Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 6 years ago.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

Highlights

The intense warm-up during the past few days has resulted in a number of large wet avalanches—both slabs and sluffs. Cooler temps today will make wet avalanches less likely, but continue to monitor snow surfaces and avoid being on or beneath steep slopes with wet, mushy snow. Weak layers in the top 3 feet of the snowpack are stabilizing—triggering a dry slab avalanche on upper elevation, northerly-facing slopes is becoming less likely but not impossible.

Avalanche problems

  • Loose Wet

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

    Over the past several days, very warm daytime temperatures, intense sunshine, and weak overnight freezes have pumped a lot of water down into the snowpack on all but the highest and most north-facing slopes. These conditions have produced numerous wet snow sluffs, some of which are gouging down deeply into weak snow near the ground (photo above/right).

    This dramatic warm-up is winding down, and temperatures today will be cooler than days past. However, with a poor re-freeze at lower elevations, and sunshine in the forecast, wet loose snow avalanches will remain possible today. The best way to manage the problem is by monitoring the snow surface conditions—avoid steep slopes with wet, soggy snow or where you're beginning to punch through previously supportable crusts. Given the significant spring transition we're experiencing, it pays to be on the conservative side—don't overstay your welcome if the snow starts to become wet.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    The recent heatwave has been producing meltwater at the surface. As this trickles deeper into the snowpack, it can destabilize weak layers (facets and/or crusts) and produce wet slab avalanches. We've observed a number of natural wet slab avalanches, primarily in the Boulder and Pioneer Mountains (photo above/right) where a weaker snowpack exists, but also in the Smoky Mountains.

    Although temps will be cooler today, there's a lot of water lingering in the snowpack and this will take time to drain through the snowpack. So while wet slabs will be less likely today, they're not completely off the table. Wet slabs can be unpredictable and produce avalanches that you want no part of. Manage this problem the same as the wet loose problem described above—by avoiding slopes once they thaw and become wet, or slopes where you're beginning to punch through previously supportable crusts. 

Avalanche Discussion

As the Sawtooth Avalanche Center winds down our daily Avalanche Forecasts (the last one is tomorrow), we've all had to buckle our seatbelts and hold on for a wild ride. It's been an exciting past two weeks:

  • COVID-19. The pandemic hit Blaine County and the Wood River Valley hard, leading to a stay-at-home order and the early closure of the Sun Valley Ski Area. There has been a significant increase in backcountry traffic, especially on Galena Summit. This prompted us to write a blog post about backcountry recreation during COVID-19.
  • Human-Triggered Avalanches. From March 28th to April 4th, there were six human-triggered avalanches failing on persistent weak layers that formed in March. All of these were large enough to bury or injure a person. This was the highest concentration of triggered avalanches we've had all season.
  • An M6.5 Earthquake. On March 31st at 5:52PM, a large earthquake struck in our Banner Summit zone during a period of HIGH danger. Incredibly widespread avalanching occurred as a result, primarily in the northern half of the forecast area but extending as far south as Ketchum.
  • An Intense Heatwave. Beginning earlier this week, we quickly transitioned from a cold, snowy pattern to the warmest temperatures of the year. Temps in the mountains soared into the 40s and 50s F, and valley bottoms hit the mid-60s F. Not unsurprisingly, this warm-up led to widespread wet snow avalanching, including some wet slabs.

So what does the future hold? Most of the forecast area is in a spring snowpack pattern where the avalanche hazard is driven primarily by daytime thawing due to warm temperatures and solar radiation. Persistent weak layers, while showing signs of improvement, remain a concern on the highest and shadiest slopes. Late-spring storms and squalls could lead to storm slab instabilities, especially when accompanied by wind.

Regions covered