Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Triggering large avalanches that break widely remains a disconcerting possibility here. Slides that break in the upper 1-2 foot of the snowpack will be smaller, but easier to trigger. Much larger avalanches failing on weak snow near the base of the snowpack will be harder to trigger, but hard to survive if you do. Dense, freshly formed wind drifts may be sensitive to your weight in steep, upper elevation terrain. Smaller, wet snow avalanches may occur on steep, rocky slopes where the snow is being melted by the sun. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Triggering large to very large avalanches here is a disconcerting possibility. These will come in two flavors:

    • Weak snow from December forms the base of the snowpack and has produced dozens of avalanches large enough to turn your car into scrap metal. A very dense slab rests uncomfortably on top of this weak snow. This slab makes triggering one of these avalanches much more difficult, but the resulting slide would be destructive and likely unsurvivable. The first sign of instability on this weak layer will be the very large avalanche you trigger. The most likely terrain for making one of these beasts is steep, rocky, wind-affected terrain where the snowpack has thinner spots that give you access to the weak layer. 
    • Several weak layers exist in the upper 12-18 inches of the snowpack. These layers are highly variable. On some slopes they are well bonded, while on others they are producing large avalanches. You may find good stability on one slope and then trigger an avalanche when you change to a nearby slope. Cracks shooting out from your skis or machine are a clear sign you've found an unstable slab. The human-triggered slides that have failed on this layer have involved crust+facet combinations and have been triggered from a distance (remotely). 

    Persistent Slab avalanches behave in ways that catch experienced users off guard. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. Dozens of skiers or riders can ski/cross/highmark large slopes before a very avalanche releases. 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Winds picked up significantly yesterday and continued overnight. Look for dense, relatively thin wind slabs that have been plastered into the terrain by the ongoing wind. While these aren't likely to be big, triggering a small hard slab can pull the rug out from under you and send you tumbling downslope. Ski patrol at Soldier Mountain reported triggering small slabs of recently drifted snow on Friday. 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Today will be a few degrees warmer than yesterday and somewhat windier. Wet snow issues should remain relatively small and predictable. Sunny slopes start the day capped with a stout crust that will break down as the sun goes to work warming and melting the snow. If you are finding stacks of wet snow on the surface, these types of slides are coming onto the menu.

    Even small slides can knock you off your feet and send you down through unpleasant terrain. Natural and triggered slides will travel quickly downslope on buried crusts. Smaller slides can also serve as triggers for the larger avalanches failing on layers of weak snow described above.

Avalanche Discussion

50 Shades of YELLOW

Yesterday, the Avalanche Danger dropped to MODERATE for the first time since January 10th. Each level of the danger scale describes a broad range of conditions, and conditions vary widely across this forecast zone. On the eastern side, expect to see a snowpack that has remained thin all season long. Low elevation slopes facing the sun are brown, and much of the snowpack is faceting on shaded slopes at low and middle elevations. As you travel west, snow depth increases significantly and the nature of the snowpack changes. From Dollarhide and west into the Soldiers you'll encounter a snowpack that much more closely resembles that found in the Sawtooth and Western Smoky Mtns Zone.

The December drought produced a widespread layer of weak snow. This layer was loaded by storms in January and February and has produced many very large avalanches along the way. On most slopes, this layer is buried beneath a very dense, 2-3 foot thick slab of snow. This slab makes impacting the weak layer underneath more difficult, but triggering a slide involving this snow remains a possibility. This slab+weak layer combination is your primary concern in the eastern portion of this zone. We can stack the odds in our favor by avoiding the type of terrain where triggering one of these slides is most likely:  big, alpine terrain that is steep, wind-swept, and peppered with rocks. Here, the snowpack has a lot more trigger points where we can access the weak layers underneath the very dense slabs. 

Closer to the surface you'll find another prominent weak layer: sun crusts, rain crusts, and facets formed at the end of January. A smattering of natural and human-triggered avalanches involving this layer clearly indicate that it is capable of making avalanches, but stability varies significantly from slope to slope. On some slopes, you'll find a strong bond at this interface, while neighboring slopes may be harboring an unstable slab+weak layer combination. In the eastern portion of this zone, this layer is only buried around 12-16 inches down and in most locations you'll need some wind stiffening to encounter problems here. As you travel west to Dollarhide the thickness of the slab overlying this weak layer increases. 

A few smaller issues are going on at the snow surface. Winds picked up significantly yesterday. Look for dense, relatively thin wind slabs that have been plastered into the terrain by the ongoing wind. While these aren't likely to be big, triggering a small hard slab can pull the rug out from under you and send you tumbling downslope. In steep, rocky, sunny terrain, wet loose avalanches will become possible again as the day warms. If the snow you are moving through is wet, these types of slides are on the menu. Pay attention to what is above you, these may release naturally and they can pick up a lot of steam in steep terrain.

As we choose to enter avalanche terrain with buried weak layers, we accept the outcome of those choices. If we're lucky, we can play in big, steep terrain, get tons of snow in our faces, and return home to tell our friends about it. If we are not so lucky, we trigger an avalanche that can wipe our house off its foundation. The goal of this forecast is to give you the information you need to travel how you want to travel in the mountains. What you do with that information is completely up to you. If you are entering avalanche terrain today, be aware that triggering avalanches large enough to bury you (or much worse) remains a worrisome possibility. 

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