Lawinenlagebericht

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Human-triggered avalanches involving the new snow are possible. Look for areas where the wind has built small drifts and slabs out of the new snow from the past few days. Avalanches may break wider than you might expect, thanks to the weak snow buried underneath the new snow. Even small slides that knock you off your feet or machine in rocky, treed terrain can carry high consequences.

The likelihood of triggering avalanches will increase through the morning hours as the storm brings new snow and strong winds. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    2-3" of new snow fell overnight in this zone and an additional 3-5" are expected to fall this morning. Moderate to strong gusty winds blowing out of the W are transporting this snow and building 1-2 foot thick drifts and slabs. These slabs will be largest and most reactive in exposed middle and upper elevation terrain. Look for them near ridgelines and on the sides of mid-slope features like ribs and gullies. In the steep, rocky terrain of the Sawtooths, slabs commonly form underneath large cliffs and on aprons below couloirs. Strong winds can build slabs in unusual locations, keep your eyes peeled out there. Dune-shaped drifts and textures on the snow surface like waves and ripples are signs that the wind has been at work, as are fresh cornices along ridgelines. Cracking and collapsing are clear indicators that you've found an unstable slab. Consider the consequences of being swept off your feet and carried through the terrain you are in. Even small slabs can carry high consequences if they drag you through trees or over rock bands. 

    Fresh slabs are building on a variety of weak layers that developed over the past several weeks. Avalanches that fail on these weak layers will break wider and may be more sensitive than you might expect a "simple" wind slab to be. These layers appear to be at their worst on slopes that directly face the sun where crusts+facets are buried. Slides failing on crusts can pick up speed quickly, thanks to the slick crust underneath.

    ADDITIONAL DISCUSSION: In terrain steeper than about 35 degrees it will be possible to trigger small loose snow avalanches involving both the new snow and the weaker facets underneath. At lower elevations, temperatures have remained above freezing and the upper snowpack is warm and moist. There, these loose snow avalanches will have a wet character. Loose snow slides are unlikely to bury you, but may be able to knock you off your feet and send you downslope.

Avalanche Discussion

There is a good deal of uncertainty with today's Forecast. Thus far, the storm has been a significant underachiever—more of an atmospheric rivulet than an atmospheric river. Snow totals have been on the light side, but there are still some storm-related issues to be looking out for today:

Wind slabs: The combination of fresh snow and strong winds is building sensitive wind slabs. Strong winds build slabs in unusual locations. I expect to see slabs at most elevations, though these will be largest and most reactive in exposed middle and upper elevation terrain. Slabs may be building even at lower elevations. These are likely to be smaller and your biggest concern with them involves being pushed into terrain traps like creek bottoms and dense trees. Slabs are building on a variety of weak snow surfaces that developed over the past weeks. Avalanches that fail on these weak layers will break wider and may be more sensitive than you might expect a "simple" wind slab to be.

Loose snow: If you are finding soft, sheltered snow in very steep terrain (approaching 40 degrees) you'll be able to trigger loose snow avalanches today. These will involve both the new snow and the weak, faceted snow described above. Today's cold front should keep things cooler than yesterday, but if you're playing on slopes that face the sun and finding moist/wet snow you'll be well served to think about triggering a small wet loose avalanche as well. If the snow feels wet and you can easily make a snowball this type of problem will be possible.

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