Bollettino valanghe

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Sawtooth Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Expect to find sensitive wind drifts in steep, exposed terrain. These will be most common along higher ridgelines, but look for them on mid-slope terrain features such as ribs, gullies, and below cliff bands. If prolonged periods of sunshine occur today, natural and human-triggered loose snow avalanches (sluffs) will become possible on very steep slopes.

Problemi valanghivi

  • Wind Slabs

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

    Gusty, erratic winds easily transported the 8-18" of recent snowfall, forming a variety of wind slabs in exposed terrain. On Wednesday, I triggered small, sensitive wind slabs in exposed middle and upper elevation terrain near Williams Peak in the northern Sawtooths. Tuesday on Copper Mountain, Scott found the wind had drifted the recent snowfall at upper elevations. The fresh slabs were mostly isolated to the northern half of the compass at and near ridgelines. In the Sawtooth's, wind-transported snow also collects on aprons and slopes below large cliff bands.  

    No matter the size of the slide, managing travel in wind-loaded terrain is straightforward; avoid slopes where you see or feel obviously wind-affected snow to reduce the chances of triggering avalanches. Look for signs of wind drifted snow such as pillows and dune-like drifts. A rippled surface texture is another good sign that the wind has been at work. If the snow depth rapidly increases, or you move from soft, powdery snow into thicker, denser snow, you are probably pushing into a wind drift. Cracks shooting out from your skis or board are a clear indication that you've found a sensitive drift. 

    ADDITIONAL DISCUSSIONThe forecast today is calling for unseasonably cool temperatures and increasing cloud cover, decreasing the risk of wet snow avalanches. However, the recent unsettled spring weather has been tough to predict. If the sun pokes out today for a prolonged period of time, both natural and human-triggered wet snow avalanches will become possible on steep slopes that are getting direct sunshine. Keep a close eye on the cloud cover, and evaluate overhead terrain if conditions warm up more than expected.

Avalanche Discussion

When spring weather serves up warm, sunny days and clear, cold nights, we enter a predictable "diurnal" pattern of avalanche danger. Conditions are safe at the start of the day when the snowpack is frozen, and the possibility of triggering a wet slide increases as the day warms up. But the unsettled and snowy spring weather we've been experiencing—while nice for catching up on powder skiing/riding we missed in February—has lead to a less clear-cut pattern of avalanche conditions. Many of us expect a more stable snowpack in the spring, and while you're less likely to trigger a large avalanche now compared to mid-winter, there are more ways that you could trigger something. That something may come in the form of:

  • Triggering a larger persistent slab avalanche remains possible in the SE corner of the forecast area, where recent snowfall fell on a thin snowpack weakened by the February drought.
  • Wind slabs become an issue with each spring storm, and may form unexpectedly with localized spring squalls.
  • The likelihood of wet snow avalanches and sluffs is directly tied to the cloud cover, which is notoriously unpredictable during this unsettled spring weather. Even when the forecast calls for cloudy skies, be ready to adjust your plans if the sun comes out. New snow can slide nearly instantaneously the first time it gets hit with spring sunshine.
  • This last storm laid down a blanket of unusually light, dry snow in our northern mountains. Loose snow sluffs, while generally a "manageable" problem, can catch you by surprise in steeper terrain.

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