Banner Summit

Dangerous avalanche conditions exist due to widespread weak layers in the snowpack. The hazard is greatest in wind-loaded terrain, but exists on sheltered slopes too. Avalanches may be triggered remotely — from above, below, and to the sides of slopes. Today, avoiding avalanche hazard requires you to pay close attention to the terrain you are traveling in and to exercise conservative route-finding.

We are dealing with a persistent slab monster right now. Layers of weak, sugary snow (facets) are a common problem in our area. However, a widespread deposit of reactive surface hoar like the one we have now is an infrequent occurrence. This surface hoar developed in the clear, cold days that followed the set of storms over the Thanksgiving holiday. I’ve found these weak, feathery crystals buried in the mountains spanning from Banner Summit, down to the Sawtooths and Western Smokys, across the valley into the White Clouds, south to Galena Pass, further south into the Boulders, and across Trail Creek into the mountains above the Wood River Valley. In short, I’ve found it everywhere I’ve looked. The nature of the snowpack varies widely across our forecast zones, but this layer is a disturbing constant. 

Yesterday was the first day since the storm ended that we did not receive a report of a human-triggered avalanche. However, obvious signs of instability, such as cracking and collapsing, continue to point out this problem. On Saturday, two separate parties of skiers triggered avalanches in the Galena Summit area. That same day, two separate groups of riders triggered avalanches on wind-loaded slopes in the Soldier Mountains. On Friday, Saturday, and Sunday, as I traveled on ridgelines that we’re not exposed to avalanche hazard, I remotely triggered multiple avalanches. These avalanches occurred in three different mountain ranges. Don’t just skim over these details, this is important stuff. Take a minute to let that sink in.

If you’re the kind of person who reads the two paragraphs above and thinks, “I wish there was more to worry about,” I’ve got some great news for you. Large, sugary grains of depth hoar can be found in the Sawtooths, Western Smokys, White Clouds, northern Boulders, and Banner Summit area. On Sunday, in the White Clouds, I observed a 600-800’ wide avalanche that had failed just above the ground on this weak snow, wiping out the vast majority of the snowpack. That same day, skiers in the Sawtooths yesterday reported unstable snowpack test results and widespread cracking and collapsing on this layer and they stuck to low angle slopes not threatened by avalanche terrain above.

The year is just getting going but the list of problems to worry about is long. Complex, overlapping patterns of weak snow are very difficult to deal with. The easiest solution is to exercise conservative route finding and decision making in your backcountry travels. I know, that’s not what you want to hear. I’d love nothing more than to be running around in the mountains, skiing and riding everything in sight. But we don’t have any input into the behavior of the snowpack; the only thing we have control over is ourselves.