The looming threat of drought next summer has water managers willing to try anything to build up winter snowpack. Idaho and other Western states are hoping to squeeze more snow out of the clouds with a method called cloud seeding.
So what exactly is cloud seeding?
"It’s trying to increase precipitation in an already existing storm,” Idaho Power meteorologist Derek Blestrud explained.
Existing is the key word here. Cloud seeding isn’t about creating new precipitation. It’s supposed to squeeze more snow out of a cloud that already has some ice-crystals in it. It works best when a snowstorm is already underway.
“When you look at the mountains, and they’re covered with clouds, and it’s snowing in the mountains,” Blestrud said. “That’s what we want.”
The goal is to increase that snowfall and thereby the overall winter snow-pack. In the summer, that snow melts, feeding rivers and spinning turbines in hydroelectric dams -- including those run by Idaho Power, the utility company Blestrud works for.
Helping clouds make snowflakes
Brook Mueller is a weather modification pilot. The company he works for sends him all over the world to change the weather.
During the summer, he’s in Canada. Currently, he’s at the Boise airport helping to train pilots. His crew will be seeding clouds this winter for Idaho Power and the State of Idaho.
The planes carry a special kind of cargo.
“The burn-in-place flare is kind of like a roadside flare, but it’s about a foot-and-a-half long,” Mueller said.
Clouds aren’t always good at making snowflakes. There’s a chemical inside these flares called silver iodide that’s supposed to help. It bonds with water droplets in the clouds. And if the conditions are right it forms snow.
‘We can’t afford not to try it’
More snow melt also means more drinking water for cities and cooler rivers for salmon. That’s partly why the state of Idaho is now involved.
“Cloud seeding has a very, very high priority,” said Brian Patton, a manager at the Idaho Department of Water Resources.
This year, his department spent $200,000 on cloud seeding. He said that with looming drought and low water levels, his agency is willing to give cloud-seeding a go.
“We’re gonna try it,” Patton said. “I think that we can’t afford not to try it.”
Idaho is the only Northwest state with a cloud seeding program. It is used, though, in other western states including Nevada, Colorado, and California. Los Angeles County’s program is among the most ambitious. To get more drinking water from the Colorado River, the county pays to seed clouds all the way in Colorado.
In Idaho, Patton said he would be happy even with marginal results.
“If we could can produce say an overall 5 percent increase in total runoff that would be definitely a success,” he said.
Promising data and skeptical scientists
Roy Rasmussen, a scientist with the National Center for Atmospheric Research in Colorado thinks that Patton could get at least that much. If the conditions are right.
“We most likely have a 5 to 15 percent increase in the seeded storms,” Rasmussen said.
Rasmussen found these results while evaluating the longest running cloud seeding study. It wrapped up about a year ago in Wyoming.
While the scientific community saw it as a major step, there are many who say there is still not enough convincing proof. That was the conclusion the Bureau of Reclamation reached in a report published this year.
“I think most current scientists would heavily weight the statistical results,” Rasmussen said. “And so, if you’re putting all of your money on the statistics, then you may question these results.”
In Idaho, water managers are considering the scientific data. But, Patton said his department is also interested in what it can learn by actually trying to seed clouds in the weeks to come.
Depending on how that goes, there may be more airplanes flying into winter snowstorms.