Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The danger will rise to CONSIDERABLE due to new snowfall and wind. Three avalanches have been triggered in the past three days. Conditions will become increasingly dangerous today on steep, upper elevation slopes that are affected by the wind. Avalanches may be triggered remotely—from areas below, above, and to the sides of steep slopes. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Three avalanches have been triggered in the past three days:

    1. Snowmobile triggered avalanche in Mill Gulch, a sub-drainage of Smiley Creek in the Western Smokys (Jan 2)
    2. Large avalanche triggered remotely from 800-1000' away in the Western Smokys (Jan 1)
    3. Avalanche remotely triggered from a ridgeline in Anderson Creek north of Baker Creek (Dec 31)

    Combined with the triggered slides after Christmas, there have been 6 human-caused avalanches in the past 8 days. These avalanches occurred in two separate zones with somewhat different snowpack properties. But all our forecast zones have one important thing in common: a layer of very weak faceted snow buried 8" to 24" deep.  Also of note is that all these slides occurred in upper elevation terrain affected by the wind. 

    Compared to this bullseye information, the continued reports of collapsing of the snowpack and poor test scores are secondary. But it all points to the same conclusion—we have a tricky and dangerous snowpack. Conditions will become increasingly hazardous during the day today, primarily on upper elevation slopes being loaded by new and windblown snow. 

    Stick to simple terrain and lower slope angles, and rule out steep, upper elevation slopes that are likely to get loaded by today's storm. Half of the recent avalanches have been triggered remotely—from areas below, above, and to the sides of steep slopes. Be aware of both the terrain you're in, as well as the terrain above you.

    (1/1/2021) Sun Valley Heli Ski remotely triggered this avalanche from lower angled terrain 800-1000' away. The group felt a collapse that propagated across the bowl into steeper, wind-loaded terrain. Avalanche released on a 9400', E aspect in the Western Smokys. Photo courtesy of Sun Valley Heli Ski.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Throughout the day, new snow and moderate to strong westerly winds will be loading upper elevation ridgelines and exposed slopes. By later today, these wind slabs may become large enough to be dangerous if triggered. The added weight from wind loading will stress buried weak layers described below. Long story short: avoid steep slopes where you find evidence of windblown snow.

Avalanche Discussion

If conditions weren't bad enough, they're about to get worse. The recent spate of triggered avalanches points to a snowpack that is on the verge, and the forecasted storms today and especially tomorrow (Monday) are likely to make the wheels come off the bus entirely. I tend to avoid making dire predictions—especially about events that are more than 24 hours out—but in this case, I'm going to go out on a limb. It's not really a matter of "if" but of "how much" of our forecast area takes a nosedive.

The Galena Summit & Eastern Mtns zone has been waiting for the straw that breaks the camel's back. Although 4 of the recent 6 avalanches have occurred in this zone, unstable conditions haven't been widespread. The Soldier & Wood River Valley zone has an extremely weak snowpack but has seen little recent snowfall. Tomorrow's storm may provide the first big thump this zone has yet to experience.

In our northern and western zones, things are a bit more complex since the persistent weak layer is buried 18" to more than 24" deep. These areas may handle the new loading a bit better, but—and it's a big but—any avalanche that releases will be a big one.  Take a look at a video I took yesterday in the northern Sawtooth Mountains explaining this double-edged sword.

We sure to catch up on this past weeks' conditions with Scott's new Weekend Update!

Regions covered