Avalanche forecast

East Cabinet Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Dangerous avalanche conditions persist above 5000'.  Additional snow and moderate winds formed wind slabs on all aspects at upper elevation ridgelines and leeward slopes. Persistent weak layers buried 2-4' down remain a concern and have potential to trigger a larger than expected avalanche.  This problem is widespread in the Purcell Range.  Avoid travel in or under steep terrain near ridgelines, and steep, open, or rocky slopes to minimize exposure to avalanches. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Light, low density snow and shifting winds during the past 72 hours formed wind slabs on all aspects above 5000'.  In many locations these slabs are forming on a firm bed surface and may be easy to trigger. You may encounter wind slabs in unusual locations.  Stiff or hollow feeling snow are a good indication you've found a wind slab.  Watch for pillowed or rippled appearing snow and steer clear of start zones above large open slopes or above terrain traps such as cliffs or gully features.  

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3

    Weak basal stucture in the form of facets, decomposing crusts ,and buried surface hoar are present 2-3 feet down in the Purcell Range, where the snow pack is thinner.  Avoid thin rocky areas and convex terrain to help manage this problem in the Purcells.  In the East and West Cabinets where the snow is deeper, distribution of these weak layers is spotty, and have only been observed on north facing aspects near treeline and above.   

Avalanche Discussion

Snow from Wednesday night's storm produced and average or .9" SWE  between four snotel sites across the Kootenai Zone.  Observations reported almost a foot of new snow at middle and lower elveations Thursday morning.  The storm came with relatively low temperatures and westerly and  southwesterly winds that transitioned to blowing out of the East and North on Thursday, and are blowing out of the East this morning.  Reactive wind slabs were observed on Northerly aspects in the Purcells on Thursday.  Larger terrain in the East Cabinets has the most potential to harbor large and sensitve wind slabs.  

This past weeks cold temperatures have prolonged the healing of both persistent weak layers and recently developed wind slabs.  In the Purcell's, the cold temperatures have promoted facet (weak snow) growth around the December rain crusts and at the base of the snow near the ground.  In the East and West Cabinets where snow heights are significantly greater there is more uncertainty around the distribution and reactivity of these persistent weak layers. 

Snow that fell Wednesday is soft and deep and sluff has potential to knock you off your feet and run a significant distance in steep terrain.  Take care to manage this problem if you step into steep terrain today.

Presently there is significant variability in snowpack structure between mountain ranges within the forecast zone.  If uncertainty exists take the time to dig in and evaluate the snow in the area you are riding, skiing, boarding, or trekking through. 

Temperatures are predicted to warm up through the weekend with small amounts of snow in the mountains and rain in the valleys.  Potential for increased instability exists if these forecasts hold true.  

Regions covered