Rain watchers wanted

Into every life a little rain must fall. Sure, but how much and when? University of Arizona climatologist Mike Crimmins and hydrologist Gary Woodard are asking for the Valley’s help in answering those questions.

Crimmins and Woodard are behind an Internet project called RainLog.org, which is a statewide network of volunteers measuring rainfall at their homes and businesses. Every day that a drop falls, volunteers record the data and electronically send it to Crimmins and Woodard in Tucson.

In a region where a summer storm can drench one neighborhood yet leave another bone-dry, the goal is to create detailed maps of where the rain fell, for how long and with what intensity. Such knowledge could go a long way in the fields of flood warnings, water conservation, agriculture and, of course, weather forecasting.

“It gives us more texture and context to make spatial decisions as far as drought status across the state,” said Crimmins, who runs the school’s Cooperative Extension Climate Science Applications Program.

Right now, RainLog.org has about 500 volunteers, most in the Tucson area.

“The urban area (of Phoenix) is so much bigger, we need more than 500,” said Woodard, an associate director at the National Science Foundation’s Sustainability of Semi-Arid Hydrology and Riparian Areas center.

So, Crimmins and Woodard are hoping Valley residents who share their interest in weather will step forward. Volunteers will register on the Web page, enter the location of their gauges and learn how to enter rainfall data.

Once the information is collected, research can be proceed by extrapolating the results. From the results come answers to such questions as: Why does it rain here but not there? And do weather radar returns accurately portray how much rain is falling?

“We’re now seeing patterns fill in and data sets flesh out,” Crimmins said.

Already scattered around Arizona are scores, if not hundreds, of rain gauges operated by various agencies. But in a state measuring 113,998 square miles, the official buckets are too far and few between to provide accurate readings when looking at rainfall over, say, the Tonto Basin. Woodard said a soonto-be-published paper shows the best data comes when gauges are spread, at most, a mile apart.

For weather enthusiasts, the project’s Web page is a treasure trove, matching the data and Google maps in an easy-to-read format. The big storm of Aug. 11 is charted in all its wet glory, with three readings in a small area of Gilbert showing 0.4 inches, 0.3 inches and 0.0 helping prove the merits of RainLog.org.

Aid in spreading the word comes via a grant from the U.S. Bureau of Reclamation. Crimmins, and Woodard said the federal agency was sold on how RainLog.org could help save water.

“I think a lot of people think it rains a lot more than it actually does,” Crimmins said. “When they pay attention to rainfall, they’ll make better decisions about how they water their plants and be more engaged in larger-scale drought issues.”

Right now, the network is rather rudimentary. Volunteers mostly use simple gauges and the data is manually entered into the Web page.

In the future, Woodard said, a goal is to have a network of tipping bucket gauges to also measure intensity and time. Also, the gauges could have imbedded processors to automatically upload data.

But that’s many monsoons into the future. For now, Crimmins and Woodard just want the data — and public input.