Silver Valley & Bitterroot Mountains

Problèmes avalancheux

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1–2.5

  Overnight temperatures have been sufficiently cool to create a thin layer of surface freeze, thereby reducing the morning avalanche risk. However, this freeze has been brief. With the sun rising high and early, particularly impacting South and East facing slopes as early as 8 AM, we anticipate another warm, sunny day ahead. By around 10 AM, we can expect the surface to thaw, and the avalanche risk to begin escalating. If you opt to venture out today, it's crucial to remain mindful of these evolving conditions. The combination of air temperature and sunshine can swiftly deteriorate slope stability. Both natural and human-triggered avalanches are equally probable under such circumstances. Determining the stability tipping point amidst rapid warm-ups like this can be challenging. Typically, there are discernible signs of snow weakening, such as punchy snow, rolling pinwheels, or small point release avalanches, indicating the snowpack's susceptibility to avalanches. It's advisable to embark early in these conditions while some slopes are still cool. Planning to exit the mountains early and avoiding steep, sun-exposed slopes and those under rockbands is strongly recommended.

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Unlikely

  Taille

  1–2

  We've been tracking a layer of surface hoar which is buried 1 - 2 feet deep, with intermittent distribution and reactivity. Melt freeze crusts exist in the snowpack that can be easy wet snow slide planes. Glide cracks on smooth ground features turning into natural avalanches are also more likely to occur now with melt water in the snowpack. These persistent weaknesses have built a poor, weak, snowpack structure. These types of weakness often do not show signs of obvious instability before avalanching. 

  For the most part, these layers have been resistant to failure and stubborn to failure, however rapid changes to the snowpack, like we're experiencing, can wake these layers up.  The timing can be difficult to figure out so we don't have a lot of confidence  on 'if' and 'when' these layers become a problem.

  **We've recieved 2 recent reports of human triggered avalanches in the Silver Valley zone. Both avalanches appear to be slidding on the buried surface hoar layer approximately 1-2 feet deep in the snowpack. Both avalanches were reported to be on N-NW slopes.