Bollettino valanghe

Bitterroot

West Central Montana Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Skiers and riders could trigger a slab avalanche 1-3 feet deep at upper elevations. If you find a crust and facets directly under the new snow or experience collapsing, step back to terrain under 30 degrees.

Dry loose avalanches are likely in steep terrain. Use good sluff management, as even a small avalanche can carry you through rocks or injure you.  

Problemi valanghivi

  • Persistent Slabs

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

    A buried crust with facets above it has created a persistent weak layer below the new snow. Since the crust formed, 1-3 feet of new snow has fallen, forming a slab above the weak layer. 

    This issue can be found on aspects that received sun and formed a crust prior to the storm starting Friday. This time of year, with the higher sun angle, sun crusts can be found even on north aspects or slopes that were hidden from the sun just a month ago. 

    Dig into the snow and be suspicious of any crust buried at the base of the storm snow. Multiple human triggered avalanches have failed on this layer in the past week. 

    If you experience collapsing or whumfing, stick to terrain under 30 degrees. 

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Skiers and riders in steep terrain are likely to trigger dry loose avalanches today. The new snow fell with minimal wind for the past 48 hours, and even at upper elevations, start zones are full of non wind affected snow.  A dry loose avalanche that starts small today could entrain more snow and become larger.

    If you step out into steep or complex terrain today, use good sluff management and only expose one skier or rider at a time. 

  • Wind Slabs

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

    Overnight, wind speeds pushed briefly into the moderate category out of the north. With the amount of low density snow available for transport, this was enough to build pockets of wind slab on south aspects. 

    Winds Saturday were pushing strong out of the northwest but ever since have calmed to light. 

    There may be pockets of lingering wind slabs remaining that formed Saturday at upper elevations. The sensitivity of these older slabs is decreasing, and the likelihood of triggering one is going down. 

    It will be difficult to identify wind slabs as they are buried under new non wind affected snow. You may not see the usual smooth wind features or pillows, and cracking could be difficult to see until you are well onto the slab. Be suspicious of ridgeline terrain, and when in doubt, step back to a lower slope angle. 

     

Avalanche Discussion

It may be April, but today's avalanche problems read more like a mid winter forecast than a spring forecast. Since Friday, nearly 3 feet of new snow has fallen in the southern part of the forecast zone. Snow totals further north aren’t far behind, with 2 feet falling in the Rattlesnake. In Seeley Lake, SNOTEL totals are closer to 1 foot for the storm, but areas within the Seeley forecast zone likely received more. 

We do not often have a new persistent weak layer to deal with in April. This time of year is usually low hazard and prime time to step out into large and remote terrain. While it is tempting to still move toward that spring zone you have been thinking about all winter, current avalanche conditions are complex and it is still a winter snowpack. The good news is that with warmer temperatures to come, these problems will not last long. 

As ski resorts begin to close for the season, respect any closures that remain in place. Recognize that they are no longer doing avalanche mitigation within their boundaries and you are essentially traveling in the backcountry even inside their area. 

There is excellent powder skiing and riding to be found in all zones. Let us know what you are seeing today by submitting an observation. 

Ski and ride safe. 

Regioni coperte