Weather Underground Organization (Weatherman): Declassified FBI Documents In 1976, the FBI's Chicago Field Office prepared a summary which described the activities of the Weather Underground Organization, also known as Weathermen. This organization described itself as a revolutionary organization of communist men and women. The FBI's analysis of its motivations, beliefs, and international travels are outlined in this summary. This book also includes manifestos issued by the Weather Underground Organization as part of the volume, including The Weathermen Manifesto.