As Minnesota heads into the spring and summer thunderstorm season, volunteer observers across the state will be sharing weather reports from their communities.
And there's an effort underway to get more observers signed up.
The program is called the Community Collaborative Rain, Hail and Snow Network — CoCoRaHS for short.
"There are parts of the state here where we have gaps in the radar, and so it makes it more challenging for us to try to estimate how much it actually rained or snowed in a particular location," said Luigi Romolo, who is the Minnesota state climatologist with the Department of Natural Resources. "By filling in those gaps with CoCoRaHS observers, we're able to gather key critical information that we normally wouldn't get."
Even where there are not gaps in radar coverage, he said, it’d be helpful to have more observers to detect local variations in rainfall and snowfall.
Romolo said observers need to purchase and install a standardized 4-inch diameter rain gauge, and measure precipitation. They enter that data online or through an app on their phone, and it's collected into a national database of observations.
"It helps us monitor drought, and helps us verify high rainfall totals, or high snowfall totals," he said.
In winter, snowfall is measured by melting what falls into the gauge to get the liquid equivalent. The program also collects hail reports, among other weather observations.
The data is used by the National Weather Service, researchers, cities and a wide range of industries.
The CoCoRaHS program started in Colorado in the late 1990s and has since spread across the country, with more than 20,000 volunteers including several hundred in Minnesota.
"There are farmers who like to get involved in CoCoRaHS, there are teachers who like to set up gauges at their schools," Romolo said. "There are families who are trying to encourage their children to get more involved in science. …
"It's something that you can do in your own backyard, so it doesn't violate any restrictions with social distancing. And it's just something that helps you do something fun in a time when the world around you is throwing rain clouds at you."
It's ideal if observations are submitted each day, though Romolo said there's an understanding that may not always be possible. If volunteer observers are away from home on a trip, they can submit a multi-day precipitation report when they return.
"Even if they're only reporting intermittently, if it reports on a day when it's important with respect to what's going on weather-wise throughout the state, it's extremely valuable," he said.
To sign up for the program, visit the CoCoRaHS website at www.cocorahs.org/application.aspx.