Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
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Avalanche danger

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

Human triggered avalanches are likely today. Expect sensitive wind slabs in wind affected terrain and storm slabs in sheltered terrain.

It will be possible to trigger avalanches remotely from below or to the side. 

If you see fresh wind slabs, snow being actively transported by the wind, shooting cracks, or fresh avalanches,  avoid avalanches by sticking to slopes less than 30 degrees in slope angle.

Avalanche problems

  • Storm Slabs

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

    Storm slab avalanches will be possible in areas unaffected by wind. New snow totals vary today, even within the same zone as precipitation bands moved through last night. If you find 6 inches or more of new snow, expect the possibility of storm slabs. 

    Storm slab problems are short lived with peak sensitivity lasting hours. Even after the peak sensitivity period has passed, it will still be possible to trigger a stubborn storm slab for a day or two, especially if new snowfall continues. 

    Even small storm slabs can be dangerous if they push you into terrain traps like streambeds and gullies or carry you through trees and rocks. 

    Look for shooting cracks or small avalanches on test slopes. If you see these, enjoy low angle powder skiing by sticking to slopes less than 30 degrees in slope angle and be cautious of convex rollovers or terrain traps.

  • Wind Slabs

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

    Increasing west winds and new snow have built fresh wind slabs for the past 24 hours. Today, these slabs are expected to grow in size and sensitivity as another 6-8 inches of new snow falls. 

    Yesterday, Forecasters found reactive but small wind slabs in the Rattlesnake. Although small, these slabs were stout enough to take skiers off their feet. By today, these slabs will be large enough to bury you. 

    Identify wind slabs by looking for areas of smooth or pillow-like snow. If you poke or dig into the snow and find a slab at the surface with a hollow feeling or see cracking around your skis or sled, you've likely found a wind slab. 

    Avoid wind slab avalanches by sticking to slopes under 30 degrees in slope angle or terrain unaffected by blowing snow and wind.

    (3/21/2025)

    A small wind slab avalanche on a wind loaded, upper elevation east aspect

    Photo: Arden Feldman

Avalanche Discussion

We’re in the middle of another winter storm this weekend. Expect a busy day for avalanches in wind affected terrain.

 So far, the new snow numbers have been lower than forecast. However, there are multiple reasons for this. The storm moved through last night with precipitation bands instead of one large storm front. Combined with sparse SNOTEL locations, it is possible that areas hit harder by the precipitation bands met or exceeded the forecasted snow totals. Alternatively, with spring storms, snow totals can shift with warmer temperatures with the same SWE (snow water equivalent) as the forecast, falling as less snow but a higher density.

Look for growing cornices today along ridgelines, and do not travel below them. Dense spring snow with wind can build large overhanging cornices rapidly. If one of these cornices failed, it would also likely trigger an avalanche. 

We have dropped the persistent slab problem from the forecast. Pockets of rounding January facets might remain in very specific terrain,  however, no avalanches have been reported in a month and the problem has become unreactive. Recognize that where you are traveling may be an outlier with a more complex snowpack than the rest of the zone. It is always worth digging in the snow, even if you don’t suspect anything. If you encounter weak or sugary snow with a slab above, the best advice is to avoid avalanche terrain. 

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Ski and ride safe.

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