The Colorado Climate Center helped establish the Community Collaborative Rain and Hail Study (CoCo RaHS) in 1998 in response to a highly localized extreme rainfall event that occurred over Fort Collins, Colorado in July 1997. Since that time, hundreds of volunteers of all ages have been recruited, trained and equipped to measure and report rainfall, hail and snow on a daily basis over northern Colorado. As many as 250 volunteers per county are helping to supplement precipitation data from traditional sources. Most data collection is accomplished via the CoCo RaHS website at: http://ccc.atmos.colostate.edu/~hail

Results from four years of data collection will be presented showing some of the applications that have evolved from this remarkable volunteer network. A large base of users and sponsors has developed since the project first got started. Current users of the data include the National Weather Service, the U.S. Bureau of Reclamation, U.S. Department of Agriculture, U.S. Geological Survey, the Colorado Water Conservation Board, regional water conservancy districts, local utilities, farmers and ranchers, school teachers, mosquito control districts, and many more. Prospects for continuing and expanding CoCo RaHS will be discussed. The costs and work effort required to establish and maintain this type of network will also be described.