Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Stormy weather will build fresh slabs, particularly in wind-affected areas Sunday. Blowing snow and fresh drifts should help you identify potentially loaded slopes you want to avoid.

Lawinenprobleme

  • Wind Slabs

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

    Windy weather will be the biggest factor in this storm for the entire West South zone. That means you will likely encounter wind slabs no matter where you travel. Since the storm will still be going, use simple clues like blowing snow and textured surfaces to anticipate wind-loaded areas. Steer around these steep slopes and use more sheltered or wind-scoured terrain to avoid the problem. 

    While you’ll likely encounter wind slabs everywhere, expect them to be larger and more dangerous in locations that receive more snow and at upper elevations. You’re most likely to encounter wind slabs below cornices, along the base of cliffs, and in the tops of chutes.

    (2/24/2023) Wind clues like these can help you anticipate wind loaded aspects. Photo: Dallas Glass

  • Storm Slabs

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

    For places that receive more than 8in of snow, you could encounter storm slabs on any open slope. The biggest factor for this problem will be how well the new snow bond to the old surface. Variable conditions were reported prior to the storm. So, unfortunately, you may find the snow reacts differently from one slope to the next. While hand pits, up track tests, and small slopes can help you observe the new snow bonding, don’t be too reliant on their results. They may not adequately represent the terrain in front of you. 

    Instead, choose simple low consequence terrain where you can easily identify and travel around steep open areas.

    (2/7/2023)

    Example: An intentionally triggered storm slab from earlier this winter. 

    Photo: Dallas Glass

Avalanche Discussion

In classic West South zone fashion, this storm will impact each area differently. In locations that receive less snow, you may encounter slightly lower danger. We’re expecting the most new snow and the greatest danger on the volcanoes. 

As the stormy weather continues Sunday. You could see slabs trigger more easily or even fail naturally during periods of heavy snowfall or stronger winds. If the storm intensifies, dial it back, and seek out lower angled terrain. 

Prior to this storm variable snow surfaces were widely reported. This includes firm icy crusts, soft powder, wind-affected snow, and very weak grains (facets/surface hoar). This is one time that the variable surface should work in our favor. These nasty persistent grains should only exist in pockets, which will limit their ability to cause bigger, wider avalanches. However, the West South is a big zone, and persistent grains like these are nothing to mess around with. This is just one more reason to choose low consequence routes that help reduce your risk. 

Avalanche activity in the West South zone has been pretty limited this week. The only recent slide we’re aware of was on Hogback Mt (NE, 6600ft) Thursday. As a result, we think this round of slides will typically fail at or above the new/old interface.

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