Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Highlights

Large avalanches are unlikely, but watch for 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. Over the past 2 months, we've had more wind than snow. Each wind event has created fresh pockets of drifted snow—some of which formed on weak layers from the mid-winter drought. A handful of natural wind slab avalanches occurred after the wet and windy storm earlier in the week, including one in the Southern Sawtooths (pictured above/right). 

    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 head into 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. In the Sawtooths, wind slabs often form at the base of cliffs (from spindrift) or along the edges of couloirs and chutes. Cracks shooting out from your board(s) or sled are bullseye evidence of having found a sensitive wind slab. 

    (3/2/2022) This small wind slab avalanche released just below an upper elevation ridgeline near McDonald Pk. The slab entrained wetter snow as it moved down slope.

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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