A devastating flash flood in Fort Collins, CO, on July 28, 1997, rewrote the records for rainfall in that western state. 

The storm was so localized that weather observing networks and remote sensing technologies (radar, satellite, and lightning detection) did not immediately identify the severity of the storm.  In a matter of just a few hours, rain poured down over an area of a few square miles and flood waters roared though parts of Fort Collins and the campus of Colorado State University.  In the end, over 14 inches of rain fell on portions of Fort Collins -- the heaviest rainfall ever over an urbanized area in Colorado.  Five lives were lost.  There were hundreds of rescues and flooded homes, and over $200 million in property damage.

Since that fateful night, the Colorado Climate Center at Colorado State University in Fort Collins, CO, has worked in collaboration with NOAA and other organizations to launch a nationwide volunteer rain gauge network known as CoCoRaHS -- the Community Collaborative Rain, Hail, and Snow network.  Using low cost plastic rain gauges to measure liquid precipitation, and rulers and white boards to measure snow, volunteers from all over the country are now helping to fill the gaps and provide more localized and timely data on precipitation patterns.

"There may already be thousands of weather stations across the U.S., but when it comes to precipitation we need thousands more," said Nolan Doesken, State Climatologist for Colorado and the founder of CoCoRaHS.   "But precipitation is so highly variable that having one weather station every 400 to 600 square miles across the country is insufficient.  With CoCoRaHS, we hope to someday see at least one rain gauge per square mile over urban areas and one every 36 square miles in rural areas."

Today, CoCoRaHS has spread from Colorado to most of the country - 38 states to date (with five more scheduled to join this year).  There are over 12,000 active volunteers reporting rain, hail and snow amounts on the CoCoRaHS website.  As more people learn of this useful project, the number of volunteers grows.
 
Active and retired NWS employees are among the many volunteers who play a major part in CoCoRaHS.  Many NWS employees have rain gauges in their backyards.  Others have volunteered to help recruit and train volunteers from their communities.  These efforts are mutually beneficial, as data from CoCoRaHS contributes to NWS weather forecasting and severe weather warning efforts.

Go to the CoCoRaHS web site if you would like to volunteer a few minutes of your time each day (or as often as possible) to help measure and report precipitation from your back yard.  Click on "Join CoCoRaHS."  You will immediately receive a station number, a username, and instructions for getting started.  If you would like to help the program in other ways, please contact Henry Reges, CoCoRaHS National Coordinator, at (970) 491-1196 or e-mail: hreges@atmos.colostate.edu.