Lawinenlagebericht

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Dangerous avalanche conditions exist. Triggering 1-3 foot thick avalanches is likely today.  Avalanches will be easier to trigger in terrain affected by the wind, but are possible in sheltered terrain as well. Avalanches can be triggered from long distances above, below, and to the sides of steeper slopes. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2

    What is it? A significant amount of natural avalanches occurred in the last 48 hours. Most of the larger avalanches were in areas where the wind has added additional weight to the recent snow. Today, you can trigger the same sensitive 1-3 foot thick slabs in many areas with wind-affected snow.

    Where is it? These slabs will be the largest and thickest at upper elevations, but you'll also find wind slabs in exposed middle-elevation terrain. Be on the lookout for wind slabs near ridgelines and on the sides of mid-slope features like couloirs, gullies, and ribs. The rocky nature of the Sawtooth Mountains allows new snow to run down the sides of cliffs and build up additional weight in the aprons. In these locations, it is also likely to trigger slab avalanches today.

    How can you recognize it? Cracks shooting out from your skis or sled and collapsing clearly indicate instability. Look for ripples in the snow, dunes capping ridgelines, and drifts along the sides of gulleys or chutes. Wind-deposited snow will be stiffer and keep your skis or snowmobile on or closer to the surface. Some of these slabs might be masked by recent snow and be more hidden.     

    How can you manage it? Most wind slabs are building on top of persistent weak layers in the snowpack (read Problem #2 below). Because of this, the wind slabs you encounter today may behave more like persistent slabs than "simple" wind slabs. Fresh slabs will be reactive to your weight and may produce avalanches that break wider and deeper than you might expect. Triggering these avalanches remotely (from a distance above, below, or to the sides of steeper slopes) is a real possibility.

    (3/5/23) A large avalanche in a heavily wind-loaded east-facing slope around 9900' in Beaver Creek. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    What is it? Layers of weak snow in the upper snowpack can produce wide, destructive 2-3+' thick slab avalanches. Professionals dug many snow pits yesterday and compiled numerous unstable test results on this weak snow. Expect to find weak, sugary facets on shaded slopes and crust+facet sandwiches on slopes that face the sun. 

    Where is it? The depth of these weak layers varies from slope to slope, but it's safe to assume that they exist on most slopes. The sensitivity will be amplified in wind-affected terrain in more exposed terrain.  However, enough snow has fallen here that avalanches failing in terrain sheltered from the wind are a real possibility.

    How can you recognize it? Shooting cracks and collapsing are clear signs of an unstable snowpack. Natural and human-triggered avalanches will offer guidance on what type of terrain and slopes these avalanches are likely to be triggered on, but it's safe to assume that they exist on many slopes.  It might take some digging into the snow to reveal previous wind-affected layers that the new snow has masked in more sheltered locations. 

    How can you manage it? Persistent weak layers can fail unpredictably and break significantly wider and deeper than you might expect, producing much larger avalanches. Today I recommend you choose simple, conservative terrain to play in. Pay close attention to the terrain around you and what you are connected to in slope steepness. The combination of a recent large natural avalanche, an ugly snowpack structure, and unstable snowpack test scores is plenty of evidence to keep me out of big, steep, complex avalanche terrain.

    (2/28/2023) NE face of Copper Mountain at 8,400'. This avalanche appeared to be remotely triggered by a skier from above. This crown in sheltered terrain points to the potential for encountering avalanche problems outside of areas that are obviously affected by the wind.

Avalanche Discussion

Now is the time to be conservative. Don't let the light, fluffy powder lure you into avalanche terrain. The steeper slopes you may have played on last week look much different now. The warning signs are showing themselves in various ways. Recent skier and rider-triggered avalanches should be the biggest red flag, but evidence of natural avalanche activity solidifies this point (see the Avalanche Database).

Pay close attention to the terrain around you and what you are connected to in slope steepness.  Slopes can release while approaching them from below on more mellow terrain. Pockets of slopes steep enough to slide have proven to be enough to cause avalanches, like the one on Baldy "out of bounds" (report), Olympia Gulch off Paterson Peak (report), Quigley Canyon (report), East Fork of Baker Creek (report) and Della Mtn. (report). Cliffs, trees, rivers, and other terrain traps magnify the consequence of even small slides.

Persistent slabs are notorious for not always failing while the first person plays on the slope. Sometimes it will take the next person or the last member of the group to find that "sweet spot" in the snowpack that causes the whole slope to become unglued. Luckily, the terrain in the surrounding mountains offers non-avalanche slopes to have loads of fun on right now. Double-check while measuring slope angles, and when in doubt, err to the side of caution by calling it steeper than you might think. Treat slopes with avalanche terrain with respect and give them a wide berth. 

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