Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a larger avalanche remains possible in the eastern portion of this zone (the Little Wood drainage, southern Wood River Valley, Pioneer Mtns, and near Bald Mtn), where 16-20 inches of recent snow fell on a weak snowpack. Avalanches can be triggered remotely—from a distance below, above, and to the side of steeper slopes. Avalanches are most likely in areas with recent wind loading but are possible in sheltered terrain as well. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Thanks to significantly below-average precipitation and a prolonged drought in February, a very thin and very weak snowpack exists in much of this zone. Beginning last weekend, 16-20" of new snow fell on this weak snowpack, resulting in a large amount of natural avalanche activity (photo at right). As the days without additional snowfall pass, the likelihood of triggering a slide on this weak snow decreases, but this process is happening very slowly. Yesterday, as I traveled in the East Fork of the Big Wood, the snowpack collapsed underneath me in a number of places and my snowpit tests yielded unstable results. That same day, an observer on Patterson in the mountains east of Hailey reported triggering collapses that traveled hundreds of feet. They stuck to low angle terrain to manage their exposure to this problem. 

    Persistent slab avalanches can fail in ways that catch even experienced backcountry users by surprise. You may be able to trigger slides remotely: from flatter terrain above, below, or to the side of a steep slope. Choosing lower angled terrain is the only way to safely "manage" this problem. 

Avalanche Discussion

The Avalanche Forecast is a tool that helps you to orient yourself to the types of problems you may encounter in the backcountry. It provides a starting point for your mental model of the hazards you will be dealing with on any given day. Let's walk through my day yesterday to get a sense for how you might use it:

The area I was heading (East Fork of the Big Wood) sits near the boundary between two zones, so I checked the forecast for both. Persistent slabs and wet loose avalanches were on the problem list and the forecast text specifically called out where I was headed as being problematic. I made a mental note of these issues, checked the weather, and headed out the door.

As I drove to the trailhead, the sound of refrozen mud crunching underneath my tires told me that there had been a good freeze overnight. I unloaded my sled, and headed up the road, struggling to keep the engine cool even with my scratchers down. I had to stop and pack the tunnel with snow a few times and I felt comfortable knowing that wet loose problems were unlikely at the moment. 

When I got to where I planned to park my sled, I transitioned from a sun-baked slope to a colder, shaded slope. Immediately, I noticed the character of the snow beneath me change. Instead of riding on top of a firm, icy crust, I felt the track of my sled dropping into weak, sugary snow. I parked my sled and stepped off, immediately sinking straight to the ground. "So this is the weak snow that Chris was writing about in the forecast," I thought to myself. I'd found one of the ingredients for the persistent slab problem. These types of avalanches are unpredictable and the best management strategy is to avoid terrain where the problem exists. I'd already decided that morning to do just that.

Skinning up the drainage, I found that slopes that faced the sun were free of snow. No avalanche problems here. On the other side of the drainage, weak sugary snow made up almost the entire snowpack. As I climbed in elevation, the amount of new snow increased and I felt the snowpack collapse underneath me in a number of places. Persistent slab problem located. I stopped to dig a pit and perform some snowpack tests. I stepped out of my skis and sunk through four feet of snow to the ground. A weak snowpack indeed! My snowpit tests yielded unstable results, confirming my earlier decision to avoid slopes where a weak snowpack existed below the slab of recent snow.

I readied myself to head down, choosing low angle terrain to avoid the persistent slab problem. The sunny slopes I encountered had softened a bit, providing some good corn skiing. Fortunately, I'd left early and was getting out of the mountains early, and in doing so I avoided the wet loose avalanche problem. Another good, safe day in the hills.

 

 

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