Backyard Weather Spotters Provide a Piece of the Precipitation Puzzle

It’s true that the weather here in San Diego County can be considered tame by residents in other regions in the country. Blessed with steady sunshine and mild temperatures along the coast, a one-inch rainfall is considered a major storm that would barely be noticed in the Midwest.

Even though the yearly rainfall total here is a fraction of what many regions record, the National Weather Service still needs accurate precipitation data that is regularly updated from all corners of the county.

Automated weather stations can paint a broad picture for forecasters, but a growing network of volunteers armed with nothing more than a rain gauge and a computer are filling in the dots. It’s called CoCoRaHS, and thousands of people in every state and Canada participate by checking their rain gauge every morning and entering the amount online.

The acronym stands for Community Collaborative Rain, Hail and Snow Network, although in most parts of San Diego County participants can ignore the hail and snow part and focus on recording rain. Joining CoCoRaHS is free and open to anyone willing to spend of few moments of their morning helping the Weather Service with future forecasts.

“We use the data to verify our forecast to better re-train and educate our forecasters in anticipating similar types of events,” said Alex Tardy, meteorologist for the National Weather Service’s San Diego office, which covers San Diego, Orange, Riverside and San Bernardino counties.

While automated weather stations can cost hundreds of dollars, the CoCoRaHS network uses a simple plastic, four-inch rain gauge that costs about $30. The CoCoRaHS website has instructions on how to install and use a rain gauge. A training slide show is attached to this article in the PDF section.

“We remind people not to install it near sprinklers or under a tree or next to your house where you get water splashing off of rooftops,” Tardy said.

The data sent in by volunteers appears on an online map that is updated daily. Volunteers are asked to check their rain gauges every day at 7 a.m., but data collected 5 a.m. and 9 a.m. will appear on the map.

Currently there are around 150 CoCoRaHS volunteers in the region and the Weather Service is always looking to add more. Tardy said volunteers are especially needed in mountain areas where precipitation is heavier than along the coast, but everyone that wants to participate is encouraged to join in.

“It’s a significant tool with a nice human element to it because people are physically going out and checking the gauges,” Tardy said. “They’re reported the weather as part of our weather-spotter network.”

For more information visit the CoCoRaHS website, or call the National Weather Service office in Rancho Bernardo at (858) 675-8700.