It's the time of year when skiers and boarders start praying to the Snow Gods.
But in Colorado, mountain operators are turning to mere mortals for help.
For the past 40 years, Vail Mountain Resort has worked with Western Weather Consultants (WWC) to increase snowfall. The private company uses a process called "cloud seeding" to increase the amount of snow that clouds release.
"I believe that (Vail Mountain Resort) noticed over the years that it's helped them reduce the amount of time that they have to produce man-made snow to get a good base in the early part of the season," explained Eric Hjermstad of WWC.
Hjermstad's father, Larry, started the company after studying the process at the University of Colorado.
WWC now has contracts with a number of Vail-owned resorts — including Keystone and Breckenridge — and a number of water management entities that rely on the Colorado River and the lakes it feeds.
WWC now has 70 generators, which look like propane tanks with chimneys, across the state.
The generators are used to vaporize an acetone solution that includes silver iodine.
"It creates these tiny artificial ice nuclei," said Hjermstad, who likens them to dust.
"The winds carry it up into the clouds. And when it gets into the moisture of the clouds, it begins reacting with super-cool liquid water and gains mass until it's heavy enough to fall out of the sky as a snowflake."
How much effect the process has rests largely on the nature of the targeted cloud. The Vail program traditionally starts in November and continues until the end of January. According to Hjermstad, it increases snowfall by 15 to 20 per cent.
Hjermstad's team looks for "deep clouds" that are forecasted to produce at least 2.5 millimetres of precipitation over a 24-hour period.
The temperature matters as well: Silver iodine will only activate between -5 and -20 Celsius.
But what about the quality of the extra snow that's produced?
The texture matches what would naturally be produced, said Hjermstad. So clouds that come in from the north produce nice dry stuff, while clouds from the south tend to produce wet stuff.
The idea is to marginally increase the amount of snow each cloud produces, creating a larger snow base over time.
"We want to help get a little more out of each storm that comes through," he said.
Cloud seeding operations have popped up throughout the western United States in recent years. The North American Weather Modification Council, an organization that seeks to promote and advance the use of cloud seeding, currently has over 20 members.
The process does have some detractors, with some raising concerns about its effect on snowpacks. But Hjermstad said that that is accounted for and that scientific studies have proven that it is not harmful to the environment.
"Once the silver is put into the acetone, it's broken down to a point where it can no longer combine with another element. When it falls, it just becomes an inert piece of dust on the ground," he said.
"People have come to realize there's really no harmful effects from it," he said.
The technology is getting better every year, and he anticipates further growth in the industry.
"Every year, they're doing bits of research here and there, tracking plumes, making sure targets are correct. I think it will continue to grow as water needs become more needed."
To boot, getting a system online is relatively cheap — $100,000 could get Whistler a dozen generators and provide an operational budget for a year, said Hjermstad.
"And from there you could see if you want to expand it out a little bit," he said.
But for now, Vail Resorts-Whistler Blackcomb said that bringing cloud seeding here is not on its priority list.
Said WB's senior manager of communication in an emailed statement to Pique: "This is not something that we are looking at right now as our focus is integrating WB into the broader Vail Resorts portfolio."