Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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2 · Moderato
Sotto il limite
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In sintesi

Temperatures are on an upward trend, and if snow changes over to rain at lower elevations, you may see small wet avalanches in steep terrain. There is also an unlikely but high consequence chance of triggering avalanches on deeper weak layers in the eastern mountains. Make sure to travel with these larger avalanches in mind and consider steering clear of steep, open slopes further east in the zone. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Warming temperatures and rain on the recent snow could produce small wet loose avalanches in steep terrain. Wet avalanches often start from trees or rocks shedding snow onto slopes below, but you can also trigger them with your skis or snowmobile. If it's raining on dry snow or snow becomes wet and heavy, consider moving to lower angle slopes. 

    Roller balls were seen on Jan 21st in low elevation terrain and mid to upper elevation terrain in direct sun

    Photo: Willie Webster

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–2.5

    While persistent slab avalanches are unlikely, the uncertainty and consequences of triggering one have kept the problem on the forecast. In addition, peppered throughout the zone are observations of unstable snowpack test results and large rolling collapses propagating across terrain. Mountains in the central third of the zone (near and east of Mazama) would be most suspect for these avalanches. If you travel in areas near Hart's Pass, the Lost River, Eight Mile Creek, the Twisp River drainage, or the Chewuch River, be ready to make assessments of the snowpack. We know less about conditions in those areas other than they hold a weaker snowpack. If you managed to trigger one of these avalanches, it could break widely across terrain features. Any red flag signs of danger, like shooting cracks or whumphing collapses, should be heeded. The problematic snowpack structure is a series of crusts and weak layers buried in December, now in the lower third of the snowpack. To be safe, you can choose well-supported and lower-angle slopes for travel. Stop and regroup in safer areas, well away from and out from under 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

Observers reported the impacts of warming temperatures in the past few days. On Saturday and Sunday, observers reported rollerballs and small, wet loose avalanches. On Friday, observers experienced warmer temperatures and a little light rain below 3,000ft. The recent storm snow is bonding well and has become difficult to trigger. The interface below the storm snow produced resistant failures in tests with no reported avalanches since the 17th. On that day, observers reported widespread slab avalanches in the 1 foot of new snow on almost all slopes steeper than 30 degrees. 

An NWAC 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. NWAC observers near Mt Tiffany and the far eastern mountains near Conconully. Generally, there wasn't enough consistent snow cover to sustain large avalanches. The deepest area he found had 2.5 feet of snow at 6,800ft. Many slopes have logs and brush sticking through the snow on the ground.

On the 19th, observers on North aspects near Cutthroat Lake reported two collapses. They also saw what may have been a deeper crown in poor visibility. An observer also reported a collapsing on January 16th on an ESE aspect at 6,200ft near Varden Creek. It's been some time since the last confirmed avalanche on deeper layers. On the 12th, an NWAC observer recorded recent wind slab avalanches, one of which may have stepped down to a deeper layer near Goat Peak. On the 10th and 11th, natural avalanches occurred on persistent weak layers near Harts Pass and Cutthroat Lake.

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

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