ElI5 How do meteorologist know that this tropical wave carries a 10% chance of forming. Why not 5% or 15%?

Question

ElI5 How do meteorologist know that this tropical wave carries a 10% chance of forming. Why not 5% or 15%?

In: Planetary Science

Answer 1

One important thing to understand about weather forecasts is what “10%” means. It tells you that of the simulations run, the forecasted thing occurred in 10% of simulations. By the same token, it might be the case that something else happened in 30% of simulations. This is why you can have a 60% chance of rain and then go outside to a perfectly sunny day.