Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Another round of snowfall may create shallow new snow instabilties on Wednesday. Any small slide, cornice fall, or large trigger could initiate a much larger, deeper avalanche on persistent weak layers from December that are 2-3ft deep. Stick to lower angle and well supported slopes if you don't want to risk a big one.

Lawinenprobleme

  • Persistent Slabs

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

    A problematic snowpack structure exists due to a series of crusts and weak layers buried in December, now in the lower third of the snowpack. Observations of large rumbling collapses and unstable snowpack test results have continued to come in over the past week, including the fairly fresh looking large slide that seems to have been triggered by a cornice on the 21st. If you managed to trigger one of these avalanches, it could break 2-3ft deep, and widely across terrain features. 

    Persistent slabs are a tricky problem, often leading to a false sense of security with no apparent signs of instability, such as collapses or shooting cracks. A cornice fall, small surface avalanche, or snowmobile could be the trigger for one of these. Maybe it's not the first skier or rider on the slope, but it could be the second or third. A good strategy is patience and conservative travel choices. Choose well supported and lower angle terrain. Stop and regroup in safer areas, well away from potential runout zones. 

    (1/21/2024) Photo: Luke Huntington

    Large, fresh persistent slab triggered by a cornice fall in Cutthroat drainage.

Avalanche Discussion

With a shot of new snow comes potential for small avalanches on Wednesday. Loose dry slides could run off steep cliffy areas during periods of heavier snowfall rates. Shallow storm slabs could form if enough (>6") new snow falls. Look for shooting cracks as a sign of this instability. Later in the day at lower elevations, the new snow may become wet, so look for rollerballs to clue you into the potential for small loose wet slides on steep slopes.

On the 23rd an observer in Cutthroat drainage reported some recent small loose avalanches off very steep slopes. They found minor cracking in wind drifted snow near the entrance of a chute. With the warm temperatures, snow surfaces had become moist on all aspects up to about 5,800ft. Tuesday, Sunday and Saturday, observers reported rollerballs and small, wet loose avalanches. 

The most notable observation regarding persistent slabs that we've received recently was a large cornice triggered slab in Cutthroat drainage on the 21st. Observers have been reporting collapses in the Cutthroat Lake area, Varden Creek area over the past week. Deeper crowns had also been spotted, albeit with poor visibility.

Further east, on the 21st an observer in the Twisp River area found that the mid-December crust produced unstable propagation saw test results. They also experienced loud whumphs that shook trees as the collapse propagated widely across the terrain. The snowpack near Mt Tiffany near Conconully was found to be very thin, and the deepst area was only 2.5ft deep at 6,800ft. 

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

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