Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Sun
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

Slopes where the wind has deposited snow onto them are where it's feasible to trigger both small and large avalanches, but small avalanches are more probable. Consider navigating around terrain steeper than 35 degrees where you find pillow-like drifts and cornice development, particularly on aspects and elevations that harbor a weaker snowpack. You can further reduce your risk by choosing short, planar slopes free of hazards and terrain traps.

Lawinenprobleme

  • Wind Slabs

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

    This week was windy,  and the distribution of wind-affected snow is widespread. The sensitivity of wind slabs is more irregular, however, and will continue to change with another small shot of new snow on Saturday. Larger and deeper slabs will be more apparent in the southern half of the zone in areas like the Salmon La Sac, Teanaway, and Wenatchees. These slabs could fail on buried weak layers and be more akin to a persistent slab avalanche. Smaller, fresher slabs will build during the day throughout the zone. 

    Regardless of where you are, you should look for signs of instability. Cornice development is the most obvious clue of previous wind transport and signals that older slabs might lurk just below. Look for fresh slabs on slopes where you see the wind blowing snow onto them. If you get big cracks shooting from your equipment, hear or feel a collapse, or see a recent slab avalanche, dial back your terrain choices to more sheltered slopes.

    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.

    (2/14/2025)

    You can see nearly the entire slab fail and displace, but it just wouldn't quite slide. If the slope was any steeper, this would be a small wind slab avalanche. 

    Photo: Dallas Glass

  • Persistent Slabs

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

    The likelihood of triggering a large and potentially fatal avalanche is low but not impossible. This zone hasn't had much confirmed activity or signs of instability on weak snow layers associated with the January Drought Layer (JDL) this week, but poor snowpack structure still exists. Areas that have been wind-loaded - where the wind has built a larger and more cohesive slab over weak layers - will be more untrustworthy. 

    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 even a small wind slab avalanche can "step down" and trigger a deadlier persistent slab avalanche. You can reduce your risk by choosing more simple terrain free of consequential runouts. And when in doubt, low-angle it out.

    (2/14/2025)

    You can clearly see the grey-ish line of weak facets in the wall behind the failed snowpack test. These weak grains aren't hiding, they're easy to spot. 

    Photo: Dallas Glass

Avalanche Discussion

The East Central zone has received small inputs of snow on most days this week, and Saturday is no exception, with another 2-3 inches in the forecast. Additionally, we saw a strong easterly wind event that loaded atypical slopes. The wind shifted back to more typical westerly directions on Friday. This has kept what one could call a "lingering" wind slab problem on the table all week. However, the extent of the wind slab likelihood and size is inconsistent. Small amounts of new snow have been available for transport, but not everywhere in the zone. Combined with shifty wind directions and a lack of on-the-ground data, this problem has been tough to nail down. On Friday, NWAC Forecasters traveling in the Salmon La Sac noted how variable the wind-affected snow was just within this one specific area. They found reactive wind slabs on both sides of a ridgeline. You may encounter locales like this where it is more likely to trigger an avalanche.

We are also closely watching how the slab associated with the persistent slab problem has been settling, bonding to the JDL, and reacting to wind loading. Numerous avalanches were triggered in wind-loaded areas in the East North zone and failed on the JDL this week. The NWAC Forecasters in the Salmon La Sac got inconsistent snowpack test results in an area with poor snowpack structure. We are now looking at a more significant storm system rolling in later on Saturday, which could quickly bring persistent slab avalanches back to the forefront. It is not so big of a system that we feel much assuredness with that claim at this time, but it's worth putting back on the radar.

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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