Backyard weather observers work national precipitation puzzle

The state of Florida is now on board. In October, weather enthusiasts in the Sunshine State joined the CSU-run, 22-state network of volunteer observers who measure and report rainfall for a free online database.

The nonprofit, grassroots project called the Community Collaborative Rain, Hail, and Snow Network, or CoCoRaHS, boasts 5,500 members across the country who gather information on rainfall, hail, and snowfall from multiple locations, which is then posted online.

Weather variability

Multiple observers help document the variability in local weather. "It can be pouring in one place and not a half-mile away," said Henry Reges, Colorado State University meteorologist and national coordinator for the network. "This will try to fill in the gaps," Reges told The Tampa Tribune about the addition of Florida’s data-collectors to the network.

The volunteers’ high-quality measurements supplement existing networks and provide useful information for scientists, resource managers, and other decision-makers. Although the network’s rainfall readings are not officially used by the National Weather Service, service meteorologists match CoCoRaHS readings against the rainfall estimates from their radar observations. Flood control districts, ranchers and farmers, mosquito control units, hydrologists, emergency managers, insurance adjusters, and the USDA also use the data, Reges said.

Filling a need

Observers take precipitation measurements each time a storm crosses their locations. These precipitation reports are then recorded on the network website at www.cocorahs.org. The real-time data are then displayed and organized for end users to analyze and apply to daily situations ranging from water resource analysis and severe storm warnings to neighborhood-backyard rainfall comparisons.

The CoCoRaHS network was started in 1998 after major flooding hit Colorado, but few official measuring-stations recorded any rain, Reges said. Now, volunteers’ observations are immediately available online in map and table form for scientists and the public to view.

CoCoRaHS, which is supported by the National Oceanic and Atmospheric Administration and nearly two-dozen other sponsors, also develops classroom resources for teachers and conducts teacher workshops on weather and climate.