Articles

By Dave Zinn, Forecaster, Gallatin National Forecast Avalanche Center

Digging a Snowpit Matters

An online article posted October 29, 2015 for BackcountryMagazine.com on snowpits, avalanche character, and the difficulties and risks of traveling in various types of snow, is a welcome early season jump-start to get us thinking about snow and avalanches. Every snow climate is different and every professional forecaster looks at the snowpack through his and her own forecasting lens, but we are all trying to increase the understanding of avalanches in order have fun and stay alive.

Published in the Winter 2018 issue of Outside Bozeman

Saddle Peak sits south of Bridger Bowl as a pair of equally high points on the ridgeline. The familiar eastern slope rises 3,500 feet above the highway on the way to Bridger Bowl, and provides an iconic view to those at the ski area. The peak’s extraordinary gullies and faces are the siren’s song to the southwest Montana powder skier.

Published in the Dec 2014 Carve

Put your shovel in the snow!

This simple act could save your life. Pausing to assemble your shovel and dig a few scoops can sometimes reveal a hidden but, once exposed, obvious weak layer. Taking a few more minutes to perform an Extended Column Test (ECT) may give you strong evidence of unstable slopes. When conditions seem good most people have already made their decision to ski or not by the time they reach the top of a slope, but an ECT might change your mind and save your life. Conversely, if you decide to not ski because of dangerous conditions there is no need to dig. Regardless of experience, if we play in avalanche terrain we should hunt for instability.

When venturing into the backcountry, answering these two questions is essential when assessing a slope to ride:

Is the terrain capable of producing an avalanche?

-and-

Can the snow slide?

Avalanches happen when four ingredients are present:  a slab, a weak layer, a trigger and a slope steep enough to slide. A key problem when assessing slope angle is that most slopes have varying degrees of steepness.  It is critical for riders to assess slope angle frequently.   

Powder Magazine

Winter is in the rearview mirror and spring is gaining momentum but we cannot forget about avalanches. As the seasons change so do the types of avalanches. There are two ways to trigger avalanches: stress the snowpack or weaken it. Dry slab avalanches are common in winter and occur when too much weight (stress) is added to the snowpack. Under a heavy load of new snow, windblown snow or skiers, layers collapse and avalanche from this added stress. In spring the snowpack loses strength and weakens when melting water breaks down snow crystals and provides lubrication between layers. Some types of layers are more prone to this type of weakening and this season the western US has one of the worst: depth hoar.

I would love to know how many sets of tracks were wiped out in Sunday’s avalanche of the Football Field on Saddle Peak. If you carved a set consider yourself lucky. I’m going to guess that not many snowpits were dug and that the only form of stability assessment folks leaned on were that others had skied it beforehand. This was not smart. The avalanche broke during early morning avalanche control on the boundary of Bridger Bowl. An explosive was placed in-bounds, but the avalanche ripped out-of-bounds. Why?

Published in CBU November Newsletter

The day dawns cold and clear with a foot of fresh snow and the promise of incredible powder riding. At the trailhead, the surrounding landscape sparkles like a field of diamonds and the anticipation of a magical day in the mountains builds.

Sled covers are hastily removed and the machines are fired up - the smell of exhaust fills the air. Feeling confident about preparations, members of the group do a quick gear check and then hop on their machines, pinning their throttles towards the backcountry and a day of powder riding.

The GNFAC is looking for an intern for the 2022-'23 winter season. Application deadline is April 22, 2022.

Published in the February 2015 issue of The Avalanche Review.

The Class