Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Mild temperatures should help the snowpack heal, but a few rouge wind slabs could exist especially in rocky areas. The more challenging issue is the outside chance for a much bigger slab releasing in older snow. Stick to simpler and planar slopes to help reduce the chance of either of these issues.

Lawinenprobleme

  • Wind Slabs

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

    While wind slabs should be few and far between, recent strong winds likely built drifts along exposed ridges, in the tops of chutes, and near the base of cliffs. After recent mild temperatures, they might be hard to trigger but don’t fully write them off. You’re most likely to cause a wind slab avalanche on a very steep or unsupported slope. 

    Textured surfaces, drifts, and wind lips should all help you figure out exactly where these slabs may be and aren’t. Be particularly leery of frim, hollow hard slabs that are much harder to assess and manage.

    (2/20/2025) Textured snow like this can help you anticipate wind loaded areas. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    There are several layers in the upper snowpack that can produce avalanches. The last round of slides was during warmer weather on 2/19 and included slabs 1-3ft thick. While we think most of these avalanches released on the 2/13 interface (more below), a few of the larger ones have us wondering. On top of that, a rumbling collapse Monday on the 1/10 interface just adds fuel to the fire. 

    It’s hard to imagine these layers “waking up” and producing avalanches during Friday’s quiet weather. But large triggers like other small avalanches, cornices, and the like might be all that’s needed. 

    These slides would be most common in complex terrain full of rollovers and rocks. While you might encounter avalanches on the shallower 2/13 interface on just about any aspect, the weak layers seem to be more worrisome in shaded terrain.

    (2/15/2025) Photo: Joe Dellaporta

Avalanche Discussion

Friday feels like the classic “calm before the storm.” Cloudy skies, mild temperatures, generally light winds, and minimal precipitation should make for a quiet day. With a decent freeze Thursday night (and likely a new crust) and the recent warm weather many of the interstorm and wind slab layers should gain strength. Most of the snow is wet and heavy. In the steepest terrain, you could cause a “push-o-lanche” but it likely won’t run far or entrain much snow. The biggest danger is these very isolated small slide acting as a trigger for the scarier persistent slab. 

Here’s a rundown of the layers we’re tracking. 

  • 2/13: S aspects: often a sun crust with weak snow just above, N aspects: rimed snow grains and/or surface hoar
  • January Drought Layer (JDL): W-N-E aspects: small facets often with a thin crust. 
  • 1/10 Complex: W-N-E aspects, a thicker layer of alternating larger facets and weak crusts. 

As we head into Saturday expect a big change in the weather with several very wet and warm storms. This isn’t a weekend to go winter camping. Expect the avalanche danger to rise significantly Saturday night.

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