Bollettino valanghe

Bitterroot

West Central Montana Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Fresh wind slabs will build today as a storm impacts the region. The avalanche danger will increase through the day and likely rise to Considerable at upper elevations by the late afternoon. Human triggered avalanches will become likely on wind-loaded slopes. Stay alert for signs of instability like recent avalanches and shooting cracks, and steer clear of steep, wind loaded terrain. 

Problemi valanghivi

  • Wind Slabs

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

    Fresh wind slabs will build today as a storm impacts the region. Human-triggered avalanches will become likely on wind-loaded slopes. Strong west winds are already blowing, and we can expect 5 to 8 inches of new snow by this evening. The Central and Northern Bitterroot are favored for higher snow totals than the Southern Bitterroot. The hazard will increase through the day and will likely rise to Considerable at upper elevations by late this afternoon. The avalanche danger may not reach Considerable in the Southern Bitterroot. 

    At upper elevations in the Central Bitterroot, you could also still trigger an older wind slab, or a fresh wind slab could step down, resulting in a larger, more dangerous avalanche. 

    Wind slabs appear smooth and rounded and are often found just below ridges and in cross-loaded gullies. Cornices, wind lips, and drifts all indicate wind direction and loading. Signs of instability like shooting cracks warn you to stay off steep slopes. The best way to mitigate this problem is to avoid wind-loaded slopes over 33º. 

  • Persistent Slabs

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

    A crust facet combo buried 1-2 ft deep has been found on most aspects at upper elevations in the Bitterroot. However, it is only reactive in isolated locations. It has produced propagating snowpit test results, but signs of instability have been limited. It appears to be most sensitive in shallower areas at upper elevations, such as around wind-swept ridges. It is worth investigating the snowpack by digging a snowpit before you commit to steep terrain. Be prepared to change objectives if you find unstable results or signs of instability like whumpfing or cracking. 

Avalanche Discussion

We have two significant storms lined up for the next several days. The first storm began impacting the region last night and will continue into tomorrow. West winds picked up ahead of the storm yesterday afternoon, gusting 40 to 50 mph at the Point 6 weather station. The west winds will remain elevated into this afternoon and then decrease. Snowfall totals are forecast to increase as you go north, with the heaviest snowfall around Seeley Lake and lighter snowfall in the Southern Bitterroot. Snow totals will range from 4 to 15 inches by this evening, favoring the Seeley Lake zone. Light to moderate snowfall will continue tonight into tomorrow, and storm totals will likely reach 15 to 20 inches in favored areas. 

Fresh wind slabs will build today, and the avalanche danger will increase throughout the day and into tonight. If we get the upper end of forecasted snow amounts, storm slabs may develop in wind-sheltered areas as well. The avalanche danger will start off today at Moderate and likely rise to Considerable by the afternoon in many areas. 

A stronger storm will arrive Sunday night, bringing widespread heavy snowfall and strong winds. The current forecast is calling for some impressive precipitation totals with potentially over 3 inches of snow water equivalent in favored areas by Wednesday. Fresh avalanche problems will grow rapidly and become touchy and dangerous. Stay alert for changing conditions. 

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

Ski and ride safe.

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