Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Expect to find wind drifts in upper elevation and alpine terrain—some of these may remain sensitive to your weight. These will be most common along higher ridgelines, but look for them lower in cirques and below large cliff faces. If prolonged periods of sunshine occur today, natural and human-triggered loose snow avalanches (sluffs) will become possible on very steep slopes.

Avalanche problems

  • Wind Slabs

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

    The 12-16 inches of new snow that fell earlier in the week was blown into drifts and slabs in upper elevation and alpine terrain. Observations over the past few days indicate that these wind slabs are relatively small in size, but may still be reactive to your weight. On Wednesday, I was able to easily trigger thin wind slabs in the northern Sawtooths (video above/right). By stomping along a ridgeline, a skier in the southern Sawtooths yesterday triggered a small wind slab that broke 8-10 inches thick and around 30 feet wide. In the neighboring Galena Summit & Eastern Mtns zone, another group triggered a small wind slab on Thursday.

    These wind drifts will be larger and more widespread in the northern Sawtooths, where more snow fell in the recent storm. Look for drifted and pillowed areas below ridgelines, below cliff bands, and on mid-slope features such as ribs, gullies, and breakovers. Surface texture and denser/stiffer snow are tell-tale signs of a loaded slope. While it's unlikely these wind slabs would be large enough to bury you, they could still be dangerous in consequential terrain.

    ADDITIONAL DISCUSSIONThe forecast today is calling for continued cool temperatures and cloudy skies, decreasing the risk of wet snow avalanches. However, this unsettled spring weather can be tough to predict. If the sun pokes out today for a prolonged period of time, both natural and human-triggered wet snow avalanches will become possible on steep slopes that are getting direct sunshine. Keep a close eye on the cloud cover, and evaluate overhead terrain if conditions warm up more than expected.

Avalanche Discussion

When spring weather serves up warm, sunny days and clear, cold nights, we enter a predictable "diurnal" pattern of avalanche danger. Conditions are safe at the start of the day when the snowpack is frozen, and the possibility of triggering a wet slide increases as the day warms up. But the unsettled and snowy spring weather we've been experiencing—while nice for catching up on powder skiing/riding we missed in February—has lead to a less clear-cut pattern of avalanche conditions. Many of us expect a more stable snowpack in the spring, and while you're less likely to trigger a large avalanche now compared to mid-winter, there are more ways that you could trigger something. That something may come in the form of:

  • Triggering a larger persistent slab avalanche remains possible in the SE corner of the forecast area, where recent snowfall fell on a thin snowpack weakened by the February drought.
  • Wind slabs become an issue with each spring storm, and may form unexpectedly with localized spring squalls.
  • The likelihood of wet snow avalanches and sluffs is directly tied to the cloud cover, which is notoriously unpredictable during this unsettled spring weather. Even when the forecast calls for cloudy skies, be ready to adjust your plans if the sun comes out. New snow can slide nearly instantaneously the first time it gets hit with spring sunshine.
  • This last storm laid down a blanket of unusually light, dry snow in our northern mountains. Loose snow sluffs, while generally a "manageable" problem, can catch you by surprise in steeper terrain.

Take-home point? You might have to check your expectations of what spring should be like at the door. Conditions are not as predictable and easily-managed as they might normally be. Keep an eye out for the problems described above, and enjoy some late-season powder!

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