So what you are saying is that you want weather to accumulate on the ground and affect the suroundings, right?
Maybe after PS is going strong and people are bored they might work on this, but you will probably have to wait 50 to 100 years for them to get to it in the list of importance

Even though it would be hard I think it would be a neat idea. But also adding more effects from weather, for instance:
1. A character could get sick if stuck out in a certian type of weather for to long
2. The rate of travel could change if there is a snowstorm
3. Areas in the game may become blocked from other areas, causing a character have to find some other method of travel(sea, magic, etc.)
4. and other effects that weather might have
Now I know this would be a lot of work and am not suggesting that any start working on it right now, just if there is a point where there are not more important things to get done, it could be considered.