Lawinenlagebericht

East Slopes South

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

It will be bitterly cold and windy on Thursday which can quickly compound the consequences of a backcountry emergency. Cracks shooting from your equipment and blowing snow are obvious signs that downwind slopes will be dangerous. To better enjoy the chilly day, stick to lower-angle terrain sheltered from the wind.

Lawinenprobleme

  • Wind Slabs

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

    An easterly wind event started on Tuesday and not only continues but strengthens into Thursday. With 2-5" of new snow forecasted, it is likely to trigger small, fresh slabs in lee terrain. It is possible you could trigger an older, larger slab that formed in previous days. Wind coming from the east has a tendency to load surprising slopes and catch backcountry travelers off guard. Older slabs will be stiffer and harder to trigger but larger and more consequential. Even a small slab could knock you off your feet and carry you over hazards such as rocks and cliffs. A new or recently formed wind slab could overload a slope with poor snowpack structure. If you were to trigger a wind slab avalanche there, it could "step down" and become a more treacherous persistent slab avalanche.

    Wind-loaded snow is often found just below ridgelines and in cross-loaded gullies. Red flags are cracks shooting out from your sled or skis, audible whumpfs, and recent slab avalanches of any size in similar terrain. Visual clues such as cornice development, rippled snow surfaces, and blowing snow that will be visible throughout the day will help direct you to the side of a ridgeline where wind-loaded snow is probably lurking. 

    (2/7/2025)

    A shallow wind slab just below ridgeline in the Crystal Mountain area.

    The textured surface and relative stiffness compared to the surrounding low-density snow are easy ways to identify wind-loaded features.

    Photo: Josh Lipkowitz

  • Persistent Slabs

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

    The likelihood of triggering a potentially fatal avalanche is low but not impossible. This zone hasn't had a confirmed persistent slab avalanche, but we have little on-the-ground data to know with much certainty what has gone down in the last week and a half. We do know that poor snowpack structure exists, and we have seen some signs of instability on weak snow layers associated with the January Drought Layer (JDL). Additionally, there was a lot of activity on the JDL just over the border on White Pass in the West South zone. We suspect that easterly wind will have made downwind terrain a more believable place to initiate an avalanche. 

    This particular persistent slab problem has been even more tricky to manage than your average uncertain persistent slab problem. 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. Use the clues laid out in the wind slab problem to help you identify wind-loaded slopes, understanding that a wind slab avalanche can "step down" and trigger a deadlier persistent slab avalanche. You can reduce your risk by choosing slopes that are shorter, more planar, and free of hazardous cliffs or terrain traps. When in doubt, default to lower angle, sheltered terrain.

    (2/3/2025)

    A skier triggered persistent slab avalanche near White Pass. This slide released over a 100ft wide and 2-3ft deep. WNW, 5600ft SS-ASu-D2-R2-O

    Photo: Dallas Glass

Avalanche Discussion

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

Cold weather has been a hot topic this week. On Wednesday, the Green Lake weather station (5920 ft) recorded a low of -4°F in the early AM hours. Thursday is no exception. It is forecasted to be an even more biting day outside, with increased wind speeds and cloud coverage. A 5°F day coupled with 30mph wind creates a wind chill value of -19°F. A backcountry emergency will quickly go from bad to worse with this kind of weather, so be prepared with extra layers, reliable communication devices, and maybe a thermos or two of hot cocoa. 

The likelihood of triggering a large persistent slab avalanche is decreasing, but the unique nature of this particular persistent slab problem has many long time avalanche professionals still traveling conservatively. An NWAC forecaster traveling in the northern end of the zone on February 7th found poor snowpack structure and propagating snowpack test results. More recently, an observer just over the border in the West South zone reported whumpfing. This problem has been hard to pin down due to the high variability of snowpack surfaces leading up to new snowfall at the end of January, as well as little data for this zone. Additionally, sustained cold weather has slowed down the healing process for the JDL. Stack the odds in your favor by choosing well-supported terrain and enjoying high-quality powder riding in more sheltered terrain.

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