Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Watch for and avoid steep slopes with stiff, wind-drifted snow. You're most likely to find wind slabs in alpine and upper elevation terrain. Triggering a large avalanche on weak snow deep in the snowpack remains a possibility on very steep, rocky, wind-affected slopes above about 9000' in elevation. Wind-protected slopes with soft snow on the surface are unlikely to produce avalanches.  

 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Avalanche professionals, including the SAC forecasters, remain leery of entering big avalanche paths in this zone that have most or all of the following characteristics:

    • "Prime-time" 35-45 degree slope angles
    • Shady (roughly the northern half of the compass)
    • Wind-affected alpine and near treeline terrain above about 9000' in elevation
    • Slopes with rocks poking through the snow and variable snow depths due to uneven terrain

    This zone is the "not so sweet spot" for the persistent slab problem. The faceted snow near the ground is especially weak, and the 2.5-4 foot thick slab is thick enough to produce large avalanches but thin enough that our weight could impact the weak layer in the right (or wrong?) spot on some slopes. 

    It's been two weeks without an avalanche or substantial snowfall. Can you ski or ride most slopes without triggering a large persistent slab avalanche? Yes. Would we be surprised if someone triggered a slide? Yes. Would we be totally shocked? Not in terrain that checks all the boxes listed above (see photo). 

Avalanche Discussion

FRESH WIND SLABS

This zone received less snow (3-5") late last week than the mountains to the north and west (5-10"), but you could find some isolated wind slabs in alpine terrain. This recap of the activity in the Sawtooths and Banner Summit area applies to the high peaks in the White Cloud Mtns and the northern Smoky and Boulder Mtns.

Saturday, Ben intentionally triggered a 6-18" thick wind slab that broke about 100' wide on a SE-facing, alpine slope in the northern Sawtooths. Also on Saturday, a group triggered two wind slabs south of Copper Mountain on steep, upper elevation, northerly aspects. The slides were 6-18" thick and broke 40-100' wide. They released near exposed ridgelines, and both slides broke wider than your "run of the mill" wind slab due to a weak layer of facets buried directly beneath the fresh wind-transported snow. 

Why does the current crop of wind slabs still deserve respect:

  • The fresh slabs are perched above variable snow surfaces, including potential weak layers (facets, crusts, surface hoar) that formed during our extended January dry spell on some aspects and elevations. Slides could break above you and be wider than anticipated, and the weak layers are slowing the stabilization process. 
  • Today's expected moderate to strong winds may continue sifting snow onto existing drifts and slabs, including "spin drifting" snow onto aprons low in alpine cirques.

While these wind slab avalanches probably won't bury you, they're too big to tangle with. They could easily take you for a ride, pile you into trees, or wash you into a terrain trap. The possibility of wind slabs breaking above you or wider than expected makes them difficult to manage.

How should we travel today?  The simple elegant solution is to steer clear of this tricky problem. Watch for drifting and changes in the surface snow texture. The variable NW-N-NE winds may have formed slabs in unusual locations, including on aprons at the bottom of large cliff bands or steep faces. If the snow surface gets stiff and supportable or you see cracks shooting out from your boards or skis, stick to gentle terrain.

Regions covered