[namibj]

On part that's what ensembles are about: they run like 20 or so simulations of the near future, randomizing the start values and simulation parameters within the range of uncertainty, and get one potential future per simulation out of the process.

A 30% rain chance every hour of the entire afternoon until sunset tends to be less actionable than "85% chance of a 50~80 minute rain shower during the afternoon, unclear when, but likely a bit longer if it'd start very late", as one can often adapt around such, for example by scheduling the homework to get done "wherever it's raining, at the latest so it'll be finished by dinner time", spending the dry time with outdoor physical activity that doesn't care about wet ground (but getting wet from above isn't nice).