Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

 6:45a Update: CONSIDERABLE all elevations. You can easily trigger large avalanches on wind drifted slopes.  Use caution on all slopes steeper than 35 degrees, as you may be able to trigger avalanches even in wind-sheltered terrain. Dangerous conditions have been brought on by a potent winter storm that will deliver over 1 foot of snow by Monday morning with very strong winds. 

Lawinenprobleme

  • Wind Slabs

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

    Cautious route-finding and conservative decision-making are essential to traveling at upper elevations on Monday. The safest option is to stick to wind-sheltered slopes below treeline. Stay off of wind-loaded, leeward slopes that are 35 degrees and steeper. Steer around drifts, wind features, and convex rollovers. Look for signs of instability such as shooting cracks, blowing snow, and fresh avalanches. Very strong, westerly winds may build slabs further downslope than usual. You may be able to trigger wind slab avalanches below treeline on slopes that are exposed to wind near the top of the pass or similar divides at the Cascade crest. The strong west winds will add to existing cornices. Continue to give them plenty of room when traveling on ridges and stay out from under them. 

    (3/28/2021) Shallow drifts formed with strong westerly winds on the afternoon of 3/28. Gemini Pass, 5,000ft.

  • Storm Slabs

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

    You can trigger avalanches in the new snow on slopes steeper than 35 degrees, especially where the old surface is smooth and slick. Steep, solar aspects that are free of old debris are suspect for triggering storm slabs. When in doubt, defer to lower-angle slopes. Steer around convex rollovers and unsupported features. Before committing to travel in avalanche terrain, use inconsequential test slopes and quick tests to see how easily the snow slides. 

Avalanche Discussion

A strong winter storm is impacting the area. Snowfall rates were near to 2"/hour on Sunday afternoon with strong to extreme westerly winds. While snowfall should slow by Monday morning, winds may keep transporting snow near and above treeline. There's a chance for enough sun to come through the clouds to drive loose wet avalanches late in the day, especially on the east side of the zone. 

On Sunday, I found up to 3cm of new snow by noon near the top of Stevens Pass. On steep, southeast slopes over 5,000ft, I could easily trigger loose dry avalanches where the old surface was smooth. These small avalanches were predictable and entrained snow efficiently. I also dug a profile almost 7 feet down to the January 24th facets. While the grains have rounded quite a bit, the layer is still notably softer than the adjacent layers.

Deep persistent slab avalanches were a concern into early March, but now they are dormant and unlikely. The layer of facets on a crust from Mid-January was responsible for the February avalanche cycles is now buried 6-8 feet deep. The last known deep slab avalanche in this zone was on March 1. Major warming events later in spring and summer could trigger further rounds of avalanches on this layer. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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