Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

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

After a quick shot of over a foot of new snow and some incoming wind, it will still be easy to trigger avalanches in the upper snowpack. The dragons in the basement are the persistent slabs- a weak structure remains in places, and new snow may stress these deeper layers. Minimize your exposure to big avalanche paths and start zones while the new snow adjusts and stick to lower-angled and supported slopes. 

Lawinenprobleme

  • Storm Slabs

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

    Storm slabs built rapidly on Wednesday with over a foot of new snow near Washington Pass. Avalanches may be easier to trigger and bigger at upper elevations and on leeward slopes where the wind forms deeper drifts. If you find signs of instability like shooting cracks, steer away from steep slopes. Small test slopes and quick, informal tests can give you a good idea of how easily the snow will slide.

     East of Washington Pass, avalanches in storm slab could step down to more deeply buried weak layers, become very large, and propagate across terrain features. So increase your margins by sticking to lower-angled slopes and creating a buffer zone between you and potential runout zones. 

    (12/14/2023)

    An example of a large slab below in Blue Lake Cirque that ran in early December. SS-N-R2-D2-I

    Photo: Matt Primomo

  • Persistent Slabs

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

    With all the new snow, persistent slabs may be easier to trigger. We've been receiving reports of whumphing collapses even as recently as Tuesday, with a few 'sapling shakers' on an ESE aspect at 6,200ft near Varden Creek. Any slide triggered would be surprising, and they can break widely across terrain features. Red flag signs of danger like shooting cracks and whumphing collapses should be heeded, but I wouldn't wait until you get one to avoid steeper slopes. The problematic snowpack structure is in place, and is thought to be more problematic in areas with a shallower snowpack from about Cutthroat drainage and east. 

    Use well supported and lower angled slopes for travel. Stop and regroup in safer areas, well away from and well away from potential runout zones of larger slopes. 

    (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

On Wednesday, observers in the Cutthroat Creek area reported widespread small avalanches in the new snow on almost all slopes steeper than 30 degrees. they reported a total of 1 foot of new snow by mid-afternoon with periods of snowfall exceeding 1"/hr.

Between January 8th and 12th, storm totals were around 2 feet for much of the zone. On the 16th, an observer reported 'sapling shaking' collapses on an ESE aspect at 6,200ft near Varden Creek. He dug down and identified the weak layer over 2ft down as soft, sugary grains beneath a crust from mid-December. On the 12th, an NWAC observer recorded recent wind slab avalanches, one of which may have stepped down to a weaker layer near Goat Peak. Earlier in the week,  multiple parties reported triggering small avalanches in recent storm snow and fresh drifts, and natural avalanches ran with strong northwest winds. Some of these may have stepped down to deeper weak layers, especially near Harts Pass and east. On the 10th, observers reported several large, natural avalanches over 2 feet deep near Cutthroat Lake (NE, ~6,800ft) that may have run on a crust from December 30th. 

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. Several decomposing crusts and layers of sugary facets developed throughout December. In some locations, these layers present as individual layers; in others, they all meld together. Near and west of the Cascade crest, the snowpack is deeper, has less weak layers, and the crusts are typically thicker and more stout.

If you're in the mountains, please let us know what you find.

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