11/2/2011 Surface Hoar
Next storm rolled through, dumped a few coveted inches on top of our much maligned basal layer. Came in warm, started as rain and cooled off as the night progressed. Nice to wake up to the first day of work at Troy’s Ski Shop to snow. Doesn’t seem right when you’re mounting skis in warm sixty degree weather. In keeping with the last post, I wanted to address another lurking hazard prevalent in(on) early season snow pack, surface hoar. As I was riding to East Vail before this last snow, I noticed the fern like crystals stacked up on the snow next to the bike path. Clear, cold skies and high humidity are ideal conditions to produce these feathery crystals that lie vertically on top the snow.
Strong in load, but not in shear, these crystals can support subsequent snowfalls until critical stress on the fragile slab is triggered by you, intrepid backcountry traveler. Surface hoar is hard to keep track of. It can be destroyed by wind in some areas while persisting in others. Even by digging a pit in the locale that you want to ski, it is hard to determine if buried surface hoar is still present in the entirety of the area you are going to put a load onto by riding. Next time a cold clear night happens with little wind, check around the next day to see if those crystals are around and file it into your never-ending assessment of the growing snowpack around you.