Wisconsin citizens take part in the Community Collaborative Rain, Hail, and Snow Network, helping map precipitation, drought, and flooding amid a changing climate

Many years ago, Rick Romeis would watch fiery storm clouds barrel towards his home at the southern edge of a Wisconsin lake. It was the perfect view of the oncoming storm, and he learned at an early age that weather was a cornerstone of the Wisconsin landscape we cherish today. 

Romeis has become one of the longest serving weather observers in Wisconsin for the Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS), a nation-wide network of over 20,000 volunteers, with over 753 based in Wisconsin. These observers provide on-the-ground weather observations to researchers, who use the data to improve radar precipitation estimates and monitor flood and drought conditions.

CoCoRaHS began in 1998 after a destructive flash flood struck Fort Collins, Colorado. After the devastation, experts discovered that if local residents had a method for sharing precipitation reports with larger databases, it could have helped experts understand the magnitude of flooding and assist the community to limit the impact of the storm.

Now, observers across the United States submit weather data — becoming an invaluable asset for the National Weather Service (NWS), and its climate and weather analyses, State Climatologist and Director of the Wisconsin State Climate Office Steve Vavrus explains. 

Volunteers use a highly accurate rain gauge to measure rainfall and collect standardized measurements of the data, Senior Service Hydrologist and NWS Meteorologist Sarah Marquardt detailed. But volunteers who do not own this type of rain gauge can provide other data about snow depth and hail size. 

Generally, there is more weather monitoring equipment in urban areas than rural areas, so citizen weather observations are hugely important to weather experts in these under-surveyed spaces, NWS Meteorologist and Observing Program Leader Michelle Margraf explained. CoCoRaHS is one network for collecting this data from local residents. 

“The CoCoRaHS measurements tell us exactly what’s going on, on the ground,” Marquardt says.

The observations help the NWS calibrate the radar for each thunderstorm or rain event. Precipitation can be incredibly variable across short distances, so having more volunteer data can help experts understand this distribution, Margraf explains.

“I like to think of it like pixels. The more pixels you have, the clearer the picture is,” Margraf says. 

The CoCoRaHS data is also used to calibrate the U.S. Drought Monitor, which depicts the location and severity of drought across Wisconsin.

For agriculturalists and water resource managers, this information helps determine if the region qualifies for federal drought aid. But the monitor is only as accurate as the on-the-ground weather observations.

Despite its large network of volunteers, multiple Wisconsin counties have no monitors, like Forest, Florence, Marinette, Langlade, Menominee, Oneida, Taylor, Jackson, Richland, and Marquette. According to Marquardt, many of these counties have experienced drought in the last year.

The CoCoRaHS observations also predict flood severity. With irregular and severe rain events occurring more frequently, observations help pinpoint the location and severity of flood risk in Wisconsin.

In the 14 years that Romeis has monitored the weather in his northwestern corner of Wisconsin, he has observed warming winters, marked by decreased snowpack and later frosts. According to Vavrus, 30 years of CoCoRaHS data provides an important long-term record that can detect climate trends in the state, coinciding with the time we’ve observed the greatest global changes in climate, Vavrus says. 

“[CoCoRaHS observers] make a difference, especially in the long run. Our climate is warming and the precipitation is changing, and we’ve got to understand that,” Romeis says.

CoCoRaHS data can also be used to predict weather conditions. When there are extreme rain, snow, or hail events, CoCoRaHS observers can report significant weather observations — helping experts tune the weather radar. Sometimes, Romeis is contacted by NWS meteorologists to corroborate unusual weather detected by their observational equipment. For Romeis, his collaborative relationship with the network makes him feel like a part of the science itself. 

Volunteer data can even predict winter weather temperatures.

“Snow cover helps to chill the air… So, the difference between who has snow and who doesn’t can be the difference in who’s really cold and who isn’t,” Vavrus says. 

CoCoRaHS data is open to the public, not just weather professionals, and it’s easy to submit. With the CoCoRaHS Observer app, you can enter your data points and descriptions right into your phone, making it easy to report as regularly as you want. Margraf emphasizes that the project is flexible, and people can report according to their own schedules and time frames. 

The CoCoRaHS network is like a community—they host a very active Facebook page and have monthly webinars about different climate topics. NWS and CoCoRaHS staff regularly reach out to community members to check with observers and express their gratitude.

“We share that passion for weather and weather monitoring in our community, and it’s really fun to be a part of that community,” Margraf says.

Vavrus recently became a CoCoRaHS observer — finding it keeps him more aware of his surroundings, and connected with the land he lives on. 

“It’s been an important part of my life,” Romeis says.

If you’re interested in making a difference, getting involved in science, and connecting with your land, you can become a CoCoRaHS observer today.