Hehe, this isn't SimCity, now is it? There is a clientside tornado resource from the early beta days that was recently fixed and uploaded to community but nothing else as far as I know. I'm sure a "flood" resource would be relatively simple to create and may be entertaining, especially if water level gradually rises or something, but I don't think it'd be too easy to have the flood "approach" or crawl across the land (correct me if I'm wrong!). A particular MTA:VC RPG server had a scripted "hurricane" resource which would change weather to rain, and may slap you randomly (subtracting 20 hp) if you were not within a specific "safe area", i.e. Vercetti mansion, VCPD station..., with text like "A plank of wood hits you" and such. Something more interactive could be created for MTA:SA I'm certain.