Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

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

Wet avalanches are becoming less frequent but could still be very large and unpredictable, even as the rain tapers off. Avoid steep terrain where you could trigger wet slides, and if you choose to travel in the mountains, don't stop in gullies or below large avalanche paths where slides may run from above. 

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–3

    Avoid steep slopes where you are sinking deeply into saturated snow and could trigger a wet avalanche. Wet slabs are unpredictable and may run naturally, so make sure you are knowledgeable of any overhead hazard from the terrain above you. Travel quickly through runouts and gullies where large avalanches can channelize and run long distances into lower elevations. Cornice failure and glide avalanches involving the entire season's snowpack should also be on your radar. Avoid traveling below deep, open glide cracks and overhung cornices. 

    Wet loose and wet slab avalanches were widespread on Monday, and we expect lingering instability on Tuesday. As temperatures keep climbing, liquid water in the snowpack will continue to drive large, unpredictable wet slab avalanches, particularly from upper elevations. 

    (3/18/2024)

    An example of a wet slab avalanche from a previous season in Wenatchee Bowl.

    Photo: Josh Hirshberg

Avalanche Discussion

The Stevens Pass zone has received 3.4" of liquid water at 5000ft over the past 48hrs with more on the way for Tuesday. Every wet avalanche cycle is slightly different. However, many times, the third day of sustained above-freezing temperatures comes with unpredictable surprises. While the day might look and feel much nicer with less rain and the potential for sunshine, there is still a high likelihood of avalanches, especially wet slabs. Consider the significant consequences of simply being in the wrong place at the wrong time. While you might be less likely to trigger a wet loose avalanche on Tuesday, a large wet slab running to valley bottom is still a concern. Choose your terrain wisely, paying attention to the terrain even thousands of vertical feet above you. With no overnight re-freeze of the snowpack, expect challenging travel in deep, wet snow at most elevations on Monday. 

On Monday, I observed widespread wet loose avalanches in the Stevens Pass area. Many were small at lower elevations, but the debris still piled up deeply in terrain traps. From upper elevation terrain, very large wet avalanches ran through elevation bands into lower elevation terrain. The snowpack was saturated to about 1 ft deep, with moist snow below that. Rain runnels and water pooling on deeper layers in the snowpack indicated that drain channels had been established and free water was moving through the snowpack. 

Before this atmospheric river, observers reported numerous triggered avalanches in the past few days, with many occurring on leeward, wind-loaded slopes. There were reports of human-triggered and natural avalanches big enough to injure or kill a person over the weekend. Both the WSDOT avalanche personnel and Steven's Pass Ski Patrol triggered large wind and storm slab avalanches during avalanche control work. A skier was caught and carried in an avalanche in Highland Bowl, in the backcountry, just outside the Stevens Pass Ski Area. Thankfully, the individual was uninjured. All these slides indicate that the snowpack was dry and layered before the rain. As water moves deeper into the snowpack, these previously dry, weak interfaces can lead to very large wet slab avalanches. 

Submit an observation to the website or the Avy App to help NWAC Forecasters reduce uncertainty. It can be short, simple, and even anonymous. 

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