Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

It is still downright scary out there. Skiers and riders are likely to trigger avalanches large enough to destroy trucks. Natural avalanches are possible. Avoid all avalanche terrain where the wind formed drifts or stiffened the snow surface. Be very careful on or near all steep slopes—slopes steeper than about 30 degrees. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes.

Avalanche problems

  • Persistent Slabs

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

    Several flavors of large destructive avalanches are possible today. The travel advice today is simple: be careful. Read the Forecast Discussion below for details on specific avalanche problems other than the Persistent Slab and Wind Slab problems described in detail.

    What is it? Triggering powerful, 2-4 foot thick avalanches is likely. Recent snowfall, wind-blown snow, and rain overloaded the buried weak layers (sugary facets or crust + facet combinations) that produced hundreds of avalanches and tragically resulted in an avalanche fatality in recent days. In areas exposed to the wind, slides could release naturally—on their own. Avalanches could be over 1000' wide and may run to the valley floors. 

    Where is it?  Given that we've received snowfall all but one day since February 26th and 1.5-2 feet in a couple of days, the slabs exist on almost all slopes. Wind-loaded slopes are the most dangerous. Some slopes have probably avalanched and "reloaded" with fresh, dense slabs. Limited observations indicate the weak layers are not as widespread in this zone, but you should assume they exist on any given slope until proven otherwise. 

    How can you recognize it? Wind-loaded slopes have stiffer, denser snow that keeps your skis or sled from sinking deep into the snowpack. You may or may not experience obvious signs of instability like snowpack collapsing and cracks shooting out in front of you.  

    How can you manage it? The prudent move is to avoid all avalanche terrain exposed to the wind and be very cautious on and near all steep slopes. Persistent weak layers can fail unpredictably and break significantly wider, deeper, and higher on slopes than you might expect, producing much larger avalanches. Smaller loose snow, wind slab, and storm slab avalanches can trigger larger persistent slab avalanches lower on slopes. You could remotely trigger avalanches from gentle terrain far above, below, or to the sides of steep slopes. Avalanches could be triggered by the second, third, or fourth rider on a slope that initially appears to be stable. 

    (3/12/2023) This avalanche failed on a SE slope at 9000' in Lola Creek. Based on the aspect and the appearance of the crown, this slide likely failed on a layer of facets below a melt freeze crust.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2

    Natural and human-triggered avalanches are likely in wind-loaded terrain. Moderate to strong winds formed and will continue to build wind slabs in exposed terrain. Be on the lookout for smooth pillows of windblown snow near ridgelines and beneath cornices. Cracks shooting out in front of your skis or sled are a sure sign you've found a wind slab. 

    While stability is better in terrain sheltered from the wind, do not assume sheltered slopes are "safe."  

Avalanche Discussion

We could face 7 different avalanche problems today: persistent slabs, wind slabs, storm slabs, deep persistent slabs, dry loose, wet loose, and cornice. How do you manage something that complex? You really can't. What should you expect to see as you move up in elevation in the mountains today?

  • Lower elevations: Most lower elevation slopes received a fair amount of rain during this storm. Today's cold front will eventually turn the lower elevation snowpack into a frozen popsicle, but you may be able to trigger wet avalanches while the snowpack is draining and beginning to freeze. Once you climb above the rain line, you'll be dealing with storm slabs and persistent slabs. A professional observer in the Soldier Mountains reported a very sensitive mid-storm layer Tuesday afternoon. Remember that large avalanches releasing in middle or upper elevation terrain can run "full track", impacting lower elevation locations. 
  • Middle elevations: You'll be dealing with the persistent slab avalanche problem described above and dense storm slabs involving the snow from yesterday, last night, and today. Smaller wind slab and loose snow avalanches are possible on very steep slopes and make great triggers for larger slab avalanches. 
  • Upper elevations: Strong wind formed and will continue to build dense, meaty slabs in exposed terrain. The wind-loading will make natural and human-triggered wind and persistent slab avalanches likely to occur, and deep persistent slabs (monster 4-8 foot thick slides) are possible. Storm slabs are likely in all very steep, sheltered avalanche terrain. The recent snowfall and wind built large cornices; they could break on their own or with the added weight of a person or snowmobile.   

Be sure to give yourself a large safety margin if you're out playing today. Minimize your exposure to overhead avalanche hazards. Have fun and be safe.

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