Bulletin d’avalanche

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Continued warm temperatures are weakening the snowpack. Snowpack conditions vary between shaded and sunny slopes but have formed an overall weak and dangerous snowpack. Avoid being on or under all steep slopes, particularly in the sun.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2

    The snow surface has become wet and weakened by sun and warm temperatures over the last 3 days. Surface instabilities may appear harmless but  wet snow can entrain enough mass to catch and injure a person and/or enough mass to trigger a step down to deeper avalanches. Roller balls, sinking down penetration and a saturated wet snow surface are signs to look for wet loose surface instability.  

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–3

    A layer of surface hoar 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.

Avalanche Discussion

As stated in the bottom line, varied snowpack conditions exist yet all aspects currently have dangerous avalanche conditions. There are currently two snowpack instability issues - the sun and the shade. These two combined cover all aspects and overlay in some spots.  

The sun - The last few days have seen a rapid rise in temperatures with intense sun. The top of the snowpack has meled, the top few inches becoming wet saturated weak snow. Additionally, overnight temperatures have not been cold enough to have much of an overnight freeze, even at high elevations. The continuation of this cycle, and forecasted precipitation later this week, will create more weak snow at the surface, creating more potential for bigger wet snow slides. 

The shade - some shaded and sheltered aspects hold significantly different conditions, untouched by the recent warm weather. Wet snow problems can be minimized in the shade but a wet snow problem is then traded for a persistent weak layer problem. A buried weak layer of surface hoar (from Feb 10th) is down 1 - 2 feet deep. Recent avalanches have been reported on this layer.

Combined - An overlay of sun weakened wet snow and buried surface hoar likely exist in some locations. Each of these two issues on their own pose a hazard but combined rise avalanche likelihood even higher. The current snowpack is complex. Both problems, persistent weak layers and wet snow avalanches are difficult to predict. Also, both tend to not show obvious signs of instability before avalanching. Choosing lower angle, simple and less consequential terrain lowers your overall risk.

Régions couvertes