Lawinenlagebericht

East Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

It is possible to trigger an avalanche in wind-deposited snow at middle and upper elevations or at lower elevations where the snow is getting wet and unstable. On aspects that harbor a weaker snowpack, it is unlikely - but not impossible - to trigger a large and deadly avalanche. Consider navigating around terrain steeper than 35 degrees where you find pillow-like drifts and cornice development. You can further reduce your risk by choosing short, planar slopes free of hazards and terrain traps.

Lawinenprobleme

  • Loose Wet

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

    There is a decent chance that rain will fall up to 5000 ft on Friday. If that happens, the upper portion of the snowpack will rapidly destabilize. Wet snow avalanches can travel further and fan out wider than expected. The heavy debris can be difficult to escape from. They can initiate from blobs of snow falling from rocks or cliffs. If you find yourself getting rained on, avoid slopes steeper than 30 degrees, and don't linger below hazards where snow can fall from.

    (2/18/2025)

    Wet loose avalanche activity in the Baker backcountry. 

    Photo: Zack McGill - Cascade Mtn Ascents

  • Wind Slabs

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

    In the last few days, new snow accompanied by moderate to strong winds built wind slabs in exposed terrain. Avalanche professionals noted reactivity in wind-loaded terrain on Wednesday and Thursday in the East Central zone. Expect these slabs to become larger and more widespread as you gain elevation. A warming trend might weaken cornices and cause them to break off and fall more easily.

    Wind slabs usually form just below ridgelines and on exposed convexities and gullies. Visual clues such as cornices, rippled snow surfaces, and dunes will help you identify where the wind has transported snow. Give cornices a wide berth when standing at ridgeline, and don't linger right below them either. Long shooting cracks from your equipment, collapsing, and recent slab avalanche activity are good reasons to choose more sheltered and lower angle terrain.

    Although fairly unlikely, a triggered wind slab could "step down" and become a more treacherous persistent slab avalanche where poor snowpack structure exists. Read below for more details.

    (2/20/2025)

    Morning mitigation at Mission Ridge resulted in wind slabs 1.5-2 ft deep mainly on N-NE aspects.

    Photo: Payton Schiff

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2

    We haven't seen recent activity on the January Drought Layer (JDL) that brought on a persistent slab problem at the end of January. However, the JDL is still weak and faceted in many areas, so it's worth keeping in the back of the brain. A new weak layer interface that formed around Valentine's Day showed itself to be reactive this week and brought on a new persistent slab problem. After a day or two of warm temperatures without the direct input of sunshine, we expect this layer to be well on its way to healing. Areas that have been wind-loaded will be the most likely places to trigger a deeper avalanche on either of these two interfaces.

    You may or may not see clear signs of instability - cracking, collapsing, or recent slab avalanches - telling you to back off before it's too late. Persistent slabs can break in surprising ways, so be cognizant of the terrain around you. Use the clues laid out in the wind slab problem to help you identify wind-loaded slopes, understanding that even a small wind slab avalanche can "step down" and trigger a deadlier persistent slab avalanche. You can reduce your risk by choosing simpler terrain free of consequential runouts. And when in doubt, low-angle it out.

    (2/19/2025) Photo: Payton Schiff

Avalanche Discussion

The JDL and its overlaying slab are stiffening, making it harder and harder to trigger an avalanche. That being said, one should not forget the abnormal weather circumstances that surround the lore of this layer. Formed over a very long dry spell in January, the JDL is a thick layer, and the facets became well-developed. The contrarily cold weather we saw for a week in February then extended the persistence. This layer has taken longer than we might expect in the PNW to heal, so that's why we're still talking about it. 

We now face an atmospheric river event starting on Saturday that could rapidly destabilize the snowpack, especially at these weak layer interfaces. If you plan to get out, it will be vital that you pay attention to the weather and avalanche forecast.

Submit an observation to help NWAC Forecasters reduce uncertainty. It can be short, simple, and even anonymous. Any information you have will help us write more accurate forecasts that will, in turn, better help guide your backcountry decision making.

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