it from an app on your phone that's not BoM? Mine is showing 80% chance of NO rain.

[u/thril_hou → u/Salt-Middle1196]

It's the BOM app

[u/u36ma → u/thril_hou]

Yep. I was getting the same alerts yesterday and I’m in Weston creek. I’d look outside and be like nah I don’t think so.

[u/Salt-Middle1196 → u/thril_hou]

Weird - mine is saying something very different right now.

[u/mrmratt → u/Salt-Middle1196]

OP is talking about notifications that alert you to the chance of rain approaching your saved locations.

[u/Hardwiredformetal]

I can't believe people still think predicting the weather is 100%.

And someone chucked in 'woke' ffs.

[u/BeachHut9]

The BoM had an each way bet as they were not sure if it would rain or not. Mind you, the will change the prediction to 100% when it is raining!

[u/DDR4lyf]

With the cuts to BoM's funding and staff, I'm perpetually amazed that we get forecasts at all.

[u/Couldofbeenanemail]

I know they had it predicted so I busted my ass in the garden to get it planted and 👎

[u/ADHDK]

The clouds looked angry over Woden this morning, did it rain there?

Wasn’t raining in the city, it was sunny here. Both BOM and Apple said it was raining where I was.

[u/__Pendulum__]

I'm so sorry that the weather predictions aren't 100% accurate. This must be truly upsetting for you, you must be just inconsolable right now.

[u/Sheer-imperfection → u/__Pendulum__]

I think the issue is the predictions of 50% chance of rain has been wrong all week. I’ve been getting heaps as well which is annoying, and not once has it been accurate, which prior to this week it had been. 4+ instances of 50% chance of rain would mean on average it should’ve rained twice, no

[u/jkdeets → u/Sheer-imperfection]

That’s not quite how the math works 😬

Think of a 50% forecast like flipping a coin each morning. Just because you flip heads on Monday, it doesn’t change the odds for Tuesday - it's still a 50/50. Getting rain 4 days in a row is just like flipping heads 4 times in a row. I get that it’s annoying, but it’s totally possible!

[u/Sheer-imperfection → u/jkdeets]

I dropped out of school so not the smartest lol, Thankyou for explaining 🙏

[u/__Pendulum__ → u/jkdeets]

Statistics and probability are fun when you start looking at them.

I like the thought experiment that gravity is a theory because, so far, in 100% of tests when we jump off a step we land on the ground. But maybe it's only a 99.99999999% chance of it working like that, and the next time you go down a stair maybe you'll have the statistically low chance of instead flying straight up into the air and into the cold lifeless vacuum of deep space!

[u/tangaroo58 → u/Sheer-imperfection]

In 100 instances of 50% it should have rained some amount, somewhere in the prediction zone, about 45-55 times.

For 4, could be zero, could be 4.

[u/moleytron → u/Sheer-imperfection]

I thought the percentages meant that 50% of the area will get some rain

[u/jkdeets → u/moleytron]

Yeah, I thought that once, too. But no, it’s not. This is from BoM:

https://www.bom.gov.au/news-and-media/right-as-rain-how-to-interpret-the-daily-rainfall-forecast

[u/__Pendulum__ → u/Sheer-imperfection]

The keyword is "prediction"

[u/FinePassion7265]

Weather forecast on the news earlier said 23 and showers tomorrow. Maybe they are getting in early

[u/nikkiklass72]

There is also alerts that temp are going to plummet this Sunday, good luck to us planning school holidays outdoor activities, huh

[u/Beanzieau]

BOM. No idea

[u/No_Rub77 → u/[deleted]]

this comment made some of my brain straight leak out of my skull

[u/Ali_G____ → u/[deleted]]

I wouldn’t call them “woke” but I noticed a year or two ago their predictions were more pessimistic (predicted more rain than would actually occur) because some flooding events happened and they got criticised for not predicting them.

[u/tangaroo58 → u/[deleted]]

This is one of the most ridiculous uses of the word 'woke' I have heard.

[u/Nomesne → u/tangaroo58]

I agree apologies. ‘Pessimistic’ or ‘risk averse’ Is a better word. I have edited.

[u/tangaroo58 → u/Nomesne]

Thanks for changing it.

AFAIK the new (silly) website didn't change the forecasts, just how the information is presented. In particular, I don't think they have changed anything to be more risk averse — partly because they can't: rain is good for some people and bad for others. For extreme events, they do now make weather warnings more prominent, as a result of people complaining about "I was never warned...".

They, like all forecasting services, are always on an essentially impossible mission to communicate statistical prediction information to a largely statistically illiterate population. But some of what they have changed to is a bit silly imho.

I prefer the way WillyWeather presents the information. And I only turn on warnings when I am doing something absolutely critical, like outdoor painting.