How Ski Resorts Make It Snow, Even When It Doesn’t

The modern ski industry wouldn’t exist if it weren’t for snowmaking.

“The modern ski industry wouldn’t exist if it weren’t for snowmaking,” says Michael Berry, president of the National Ski Areas Association (NSAA), the trade association for ski-area owners and operators. “Flat out. It’s unequivocal.” America’s eastern ski resorts need to be prepared to cover their entire skiable area maybe four or five times a year. And in the west, resorts make snow at the beginning of the season to get people on the hill as early as possible. If there’s no snow on the ground, ski season can’t begin. And if ski season can’t begin, there’s less money being made. That’s why in the past few decades, snowmaking has become big business and a modern engineering miracle.

The first snowmakers were developed and patented in the early ’50s by Tey Manufacturing Corporation. The Tey crew weren’t “ski area guys,” Berry says, meaning they weren’t from the mountain towns. But down in the lower altitudes, this group was developing some of the first aluminum skis. During that design process, they fancied that if they could guarantee snow on the mountain, it’d sure help ski sales. And so, in that spirit, the elementary snowmaker was born. As the Times reported, the first machine used a garden hose, a 10 horsepower compressor and a spray-gun nozzle.

By the ’70s, snowmaking had become standard for resorts in the East and commonplace for those in the West. Systems debuted at resorts like Keystone and Vail, then moved to places like Breckenridge and Steamboat before proliferating onto most mountains. These first systems were designed to link the upper and lower mountain early on in the ski season, and also to ensure there was still snow to ski in the spring. Today, the only resorts that don’t have extensive snowmaking systems are in the Pacific Northwest, where a maritime climate makes it much more difficult to make snow (and therefore the purchase cost of a snowmaking system becomes difficult to justify).

Making the White Stuff

Turning Water and Air into Fluffy Snow

To make snow you need water and cold air. Simple enough — but when maximizing production, things get exponentially more complicated. The process for making snow has been fine-tuned over the past 20 years, particularly the most important component: creating a fine mist that hangs in the air for a long time. The longer the mist hangs, the more likely it is to crystalize into snow; to get a perfect mist and perfect loft, a snowmaking machine needs three things: electricity, compressed air and wind. (For the details on this process, check out SMI Snowmaking’s website.)

The most popular snowmaking machines are either air/water fan guns or air/water towers (also known as lances). Towers such as the HKD SV14 get water from a pump and air from a compressor, both of which are located in a building at the bottom of the mountain. The water and air are sent through separate pipelines to hydrants adjacent to the snowmaker, then pumped into the tower. Instead of creating wind, these towers use the compressed air to loft the mist out over the trail, and then they let Mother Nature take it from there.

Fan guns, unlike towers, require only one pipeline (for water), and they generate their lofting air with a propeller. Many fan guns also have on-board electric air compressors, to help mix the water and air at the nozzle. The guns have a higher electricity cost than air/water towers and they generally need colder temperatures to work, but, on the whole, they’re less expensive and more portable. Many resorts use a combination of both guns and towers to generate snow.

In the last five or so years, ski areas have adopted what Berry calls “version 3.0” of snowmaking systems — they use less water, less energy and can make more snow in shallower, shorter windows

Snowmaking systems at ski resorts cannot operate unless it’s 32 degrees Fahrenheit or below. As temperatures drop, the quality and quantity of snow increases. But humidity also plays a role; the lower the humidity, the better. In the industry, the combination of these measurements is called “wet bulb” temperature. A low temperature with a low humidity is the best atmosphere for snowmakers, as it creates the driest snow. It is possible to make snow when the temperature is above freezing, as long as the humidity is very low. But with above-freezing temperatures and even moderate humidity, dreams of a white resort go out the window. (Note: both air/water machines and fan guns sometimes add nucleating agents to their water, which help the droplets freeze more quickly. This helps produce snow when the temperature is right at the freezing point.)

The resulting amount of man-made snow also depends on how well the machines can mix air and water. According to Will Bastian, the snowmaking manager at Sunday River in Maine, resorts used to max out on compressed air before running out of water. That was a problem. “If you’re running out of air before water, that means that there’s still water left to make snow with,” says Bastian. “So you always want to be maxed on water.” That’s where new equipment comes into play. In the last five or so years, ski areas have adopted what Berry calls “version 3.0” snowmaking systems — they use less water, less energy and can make more snow in shallower, shorter windows. These new, highly efficient snowmaking systems make a huge difference for a resort’s bottom line, especially in a difficult year like 2016 (for the East Coast).

Sunday River is one of the top — if not the top — snowmaking mountains in the East, according to Bastian. At the moment, he says they can pump up to 8,000 gallons of water a minute onto the mountain. That translates to 400 million gallons of water pumped a season, which Sunday River pulls from their eponymous river. In the next few years, Bastian says they hope to double that amount.


Most North American ski resorts, from Vail to Mountain Creek in New Jersey, look to improve their snowmaking systems every year. This typically means a gradual replacement of older guns with newer ones, which Berry calls a “phase-replacement.” This is, admittedly, a patchwork job, but it’s the more economic option. When resorts upgrade, there are several manufacturers of snowmaking machines they go to. HKD Snowmakers, Demaclenko, Ratnik Industries, TechnoAlpin, SMI Snowmakers and CHS Snowmakers are some of the big boys. They all sell cutting-edge, highly efficient snowmaking machines.

In the near future, Berry anticipates that resorts will make a big push towards having automated systems, meaning the guns and towers will be controlled electronically, but switching to automation all at once is incredibly expensive. There are a couple of mountains in the US with a few fully automated trails, like Sun Valley in Idaho, and a few European resorts have automated systems because of the high cost of labor. But that’s it. Most ski resorts, like Sunday River in southern Maine, are still 100 percent manually operated.

Distributing the Goods

Covering Trails in the Dead of Night

Throughout the season, 95 percent of Sunday River’s trails are covered with man-made snow. To get the trails open, the production uses a combination effort between snowmaking, ski patrol, lift teams and grooming.

The first step in properly distributing snow is aiming the guns or wands in the right direction. To maximize efficiency (in terms of helping the snowcats easily move snow), the guns try to evenly cover the trails — no massive piles, no long drifts. This means the machines constantly need to be re-aligned, and each requires a man on the ground to manually aim it and turn it on and off. On some trails, there are snow guns every 85 feet. Every trail requires men walking uphill, in deep snow, usually at night, in the freezing cold to control the machines.

“It’s a battle to go out there and make snow night-in and night-out, but I love it. It’s such a unique and an amazing thing to do. You get to create ski terrain for people.”

The second step is directing the grooming fleet. At Sunday River, Bastian says they have roughly 15 snowcats, each of which is required to evenly spread snow and groom trails. And, just as snowmaking technology changes from year to year, so too does snowcat technology. These cats are becoming more fuel efficient, stronger and faster, says Bastian, who adds that Sunday River has even demoed the new Pistenbully 600 E+ — a mostly electric snowcat.

The vast majority of the snowcats’ grooming gets done at night, as they need room to work and can’t have skiers on the slopes. The nighttime is also more conducive to snowmaking because it’s colder and typically less humid. But nighttime isn’t the only time snow is made. Bastian says snowmaking for Sunday River is a 24-hours-a-day operation, from October until March. And it’s not easy on the crew of control room operators, supervisors and on-hill snow makers. The latter bear the brunt of the physical labor. “It’s pitch black and you’re hiking around the side of a mountain trying to cover it with snow. It’s a battle to go out there night in and night out,” says Bastian. “But I love it. It’s such a unique and an amazing thing to do. You get to create ski terrain.”

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