Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

You're most likely to trigger a large avalanche on steep slopes facing the northern two-thirds of the compass. Watch for and avoid fresh, stiff wind drifts, and anticipate sluffing in very steep terrain. 

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    This zone has picked up over a foot of snow since the weekend, with more expected today, creating two potential avalanche problems to keep on your radar:

    Loose snow avalanches or sluffs are possible in very steep terrain. Although most will be small, they may be large enough to knock you off your feet. Even small slides can be consequential above terrain traps such as gullies, creeks, and thick timber.

    Wind slabs may have formed immediately beneath exposed upper elevation ridgelines and on the sides of cross-loaded gullies. The slabs could rest above weak crust/facet combinations on southerly aspects or small sugary facets on more north-facing slopes. They can be up to 2 feet thick and break wider than expected. 

    (2/15/2025) This natural wind slab avalanche released on Feb 14th or 15th in the Boulder Mountains. The slide may have been triggered by cornice fall. Photo: Sawtooth Avalanche Center

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    Slabs that formed in early February rest above a variety of ugly, widespread, weak layers (facets, surface hoar, crusts, and combinations). Before triggering an avalanche, you may or may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Persistent Slabs can release in surprising ways and break much wider than expected. You are most likely to trigger a dense, 2-4 foot thick avalanche where:

    • The slab is less than about 2' thick—relatively shallower spots may exist where the wind frequently blows, and the slab is not uniformly thick.
    • Any part of the slope you are on or connected to is steeper than about 35 degrees
    • The slope faces the northern 2/3 of the compass
    • A smaller wind slab or loose snow avalanche overloads the buried weak layers (problem above)

    (2/17/2025) Avalanche on Sun Mountain in a thin snowpack near Ketchum.  Photo: Sawtooth Avalanche Center

Avalanche Discussion

We continue to receive reports of relatively stable conditions in the Banner Summit area, and triggering a large avalanche involving deeply buried weak layers is unlikely. Given the recent snowfall and wind, continue to look for and avoid steep slopes with obvious recent wind loading or signs of instability, like snowpack cracking or collapsing. Be aware of where even small avalanches may take you; terrain traps increase the consequence of being caught or buried.

Regions covered