Answer:
A perfect storm is an expression that describes an event where a rare combination of circumstances will aggravate a situation drastically. The term originated with how Bob Case, a meterologist, described the 1991 Nor'easter that struck New England. In that case three things happened that made for a worse-case scenario:
1. warm air from a low-pressure system coming from one direction
2. a flow of cool and dry air generated by a high-pressure from another direction, and3. tropical moisture provided by Hurricane Grace