Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 7 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a large 1-3 foot thick slab avalanche involving buried weak snow is possible. In upper elevation terrain, the combination of new snow and wind will create new, thin slabs that may be sensitive to the weight of a skier or rider. Avalanches are most likely where the wind has formed drifts or stiffened the snow surface. To reduce your risk, steer clear of obviously wind-loaded terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Yesterday, I traveled in the mountains above the Eagle Creek drainage, just west of this zone. I found a thin and very weak snowpack that produced unstable snowpack test scores and I chose not to enter avalanche terrain. A variety of persistent weak layers exist on most slopes in this zone, generally buried 1-3 feet deep. Crusts with facets, depth hoar, and surface hoar have all produced avalanche activity here, and periodic storms aren’t giving the snowpack time to heal. Another few inches of snow today will keep these weak layers grumbling.

    When dealing with persistent weak layers like these, here are a few approaches to reduce your risk:

    1. Avoid recently and previously wind loaded terrain. In these areas, slabs are adding stress to the weak snow buried underneath and providing a stiff layer of snow to help fractures propagate through the snowpack.
    2. Be aware of the direction that the slope you are on faces. Last week’s avalanche activity in this area was more common on slopes where the sun had built crusts.
    3. Keep an eye on the terrain you are traveling through and underneath. Avalanches are most likely on slopes between 35-45 degrees of steepness. However, persistent slab avalanches can be triggered remotely — from below or to the side of steeper slopes.

    ADDITIONAL DISCUSSIONToday’s storm will bring another 2-5” of new snow to this zone. Winds blowing out of the western half of the compass will build slabs with this new snow. Wind slabs that you encounter today will likely be isolated to exposed, upper elevation terrain. These slabs will be more sensitive to your weight where they are sitting on icy crusts or slick, alpine surfaces.

Avalanche Discussion

Each winter we are faced with a different snowpack when we head out into the mountains. It's easy to get lost thinking only about the powder you are riding through, but pause for a moment and try to zoom out a bit. I like to think about the snowpack as a record of a season’s worth of weather, written in snow and ice. Thinking about it this way helps me to understand the snowpack as a dynamic animal that exists on a longer timeframe, instead of a static, stationary object.

Some years are marked by generally good stability with relatively easy to assess and manage avalanche problems. It snows and the wind blows, we give the wind slabs a few days to heal, and bam, we’re back out in avalanche terrain. Other years have us traveling through the mountains with our tails tucked and the hairs on the backs of our necks raised. All...season...long. Many days pass without snowfall, the likelihood of triggering avalanches decreases, but we’re still traveling conservatively knowing that the possibility of triggering large, destructive avalanches is on the table. If you’ve been tuning into the forecast this season, you know that we’ve found ourselves in the later category. 

In our northern areas, where the snowpack is deeper, triggering an avalanche involving weak snow near the ground is less likely, thanks to the thick slab of snow on top of it. Picture a well-armored, sleeping dragon — you can walk in a lot of places without waking up the beast, but if you find the chink in her scales (thin trigger point), you’ll find yourself facing an unsurvivable problem.

In our southern areas, where the snowpack is thinner, we are dealing with the flip side of this equation. Avalanches here will be smaller, thanks to the thinner slab that would be involved. But, you’re more likely to find a trigger point because the weak layers are closer to the surface. And notice that I said “smaller”, not small. The consequences of triggering one of these slides could be very high, particularly in areas where you would be carried through trees or swept into an abrupt terrain trap where avalanche debris can pile up more deeply.

To complicate matters, both of these persistent slab problems are capped with a few generations of recent wind slabs that are variably thick and variably sensitive to triggering. Is this all starting to sound complicated? Well, good. That means I’m doing a good job of painting the picture for you.

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