We all know what it’s like to ride on corn snow – that smooth, easy turning velvet that is so conducive to high speed ripping. We know if we get on it too early in the morning that it tends to rattle our teeth out of our skulls; if we get on it too late it is slurpy mush that sucks on our skis like quicksand. But what is the stuff we call corn snow?
The best definition and scientific explanation for corn snow I found is on fsavalanche.org, where they describe corn snow as: “large-grained, rounded crystals formed from repeated melting and freezing of the snow.” Their page on the subject includes the image below that illustrates how it is the surface tension of the water between the rounded ice crystals that creates the perfect corn snow. After a cold night, the water between the ice crystals is still frozen; when the ice crystals melt too much, the matrix of ice and water loses cohesion, falls apart and turns to slush. The magic time between too hard and too soft under intense sun is often no more than an hour.
Because of the short window of perfection, the tricky part about corn skiing is the timing, and on really long runs, it is almost impossible to get it just right. On a spring descent of Mt Shasta, known as one of the longest ski runs in the United States with over 2100 metres (7200 feet) of vertical, we waited on the summit until the steep upper slopes were just soft enough to ski but still rattled down the first 500 metres of sketchy, still-too-frozen corn. Then we had a thousand metres of glory before the surface melted out from under us and we wallowed in the slush for the last 500.
There is an atmospheric phenomenon that can preserve the corn low in the valley, while the sun bakes the upper slopes, and that is valley fog. The only time I’ve experienced perfect corn snow from top to bottom on long runs is when valley fog insulates the lower elevations. The Wasatch Range, the Cascades, the Columbias and the Alps are all mountain ranges known for frequent valley fog conditions. If you are in any of these ranges in the springtime, and getting frequent valley fog in the mornings, go find the biggest, safe, corn run in the area and enjoy gorging on the stuff.
Leo Grillmair, shown in the photo at right Heli-Skiing in the Bugaboos in 2005, is one of the founding guides of CMH Heli-Skiing. He explained to me once that the best corn snow forms when temperatures reach 10 degrees C during the day, and fall to minus 10 degrees C at night.
For beginners, corn snow is the very best, most forgiving, most comfortable snow condition for learning to ski or snowboard.
In a ski area, corn snow behaves a little differently because of all the ski traffic, but still there is often a good corn cycle when conditions are right. The best tactic for getting it right in a ski area is to take it easy.
- Don’t shoot for first chair unless your area has a lot of south facing terrain - give it an hour or so extra.
- Find the aspects that have been in the sun for a couple of hours.
- Ski the side of the run where there is less tree shade and the snow has warmed uniformly.
- Avoid entirely shady terrain until very late in the day.
- Wear a carving ski/board rather than a fat powder tool.
However, without a doubt the best way to feast on corn snow, cooked to perfection, is with a helicopter. Interestingly, for the last few years at CMH Heli-Skiing, corn snow has been a largely absent part of the CMH Heli-Skier diet. Nobody’s complaining, because epic powder conditions from the first to last day of the Heli-Ski season in the Revelstoke region has more than made up for it, but still, there is nothing quite like a perfect corn feast with a Bell 212 helicopter and a group of savvy mountain guides to dial the timing and serve it up just right.