Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
View on map

Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The likelihood of triggering avalanches will increase throughout the day as the combination of 5-10" of new snow and wind builds reactive drifts and slabs in exposed terrain. These will grow in size and become easier to trigger as the storm progresses. Avalanches that break down into weak layers in the upper few feet of the snowpack are possible, resulting in larger, more destructive slides. You can reduce your risk today by steering clear of recently wind loaded slopes.

If storm totals are on the upper end of the forecast, the Avalanche Danger may rise to CONSIDERABLE by this afternoon.

Avalanche problems

  • Wind Slabs

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

    Today's storm will bring 5-10" of snow to this zone. Moderate winds accompany this snowfall, blowing first out of the S-SE, then shifting to W-NW by mid-day.  Expect to see wind slabs building throughout the day, growing in size and sensitivity as they do. You're most likely to encounter a wind slab in exposed upper elevation terrain, near ridgelines and on the sides of terrain features like gullies and ribs. These features slow the wind down and force it to drop the snow it is carrying. In the steep terrain of the Sawtooths, slabs also commonly form below cliff bands and on the aprons below couloirs during storms. 

    As you travel through the mountains today, look for signs that the wind has been at work. Dunes, pillows, and ripples on the snow surface are all indicators that the wind has been transporting snow. If the snow you are moving through is becoming deeper and denser, you're likely moving through wind-deposited snow. Cracks shooting out from your skis or machine are a clear sign of an unstable slab. A variety of weak snow surfaces have developed in the time since our last snowfall, which may make today's slabs more reactive.

    (1/29/2023) This small wind slab released naturally on Titus Ridge near Galena Summit. It failed on a E/NE-facing slope at 9,600'.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Several weak layers exist in the upper few feet of the snowpack. A prominent layer of surface hoar buried 1.5-2 feet deep has been responsible for a handful of skier and rider-triggered avalanches in the past few weeks. Above this layer, you'll find a few layers of crusts, facets, and/or surface hoar that were buried in the second half of January. Last week, observers in the Sawtooths reported unstable snowpack test scores and cracking and collapsing involving these newer weak layers. Today's storm will add stress to these buried weak layers.

    Slides that fail on persistent weak layers are less predictable than simple wind slabs. They may break wider than you expect and may wrap around terrain features that confine wind slabs. Persistent slabs can break well above you on the slope you are skiing or riding on.  Triggered wind slabs can "step-down" to these deeper weak layers, resulting in larger, more destructive avalanches.

    ADDITIONAL DISCUSSION: Older weak layers (facets, crusts+facets, and surface hoar) exist deeper in the snowpack. These layers are buried beneath dense, 3-4+ thick slabs. While triggering them is unlikely, it can't be ruled out in steep, rocky, wind-affected terrain. 

    A skier triggered this 1-2 foot thick avalanche on Sunday Jan 29th on a N-NE aspect at 9100' near Titus Ridge. It failed on a layer of buried surface hoar.

Avalanche Discussion

STEPPING BACK

Snowfall returns to our region today. In the past week, we've seen the likelihood of triggering avalanches gradually decrease. Today, we head in the opposite direction. While forecasted snow totals aren't in the same range as the monster storms early this winter, there will be plenty of new snow to change the picture out there. Your likelihood of triggering avalanches will increase throughout the day as the snow piles up. Today's snow is falling on a variety of snow surfaces, many of them weak. Surface hoar, facets, and crusts with facets on top have all been observed in the previous few days. This weak snow will make today's wind slabs more reactive than they would be otherwise. This zone is expected to pick up the most snow from today's storm. Avalanche Danger may increase to CONSIDERABLE by this afternoon if storm totals come out at the upper end of the forecast.

Moving our focus a bit deeper, we find several weak layers in the upper few feet of the snowpack. A few layers of surface hoar exist on sheltered, shady slopes, while crusts with and without facets on top can be found on slopes that face the sun. These weak layers will be stressed by today's storm, particularly in areas where the wind is building slabs. Wind slabs can step down to these weak layers, resulting in larger, more destructive avalanches.

Today, it's a safe bet that conditions will become more dangerous as the storm progresses. Go into the mountains ready to take a step back from the type of terrain you played in yesterday. Choose your terrain with this in mind.

Regions covered