Maybe we could create a few default weather.txt, ( controls the weather in "Changeable" conditions) from which to choose from. The autogenerated Weather.txt is so flawed that it cant be used; it stretches the events to unusable lengths, also the amount of randomness is way too small. I have tested this in the past and out of 12 sessions, i saw water in 2 of them and the amount of water didn't change at all... With Autosim Weather Generator you can make any weather for every minute of every session (actual game response is slower as it smooths spikes by nature).. Bad thing is that these weather programs need to be tested as the "sweet spot" of enough water and not too much is not that simple in every class.. Formula 1 cannot survive under heavy Rain but WTCC will cook the tires on F1 Intermediate conditions.
I've been meaning to study the weather system and custom weather generation, i could make a few custom weathers for 30 minute 2 race format. Oh, the custom weather needs to be made specifically for some base format as session lengths need to be somewhat correct. Also longer sessions decrease the resolution of the weather changes at least in Autosim WG. Tested weather.txt library doesn't sound that bad.. And someone with just enough knowledge of simple scripting and the use of a scheduler on server-end could make this at least semi-automatic feature to the future Wet races..
This brings us the option to race a classic from the past as weather conditions could be simulated using real world data.. Recent Canadian GP for example?