Behind the Scenes: Grooming (and Why Cooper’s Snow is Always So Soft!)

A PistenBully 400 lays down corduroy on 10th Mountain

by Patrick Torsell, Cooper’s Director of Marketing, IT, & Slope Maintenance (2015 CSCUSA Groomer of the Year; published 6 times by Ski Area Management Magazine on the topic of grooming)

Grooming is an interesting topic. People have really strong opinions about it. One person says you groom too much; the next says you don’t groom enough. The trail that is someone’s favorite cruiser turns out to be someone else’s favorite bump run. It’s impossible to please everyone. But it is possible to deliver consistently smooth and soft groomed trails. And that’s something we put a lot of time and energy into here at Cooper. Here’s a little behind-the-scenes view of the art and science of grooming, and our methods here at Cooper.

How Does Cooper Decide What Trails to Groom?

The daily grooming plan is developed by the mountain management team based on a variety of important factors. First, we take a few runs during the ski day to assess the conditions on both the groomed and ungroomed runs (working in the ski industry is obviously really terrible…). That gives us a first-hand idea of the actual state of the snow surface around the mountain, and at critical spots like lift mazes and ramps, terrain park, race trails, etc. Then we review the events for the following day to determine if any races, training, or other on-mountain events dictate specific grooming needs. Next, we consider anticipated ski traffic for the following day to determine which/how many main green/blue thoroughfares need to be groomed. The weather forecast is used to determine if fresh snowfall will alter the planning or timing of certain trails. Finally, we take a look at the previous night’s grooming plan to help formulate the next night’s plan.

Those are the factors that vary from day-to-day. There are other considerations that are more constant. For example, other things being equal, we try to groom at least one green run and one blue run on both sides of the mountain each night. This ensures a good variety of groomed terrain for the core skiing public. We like to add a back-side black diamond into the mix at least 3 times each week, to keep some smooth steep cruising. And, of course, we have to consider the beginner/learning terrain on EZ Street, and above the Children’s Center. We don’t groom this every night (for reasons that will be clear later in this post), but we do usually groom it for every weekend and holiday.

Taking all of these factors into account, a map is generated for the groomers highlighting the trails to be groomed, special tasks to be completed (lift work, park work, base area projects, etc.), and the timing of the tasks. Timing is particularly important. The longer the time after a trail is groomed, the harder the snow surface will become. Certain types of trails actually need to set harder, such as race trails, terrain parks, and steeper terrain, where more advanced skiers do more “damage” to the snow surface. Those trails are assigned to the swing shift (4pm-12am) so that they have time to set up before the ski day. Other terrain, however, we want to keep as soft as possible. Beginner and intermediate runs we prefer to groom on the graveyard shift (12am-8am). That way, the surface doesn’t have too much time to set up.

So, with the plan made, it is delivered to the shop, where the groomers review it when they arrive for their shift. Each groomer is assigned approximately 40 acres to be covered during his shift. Is it possible to cover more? Sure. But at the expense of quality. And quality is more important to Cooper than quantity. We think you’d agree!

Why Is Cooper’s Snow So Soft?

For starters, Mother Nature takes good care of us! Our base is all-natural, which means it is softer. While man-made snow (found at most other resorts in Colorado) serves a very useful purpose (allowing early openings, ensuring a durable base, allowing recovery from dry/warm periods, etc.), it also creates a much harder surface. From a scientific standpoint, that’s because the water content in man-made snow is significantly higher than natural snow, making a more dense product. Additionally, the snow “crystals” formed by snowmaking are more like little frozen balls rather than snowflakes. In other words, they don’t have interlocking arms and unique shapes like real snowflakes. This, too, makes a denser snowpack, since it is the shape of natural snowflakes that make natural snow so soft and fluffy: the arms interlock, but leave space for air in the snowpack. Natural snow–with its lower water content–stays softer longer. High water content snowpack will freeze solid in particularly cold temperatures.


At Cooper, we don’t make any man-made snow. Mother Nature graces us with an average of about 260″ of natural fluffy stuff each season, and our high base elevation (10,500′) means that the snowpack remains cooler and drier, and thus lighter & softer.

And we’re here to supplement Mother Nature’s efforts as well, with our unique grooming philosophy. Unlike most other ski resorts, Cooper doesn’t believe in over-grooming trails, which results in hardpack conditions. Cooper applies industry trend-bucking grooming practices to avoid over-working the snow, meaning a softer, smooth surface. Each time a snowcat pulls a power tiller (the rear hydraulically-powered implement which processes snow by spinning an auger with sharp teeth at high RPMs in the top several inches of snowpack) over the snow, the crystals break down and form new bonds, resulting in a harder and slicker base. Cooper has established a carefully-planned grooming terrain rotation to guarantee plenty of corduroy, while ensuring that the snowpack remains as soft as possible across the mountain. This is why considering the trails that we groomed the previous night is so important in planning our grooming for the next night. At Cooper, we very rarely groom the same trail two nights in a row, and that is to keep our snow as soft as possible for YOU!


Cooper also believes in using alternative implements to the aforementioned power tiller. We use compactor bars (known as c-bars to industry insiders) whenever possible, especially in early season and in particularly snowy weather cycles. The compactor bar is just that: a metal bar, with a rubber flap and poly combs to leave a corduroy pattern in the snow. But since there is no rotational or mechanical processing of the snow, it does not have the same deleterious effect that the power tiller does. Over time, the snowpack does still harden from use, and from driving a 14,000lb machine over it. But using a non-mechanical implement substantially slows the process.

Most ski areas have fallen into the trap of believing that they must groom certain trails (with a power tiller, no less!) every single night. This is understandable in high-traffic areas where lots of skiers “damage” the surface during the course of the day, leaving cuts, bumps, and slick areas. Under those circumstances, of course the trail should be groomed. However, at Cooper, we have the distinct advantage of a low average skier density per acre. A trail that is groomed, say, on an average Tuesday, should not need to be groomed again until Friday. In fact, it shouldn’t be. As explained above, each time a trail is groomed, it gets harder and harder and harder, until a fresh fall of snow can be mixed in.

This is tough for some skiers to get used to. They’ve been conditioned by their experience at most ski areas to believe that a trail has to have fresh corduroy on it to be soft and smooth. Not true! Sometimes the softest and smoothest run might be one that was groomed several days ago! Keep that in mind as you ski around, and you might just find that, while corduroy is certainly nice to look at–and makes a satisfying “crunch” as you turn on it–it may not actually be the softest snow on the mountain.


If you have any questions about grooming, please feel free to comment below. It’s a topic near & dear to my heart, and one I never tire of discussing!

And now, just for fun, here are a few bits of grooming multimedia I’ve put together over my seven years in the grooming world:

Helmet Cam Grooming at Cooper, December, 2013, using c-bar in fresh, deep snow on Black Powder. In this video, I’m using a pattern called “skip pass,” in which I leave a narrow section of ungroomed snow between two finished passes, then finish that middle section with an uphill pass. This makes a cleaner and more seamless surface in deep conditions, and when a trail has multiple fall-lines:


Here’s a video of some fun storm grooming from last season, also on Black Powder. I was running our old BR-275 with a power tiller in this one:


Here’s a slideshow I put together. I called it my “Grooming Portfolio.” Lots of pictures from my previous mountain playground, but quite a few from Cooper as well: