It’s a privilege to ski with smart, accomplished friends. Not only is it safer, but you manage to learn something every time you get out.
Buddies and I embarked on a tour February 8, on a day rated “considerable,” with little spots of “high” on the danger rose. Paul and Diana, two of my fave partners, were along, as well as Brian Lazar, the assistant director at the Colorado Avalanche Information Center (CAIC) and the executive director of the American Institute of Avalanche Research and Education (AIARE). We were stoked to make turns, but nearly as jazzed to get some avy and snowpack obs, as stability was poor (at best) and there was bound to be some action.
The above photo shows Teacup Bowl, a feature in the Current Creek drainage on Berthoud Pass. It faces southeast and is generally top- and cross-loaded from southwest, west, and northwest winds. On a sketchy day it’s not only a good feature to avoid, but it also gives some interesting obs. We approached it from below, wrapped around to the west and then skied up to it, hoping to see if we could trigger it. Sure enough, from approximately 80 feet away the thing ripped, fracturing several hundred feet across and running full track. Let’s call it R3, D1.5.
Above you can see Lazar at the crown of the avalanche, studying its characteristics. Completing a “snapshot” like this reveals quite a bit about snow stability, avalanche mechanics, and gives keen observers a bit more experience–which goes a long way to avoiding avalanches in the future. Below you’ll see the snow profile (done in SnowPilot once Lazar returned home) taken at the crown of our slide.
Most notable in the profile is the knife-hard layer, depicted as the thin rectangle extending further left than the rest of the purple areas. This is a melt-freeze crust which developed during the dry, sunny period in late January. Above and below that layer are “facets,” or angular-shaped snow grains that do not adhere well to other grains. So, we had a very hard (think: slick) layer with snow grains above and below it that don’t want to adhere to other snow grains. Atop our melt-freeze layer last week’s storm snow fell. It doesn’t take a rocket scientist to imagine a bunch of new snow falling on a hard, slick layer capped with poorly bonded grains…and then sliding off. Voila–avalanche.
There are several “red flags” present in the above scenario. Radical jumps in “hardness” indicate instability–notice the different layers in the snow profile (depicted by the purple areas). The further left on the profile these extend, the harder they are. Get a really hard layer above a really soft layer and it can spell trouble. In addition to the layers, the types of snow grains present in each layer are depicted by symbols to the right of the layer itself. A square indicates a “facet,” those nasty grains that don’t want to adhere to anything else. A slash to the right (/) represents a decomposing particle–in this case snow flakes that fell out of the sky and have begun breaking down due to wind, sun, and other conditions.
These are the kinds of skills you’ll begin to learn in an AIARE avalanche course. The Level 1 is a great intro to terrain and weather factors, while the Level 2 and 3 courses really drill down into the physics and subtleties of snow science. Super fun stuff and worth the time-commitment if you’re going to be a lifelong backcountry skier.
Thanks to Brian Lazar, Diana Rogers, and Paul Rogers for the good tour that day. Sadly Lazar busted a binding heading into our second run…but the snow was sublime and we played safe. March, typically our snowiest month, is upon us…so buckle up, wax yer boards, and see you out there!
