How Is Snow Made? The Science Behind Snowmaking

When it started snowing last week at several Colorado ski resorts, there were few clouds in the sky and no natural precipitation in sight. The forecast was for sun. 

But the weather was perfect — for snowmaking. 

Making snow is a tricky and essential business for ski resorts. 

In the west, resorts use snowmaking as an insurance policy to help them meet their opening date targets. In the east, snow is made throughout the season to help mitigate the vagaries of climate and weather. 

Perfect Conditions

Snowmaking is an energy and water intensive operation, so resorts aren’t going to fire up their snow guns until the conditions are optimal and they are confident that the snow they blow will last. 

Optimal conditions call for a maximum temperature of 28 degrees wet-bulb Fahrenheit, or -2 degrees wet-bulb celsius, with a preferred temperature in the range of 15 to 18 degrees wet-bulb Fahrenheit or -9 to -7 degrees wet-bulb celsius.

“This is the temperature at which our snow guns run at 100% efficiency,” Scott Enos, snowmaking manager at Utah’s Deer Valley Resort shared in a 2017 conversation. 

“It’s cold enough that equipment runs properly and not so cold that the equipment freezes up.”  

And lest you be tempted to google “what the heck is wet-bulb temperature,” let me share. 

Wet-bulb temperature is the temperature of air at 100% relative humidity. To get a reading, all you need is an outdoor thermometer wrapped in a piece of wet muslin with air passing over it.

How to Make Snow

Once the temperature is right, it’s time to fire up the snowmaking infrastructure: hydrants, hoses, pipes, and snow guns. 

Snow guns come in two varieties: fan guns and air/water guns. Fan guns have the most coverage, throwing snow up to 250 feet away. They are often used for laying down early season base. 

Air/water guns are more targeted. These are the snow guns you may see creating deep piles of snow in anticipation of a future terrain park. 

A Word About Water

While air and machinery get the job done, water is the key ingredient. And we’re talking a lot of water, with 200,000 gallons of water needed to cover just one acre of land, one foot deep, in machine made snow. 

Typically, resorts with extensive snowmaking will use millions of gallons of water in 24 hours, depending upon how many guns are blowing.  

Which Resort Will Be the First To Open?

For the first time since 2001, the opening day derby in Colorado is a three-way heat, including perennial competitors Arapahoe Basin and Loveland, with the addition of Keystone Resort. 

While one of these three high-altitude ski players will likely be the first to open (fingers crossed for October), Wolf Creek in southwestern Colorado is a contender if the snow gods deliver.

Still, being the first in Colorado doesn’t guarantee being “first in the nation.” Maine’s Sunday River tested their snowmaking equipment over the October 5th weekend, with a goal of opening by Halloween. Their guns will fire up as soon as temperatures consistently reach 25-30 degrees Fahrenheit overnight. 

“With natural snow and increased capacity in our snowmaking system, we were able to open for skiing and riding on October 19 last season,” says Steve Boulanger, Vice President of Mountain Operations for Sunday River. “Rest assured, Sunday River’s snowmaking team is at the ready to provide a great snow surface as soon as possible.”

To which, all of us say — no matter where we live — bring it.