Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Very dangerous avalanche conditions will develop this afternoon as a powerful storm brings heavy snowfall and strong wind. Naturally occurring 1-2 foot thick avalanches may break widely on buried weak layers. Slides can be triggered from long distances away from the slope that releases. Triggering 3+ foot thick avalanches on deeply buried weak layers is a real possibility. 

AVALANCHE WARNINGS may be issued this evening as the intense storm continues overnight.

Avalanche problems

  • Wind Slabs

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

    Today's 5-12" of snow and strong S and SW wind will build fresh, sensitive wind slabs in exposed terrain. Given the intensity of the wind, anticipate these slabs on any open slope, including the mouths of main drainages and roadways that typically funnel wind.

    While dangerous on their own, these fresh slabs are likely to release on the persistent weak layers described below. Cornices will grow rapidly, calving off to release slabs on the slopes below. Drifts, dunes, rippled snow surfaces, and chalky snow pillows are clues that the wind has been at work. If you're experiencing whiteout conditions, you're traveling through the most dangerous overlap of today's avalanche problems. 

    (2/27/2024) This slab avalanche was triggered Tuesday from 50 ft away on a low-angle ridgeline. It broke widely in wind-drifted snow on a thin layer of facets above a crust. Cracks extended another 100' cross-slope beyond the crown. Smiley Ck, ENE @ 9,100'. Photo: Sawtooth Avalanche Center

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Expect to find dangerous slabs in areas affected by the wind. You could also encounter thin, sensitive slabs in areas sheltered from the wind as storm snow accumulates throughout the day. These slides will break widely on a weak snow interface, including slick facets, crusts + facets, and surface hoar, shallowly buried by Monday's storm.  

    Triggering a very large, destructive 3+ foot thick avalanche on weak layers near the middle and base of the snowpack is a real possibility. The odds that these deeper weak layers wake up will only increase as the storm intensifies this evening and tomorrow. Observations indicate these avalanches are most likely as you move away from Galena Summit to the shallower southern, eastern, and northern portions of this zone. 

    Anticipate touchy conditions that will only worsen late in the day and as you climb into windier terrain. Persistent Slab avalanches can release in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. Snowpack cracking and collapsing are obvious clues that the slab + weak layer combination you've encountered is unstable. 

    (2/26/2024) This slab avalanche released in the Banner Summit Zone during an intense period of precipitation on Monday. Today's storm will build similar slabs, creating dangerous conditions on steep slopes.  Photo: VandenBos

Avalanche Discussion

A powerful storm is directing a fire hose of atmospheric river moisture at our region. Expect wind speed and snowfall intensity to increase throughout the day, causing whiteout conditions. The chance of natural and human-triggered avalanches will increase rapidly this afternoon and overnight, creating very dangerous avalanche conditions in many areas. AVALANCHE WARNINGS may be issued this afternoon. 

Regions covered