Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
Open full map
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Kernpunkte

Another day of spring-like weather will maintain the possibility of loose avalanches on sun-exposed slopes. If you see snow shedding from trees and rocks or the surface is wet and sticky, head for shadier aspects. If you plan on venturing toward the high peaks, storm snow related problems such as wind slab still exist. 

Lawinenprobleme

  • Loose Wet

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

    Sunny skies will again grace the Pass on Wednesday. Solar input could assist in the development of loose avalanches ranging in moisture content from dry to wet. Snow shedding from trees and rocks could trigger avalanches on the slopes below. If the March sun is able to overcome the cool ambient air temperature, expect avalanches to start to tip toward wet. Lower elevations and slopes that see direct sunshine have a higher chance of producing slides. These same slopes have the highest chance of snow "slabbing up" due to solar input. This happened on Monday and Tuesday according to public observations, resulting in human-triggered slides.

    Regardless of their moisture content, loose avalanches will start at a point and fan out as they move downhill. They are capable of growing large or triggering slabs as they descend. If you're on a sunny slope and see signs of natural avalanche activity, head for shadier aspects where this problem is less likely. 

    (3/5/2024)

    Wet loose activity on sun-exposed slopes in the Alpental Valley.

    In the shade, you can see a wind slab crown and textured surfaces.

    Photo: Matt M

  • Wind Slabs

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

    It's been a few days since we've had much wind or new snow at Snoqualmie Pass, but we keep receiving reports of human-triggered slabs. They should be trending downward in reactivity, especially on sun-exposed slopes. But if you take advantage of the nice weather to get high in the mountains, keep them on your radar. The wind likes to drift snow toward features such as the base of cliffs, convex rollovers, and the tops/sides of narrow chutes. You may notice textured surfaces, cornices, or large drifts indicating wind-loaded slopes that you should avoid. In some areas, a layer of graupel may be to blame for reactive slabs 4-6 inches deep.

    (3/5/2024)

    A natural wind slab avalanche at the base of cliffs in Great Scott Bowl.

    You can also see dry loose avalanches due to snow shedding from sun-exposed rocks.

    Photo: Bunkhouse Billy

Avalanche Discussion

Tuesday was beautiful at Snoqualmie Pass, with bright sunshine, popcorn clouds, little wind, and relatively cool temperatures. For those of you who are into that sort of thing, Wednesday should be an almost carbon copy. Temperatures should be just a notch warmer, and you may notice a little more wind.

Avalanche activity was on the rise in the March sunshine on Monday. Snow was shedding from trees and rocks, triggering loose avalanches on the slopes below. Most of these were dry, but a few became moist as the morning wore on. As an off-duty forecaster left the Pass shortly after lunch,  a thin sun crust was forming on slopes that saw morning sunshine, and they spotted a few larger piles of wet avalanche debris in the highway paths. Backcountry travelers and Alpental Pro Patrol both reported wind slabs near the base of cliffs or on unsupported slopes.

We've been talking about neighboring zones running a persistent slab problem for the past week due to slabs failing on weak layers at or just above the Early February Crust (EFC). We do not have any confirmed avalanches on this layer at Snoqualmie Pass. However, a public observation on Tuesday may have found one in the western part of the zone. A very deep crown was spotted near Granite Mountain on a north-facing slope. It's hard to date how fresh this slab is with only 1 picture, but consider it if you're planning on venturing into big open terrain or exploring the high peaks during this week's nice weather. A skier triggered a deep avalanche suspected to be on these layers at Stevens Pass on Tuesday.

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