Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a persistent slab avalanche on the old November drought layer has become increasingly difficult. Although not impossible, it would take a lot of weight (one or more snowmobilers) to find a shallow spot in the snow to trigger an avalanche. The recent cold, clear weather is weakening the upper part of the snowpack. Instability is increasing on buried weak layers in the upper 1-2 feet of snow. Dry loose snow sliding (sluffing) is possible on steep terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    The persistent weak layer we've been talking about from the mid-November drought is becoming very unlikely to trigger an avalanche. Very unlikely does not mean impossible, The weight of a person (i.e. skier or snowboarder) will have a much more difficult time initiating a collapse of this weak layer. However, heavier objects (i.e. snowmobilers) would be more likely to initiate a collapse on this weak layer, especially in areas where the dense slab (late November snowfall) is the thinnest. Areas in the terrain where you would find a shallower snowpack would be southern aspects on the compass or around rocks and cliffs where thinner snow exists.

    The lower snowpack (underneath the dense slab from late November) is strengthening. The upper snowpack (between the dense slab and the surface) is weakening. The cold, clear days and nights are weakening layers in the upper snowpack and we're beginning to find more instabilities in the upper two feet of the snowpack. The potential size of an avalanche in the upper snowpack is less, but the likelihood (although still low) is higher than triggering an avalanche on the November drought layer. 

    (12/16/2022)

    Snowslide Pit

    Photo: Studley

Avalanche Discussion

Today's avalanche forecast is sponsored by Mile High Powersports of McCall. Thank you for supporting the Payette Avalanche Center.

Brrr! For anyone who has been out in the mountains, you know it's been COLD! This week has brought cold, clear weather to our forecast area. We continue to see signs of strengthening in the lower portion of the snowpack. However, given our recent weather, we are seeing the opposite trend with the upper part of the snowpack. The upper one to two feet of our snowpack is weakening in places where faceting is taking place.

With this weakening of the upper snowpack you can expect to encounter changes through the weekend:

  • Sluffing, or dry loose surface snow moving easily in steeper terrain (particularly shaded, north aspects)
  • Weakening of layers around 1.5-2 feet deep (watch for signs of instability on these buried weak layers)
  • Isolated pockets of wind slabs. Winds are forecasted to increase today out of the southwest. With very light snow on the surface, winds as low as 10 m.p.h. can drift snow into shallow wind slabs in certain locations facing north through east on the compass.

 

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