Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Recently formed wind slabs may be surprisingly reactive in pockety locales. The new snow is covering a widespread batch of large surface hoar, so make observations as you travel and look for signs of instability like cracking. Steer around steep slopes if you find thicker slabs or instabilities. Small sluffs may run fast on very steep slopes, be ready to confront this hazard in steeper terrain.

Lawinenprobleme

  • Loose Dry

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    With up to a foot of new, low-density snow on weak surfaces, loose slides or sluffs may become a problem that you'll have to manage in steeper or larger terrain features. You can check to see how the snow reacts with a fast 'hockey stop' on the edge of test slopes. If it entrains and runs, then expect it could do the same on larger features. 

    Example loose dry avalanches, triggered by skiers. Photo: Dallas Glass

  • Wind Slabs

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

    New snow has stacked up, and winds from the west quickly redistributed it near ridgetops. Westerly winds will continue to drift the very low-density new snow into thicker pockets near exposed features. Recently buried surfaces range from widespread surface hoar, facets and crust. The thing to emphasize here is that most surfaces were weak before this storm, and the new snow may not bond well.

    It will probably take wind-stiffened snow to create enough cohesion for a slab avalanche, but a foot of new snow might do it on its own. In any case, look for signs of instability as you gain elevation, and check test slopes for cracking. Steer around steep slopes that appear freshly loaded, or if you find signs of instability. 

    Example small wind slab

    Photo: Ryan Minton

Avalanche Discussion

It will feel pretty arctic out there on Monday, so bring an extra layer or two and consider that a potentially stronger storm may arrive later in the evening. On Sunday a convergence zone set up and delivered a quick-hitting round of heavier snowfall to the pass. Observers noted that widespread and large surface hoar got buried intact during the day.  Other surfaces that got buried were soft 'recycled pow' (surface facets) on sheltered, northerly aspects with various thicknesses of crusts on southeast to southwest slopes. Winds were moderate to strong at times, especially in areas exposed to westerly wind. We can expect an increasing trend for avalanche danger this week with more storms on the way.

Layers of weak snow and crusts were buried by a small storm on December 8th  (surface hoar). These layers are now down about a foot or two. This layer generally hasn't been a problem for avalanches in this zone as much as others throughout the forecast region, though it's something to consider, especially as it gets buried more deeply, and in any heavily wind-loaded area.

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