Hatcher Pass

Problèmes avalancheux

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Above 2500 ft it remains possible to trigger large slab avalanches 1-3 ft deep on weak persistent grains in the snowpack.

  Our current snowpack structure is poor with generally strong snow sitting on weak faceted snow. An active first half of the month left us with a foot or more of new snow that fell on an old, weak, and faceted snowpack. The persistent slab problem that this setup creates can be a challenging and dangerous one to navigate. Triggering one of these avalanches is a relatively low probability, high consequence scenario. This means that while you might be able to travel all day without your weight collapsing the weak layers buried below, if you do it's got the potential to be a painful or deadly experience.

  Things to know and keep in mind that will help you navigate this problem:

  • Periods of strong to extreme east through (clockwise) southwest winds transported snow, loaded slopes, and created dense slabs on crossloaded or leeward slopes. While this does mean that all snow we want to ride is where we're more likely to encounter the problem, we can travel on scoured terrain to help minimize our exposure. 
  • It's more likely to trigger an avalanche on a slope steeper than 30°. While persistent slab avalanches can behave in novel ways and be triggered remotely or from lower-angeled terrain, you'll generally be safer sticking to smaller, less consequential, and lower-angled slopes.
  • Maintaining a conservative mindset, observing for red flags, and practicing safe travel protocol will keep you grounded in safe practices while we wait for this problem to resolve.

  This problem will be less likely to be encountered at lower elevations where there was generally less new snow and the slab is overall a bit softer and lacks cohesion. That said, riding in this terrain can still be challenging due to vegetation and punchy snow.

  *ADDITIONAL CONCERNS* - Moderate to strong southeast winds yesterday and overnight will have created fresh drifts and thin new wind slabs on upper elevations leeward slopes. These could be sensitive to human trigger. Accumulating snow this evening into Monday could contribute to storm snow instabilities including loose dry or soft slab avalanches.