LYONS, COLORADO —
Political storms in Washington often batter the White House, but actual storms can pack a punch, too. Now, we'll know how hard they hit.
The Obamas have joined the more than 20,000 members of the CoCoRahs network. These volunteers measure precipitation in their own backyards, then share their data through the Internet. A rain gauge was installed in Mrs. Obama's kitchen garden this month.
“I think there’s something kind of exciting about collecting information that would, you know, if you collect it for enough years, it represents climate data,” said Bunny Pfau, a Lyons, Colorado, homeowner who has been gathering weather data for 15 years.
In September 2013, during a week of historic rainfall, when local rivers overflowed and nearby buildings were swept away, Pfau stayed home — and checked her rain gauge.
“The night when the flooding began, there was about three-and-three-quarters inches of rain that fell here in my yard that day," she recalled. That was "the largest amount of rain, by far, that I’ve ever recorded in a 24-hour period.”
Measuring precipitation as it falls
CoCoRaHS, which stands for the COmmunity, COllaborative, Rain, Hail and Snow network, began in 1998 at Colorado State University. Its founder, Colorado’s state climatologist, Nolan Doeskin, explained that while radar and satellite data can predict regional weather, they don’t provide accurate on-the-ground detail. That comes from the 20,000 CoCoRaHS volunteers.
“By giving that ground validation, we can then improve the relationships between what we’re seeing from space or from a remote transmitter, and relating it to what’s happening at our point, in our town, our city, our county or state,” Doeskin said.
CoCoRaHS is the largest provider of daily precipitation observations in the U.S. Still, Doesken said there’s room for more.
“We see that rainfall varies on a mile-to-mile, actually a block-to-block basis, and if we had one citizen to do a measurement in every square mile of the entire country, it wouldn’t be too many,” he said.
A detailed view
Pfau and the other backyard weather watchers enter their measurements on the CoCoRaHS site, where each entry appears as a dot on a map. The dots, thousands each day, are color-coded to indicate the amount of precipitation — from gray for no rain, through various shades of purple, blue and green, to red for a downpour.
Meteorologist Matt Kelsch coordinates a two-county region of 200 CoCoRaHS volunteers, and he said the information they provide is invaluable.
“Citizens can get a tremendous amount of information about rain and snow that falls or rain and snow that doesn’t fall. And certainly it benefits the meteorological community, like the community I am in," he said from his office at the University Corporation for Atmospheric Research in Boulder, Colorado. "But it also greatly benefits hydrologists, water resource managers, even people that aren’t trained as scientists that are dealing with water resources.”
There are four official National Weather Service sites in his two-county region, Kelsch said, but they’re too far apart to account for what can be highly variable local conditions. Fortunately, his volunteers send in a wealth of data from many different sites.
“On a typical rainy or snowy day, we could get 100 reports from CoCoRaHS in the two-county area,” he said.
CoCoRaHS also has volunteers in most of the Canadian provinces, Puerto Rico and, later this month, the U.S. Virgin Islands.