Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You are likely to trigger wide avalanches big enough to bury people in many drainages in this zone. These slides can be triggered from gentler terrain below or to the sides of steep slopes. At upper elevations, the chance of triggering smaller, thinner avalanches is real.

Avalanche problems

  • Wind Slabs

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

    You could trigger 1-2 foot thick wind slabs in very steep, exposed terrain. Yesterday's wind formed drifts and slabs in neighboring zones, and some were sensitive to ski triggering. The fresh slabs may lie above previous generations of hard or soft wind slabs on some slopes, creating a bigger issue than you might expect. Also, some of the slabs will overlie the persistent weak layers described in Problem 1 or other thin, subtle weak layers that formed in the past week; this can produce avalanches that are surprisingly wide and easy to trigger. 

    Drifts, dunes, rippled snow surfaces, and chalky snow pillows are visible clues that the wind has been at work. If you see cracks shooting out in front of your skis or boards, you've probably found a wind slab. If you feel the snow stiffen beneath your sled or skis, its time to pay attention.

    This problem is probably more common in the Soldier Mtns where recent winds have been stronger.  

  • Persistent Slabs

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

    Triggering 1-4 foot thick avalanches remains likely. The snowpack needs more time to adjust to the weight of the February storms. Avalanche activity has been focused on the northern 2/3 of the compass (W-NW-N-NE-E-SE) in middle and upper elevation terrain, failing on faceted snow buried about 2-4 feet deep. On SW and S aspects, we've observed less Persistent Slab activity but can't yet rule them out.

    Near Dollarhide Summit on Friday, skiers remotely triggered an avalanche on a shallower crust + facet layer in the upper 1-2 feet of the snowpack (see Forecast Discussion for details on this weak layer).All of these avalanches can release in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. You may or may not experience snowpack collapsing or other obvious signs of instability before triggering an avalanche.

    If your primary goal is to not get caught in an avalanche, staying off of and out from below steep slopes is the most reliable way to reduce your risk.

    Observations indicate these avalanches are more likely in the northern part of this zone.

    (2/16/2024) This large avalanche was remotely triggered by skiers near Dollarhide Summit on Friday, Feb 16th. It failed on an E/SE-aspect near 9,100'. This avalanche likely involved a crust + facet weak layer that was buried on February 1st and is now about 2 feet deep.  

    Photo: Sun Valley Heli Ski

Avalanche Discussion

Persistent Slab issue in the upper 1-2 feet of the snowpack:  Throughout the forecast area, several 1-2 foot thick avalanches (photo 1, photo 2, photo 3) released naturally or were remotely triggered since Friday. These avalanches appeared to involve thin, sun or rain crust + facet layers on slopes commonly exposed to the wind near 9000' (upper or middle elevations). Limited observations indicate that the chances of triggering these slides is lower on SW and S aspects that have thick, hard ice crusts within 2 feet of the surface. 

This problem is tricky:

  • You can remotely trigger avalanches from gentler terrain below, above, or next to steep slopes (see photo to right/below).
  • You may not experience signs of instability before triggering a large avalanche.
  • Snowpack stability tests are generally providing stable scores on this layer. 
  • The snowpack structure, and especially the crust thickness, can change quickly due to elevation, aspect, wind-exposure, and previous rain events. 

Many slopes are safe to ski and ride; the challenge lies in accurately determining whether or not a specific slope is safe. All steep slopes in wind-exposed terrain that also have thin crusts located 1-2 feet below the surface are suspect. You can reduce your risk by avoiding these areas as well as slopes with terrain traps or severe consequences (trees, cliffs, etc) in the event you trigger a big avalanche. 

Loose snow avalanches: If skies are sunnier than weather models predict, we may see some surficial sun-induced loose snow avalanches. Whether we call them dry loose or wet loose avalanches doesn't matter. What does matter?

  • These slides release naturally, on their own. Pay attention to what's above you while you travel and when you take breaks.
  • Most of these avalanches should be relatively small, but some could be large enough to knock you over and carry you where you don't want to go. 
  • The threat of avalanches will follow the sun around the compass: E-SE aspects in the morning, S aspects by noon, and SW-W aspects in the afternoon.
  • Very steep, sunny, rocky terrain that is sheltered from the wind produces higher amounts of this type of natural loose snow avalanche activity.  
  • Watch for wet rollerballs moving downslope. These clues tell you the snow surface is becoming damp, and natural avalanche activity could quickly follow. 

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