Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Tue
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 7 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Isolated areas of unstable snow may exist on very steep slopes, particularly at elevations above 9,000'. Be on the lookout for areas where old stiff, wind-drifts overlie weak, sugary snow near the ground. If you are traveling in the furthest west reaches of this zone — the only place that got any snow — thin, freshly formed wind slabs will be sensitive to your weight. 

Problemi valanghivi

  • Persistent Slabs

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

    The last significant, reported avalanche in this zone took place 11 days ago. During avalanche mitigation work,  ski patrollers at Bald Mountain intentionally triggered an avalanche on a heavily wind-loaded slope with weak, sugary, faceted snow in the lower part of the snowpack. When you're out in the mountains today, this is precisely the type of scenario that you should be looking for: strong, dense slabs of wind-drifted snow sitting on top of weak snow near the ground.

    ADDITIONAL DISCUSSIONYesterday's storm left the vast majority of this zone dry. However, if you're traveling in the far northwestern portion of the zone you may find an inch or two of fresh snow. Unfortunately, strong winds out of the NW have likely already transported whatever "powder" you might have found into small slabs. Look for thin, fresh wind slabs in upper elevation terrain. These will have formed on a variety of slippery surfaces including icy crusts and old, hard slabs. These won't be large enough to bury a person but could be fast-moving and push you off your skis or your sled in steeper terrain.

Avalanche Discussion

The winter of the haves and the have nots continues. If you frequently ski or ride in this zone, you know that you are in the latter category. Yesterday's storm brought 1" of snow to the furthest west portion of this zone and nothing at all to the rest of the area.  This pattern has been present for much of the winter and has "helped" to generate the ongoing persistent slab problem that we're stuck with. For weeks we've been warning you about the sort of terrain where you are likely to encounter this sort of problem: steep, wind-affected, and alpine. Let's take a minute to look at why these sorts of areas are more problematic.

  • Steep: As a slope gets steeper, gravity is pulling down more intensely on the slab. Slopes in the 35-45 degree range are at the sweet spot, where it isn't so steep that the snow just sluffs off, but it is steep enough for gravity to have an appreciable downward force on the snowpack. 
  • Wind-affected: The wind plays two roles to increase the likelihood of triggering slides. In areas that are more commonly scoured, the snowpack is thinner and the weak layers are closer to the surface and easier to impact. In areas that are loaded, a stiff, dense slab of snow is stressing the weak snow underneath. Oftentimes these areas exist right next to each other, creating a scenario where likely trigger points are adjacent to meaty slabs. Not good.
  • Alpine flavor: Upper elevation terrain is typically steeper and more wind-affected than terrain lower on the mountain. In addition, this sort of terrain commonly has lots of scree piles, rocky ribs, and cliff bands. These features help to create lots of thin spots on the snowpack where weak layers are closer to the surface and easier to impact.

Take a minute to scroll through our media gallery and look at some of the deeper avalanches that we've been seeing this season. Try to identify these characteristics on slopes that have already avalanched. Then, as you are out in the backcountry, see if you can find slopes that have similar characteristics that haven't avalanched. These are exactly the types of slopes where you are most likely to encounter this problem today. The likelihood of encountering this problem isn't high, but the consequences sure are. 

Regioni coperte