But a weather app on my phone has my exact GPS coordinates. Why can’t it tell me exactly when a rain cloud will be passing over my location?

Because they’ve never been able to do that…

When they say “50% chance of rain”, it doesn’t meant there’s a 50/50 chance it rains where you’re located

It’s that for the broadcast area, about half is gonna get rain.

I just looked at my weather app (Today Weather), and the report of the current temperature varies by 6°F depending on which data set I choose. I go with the National Weather Service (federal govt).

As far as predicting precipitation, the radar seems pretty good for the next few hours. I press play on it, and it tells me what it thinks the radar will look like for the next 7 hours in 15 mins increments.

I think that predicting the weather beyond a day gets pretty difficult because the weather is too chaotic. The best they can do is to gather data from local weather stations and see how often it rained when they had these same data in the past. So basically, it’s like saying, “When the temp has been 85°F, humidity 62%, wind from WNW at 5 kts, pressure at 1016 mBar, and the date was July 29, it rained 6 times out of 10.”

I notice the rain predictions are quite a bit more accurate in the cooler months. You can see a weather front traveling west to east as it comes across the country (I’m in US) and rains can last all day. During the hotter parts in summer rain clouds appear out of nowhere usually in the afternoon and rains are heavy but brief. This happened here in NE Ohio just an hour ago. There was no forecast for rain that I was aware of but suddenly we got doused for twenty minutes.

Because we have tons of ground-level sensors, but not a lot in the upper layers of the atmosphere, I think?

Why is this important? Weather processes are usually modelled as a set of differential equations, and you want to know the border conditions in order to solve them and obtain the state of the entire atmosphere. The atmosphere has two boundaries: the lower, which is the planet’s surface, and the upper, which is where the atmosphere ends. And since we don’t seem to have a lot of data from the upper layers, it reduces the quality of all predictions.

Darksky could do it back in the day more or less. you’d get messages that it would rain in about 15 minutes and stop in the next 30.

Thing is, precep maps don’t work everywhere. You’re probably in a location like me where a thick front rolling through will almost always bring rain. If you get into warmer tropical climates, rainclouds will just poof out of nowhere and drop rain on your ass while other crazy fronts will pass over with nothing but some dark clouds.

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NOAA sources are usually good in the US, weather.gov for a quick map and search by zip code or city, but they follow the same % system mentioned as most do

The couple apps/widgets I’ve tried haven’t been good for working with VPN unless I want to know the weather halfway around the world.

Some airports are still reporting temps once an hour, so the info you get from an app can be old and irrelevant. Also some apps use a forecast made days before, they are too cheap/busy to update it.

Weather prediction at point locations is extremely challenging to get right because we simply can’t observe and make predictions for every single square inch of the earth. Many weather models are run on grids with boxes about the size of a few kilometers at the smallest scale, which means that any physical process in the atmosphere that is the size of that box or smaller won’t be represented well by the model.

Specifically on your point about clouds passing over your location, cloud and precipitation formation is even more challenging. Clouds and precipitation form due to atmospheric processes ranging from hundreds of kilometers all the way down to micrometers, which practically means the weather models are making an educated guess (albeit a very good one that is informed by scientific research) about when and where clouds will form. And when a model does predict a cloud, it will cover an entire grid box.

Finally, I saw you made a comment about how machine learning should improve forecasts, and in fact it does! But the weather community is still working on data driven models (as opposed to models that solve physical atmospheric equations), and most of them are run by private companies so their output is not free. As these data driven models get better, it may be possible that they will be able to make predictions at scales less than a kilometer.

Since people are sharing their weather apps, I use Breezy Weather! Multiple sources, lots of info, FOSS, what’s not to like. I tried multiple sources untill I found one that was the most accurate for me.

MyRadar is scary good, in my experience.

just because it knows where you are, doesn’t mean it has measurement equipment there.

MinuteCast from AccuWeather does exactly this. It looks at your location, looks at radar data for storm systems approaching your location, and estimates when precipitation will start at your location and how intense it will be. It’s generally pretty accurate, with some limitations. It seems to be pretty good for consistent rainstorms but it can get tripped up by pop-up thunderstorms, where the radar track can go suddenly from no rain to downpour. It doesn’t make predictions more then 2-3 hours out because past that timeframe it’s not easy to predict if weather will continue on its current track or change direction. Even with the limitations, I use it all the time. Mostly to tell if I should take the dogs out right away, or if I should wait an hour or two.

I went to Amsterdam over the weekend. The weather apps said it was gonna rain, did it fuck. I brought my puffer jacket and was almost dying from the heat until I got to the hotel room. Never had to wear it during the trip.

I am a pilot and flight instructor. I took a full year of meteorology at ERAU. Most weather forecast products presented to the general public are completely worthless, and we really should run “AccuWeather” out of business.

The temperature number they show you for what it is “now” was probably taken by the AWOS at the closest municipal airport to your location. If you’ve ever noticed like a car GPS reporting weather from three towns over and not the one you’re in right now, it’s because the town you’re in right now doesn’t have a nearby airport or it doesn’t have an AWOS.

10-day forecasts are generated by tarot cards and have no basis in reality. Actual aviation weather forecasts seldom reach out beyond 24 hours.

Your best bet for getting a complete understanding of the weather is to start by looking at the GOES satellite imagery, ie actually look at the Earth from geosynchronous orbit and look at the clouds. You know those maps with the blue lines with triangles on them and red lines with half circles and big blue Hs and big red Ls? Those are called Prognostic charts, those map where high and low pressure systems and fronts are. Look at one of those and compare them to the satellite images. Then look at Doppler radar imagery, which shows where precipitation is. Look at what it’s been doing for the last few hours, and then you can get a good sense of generally what the weather is going to do in the next few hours. Beyond that, not even God knows because the prick hasn’t decided yet.