I'm assuming that you'll allow a list of echoes, rather than just one of them, to be played in the same room in identical circumstances... Other than that, there is one thing I'm unsure about. How many details will be taken into account when deciding what echo to choose? In other words, will there be a sub-list of echoes for different wind directions, wind strengths and storm strengths, or just a single list for every room? I ask this because I know of at least one place where, taking its position and the presence of other buildings into account, a powerful windstorm from the north would have a far greater effect than a storm of similar strength that came from the south. While it might tell people there's a storm outside, it wouldn't be that realistic to describe sand flooding the northern entrance when the wind could have been actually throwing it northwards from over the roof. Without too much difficulty, I could imagine several other places, and several situations that can be affected by the intensity and/or direction of a storm/wind, and specific echoes that take this intensity into consideration would allow players to better use the environment for their RP.
Since I'm going to take a small part in this project, I must know this... Should I bother making situation-dependent echoes, or should the echoes just take the existence of a storm (no matter how powerful) into account?