How about if rangers could sense when a storm is near, and perhaps the intensity of it? Realistic and useful, no?
I'm fairly sure this can already be accomplished (by anyone, as far as I know) by a simple weather <direction>
help weather should cover any questions.
I know this command can't allow you to sense weather three 'squares' away, but out in the wilderness one 'square' is supposed to be quite a distance in most cases, so using the weather command should suffice.