Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You may observe a wide range of storm instabilities as new snow piles up, but you’ll likely trigger the largest and most destructive avalanche in locations where the wind will blow new snow in thicker slabs.  Be especially cautious at higher elevations on the eastern edge of the zone, where it remains possible to trigger an avalanche failing on old snow near the ground.  Take a step back and avoid steep slopes if you see active wind loading or observe shooting cracks, hear whumphs, or notice recent avalanche activity. 

Problemi valanghivi

  • Storm Slabs

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

    As new snow piles up throughout the day, storm slabs may start developing at all elevations.  Expect these storm slabs to be touchy in locations where surface hoar or near-surface facets have been buried. Expect larger slabs to develop at mid and upper elevations where moderate to strong west winds will redistribute new snow into thicker drifts.  You will find these larger slabs living on the lee sides of ridgelines, below cornices, and scattered at mid and upper elevations.   

    Use hand pits or small test slopes to assess how the new snow is bonding to the old snow surface.  If you observe hard over soft layering, see cracking in the new snow, or notice recent avalanche activity - avoid steep slopes. 

    (4/10/2022)

    Storm slabs like this may be easily triggered as the day progresses, especially on the western edges of the zone during the later hours of the day.  Evaluate how the new snow bonds to the old snow surface.  

    Photo: Public Observation

  • Persistent Slabs

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

    Persistent slab avalanche problems take time to heal. Current observations have been limited across the east-south, however adjacent zones are dealing with a similar snowpack structure.  There is uncertainty with the distribution of these weak layers across the east-south. That being said, the most likely spot you can trigger a large persistent slab avalanche is on higher elevation slopes that face north and east and have been recently wind-loaded. 

    Dig down into the snow and look for sugary, weak grains near the bottom of the snowpack from late November.  You can use snowpack tests such as compression tests or extended column tests to locate these possible weak layers. 

    Stick to lower angle terrain if you observe recent avalanche activity, see shooting cracks under your skis/sled, or hear whumphs.

Avalanche Discussion

Tuesday is shaping up to be another cold and snowy day across the East-South.  Expect higher snowfall amounts on the western edges of the zone, such as areas closer to White pass and Chinook pass.  In these areas you may observe up to 4-6 inches by the end of day on Tuesday.   

These light trickles of snowfall will be falling on a patchwork of snow surfaces such as preserved cold snow in sheltered areas (including surface hoar and near-surface facets),  wind affected snow in the alpine, and a sun crust on steep solar aspects.  As new snow piles up, keep an eye on if surface hoar and near-surface facets are getting buried. This weak surface snow could be tomorrow's weak layer.  

Many lower elevation areas are still plagued with a shallow, early season snowpack.  Watch out for shallowly buried obstacles, such as downed trees, rocks, and open creeks.  Tread lightly if you're snowmobiling or skiing around!

Observations have been quite limited across the zone. So if you get out, please let us know what you see by submitting an observation! 

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