How do we inform community members about the upcoming change?
As soon as the CEO gives her departure date (or departs unexpectedly) and you have appointed an interim CEO, send a press release and post a notice on your website announcing the change. Try to be as transparent as possible about when the CEO is leaving and how the community foundation will seek a successor. In the case of an unexpected departure or leave of absence, simply state who is acting as interim CEO and fill in the remaining details later, as they are determined.