Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

Large avalanches are unlikely, but you could trigger isolated pockets of windblown snow at upper elevations. Generally safe avalanche conditions exist in wind-sheltered terrain or where the snowpack surface is frozen hard.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    There's still a chance of triggering a small, isolated wind slab in upper elevation terrain. We've only received bits and spurts of snowfall over the past 2 months, but there's been plenty of wind. Each wind event creates fresh pockets of drifted snow—some of which are sitting on weak layers formed during the mid-winter drought. A handful of natural wind slab avalanches occurred after the wet and windy storm earlier in the week, including one larger slide in the Smoky Mountains (report).

    On Wednesday, I was with a professional avalanche course sledding in Pole Creek. Once we broke out into open, upper elevation terrain, the effect of recent and past wind events was readily apparent. Slope cuts on a small, safe test slope produced shooting cracks up to 10' long (photo above/right). We found multiple layers of wind-blown snow atop weak, sugary facets.

    This is not a widespread problem, nor is it likely to produce large avalanches, but think about the consequences of taking a ride in a small avalanche before committing to a slope. If you find yourself in the wind slab's natural habitat—upper elevation, wind-exposed terrain—be on the lookout for evidence of windblown such as stiffer snow, drifted pillows, and dunes. Cracks shooting out from your board and sled are bullseye evidence of having found a sensitive wind slab. 

    (3/2/2022) On Wednesday in Pole Cr, slope cuts on a small test slope (9400', N) produced cracks up 10' long. The 10-12" thick slab consisted of multiple layers of wind-transported snow atop  weak facets.

Avalanche Discussion

We all know that to have avalanches, you need both a slab and a weak layer. Weak layers usually form in the dry spells between storms; snowfall and wind during stormy periods build the slab. Our 2-month mid-winter drought has produced persistent weak layers near the surface of the snowpack—at least on slopes protected from the intense sunshine, warm temperatures, and wind that have been more common than snowfall. The intense weathering of the snowpack surface means that these weak layers are not as widespread as they could be—they're most common on shaded and wind-sheltered slopes. And—thanks to the dry weather—most of our area lacks a slab atop these weak layers. Here's how it breaks down across the forecast area:

Soldiers & Wood River Valley: The number of inches of snow that have fallen in this zone over the past 2 months can be counted on one hand, maybe two. Where snow still exists, it's often full-depth facets. TL;DR: plenty of weak snow, but little to no slab.

Galena Summit & Eastern Mtns: Weak facets can be found about 4-8" below the surface on shady/sheltered slopes. Slopes with a sufficient slab for unstable conditions have been limited to wind-loaded areas. After nearly every round of wind, folks have triggered small pockets of wind slab sitting on weaker snow.

Sawtooths & Western Smokys: While this zone has received a bit more snow than the Galena Summit & E Mtns zone, the avalanche conditions have been fairly similar. Wind-loaded slopes have been the primary place to find the necessary combination of a slab and weak layer.

Banner Summit: This zone has fared the best during the mid-winter drought. We've been slowly building a slab atop weak layers of facets and surface hoar. The wet storm earlier this week produced 6-10" of new snow at upper elevations. The scales finally tipped, and we observed a cycle of natural persistent slab avalanches breaking 12-16" thick. 

Catch up on what happened with this week's wet, wild, and windy storm in our latest Weekend Update!

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