On July 31, 2010, Atlantic 57 'Anna' capsized in a violent 60+ knot squall. Thankfully, the skipper and crew were soon picked up by a passing freighter and suffered only minor cuts and bruises. The links below contain a summary of the weather at the time of the capsize, several 'squall stories' from the skippers of other catamarans, and Chris' suggestions for a protocol to follow in squalls and very gusty conditions.
What we can learn from Anna's capsize, by Chris White
Inhabiting an overturned boat, by Chris White
Weather Conditions for Anna, by Jennifer Francis, PhD Atmospheric Sciences (PDF)
Squall Stories - Comments from some experienced Atlantic Cat sailors