Weather-watchers now have an opportunity they've been waiting for: to improve the National Weather Service's accuracy.

Officials are calling for volunteers to tap on their smartphones to report snow, rain and other forms of precipitation as it is falling so they can establish clearer connections between what they're seeing on radar and what actually falls to the ground.

The Precipitation Identification Near the Ground project -- PING, of course -- has been up and running in other parts of the country since 2006. The National Severe Storms Laboratory in Norman, Okla., has just put out the call for participants in the 51-county forecast area of south-central Minnesota and western Wisconsin covered by the Chanhassen office of the National Weather Service.

Last August the Weather Service installed "dual-polarization" radar, which is able to determine the size, shape and density of precipitation in a cloud. But it doesn't tell what's hitting the ground. That's because, while the radar can tell what's 100 feet above the ground at Chanhassen, where it is generated, it can't see below 8,000 feet at, say, Alexandria, because the Earth has curved down from the beam at that distance. And a lot can happen in those 8,000 feet.

PING will enable participants to generate a sort of electronic eyewitness account of what's falling at their location, and send it to the National Severe Storms Laboratory, which ultimately will use it to make radar more exact.

"We'll never be perfect, but we'll certainly get better," said Kim Elmore, a University of Oklahoma research scientist who has collaborated on PING with the storm lab.

Smartphones and the PING website will enable users to transmit information anonymously and instantly, anywhere, anytime, Elmore added. No commitment to getting up every day at 6 a.m. to check a backyard rain gauge.

Tom Hultquist, chief science officer at the Chanhassen weather service office, added that PING will amplify the research that produced dual-polarization radar. Most of that research was done in Oklahoma, he said, but PING will add real-world weather experiences from other parts of the United States where the atmosphere often behaves differently -- Minnesota, for example.

Just last weekend, he noted, PING could have provided valuable new information in support of radar if people could have reported the frequent changes in precipitation -- rain, sleet and snow -- across southern Minnesota.

More information, plus links to the apps that PING participants can use, is available at

Bill McAuliffe • 612-673-7646