Making snow&rain "affect" some things?

[FlawlessHappiness]

I'm just thinking out loud now...

Create a particle system of rain, that acts like it is being stopped by an umbrella in the middle, but all other places it appears normal.
Then have a timer fire very quickly, while spawning a new particle effect at the player's location, and deleting the previous one?

The scripting isn't very hard. You just need to create the particle system first...

The only thing I'm worried about is if it's going to look natural.

To illustrate:

Spoiler below!