Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Light snowfall may lead to shallow new snow instabilities on Thursday. A large trigger like a cornice fall, snowmobile, or group of people in the wrong spot could trigger a large and destructive avalanche that runs on old facets and crusts from December. Identify steep and unsupported terrain to steer clear of,  and give yourself a wide buffer away from complex terrain for the time being. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    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. Although the chances of triggering one of these avalanches have declined, if you did trigger one it could be 2 to 3ft deep and destructive.

    Persistent slabs are a tricky problem, often leading to a false sense of security with a lack of 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, with a wide buffer away from potential runout zones. The snowpack further east in the zone is more shallow, so it would be worth more caution in those areas as slabs may be more reactive. 

    (1/21/2024) Photo: Luke Huntington

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

Avalanche Discussion

Observers reported 3 inches of new snow near Blue Lake on Wednesday, and another couple inches may fall on Thursday. With the new snow comes potential for small sluffs on Thursday. These loose dry slides could run off steep cliffy areas during periods of heavier snowfall rates, and could be triggered on steep slopes. Later in the day at lower elevations or in the sun, look for rollerballs and feel for moistning snow as a clue to potential wet loose slides. At upper elevations, light winds could drift the new snow into small wind slab pockets. Look for slightly textured surfaces and cracking as a sign of these near ridgetops.

On the 24th observers found sudden collapse failures on old facets and crusts from December with tests on a NW aspect at 6,800ft west of Washington Pass. On the 23rd observers reported a number of small loose and wet loose avalanches of very steep, craggy terrain. Warming temperatures noistened snow surfaces up to about 6,000ft on all aspects. 

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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