Feels like an accurate hourly rain forecast is not too much to ask for in 2021.
Why is it that it's sometimes off by a whole day?
Is it lack of computing power? Unsophisticated models? Is it that the "measuring stations" are in specific locations, and you can't really generalize that to the whole city? Will we ever get to an accurate hourly (minute?) rain forecast?
Ask HN: Why are we still so bad a weather forecasting?
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Re: Ask HN: Why are we still so bad a weather forecasting?
#2Elephant in the room: models are desyncing because we broke the planet.
Re: Ask HN: Why are we still so bad a weather forecasting?
#3Here in Switzerland, there are tons and tons of measure points, and in my experience, the resulting predictions are fantastically accurate.
For example, here is one of the measurement stations in Zurich:
http://wetterstationen.meteomedia.de/messnetz/vorhersagegraf...
This is outside of the city center (to minimize effects such as radiant heat due to pavements etc.), so it gives a good base value to compare against.
Re: Ask HN: Why are we still so bad a weather forecasting?
#4In the UK the forecasts are often very accurate up to 3 days in advance, with the hourly one accurate on 24 hours.
After 3 days there's just too much chaos normally for the models, but it does depend on the conditions, and what you are predicting.
Re: Ask HN: Why are we still so bad a weather forecasting?
#5From https://www.ecmwf.int/en/about/media-centre/science-blog/201..., more plain language discussion about low cloud at https://blog.metoffice.gov.uk/2017/04/07/why-is-forecasting-...
"Convection is complex and hard to model because it involves multiple processes, many of which take place at scales smaller than the model’s grid cell, so they need to be parametrized. The assumptions that have to be made when parametrizing convection explain many of the systematic errors in convective precipitation."
(in other words modelling physical interactions on a relatively small scale (1km) is hard)
Re: Ask HN: Why are we still so bad a weather forecasting?
#6I don't think we are bad at it. I can look at multiple weather sites, get hourly predictions that typically are correct, and even accurately predict the differences between my location and towns 30 minutes away. I can look at predicated radar for the next 4 hours, and accurately dodge storms when exploring the mountains. In my experience, forecasts are accurate all but a few days a year. To be fair, those few days tend to be notable... but if the forecasts are correct 360 days a year, with 5 glaring days of error, that still feels pretty good to me.
Re: Ask HN: Why are we still so bad a weather forecasting?
#7To my understanding, it is linked to the double pendulum problem. Weather forecasting is hard because it is chaotic.
https://www.youtube.com/watch?v=HPAYf2zpmOo
Re: Ask HN: Why are we still so bad a weather forecasting?
#8I recommend the book Chaos by James Gleick, it explains some of the limitations of predicting systems as complex as the atmosphere.
Re: Ask HN: Why are we still so bad a weather forecasting?
#9I had to look back, because I remembered a discussion here on HN based on an Atlantic article that took exactly the opposite point of view:
https://news.ycombinator.com/item?id=19045250
I'd have to disagree that we are bad at weather forecasting. While we are surprised every so often, the progress in accuracy of the modern five day forecast has been shocking over the arc of my 30-or-so years on the planet. We almost always have a substantial heads up about weather that is going to affect our movements around the world.
I agree with you that down to the minute precipitation forecasts aren't perfect (though I'd say the alerts I get from Dark Sky are at least pretty good) but that level of fidelity is asking a lot.
Re: Ask HN: Why are we still so bad a weather forecasting?
#10One thing I noticed recently which breaks forecasts is the size of the area. For example city forecast on wunderground may be valid for place where you have two or more stations in a suburb that's 1km across. (With lots of data points around, going on for kilometres) On the other hand, at home, my town area is closer to 10km across, has 2 stations in it and has no surrounding context.
Which means that I may have a forecast of 24h of rain which is accurate, but my house will still be dry.