Bollettino valanghe

Bitterroot

West Central Montana Avalanche Center
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Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wet loose avalanches will become likely today due to rapid warming. Larger, destructive avalanches resulting from cornice fall and lingering buried weak layers are possible. As slopes become wet and mushy, move to lower angle terrain, and be aware of the terrain above you. Consider digging down to look for poor snowpack structure before committing to avalanche terrain. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Human triggered wet loose avalanches will become likely today. The combination of strong morning sunshine, light winds, and temperatures reaching into the 40s at upper elevations today will rapidly warm the snowpack. Temperatures were slightly warmer last night than previous nights, with temperature inversions causing the highest temperatures at higher elevations. Surface crusts will still likely be present in most areas this morning, but some areas may not have refrozen at all last night. Areas that didn’t refreeze have a higher potential for larger, gouging wet loose avalanches and potentially wet slab avalanches. 

    There is a chance for some greenhousing this afternoon as cloud cover increases. This could heat up the snow on shaded northerly slopes and make for wet avalanche concerns on all aspects. 

    Rollerballs and point releases are signs of wet snow instability. If you find yourself in mushy, wet snow or see natural, wet loose avalanches, it is time to step back out of avalanche terrain and be aware of what terrain is above you. You can also try moving to cooler, shaded slopes to find drier snow, but this may not work if greenhousing occurs in the afternoon. Remember that even small avalanches can have serious consequences. Also, smaller wet loose avalanches could step down and trigger larger wet slab or persistent slab avalanches in areas with poor snowpack structure.

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    There are many large overhanging cornices along upper elevation ridgelines. Cornice failures can be hard to predict, but today’s sunshine, warm temperatures, and poor refreeze are a good recipe to destabilize them. Give cornices a wide berth and avoid hanging out underneath them. Cornice failures could also trigger large slab avalanches on the slopes below. 

    (2/28/2025) Avalanche triggered by cornice fall, SE aspect of Lappi point, ~7400’, 35-45 degrees

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    It remains possible to trigger a large persistent slab avalanche that fails on weak layers buried 3-5 feet deep. Although the problem has been trending towards better stability, pockets of reactive slab remain, and warm temperatures could make it more sensitive. Water percolating through the snowpack could reactivate buried weak layers. 

    Observations have shown intermittent propagation in tests, but don’t let that fool you into thinking there is no danger. There may be no red flags before a large avalanche occurs. You are more likely to trigger one of these persistent slabs in areas where the snowpack is thinner, like around rock bands or convex rollovers. 

    To identify the problem, you can dig down in the snow and look for poor snowpack structure with a slab above weak snow. Even if snowpit tests are unreactive, poor snowpack structure should be enough to give you pause before committing to avalanche terrain. Stick to slopes under 30 degrees in slope angle and without steep terrain overhead if you simply want to avoid the problem.

Avalanche Discussion

It will be another beautiful spring-like day, with warm temperatures, light winds, sunny skies in the morning, and increasing clouds in the afternoon. Don’t let the nice weather cloud your judgement. Conditions are complicated and require careful decision making. With temperature inversions last night, some areas did not drop below freezing and will have a poor refreeze this morning. You could gain elevation and find wetter conditions due to the temperature inversions. 

Depending on aspect, elevation, and time of day, snow conditions are currently quite variable, leading to a variety of potential avalanche problems to manage. Wet loose avalanches are the smallest, but also the most likely. They could also begin gouging down today due to the poor overnight refreeze. Cornice fall and persistent slabs are harder to predict but could result in large and destructive avalanches. 

Recent observations have found glide cracks opening up on a variety of slopes. The warm weather will make these glide cracks more likely to fail. Avoid traveling below slopes with glide cracks, as they can unpredictably release the entire season’s snowpack. 

Join us this week at one of our events! Sip for a cause at our Pint Night Fundraiser on Wednesday evening from 5-8 pm at Imagine Nation Brewing Company in Missoula. We are also hosting a Mountain Weather Workshop on Thursday evening for our members. Not a member yet? No worries—sign up today by visiting our membership page to gain access. In addition to supporting the avalanche center, you'll receive perks like discounts, newsletters, and additional online resources. 

Please continue to submit observations and help us keep an eye on changing conditions. Check out this video on what makes a useful observation. 

Avalanche forecasts will be issued on Saturdays and Sundays. A general information product will be issued on Mondays to cover the Monday-Friday period. Additional forecasts will be issued anytime an Avalanche Warning is issued.

Ski and ride safe.

Regioni coperte