How accurate is weather forecasting for each day in the future?

Question

I feel like for the last 20 years I’ve felt like tomorrow’s forecast is very accurate, 2 days from now is an educated guess (if it says it’s raining, it’ll rain, but not sure what time of day) and 3+ days is unknown.

What advancements have we made in meteorology and what are the current limitations for weather forecasting?

I’ve definitely seen my phone be very accurate in forecasts for the current day like “in 16 mins, it’ll rain for 22 mins and then stop for an hour”

In: Planetary Science

Answer 1

Predicting weather is something we’ve been trying to do for a *very* long time. The math isn’t even super hard, it’s just that you have to do a lot of it, and each time point you step forward in the future is iterative. In fact, when we first invented computers, meteorologists were super excited to finally put these models to the test. “Finally!” they said, “We can just plug in all the information and it will predict the weather perfectly!”

What they found is that it actually did a pretty good job predicting the next few hours… but then would go wildly off course. They would adjust their models, add in more data, and still, insanely wrong after a short period of time, but somehow it would be a different type of wrong even when they only changed a tiny thing. This sort of random destabilization is what would eventually be called “chaos theory”. It turns out that even a miniscule change in inputs would eventually generate a diverging system after a while. It’s the same idea as the “butterfly effect”: that a single beat of a butterfly’s wings in Texas can be the inciting incident for a hurricane in Brazil.

Our instruments are vastly better at collecting data than they used to be. Our computers are more accurate at doing the math. We’ve got layers on top of that where meteorologists look at weather as a system with a history and relationship to other weather systems. There’s even some really exciting work with using machine-learning to identify subtle trends. But the fundamental issue is that it is mathematically impossible to accurately describe, *down to the molecule*, the current conditions. All of our forecasts are doomed to eventually destabilize and become meaningless.