CoCoRaHS logoCoCoRaHS: Because Every Drop CountsCoCoRaHS logo

by Dennis Sleighter and Anita Silverman

Think about the times you have heard a report from the National Weather Service or from your favorite television or radio station that talked about rainfall or snowfall amounts across the area. How often have you upon hearing those reports thought or said something like, “I had much more than that here,” or “I wish I would get some of that precipitation. It has been so dry here.” There is now available to folks in Virginia and North Carolina a program they can use to share their precipitation amounts with the world.

This program is called CoCoRaHS, and its name is an acronym for the Community Collaborative Rain, Hail & Snow Network. In short, CoCoRaHS is a not-for-profit program whereby the public can input in real-time their rainfall, hail, and snow reports into an Internet based system for use by entities which have interest in such data.

CoCoRaHS originated in Colorado 10 years ago in response to deadly flash flooding that took place in the Ft. Collins area. Flooding occurred due to heavy rainfall that was very localized in area and occurred in a short period of time. The outcome of this flooding demonstrated how rainfall totals can vary significantly over short distances, and the standard distribution of rain gages (both in number and spacing between them) may not be suitable in many cases to properly capture such localized heavy rainfall events. The initial goal of CoCoRaHS was to better expand rain gage distribution in Colorado. It has expanded from this original goal into 23 states, and now includes measurement of snowfall, snow depth, moisture content of the snow, and hail size measurement.

Data provided by CoCoRaHS observers in established areas, have been, and continue to be used by the following: National Weather Service and private meteorologists, hydrologists, emergency managers, city utilities (water supply, water conservation, storm water), insurance adjusters, USDA, engineers, scientists studying storms, mosquito control, ranchers and farmers, outdoor activities and recreation planners, teachers, and students. So, as this shows, CoCoRaHS is not a program just for one group of people. The data collected are used by many people for various purposes, and reports from your own backyard can become an important part of this multi-state program.

Sign up to be an observer on the main web page for CoCoRaHS. Here you can also find links for purchasing a CoCoRaHS rain gage and for online training. If you have any additional questions about CoCoRaHS, feel free to contact Dennis Sleighter or Anita Silverman here at the National Weather Service office in Blacksburg, VA.


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