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As the West gets drier, Colorado tries to get every drop of moisture it can out of winter snowstorms

By Conrad Swanson

The Denver Post

All across Colorado, teams of cloud seeders keep watch over the winter months, looking for the right conditions to make water.

Snow, to be precise. But the temperature, moisture levels and wind conditions have to be just right before those seeders, up to 25 of them at any given time, can get to work, Andrew Rickert, manager of Colorado’s Weather Modification Program, said.

“It’s a very fine line we’re walking,” Rickert said.

When that line is walked properly, cloud seeding can bring extra inches of snow during muchneeded winter snows across the increasingly dry American West, Rickert said. The practice started strong this winter but tapered off as weather warmed and chances of snowstorms dissipated.

Scientists invented cloud seeding in the 1940s, and it has been used in Colorado since the early 1970s, Rickert said. The basic process remains the same, although the technology has improved and the practice has gained some momentum in Colorado.

In short, the kind of clouds that create snowstorms contain massive amounts of super-chilled water vapor, Rickert said. Left alone, those clouds can release some snow and retain the rest of their water vapor.

Cloud seeders look to agitate those super-chilled water particles, causing them to freeze inside the cloud. From there they form snowflakes and fall to the ground, Rickert said. Seeders can agitate those particles by plane or from machines on the ground, both processes typically use a silver iodide compound.

Airplanes will “pretty much fly right through the cloud,” spraying the compound across a flame, and spreading it throughout the air, sparking the chemical reaction, Rickert said. Ground generators do the same except they use wind drafts to carry the compound into the clouds, he said.

The end result? Up to a 12% increase in snowfall for a particular storm, Rickert said.

“So if a storm’s coming through and it snows 10 inches and we cloud-seed, that could maybe mean an additional inch of snow,” he said. “With an average of 25 to 30 storms (each winter) that could be quite a few inches of snow.”

To date, seven cloud seeding programs operate in Colorado with dozens of generators ready to go during the November-to-April season, Rickert said.

For one of those programs, Jim Baller, president of the Jackson County Water Conservancy District said his organization partnered with Wyoming’s Water Development Commission for an aerial seeding operation.

Baller estimated that in winter 2020 the extra snow from their cloud seeding program generated an extra 4,000 acre feet of water. An acre-foot amounts to about 326,000 gallons, a year’s worth for two typical families of four.

“We thought that was pretty good,” Baller said.

With an ongoing mega-drought plaguing much of the American West, that extra water can mean the difference between farmers watering and not watering their crops, Baller said.

Seeding efforts in central Colorado are working well too, according to Dave Kanzer, director of science and interstate matters for the Colorado River District, which helps manage the program in Eagle, Grand, Pitkin and Summit counties.

Water from the extra snowfall eventually melts, flowing down Colorado’s rivers and streams and eventually out of state, Rickert noted, so downstream states such as Arizona, California, Nevada and New Mexico all chip in to the state’s $1.5 million budget.

But there’s a catch, Kanzer added. Cloud seeding can’t create snowstorms out of nowhere. They can only enhance existing storms.

This year wasn’t great for winter storms. Climatologists repeated for months that Colorado needed consistent, above-average snowfall this winter to recoup moisture lost over the past two decades of drought, and it didn’t happen.

“Because this year is shaping up to be below average, that means we had a below-average cloud seeding year,” Kanzer said. “We normally get 20-plus seedable storms. This year we’re probably in the 15 to 18 range.”

Still, Rickert said the seeding that did take place this year increased Colorado’s net snowpack.

Others approach the topic with a bit more skepticism. William Cotton, a professor emeritus of meteorology at Colorado State University, wrote this month that the practice might not be as promising as some hope.

“The percentage increases in precipitation are small, and it’s difficult to tell when snow or rain fell naturally and when it was triggered by seeding,” Cotton wrote for The Conversation.

Midwest farmers also have expressed concern that cloud seeding could decrease the amount of precipitation in communities downwind of the operations, Pew Charitable Trusts reported in 2018. But Rickert said studies have disproven those concerns and even possibly shown that seeding can increase rain or snowfall downwind.

Although others might be concerned about silver iodide contaminating the environment, Cotton dismissed those fears because so little of the material is used in the seeding process.

Cloud seeding might not be the definitive solution to the West’s drought, Rickert said, but it certainly can help.

“It’s the only option for physically augmenting snowpack,” Rickert said. “And the only way to actually create and add water to the system.” Conrad Swanson: 303-954-1739,  This email address is being protected from spambots. You need JavaScript enabled to view it.

 

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