Avalanche forecast

Blues

Wallowa Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

New snow and wind have built wind slabs on northwest through east-facing slopes. It remains possible to trigger a deeper and more destructive avalanche failing on weak layers buried 2-6' deep in the snowpack.  To avoid avalanches, steer clear of terrain steeper than 30 degrees, wind-loaded slopes, and areas that harbor a shallow snowpack (less than 3 feet).  

If temperatures get above freezing and it begins to rain you should exit avalanche terrain.

This forecast is sponsored by La Grande Sno-Drifters Snowmobile Club.

Avalanche problems

  • Wind Slabs

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

    The 6-8" of snow that fell on Thursday and Friday has been easily transported by SW winds and deposited on NW-E facing terrain at and below ridgelines. Moderate south winds on Saturday continued to move snow building larger wind slabs. The snow that arrived last night was accompanied by more moderate wind adding to the already existing wind slabs.

    Look for and avoid slopes with cornices , wind pillows, textured snow, and smooth hollow sounding snow. Cracking in the new snow is a sign you've found a wind slab.

     

    (1/11/2024)

    Rippled Snow Surface and Cracking are good indications of wind slab development. 

    Photo: Caleb Merrill

  • Persistent Slabs

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

    Areas of the Blues still contain a poor snowpack structure. Weak snow sits below a very dense mid and upper snowpack. You are most likely to find this structure and trigger a persistent slab avalanche where the total snow depth is less than 3'. Avoid trigger points in the terrain including steep convex rollovers, rocky slopes, areas with lots of exposed bushes, and scoured areas where the snowpack is thinner. 

    (2/15/2024) Photo: Wallowa Avalanche Center

Avalanche Discussion

The persistent slab problem continues to plague the Blue Mountains. There are weak layers toward the bottom of the snowpack that still remain a concern.  Recreationalists should continue to be vigilant and seek out critical snowpack information to assess the reactivity of these deeply buried weak layers. If you lack the skills to gather this snowpack information you should avoid avalanche terrain.  

Snow on Thursday and Friday fell on a variable and weak old snow surface.  After a brief break in the snowfall action Saturday, snow picked back up overnight. This has likely created instabilities at the old/new interface. Where storm totals are around 6" or less, or the new snow remains uncohesive, the main problem will be loose dry avalanches on slopes > 35 degrees. These small avalanches may not bury you, but they could inflict significant bodily harm if they were to take you off your feet or sled and sweep you into obstacles like rocks and trees. Where storm totals exceed 12" there will be a storm slab problem. The best practice for avoiding this problem is to stick to slopes < 30 degrees (i.e. stay out of avalanche terrain). 

There was widespread surface hoar formation before the Thursday- Friday storm arrived. Surface hoar is a notorious weak layer when buried. There is uncertainty about whether this surface hoar was buried intact and is reactive.  Pro Observer Sarah Jakober went searching for surface hoar in the Elkhorns and did not find it.  Yesterday in the Southern Wallowas we found it buried intact but laid over and unreactive in stability tests. Another observation from the Western Wallowas mentions finding it yesterday.  Likely locations for encountering buried surface hoar include more sheltered and protected slopes at and below treeline. If you are hearing the snowpack whumpf underneath you or seeing shooting cracks propagate outwards as you travel, then surface hoar is likely present at the old/new interface. This should have you dialing back your terrain choices and keeping off and out from under slopes > 30 degrees. 

 

 

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