Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

In the western half of this zone, the size and chance of triggering avalanches will increase as today's warm, windy storm progresses. Tricky, dangerous conditions may develop—several types of natural and human-triggered avalanches will be possible. The danger could rise to CONSIDERABLE by this evening and may spike overnight. Plan your day to be out of the mountains before dark. 

In the drier eastern half of this zone, you still may be able to trigger large avalanches involving all the snow that fell in February. Focus on Avalanche Problem #2.

Avalanche problems

  • Wind Slabs

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

    In the western part of this zone where more snow is expected to fall today (Baker Ck, Galena Summit area, White Clouds), different types of natural and human-triggered avalanches could become likely. Wind slabs will grow steadily in exposed terrain through Monday morning. On some slopes, crusts and / or weak snow exist beneath the new snow; avalanches could be easy to trigger and may break wider than you expect. A couple types of slab avalanches to watch for: 

    • Wind Slabs: At upper elevations,expect to find wind slabs up to 2 feet thick. You may find some wind slabs at middle elevations. Watch for fresh drifts and slabs below ridgelines, on the sides of cross-loaded gullies, and on aprons at the bottom of steep alpine cirques and large cliff faces.
    • Storm Slabs: The dense, damp storm snow could form slabs on some slopes that are completely sheltered from the wind. These avalanches could be big enough to catch, carry, and injure people. 

    All of the slab avalanches involving the new snowfall are most likely to release where it's "steepest and deepest": on slopes steeper than about 35 degrees, where at least 6" of snow has accumulated. Cracks shooting out from your sled or boards are a clear sign you've found a slab and should stick to gentle terrain to avoid trouble. Natural loose snow sluffs or cornice fall could also trigger slab avalanches; minimize the time you spend in the runouts of large avalanche paths. 

    Avalanche conditions and stability will deteriorate this afternoon and tonight. Don't assume the avalanche path you played in this morning is still safe near dark. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    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're unlikely to 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 snowpack is less than about 4 feet 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

    Persistent Slab avalanches are most likely in the thinner snowpacks of the Pioneer and Boulder Mtns in the eastern part of this zone. 

    (2/18/2025) A skier on Patterson Pk near Hailey triggered this large avalanche. After several turns on the slope, the slide broke above and around them. Thankfully, the skier was able to ski ahead and to the side of the slab. NW @ 8,050'. Photo: Sawtooth Avalanche Center

Avalanche Discussion

Wet Loose avalanches:  If the rain-snow line rises above 7000' today, we could see some natural wet avalanche activity where significant rain falls. In addition, today's warm, steamy weather will make wet avalanches possible in lower and middle elevation terrain that does not receive rain. The wet  loose slides are most likely on slopes steeper than about 35 degrees. Most slides will be relatively small, but some avalanches could gouge down into a damp snowpack, flank out as slabs, and become large enough to break trees. 

During rain-on-dry-snow events, snow stability is unpredictable and can change rapidly. After hours of steady rainfall and no avalanches, a widespread avalanche cycle can occur as if a switch has been flipped. The safe move is to avoid playing on or under large or consequential avalanche paths where steady rain falls. 

Roof avalanches: The warm temperatures and rain will make large roof avalanches likely this afternoon through Monday. Roof avalanches have killed people in Idaho and neighboring states, and several close calls have occurred locally in recent years. Click here for information and photos.   

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