Weather Watchers Needed – Nsf and Ucar Grants Promote Expansion of Colorado State’s Coco Rahs Program Across Great Plains States

Colorado State University’s popular Community Collaborative Rain and Hail Study, or CoCo RaHS, has received grants from the National Science Foundation and the University Corporation for Atmospheric Research to expand the volunteer-based weather watcher program across the Central Great Plains. The grants are further providing opportunities for CoCo RaHS to collaborate with Colorado State’s CHILL Radar facility, one of the world’s most advanced weather research radars, to improve weather tracking, forecasting and analysis for the National Weather Service and other organizations.

CoCo RaHS is currently recruiting hundreds of volunteers to help expand the program’s region of coverage into far eastern Colorado, and soon will be looking for volunteers in southeastern Wyoming, western Nebraska and western Kansas, where water resources are often scarce but play a critical role in the livelihood of the local population. The goals of the collaboration include providing outreach and educational opportunities for citizens and obtaining significant scientific data that can lead to improved precipitation estimates and measurements for researchers.

"There is a need for greater and more accurate rain, snow and hail data across the sparsely populated, storm-prone area of the Central Great Plains," said Nolan Doesken, a research climatologist at Colorado State’s Colorado Climate Center and director of the CoCo RaHS program. "There is also an opportunity for education and community involvement. Local citizens can help, and with minimal effort can gather vital data about local storms not available from any other source."

The region’s diverse and extreme weather is a challenge to climatologists and has a direct affect on urban water supplies, fire danger, surface water, groundwater, industry, soil, crops, livestock and wildlife. Through a network of more than 500 active volunteers, CoCo RaHS is helping answer many questions about the region’s storm characteristics, providing valuable data to Colorado State researchers, the National Weather Service, water managers and many others, and educating the public first hand about weather research.

Each time a rain, hail or snow storm occurs, volunteers take measurements of precipitation using backyard gauges provided by the Colorado Climate Center. Precipitation reports and observer notes are transmitted via telephone or the Internet to the Climate Center each day. Daily updated maps of rain, snow and hail are automatically generated. Scientists and resource managers study these maps to learn how storms develop and move, and to make water-use decisions. CoCo RaHS information is updated daily and available for free public access on the Web at

"CoCo RaHS volunteers learn about weather from local weather and climate experts and make a difference by providing decision-making information for industry, agriculture, home owners, utility providers, insurance companies, resource managers and educators," said Doesken. "Volunteers of all ages are welcome. We currently have weather observers as young as 6 years old and as old as close to 90."

New data collected by the expanding CoCo RaHS volunteer network will additionally be used to validate radar-derived precipitation estimation and hail detection techniques from the CHILL Radar facility. The CSU-CHILL radar utilizes state-of-the-art technology to detect hail and quantify rainfall amounts over northeastern Colorado. The collaboration is expected to create improved methods for more accurately tracking storms and flood events using advanced weather radar technology.

"CoCo RaHS data will essentially be used as ground validation to compare with what was forecast and detected by the CHILL Radar," said Robert Cifelli, an atmospheric research scientist at the CHILL facility. "By combining the efforts of CoCo RaHS and CHILL, we will be able to create and fine tune radar algorithms that can lead to improved weather radar data, which can mean better storm forecasting and more accurate precipitation measurements."

The collaboration will give researchers new insight into storm area, duration, intensity and frequency. Researchers expect to learn more about storm tracks as well as local wetter and drier regions and about how the risk of hail damage varies from place to place across the Central Great Plains. This work is particularly relevant because the National Weather Service will be upgrading all of its current NEXRAD radars in the United States to technology similar to the CHILL radar in the near future.

"As storms move across Colorado, precipitation is generally very localized and highly variable. While damaging hail and flooding hit one farm, neighbors a mile away may be suffering drought conditions," said Cifelli. "The ability for scientists to study the climatic characteristics of storms in the region has traditionally been hampered by the lack of widespread weather data, but CoCo RaHS and CHILL are helping researchers overcome this shortfall."

Colorado’s official weather stations are 40 to 80 km apart, and entire storm systems can slip through the gaps without detection. Radar systems deployed by the National Weather Service track storms across the region to provide better forecasts and warnings. However, depending on the exact location and type of storm, radar data may only roughly approximate the amount and type of precipitation actually reaching the ground. When combined with CoCo RaHS date, researchers get a much more complete picture of the region.

"Without accurate data, poor decisions regarding the efficient uses of water, pesticides and other resources could be made," said Doesken. "The research data gathered by CoCo RaHS volunteers in combination with National Weather Service data, data from Colorado State’s COAGMET (Colorado Agricultural Meteorological Network) and other sources provides widespread information that leads to appropriate, well-informed decisions that could not otherwise be made regarding Colorado’s climate and water use."

CoCo RaHS data have been included in formal research, have provided a more accurate picture of local precipitation patterns and variability, and are currently being used routinely by several government, research and private organizations for making informed decisions. A few are highlighted below.

  • The National Weather Service monitors CoCo RaHS rain and hail data daily to help track severe weather, issue severe storm warnings and verify forecasts. Outside of work, about one-third of local National Weather Service employees in Colorado volunteer for CoCo RaHS.
  • The U.S. Department of Agriculture uses CoCo RaHS information to evaluate drought, hail and crop conditions and to improve estimates of future crop yields. Its Natural Resources Conservation Service is becoming increasingly involved with CoCo RaHS as local rainfall patterns are very important to the conservation practices that these districts monitor. The USDA Farm Service Agency is looking at CoCo RaHS data to confirm county rainfall patterns and assess which counties qualify for drought or hail disaster declarations.
  • The U.S. Bureau of Reclamation and the Northern Colorado Conservancy District both use CoCo RaHS data to look at how precipitation affects water inputs into specific river basins and how it impacts irrigation demands in those areas. The Bureau of Reclamation recently contributed 240 rain gauges to help CoCo RaHS expand into western Colorado with the goal of improving stream flow predictions on the Colorado River and its tributaries.
  • The Colorado Water Conservation Board and the State Engineer’s Office are interested in CoCo RaHS data for mapping rainfall patterns that can lead to both drought and flood events.
  • The Urban Drainage and Flood Control District closely monitors weather conditions and flood potential in the Denver metro area, and CoCo RaHS provides a low cost supplement to their network of automated rain gauges.
  • CoCo RaHS data over agricultural areas helps farmers determine how much irrigation water may be needed to keep their crops healthy, and in urban areas, the data also show how much water may be needed for lawns, gardens, parks and landscapes.
  • Teachers from throughout Colorado use CoCo RaHS information to help teach math and science to students. Lesson plans are being developed for the Web for teachers to use to utilize CoCo RaHS information in their classrooms.
  • This is a community project that benefits the entire state, and anyone can help," said Doesken. "The only requirements are an enthusiasm for watching and reporting weather conditions and a desire to learn about the power and beauty of our natural world. And it only takes a minute or two a day."

To learn more about the project or to sign up to become a volunteer, go to the CoCo RaHS Web site at or call the Colorado Climate Center at (970) 491-8545.