Precipitation is one of the most variable weather phenomena with such an incredible local impact on communities. Too little can lead to drought and water supply issues, whereas too much can lead to flooding and infrastructure damage. Across Indiana, there are approximately 120 volunteer observers (Figure 1) who provide daily temperature and precipitation data to the National Weather Service (NWS) as part of the national Cooperative Observer Program (COOP). However, there are significant spatial gaps throughout the state, with quite a few counties having no COOP weather observers!
Figure 1. Map of current 120 CoCoRaHS observers.
In 1998, a community citizen science program developed in Colorado invited weather enthusiasts to add to this precipitation data network by making their own daily observations and uploading the data online for the NWS and other public users to access. This program is the Community Collaborative Rain, Hail, and Snow, or CoCoRaHS, program. It originally began in response to a devastating flash flood that occurred in Colorado the year prior. As with many flash floods, a lack of ground truth precipitation observations was apparent. Since that time, CoCoRaHS has spread across the country as well as Canada and the Bahamas. A dense and reliable precipitation gauge network can be critical to not only understanding and predicting floods, but snow and drought events as well.
CoCoRaHS is looking for volunteers to take and report valuable rain, hail, and snow measurements. This non-profit precipitation observing network is the combined effort of many different groups and individuals nationwide. While CoCoRaHS is not an official National Weather Service nor Indiana State Climate Office program, they support CoCoRaHS through education, outreach, and promotion to potential volunteers. The network’s website, www.CoCoRaHS.org, provides information on how to join, training materials, and access to the precipitation observations.
New observers are needed in every county since precipitation is highly variable. Figure 2 illustrates where there are still spatial gaps of CoCoRaHS observers in Indiana. Anyone interested in joining – even those with many other observers nearby – is always welcome. As we all know, it can rain on one side of the street and miss the other side entirely! In addition to daily precipitation observations, CoCoRaHS observers are also able to report real-time occurrences of hail, heavy snow, and flooding in their area, which can aid in the issuing and verifying of life-saving warnings. The CoCoRaHS network continues to be a valuable asset in monitoring precipitation and climate.
Figure 2. Spatial gaps of CoCoRaHS observers in Indiana.