Bulletin d’avalanche

East Cabinet Mountains

Idaho Panhandle Avalanche Center
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Danger d’avalanche

Sat
Alpin
1 · Faible
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Our snowpack is currently in a state of good stability. The only concern we are finding within the snowpack is in isolated locations at treeline in the Purcell Range. Steep terrain at treeline in the Purcells should be treated as a potential threat until you take the time to assess the stability and presence of surface hoar.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1.5–2

    There is a layer of surface hoar in the Purcell Range approximately 15" deep at treeline that was producing results with hard force Thursday. This layer of surface hoar is underneath a rain crust and a cohesive upper snowpack, which will make it difficult to trigger. The only way to assess it's presence is to stop and perform a stability test at your location, it is unlikely it will make itself known other wise. The spots to watch out for will be steep openings in the timber on the upper edge of treeline. 

Avalanche Discussion

It's not every day that we throw out a "LOW" avalanche danger rating, and I would like to remind everyone that "LOW" danger does not mean no danger. By definition "LOW" danger means small avalanches in isolated or extreme terrain. Currently that is very fitting for our snowpack status. Because the Purcell Range is comparitively low use and a snowpack "outlier" for our forecast area I am sticking with a LOW danger rating that reflects our overall area. If I had to rate the danger at treeline in the Purcell's as an individual forecast I would be placing that isolated part of the area closer to MODERATE in danger.

This week I spent Monday in the East Cabinets and Thursday I toured up to NW Peak in the Purcells. Condition's vary between ranges which is pretty standard, but there are some uniform structure's within the snowpack across the area. The "Christmas Crust" is much thicker in the Cabinets which has created a stronger bridge abover our pre-existing weak layers. I have been above 7,200' in both ranges and found the crust layer prevelant on all aspects. The crust is covered with a fresh coat of snow that bonded to the crust quite well due to the warm and wet nature of the storm. Windslabs that developed this past weekend have become stable enough that triggering them is very unlikely unless you are in a very steep and loaded pocket at high elevations. Stability tests in the Purcell Range produced results on a layer of surface hoar that survived near treeline and is bridged by a crust layer. Although this problem is isolated and unlikely to be triggered due to the crust, it is worth paying attention to if riding in the Northwest Peaks area. Low likelihood and high consequence problems are easy for us humans to ignore and rationalize, so keep your "spidy senses" tuned in today.

FREE!! Introduction to Avalanches Course is being offered Friday evening. The class is being held at the Kootenai N.F. Supervisors office in Libby. It will start at 5 P.M. and last 3-4 hours. All are welcome to attend regardless of experience. A field day for backcountry skiers and splitboarders will follow on Saturday the 7th at Flatiron Mountain. Details for field day will be discussed in the class session.

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