The Community Collaborative Rain, Hail and Snow Network (CoCoRaHS): Citizen's Measuring, Mapping and Learning about Precipitation

CoCoRaHS, the Community Collaborative Rain, Hail and Snow Network, is a unique, non-profit, community-based, high density network of individual and family volunteers of all ages and backgrounds, who take daily measurements of rain, hail, and snow in their backyards. Volunteers as young as five years old on up to seniors close to 90, use low-cost measurement tools; 4-inch diameter high capacity plastic rain gauges and aluminum foil-wrapped Styrofoam hail pads. With some basic training and with frequent interaction with participating scientists, volunteers are able to collect and share data of considerable scientific value. Their daily precipitation measurements are transmitted on-line using an interactive web site: www.cocorahs.org. Observations are then immediately available in map and table form for project scientists and the public to view. By providing high quality, accurate measurements on the internet, the observers are able to supplement existing networks and provide many useful results to scientists, resource managers, decision makers and other end users on a timely basis.

CoCoRaHS has grown from a local endeavor in 1998 with a handful of participants in Fort Collins, Colorado to a six-state network in 2005 with over 1500 active volunteers trained in the collection of precipitation measurements. We have recently expanded into the rural regions of Kansas, Wyoming, New Mexico and Texas where weather observations in general, and precipitation measurements in particular, are scarce and people's livelihoods are greatly impacted by changes in precipitation patterns. Currently, the National Weather Service uses the network's “real-time” hail and intense rain reports to issue Severe Thunderstorm and Flood Warnings in these states.

In addition to providing critical information to local, state, and federal agencies (including the National Weather Service) on regional water resources, one of the strengths of the project has been the ability to provide important information to research scientists and forecasters who then use the data in applications ranging from validating radar-based rain and hail estimates to regional climate studies. Additionally, the engagement of citizens has resulted in the increased scientific awareness of the volunteer participants.