Vail, CO Colorado

EAGLE - When a storm approaches, Debbie Adams' phone rings. The voice on the other side of the line gives her detailed instructions.

It tells her exactly when to start up the fire-breathing contraption that stands beside her hay pasture on Brush Creek outside of Eagle. And how much silver iodide solution should be fed into the burner. And when to turn it off.

Adams then trudges out to the generator, which is made of two tanks and a pipe jutting into the air.

Once the propane and the silver iodide solution are coming out of the pipe, and it is lit, an orange flame shoots skyward. Heated to a temperature of about 2,000 degrees Fahrenheit, the silver iodide vaporizes and is cast into the wind.

The tiny particles - 20,000 of them side-by-side would be 1 inch long - are carried over the hills east of Brush Creek.

As they approach Vail and Beaver Creek, they rise higher and higher until they reach the clouds. Each silver iodide crystal has the same size and shape as a natural ice crystal. The crystals supposedly attract moisture in the clouds, growing larger and larger until they become snowflakes and fall out of the sky.

If calculations are on target, the snowflake will fall on or near the slopes of Vail and Beaver Creek mountains.

But Adams isn't going to take credit for a nice powder day.

"I don't know about that," she says. "We'll give God the credit for that."

Ten quadrillion chances

Adams and her family operate one of 17 generators that are part of the cloud-seeding operation for Vail and Beaver Creek.

"They just say, 'Put it on at this time and shut it off at this time,'" says Adams.

Vail Resorts contracts Larry Hjermstad of Durango-based Western Weather Consultants to run the operation. Hjermstad has been seeding clouds for Vail Resorts for 30 years.

The generators are in Eagle, Bond, State Bridge, Wolcott, Gypsum and Beaver Creek, all upwind from the ski mountains.

Hjermstad says his efforts can increase snowfall between 11 percent and 15 percent, in terms of water content, for many storms.

Property owners can earn between $2,000 and $3,000 a winter for operating a generator.

The generator typically emits about 10 grams of silver iodide per hour, which is made up for 10 quadrillion crystals - or 10 quadrillion chances to make a snowflake.

The generators runs at least eight hours at a time, and have run as long as 120 hours in a row, Hjermstad says.

Vail and Beaver Creek usually seed clouds from November to January. They pay around $160,000 a year for the three-month program, Hjermstad says.

Hjermstad also runs a program for Colorado Springs Utilities that targets the Tennessee Pass and Independence Pass areas, where water is collected for the Front Range.

Durango Mountain Resort and nearby water districts there also run a cloud-seeding program through Hjermstad.

Cloud-seeding is sometimes halted. Vail Resorts limited their seeding during the World Cup Birds of Prey races, when lots of snowfall can cancel the races. Cloud-seeding also stops when avalanches threaten local highways, Hjermstad says.

Some skepticism

But cloud-seeding has its detractors. Eric Hjermstad, who helps his father run the weather-modification operations and was repairing generators in Eagle County on Tuesday, says he's met with skepticism about half the time when he explains cloud-seeding.

"A lot of people ask, 'So do you fly in an airplane?' That's usually the first question," he says. "The second question is, 'Does it work?'"

A 2003 study by the National Research Council concluded there's no proof that weather modification is effective. But Larry Hjermstad says he's studied the snowfall of seeded storms versus nonseeded storms, as well as the snowfall of targeted ski resorts versus non-targeted areas.

"From a scientific and technical standpoint, documentation of weather modification is very clear," he says.

However, he admits, some scientists would like to see even better documentation. But there's not enough research money to closely study results of cloud-seeding efforts, he said.

'A reasonable number'

Roger Pielke Sr., a former state climatologist and a professor emeritus in the Department of Atmospheric Science at Colorado State University, says he believes cloud-seeding for ski areas is effective.

"A number of 10 to 15 percent (increase) localized at a ski area is a reasonable number," he says.

For ski slopes, Pielke said he doesn't see any downside of cloud-seeding. But when it comes to seeding bigger areas like water basins, the results are more hazy, he says.

"When you're talking about larger areas, I don't think the effect is well understood," he says.

Eric Hjermstad says perhaps the most vocal opponents are farmers downwind from targeted areas who say cloud-seeding leaves them with less precipitation. But the Hjermstads say there's no evidence that seeding reduces precipitation downwind.

"That has been specifically looked at," Larry Hjermstad says. "You cannot find any decreases. You can occasionally find small increases downwind."



Staff Writer Edward Stoner can be reached at 748-2929 or estoner@vaildaily.com.



Vail Daily, Vail Colorado CO