CoCoRaHS: A History
by Cindy Frank
The Community Collaborative Rain, Hail, and Snow network (CoCoRaHS) began on June 17, 1998 with a few observers along Colorado’s front range. Today, there are over 20,000 observers in the United States, Canada, Puerto Rico, the U.S. Virgin Islands and the Bahamas.
During the summer of 1997, the Colorado Climate Center initiated a small project to test the feasibility of equipping volunteers with foil covered Styrofoam pads in an effort to improve data resources during hail storms. One high school student said, “By the time it hails, we will have forgotten what you asked us to do. Wouldn’t it be better to have volunteers involved in something that can give them something to do more often?”
Then on the afternoon of July 27, 1997, it began to rain along the west side of Fort Collins, CO. The following day, the intensity grew – again, mostly on the west edge of the city. Just five miles to the east, only a light rain fell. As afternoon turned to night, the west side of town experienced a deluge. Spring Creek, usually a small stream barely four feet wide, became a raging torrent. More than 13” fell (almost a yearly average) resulting in a devastating flash flood that claimed five lives that night. NO ONE reported the heavy rain to the National Weather Service office. The opportunity to provide early warning of this flood was missed.
Fast forward to the Spring of 1998. Thanks to a small grant from the CO Office of Emergency Management, a project was envisioned to engage students and families from Fort Collins in measuring and reporting precipitation from summer storms. The name Colorado Collaborative Rain and Hail Study (CoCoRaHS) was coined. Three high school students were enlisted to help and an oldies radio station aired a public service announcement with retirees volunteering to help measure rain and hail. On June 17, 1998, the first version of the CoCoRaHS website began with serval dozen reports submitted and mapped.
During the first five years, the project gradually gained momentum. Financial and personnel resources were few but volunteers stepped in to help. In the spring of 1999 the name was adjusted to include snow. Data credibility grew.
In the summer of 2000 a proposal was written to link the National Science Foundation geoscience education with CoCoRaHS for a major thunderstorm research project. Then weather patterns changed; storms gave way to drought. Recruiting volunteers got harder and harder – all they had to measure was dust. However, by 2003 CoCoRaHS had expanded to much of the state of CO, just in the nick of time. That March, a storm system took shape over the west headed towards CO. Copious moisture from the Gulf of Mexico streamed northwestward towards CO, feeding into the storm. Thanks to excellent weather forecasts and the ability to contact volunteers efficiently by email, warnings of several feet of wet snow were communicated. The storm materialized and exceptional snowfall and water content data were collected that were immediately valuable in storm documentation and research.
In just five years, CoCoRaHS grew from a local experiment to a year-round source of reliable statewide data.
In 2003, CoCoRaHS was expanded to include potions of Kansas, Nebraska and Wyoming. The number of active volunteers grew from a few hundred in 2003 to over 2000 in 2004. In 2004, a new national coordinator was hired. During his first month on the job, he envisioned a national project and the name was revised to Community Collaborative Rain Hail and Snow. New Mexico was added in 2005 and in 2006 NOAA came on board. By 2009, volunteers numbered over 12,000 making CoCoRaHS the largest source of daily rainfall measurements in the country.
State by state, county by county, CoCoRaHS grew. CoCoRaHS Canada was born. With the help of NOAA, Puerto Rico (2014) and the U.S. Virgin Islands (2015) joined the network. It is the quality and reliability of the volunteer-collected precipitation data that has been the best asset. In 1997, the intent was never planned to become a national network and certainly not international too – but it happened. Growth continues, but at a slower rate. Over 3000 new volunteers are added each year, but attrition has begun to take its toll as nearly that many drop out or age out.
As mentioned earlier, CoCoRaHS was born from a remarkable rainstorm and flood. Over the distance of just a few miles, there were differences of over 12” of rain. One man, Nolan Doeskin, recognized that there was very little information about those huge differences in rainfall, and founded CoCoRaHS to fill that need for high-quality, high-density rainfall measurements. The devastation caused by Hurricane Harvey in 2017 was thoroughly documented by CoCoRaHS observers, and has contributed invaluable information to the forecasters and researchers studying that storm.
About precipitation and measurements: it is fun to track the stats of precipitation. Many never tire of it. Precipitation varies a lot – even more than you’d think. CoCoRaHS rain gauges are good, but not perfect. There is no perfect rain gauge at any cost. Automated rain gauges are convenient and informative. But the most reliable and consistent source for accurate precipitation totals is an interested volunteer, using a good quality manual rain gauge, measuring and reporting diligently. (Snow takes a lot more time and determination to measure; about 15% of volunteers take the winter off)
Rain gauges may be ordered from WeatherYourWay.com for around $40. Master Naturalists who record data with CoCoRaHS may count their time as volunteer service by entering it monthly under Citizen Science-FR. As of June, 2021, the South Texas chapter of Texas Master Naturalists has at least four people involved with entering data for CoCoRaHS.