Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

The avalanche danger will rise throughout the day as a thumping storm impacts the area. Triggering large avalanches is very likely, especially on slopes where the wind has drifted the snow into dense slabs. Large natural avalanches are likely. Be aware of changing conditions and plan to be back early to avoid the most dangerous conditions.

Avalanche problems

  • Persistent Slabs

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

    Accumulated snowfall during the day is expected to tip the balance on a pair of buried weak layers, making triggering 2-4' slabs of snow likely and large natural avalanches possible. Triggering these avalanches is most likely in wind-loaded terrain, but will also be quite possible in sheltered terrain. Persistent Slabs can release in surprising ways. They can be much wider than expected and be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.

    Two known buried persistent weak layers will be tested throughout this storm. Last week's storm snow buried weak facets, surface hoar, and crust-facet combinations on many middle and upper-elevation slopes. More deeply buried weak layers that formed during the extended Jan-Feb drought (facets, crust + facets, surface hoar) have not healed and remain suspect, primarily on NW-N-NE-E aspects above and below the middle-to-upper elevation transition.

    Snowpack cracking and collapsing are clear signs of unstable conditions. Avoiding being on or connected to steep slopes today is the best way to keep out of trouble.

    Additional Discussion: The chance of triggering slabs of new snow in sheltered terrain will increase throughout the day and overnight. Rising snow lines throughout the storm indicate that heavier snow will fall atop fluffier snow, quickly building unstable dense storm slabs. Given the variety of snow surfaces the snow is falling on, they may break wider than expected and act like or trigger larger persistent slab avalanches (described above).

    (2/21/2026) A skier triggered and skied out of this avalanche. This large avalanche failed about 2' deep, presumably on weak facets that were buried on 2/8. 

    NE facing at 8400'. 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2

    Triggering large wind slab avalanches is very likely today. Consistent W and SW winds are transporting snow and actively building fresh slabs in exposed terrain. These are most commonly found near or below ridgelines, along mid-slope ribs, and on aprons beneath chutes. Cracks shooting out in front of your sled or boards mean you've found a sensitive slab. Look for wind-affected surfaces, dunes, or drifts.  Feel for stiff slabs overlying weaker or softer snow.

    You can manage your exposure to this problem by identifying and avoiding wind-loaded slopes. Smaller wind slabs can also act as effective triggers for larger persistent slab avalanches described above.

    (2/22/2026)

    Winds transporting snow in the Northern Sawtooth on Feb 22, 2026.

Avalanche Discussion

The storm over the next 48 hours is forecast to be the largest load that snowpack the Banner area mountains have seen since the February 8-10 storm. Determining when the accumulated weight of new snow will tip the balance and dramatically increase avalanche danger is challenging, especially with the expected moderate wind continuing to add to the load and fluctuating rain lines complicating the picture at lower and mid-elevations. How do we deal with this uncertainty? Choosing conservative terrain, keeping our heads on a swivel for changing conditions, and planning to wrap our days up before the evening, when the avalanche danger is expected to peak.

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