Snow FarmingPosted: November 14, 2008
Got a sneak preview of things to come today during a trip to the still-closed upper mountain at Lake Louise. While there hasn’t been enough snow to consider opening any of the Lake’s expansive alpine terrain, the MG’s (Manual Groomers– Lake Louise’s Trail Crew) have been hard at work since September setting up km’s of fence in order to trap blowing snow and begin building the runs. The practice of using fence to control blowing snow is not a new idea, and if you look closely you’ll see it in use along windy stretches of highway to help keep the roads clear in winter.
Lake Louise, as in the rest of the Canadian Rockies, has a continental snowpack, which means the area receives less snow than places like BC’s coastal and interior mountain ranges. Especially in periods of low snowfall, a ski area can use all the help it can get in order to get snow to accumulate in all the right places. Luckily, Lake Louise receives a fair amount of wind, and when it blows strongly enough to transport snow, the strategic placement of snow fence can dramatically increase the amount of snow accumulation.
Snow fence comes in a few different forms, but the type commonly found in use at ski areas is a lightweight yet strong and flexible vinyl/plastic combo that makes for easy deployment and portability. It stands about 4 feet tall and comes in varying lengths, and has holes over its entire surface, usually in a 50:50 hole-to-non-hole ratio. The faster the wind blows, the more snow it can carry (provided there is snow to be carried, called fetch), and the idea of the fence is not to block the wind, but to slow it down enough so that it drops its load of snow in a designated spot. The photo below shows a drift forming on the leeward side of a length of snow fence:
In the background of the photo is a larger wooden snow fence, permanently built into the ground. Standing up to ten feet tall, these fences have the ability to form much larger drifts than their plastic cousins, but must be built so that they do not block ski runs or other rights of way. Plastic fence can be deployed all over a run, since once the run is ready to be opened the fence can be removed. At the same time, any fence is only useful if it is placed in areas that receive wind, and must be placed perpendicular to the prevailing wind direction. The wooden fence also uses the same proportion of holes to non-holes, and with careful attention to height and length, the drift can be formed close to or farther from the fence, depending on the specific needs. The next photo shows a run (Home Run) covered in snow fence:
Between each of the rows of fence in the photo above, you can see that the drifts have been packed down by people side-stepping on skis. This packs down the accumulated snow and allows more snow to accumulate in the same place, and there are a few reasons for doing this. Deploying and moving fence takes time, so the longer they can be kept in the same spot, the more effective they can be. A fence can only build a drift so high, and once that effective height is reached, one must either pack down the snow, or remove the fence. The other reason is that due to the fragile alpine environment, snow cats cannot begin to work the run until a certain minimum amount of snow is in place, and the more it gets packed down, the faster the cats can get in there to work it.
In the next photo, taken from the top of the Summit Platter looking toward Paradise Chair, there are two long rows of plastic fence on the left, and one long wooden fence on the right. The wooden fence has a space underneath, and this results in the drift being formed farther away than the plastic fences, which go right to the ground and have the drifts grow right around them. This area is almost ready for the cats to do their stuff:
There is an amazing effort that goes into building many of the alpine runs at Lake Louise, and I am continually amazed every time I venture onto the upper mountain early season at how much fence there is and how much ground it covers. I skied at the Lake before their MG program was as extensive as it is now, and there’s no question that their efforts pay off!
Finally, to change the topic slightly, here’s a shot of Boomerang taken from the top of Summit, looking as ready as it ever could to be skied: