Bollettino valanghe

Bitterroot

West Central Montana Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Open full map
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 small avalanches in the fresh snow today. Dry loose avalanches will require management on steep slopes, and small wind slabs could develop just below upper elevation ridgelines. Although these avalanches are small, they could still knock you off your feet and carry you into or over hazards. 

Problemi valanghivi

  • Loose Dry

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

    A couple of inches of snow fell yesterday and overnight, and another 4 to 6 inches are forecast to fall today. Small avalanches in the fresh snow will grow throughout the day. Skiers and riders could trigger small dry loose avalanches on steep slopes. Manage dry loose avalanches by getting out of their way and letting them run. These avalanches could push riders into or over terrain traps, especially where they funnel in chutes. 

    Today’s snowfall is arriving with light winds that will struggle to transport much snow. Consequently, fresh wind slabs will be soft, small, and isolated to just below ridgelines where the winds are strongest. There are also lingering pockets of old wind slab from last weekend’s storm. Stay alert for shooting cracks and avoid steep slopes with pillows of wind drifted snow. 

    Warmer temperatures this afternoon could consolidate the new snow into storm slabs in areas with over 8 inches of new snow. Pay attention to the new snow density today and watch for signs of instability, such as shooting cracks. If slabs are consolidating, stick to slopes under 35º and avoid convex rolls.

Avalanche Discussion

A weak storm is impacting the region today, bringing light snowfall and light winds. The storm is favoring the Bitterroot, where small avalanche problems will develop in the fresh snow today. In the Rattlesnake and Seeley Lake zones, the new snow is unlikely to accumulate enough to increase the avalanche danger. If the winds pick up or we get higher than forecasted snowfall amounts, the avalanche danger could increase to moderate at upper elevations in these zones. 

Stability continued to improve during the mild weather on Monday and Tuesday. Yesterday observers found generally stable conditions except for isolated lingering wind slabs along upper elevation ridgelines. These small pockets of hard wind slab produced cracking and collapsing, and one observer triggered a small wind slab in the Gash area. All aspects except northerlies had breakable sun crusts at the snow surface yesterday. 

Earlier this week, we received reports of a very large avalanche in the Northern Beaverhead Mountains, south of our forecast area. The avalanche was on a north aspect at around 9500 ft. It failed at the ground and created a totally new avalanche path destroying tens of acres of mature timber. It likely failed naturally on Sunday due to new snow and wind loading. 

The snowpack in the Northern Beaverhead Mountains is generally thinner, with a poorer structure and more weak layers than in our forecast area. However, the snowpack in the Southern Bitterroot near Lost Trail Pass shares some of these characteristics. If you are heading out in the Southern Bitterroot or areas further south into Idaho, stay alert for the potential for deeper and more dangerous instabilities. Digging snowpits can help identify problematic buried weak layers. A large cornice fall or sled dropping off a cliff might impact deeper layers. 

Lately, we have been lucky to generally only have to deal with new snow avalanche problems and be able to operate in a spring-like mindset. However, many other areas in the mountain west are still dealing with buried persistent weak layers and have dangerous avalanche conditions. If you travel outside of our region, be prepared to switch gears into a much more mid-winter-like mindset. 

Snow showers will continue tonight into tomorrow, and west winds will increase. Additionally, a stronger storm is forecast to impact the region this weekend. Stay alert for changing conditions and increased avalanche danger over the next few days. 

Please let us know what you find out there today by submitting an observation. 

Ski and ride safe.

Regioni coperte