@Wardez - ok.. But I am not sure how one understands what to put the surface water at. Are we just somehow translating the percentage chance of rain at that specific hour to surface wetness?
To get this really dialed in, we would have to somehow have a translation for inches of rain that have fallen. Which, IMO, would get very tough. We would have to have a preset grid of inches(cm) of rain to percentage of wetness we will set the course.
I think we need to pre-determine what percentage we are going to start the surface water for the race, well before the race. If it is raining, I think we should agree to a certain percentage. If it is 30% that is fine.
I just think for fairness there should be some sort of structure set up. If we are going to use percentage chance of rain, by xxxxx.com that is fine. It doesn't really directly translate.. but I think that would be ok, as long as the randomness of it will be chosen by an outside source. But, remember, this puts a very high probability on the day of the event, we will be starting with 100% surface wetness.