Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

This won't be the day to test your luck. Warming, persistent slab concerns, wind-drifted snow, and wet avalanches will make for a dangerous Thursday. This warm-up will be a great reason to dial it back and avoid large slopes greater than 30 degrees at middle and upper elevations. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Triggering a 2-4 ft deep avalanche that propagates across terrain features remains likely. Significant warming through the day will not help matters and could be the key ingredient pushing the snowpack over the edge. 

    Persistent Slab avalanches can release in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. They can break hundreds or thousands of feet wide. Before triggering an avalanche, you probably won't experience snowpack collapsing or other obvious signs of instability. 

    You're most likely to trigger one of these deadly avalanches on middle and upper elevation slopes, especially in wind-loaded terrain. 

     

    (3/7/2024)

    You could trigger similar avalanches on Thursday. 

    Skiers triggered this large avalanche on a south-facing aspect around 6500ft on Van Epps Peak. They triggered this slide while climbing an already established skin track for a second lap. 3/7/2024 HS-ASu-R2-D2-O

    Photo: Aaron Benevich

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    These slabs will be larger, more widespread, and possibly easier to trigger as you climb. Winds are forecast to shift more easterly, which may start redistributing snow onto unusual aspects throughout the day. You'll want to use visual clues like blowing snow, textured surfaces, sharp drifts, and cornices to help you identify wind-loaded aspects. These slabs will often appear rounded or pillow-like. Shooting cracks under your feet or sled are obvious clues you found an unstable slab.

     

    Remember that this wind slab problem likely rests over the persistent weak layer mentioned above. Any triggered wind slab could break deeper and wider than you may anticipate. 

    (3/13/2024)

    Visual  clues help highlight where wind slabs may occur.

    Photo: Dallas Glass

  • Loose Wet

    • Tutte le quote
    Probabilità
    Likely
    Dimensione
    1–1.5

    The warming temperatures will shock dry snow surfaces on Thursday. As the day progresses, you'll likely see rollerballs, pinwheels, and wet loose avalanches on steep sunny slopes. You may even witness signs of warming on shadier slopes during the later afternoon as the warming intensifies. Pay attention to snow shedding off trees, rollerballs/pinwheels initiating, and sticky surfaces to help you pinpoint what slopes are heating up. Move to shadier aspects once you notice these signs of warming. 

    Photo: Joe Dellaporta

    An example of rollerballs. Steer around slopes once you notice these signs. 

Avalanche Discussion

The Cascades are heading into a stretch of very warm sunny weather. It will be the first big, spring-like warming event of the year, with high temperatures in the 50's and freezing levels over 10,000'. Very warm conditions through the weekend could produce significant slab and loose snow avalanches. 

As with any warming event, there is a high level of uncertainty as to where, when, or even if this scale of avalanche activity will occur. On the other hand, big natural avalanches aren't really the kinds of things that should be taken lightly. It's worth noting that smaller wet loose or wind slab avalanches, cornice falls, or snow shedding from cliffs can provide the trigger needed to pull out 

Avalanche conditions remain active and dangerous across the East South. Additional warming will certainly not help matters in the coming days. As recently as Saturday, a skier triggered a very large (D3) avalanche in the Teanaway. The skier was caught and carried nearly 1000 vertical feet but miraculously came to rest uninjured on the surface. On Thursday, snowbikers remotely triggered two very large avalanches in the Teanaway, and there was a close call with a skier who was caught and carried in an avalanche on the S aspect of Van Epps Peak. Earlier in the week, snowmobilers triggered large avalanches around the Blewett Pass area, and a skier was partially buried with minor injuries in an avalanche on a NW aspect of Jim Hill in the neighboring Stevens Pass zone. Last Saturday, there were two separate incidents near Darland Mountain. One avalanche resulted in a close call, but unfortunately, in the other, a snowmobiler was fully buried and did not survive.

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