Lawinenlagebericht

East Cabinet Mountains

Idaho Panhandle Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Persistent weaknesses in the snowpack are becoming difficult to trigger in the Cabinets, but still remain a concern in the Purcell Range at treeline and above. The only way to approach this issue is to avoid steep and open terrain or take the time to dig down to the early March rain crust to verify the potential at your location. Smaller and less consequential issues such as pockets of wind slab and wet loose avalanches may be a concern as well, dependent on location. Details below!!

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    Across the area we have a combination of weak sugary snow (facets), resting on firm rain crust. The slab resting on top of this weak layer is about 20" thick or more. Test results show this layer to be consistently failing and propagating with moderate force in the Purcells last week. In the Cabinets, this weak layer has gained strength. Yesterday's stability tests in the East Cabinets varied from propagation with hard force to not propagating at all, depending on location.  This weak layer has a lot of potential and if triggered it will likely propagate widely across a slope resulting in high volumes of debris and a deep burial. In the Purcell Range,  the early March rain crust is thinner and avalanches could step down below the rain crust, to an even deeper weak layer above 6,000' in elevation. I would continue to treat  steep and open terrain with suspicion today, take the time to dig down about 3 feet and see if this weak layer is reactive at your location before committing to consequential terrain.

     

    This videos was taken on March 17th in the Purcell Range and demonstrates the current persistent slab weakness. 

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Light to moderate winds out of the west and southwest have transported snow onto leeward aspects at upper elevations near ridgeline. South and west aspects in the alpine are mostly scoured down to the rain crust above treeline. At treeline we observed pockets of drifting and loading on all aspects, wind slabs were difficult to trigger and generally small.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    Temperatures will rise today and the sun may start to poke out as well. Lower elevations are pretty crusty right now but as the sun comes out and temperatures rise we can expect the surface to start getting loose and releasing small, wet slides. This will be more of a problem on Wednesday with an increase in sun exposure.

Avalanche Discussion

Yesterday we travelled into the East Cabinets and were able to get just above the treeline. We dug in multiple locations and found that the persistent weak layer varied from propagating with hard force to not propagating at all. Time and moderate temperatures are slowly bringing the snowpack to a more stable scenario. While travelling through open timber at elevations between 5,500' and 6,500' we found evidence of wind that had moved the snow into small pockets of slab near ridgelines and depressions. There was a bit of a breakable crust on south and west aspects from the weekend sun, northerly locations were still nice and soft and remain highly "shred-able"

There are some persistent issues in the snowpack that are very widespread in type and potential, but there is also some wide variance between the Cabinets and Purcells in the thickness of our early March crust layer. This difference in the crust strength and thickness has me somewhat worried about the potential for any avalanches that are triggered to step down to deeper weaknesses and create much bigger avalanches in the Purcells right now. Last Thursday in the Purcells, the layer of concern was about 20" deep and propagating with moderate force. The upper snowpack will continue to become more resistant to triggers with time. So, to summarize I would continue to avoid steep and open terrain in the Purcells, in the Cabinets take the time to dig down to the early March rain crust and see if this weak layer is present and reactive before committing to a slope.

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