Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

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

Strong recent wind, snowfall, and weak layers in the snowpack are a recipe for very dangerous avalanche conditions. Avoid traveling on or under steep slopes, as you may be able to trigger avalanches that break widely across terrain or come down from overhead. Be prepared for very cold temperatures.

Lawinenprobleme

  • Wind Slabs

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

    The most dangerous locations will be leeward and cross-loaded slopes near ridgetops at mid and upper elevations and large avalanche paths in the eastern portion of the zone. Avoid traveling on or under slopes steeper than 35 degrees, particularly where you see blowing snow or recently formed wind slabs.

    Strong west and northerly winds formed reactive wind slabs on Thursday into Friday. Winds will shift southeasterly, though they may not be strong enough to transport snow. Watch for obvious signs of danger, like blowing snow, recently formed drifts, cracking in the snow, and recent avalanches. Given the underlying weak snowpack structure, the best way to stay safe will be avoiding loaded, leeward slopes steeper than 35 degrees. If you are traveling near Washington Pass, wind slab avalanches will be your main concern. In the eastern mountains, you could be contending with deadly persistent slab avalanches (see below).  The sun could initiate small loose avalanches on sunny slopes. 

    (1/7/2024)

    Even with little new snow, a natural wind slab occurred between 1/6-1/7 near Harts Pass.

    Photo: Jason Davis

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    Dangerous persistent slab avalanches are possible in the eastern mountains. These avalanches can be surprising, and they can break widely across terrain features. You can trigger them from below or from long distances away. You can stay safe by putting a large buffer of terrain between you and large open slopes 35 degrees and steeper. Only expose one person at a time to avalanche terrain. Stop and regroup in safer areas, well away from and out from under any steep slopes. Watch for obvious signs of the danger like cracks shooting through the snow and whumphing collapses. 

    You can find weak crust/facet combination 2-3 feet below the surface. The further east you are from Washington Pass and the Cascade crest, the weaker and shallower the snowpack will be. Observers have reported whumphing collapses and other signs of these avalanches on Delancey Ridge. On the 9th, a number of natural avalanches likely ran on old weak layers near Cutthroat Lake (see photo). At this point, those locations make up the western boundary of this problem. All of the recent snow is stressing underlying weak layers. 

    (1/12/2024)

    Natural avalanches on Tamarack Peak, near Harts Pass. These likely occurred Jan 11th with northwest winds. We don't know exactly which layer these avalanches ran on, but they look suspiciously like persistent slab avalanches. E-SE, 7200ft

    Photo: NCH

Avalanche Discussion

Observers report wind-affected surfaces, even in some low-elevation terrain, and recent storm snow totals of about 2 feet since the 8th. On the 11th, observers on Delancey Ridge and near Cutthroat Lake triggered small avalanches in recent storm snow and fresh drifts. Late in the day and overnight, natural avalanches ran due to northwest winds. Near Harts Pass, some of these may have run in older weak layers. See photo above. On the 10th, observers reported a number of large, natural avalanches over 2 feet deep near Cutthroat Lake (NE, ~6,800ft) that may have run on a crust from December 30th. On the same day, observers on Delancey Ridge reported over 20 rolling collapses at all elevations on a similar crust/weak layer that developed during the prolonged dry periods in December. 

"Weak and variable" sums up the snowpack. You may find up to 6 feet of snow on the ground at upper elevations near Washington Pass, with half that much in the mountains near Mazama. On the 12th, NWAC observers found a shallow, weak snowpack near Banker Pass and Goat Peak. There are several decomposing crusts and layers of sugary facets that developed throughout December. In some locations, these layers present as individual prominent bands; in others, they all meld together. Near and west of the Cascade crest, crusts are typically thicker and more stout, and the snowpack has fewer weak layers. On the 7th, NWAC staff went near Cutthroat Lake and found near-surface facets forming on south aspects. Crusts (Dec 30th and Dec 5th) with weak, faceted snow below and above failed on isolation in snowpack tests in the upper snowpack.

Even with the recent snow, coverage remains thin at lower elevations and in the eastern mountains. Watch for hitting rocks and logs or falling in open creeks.  If you're in the mountains, let us know what you see. Submit an observation here!

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