Avalanche forecast

Elkhorns

Wallowa Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Cooling temperatures have helped our wet snow avalanche problem, but it still remains possible to trigger a wet loose avalanche if you find yourself in wet unconsolidated snow in steep terrain.   Worrisome persistent weak layers still exist in the upper 3 feet of the snowpack and it is possible to trigger a large and destructive avalanche on mid and upper-elevation shady aspects.  If you find yourself in wet snow up to the top of your boot, it's time to scoot.  Careful snowpack evaluation is warranted before committing to any avalanche terrain that may be harboring a persistent weak layer. 

This forecast is sponsored by  CB Construction, Inc. 

Avalanche problems

  • Loose Wet

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

    The last week of warm and sunny weather has melted snow in the upper snowpack and water has dripped through the snow until it has reached a crust buried in the upper 2 feet of the snowpack.  This has created unstable upper snowpack conditions during the heat of the day.   Many natural wet loose avalanches have been observed since last weekend.  These often occur on solar aspects near rocks or cliff bands.  Last night, temperatures dropped below freezing at some, but not all weather stations.  Until we see a solid freeze at night coupled with lowering daytime temperatures, the likelihood of triggering wet loose avalanches in terrain steeper than 35 degrees remains possible.  

    Cloudy skies can help slow the onset of natural wet loose avalanches as the amount of direct sun that warms the surface of the snow is reduced.  That being said, the upper snowpack has been affected by strong solar input and multiple days without freezing temperatures and will take some time to lock back up once temperatures start to drop.   Even a smaller wet loose avalanche has the potential to knock you off your feet and carry you over consequential terrain or push enough snow into a terrain trap to bury you.  

    In your travels in the mountains today, pay attention to how wet the snow is under your feet or machine.  Get curious and dig down a few feet and see how wet the surface snow is as well as how deep water has percolated in the snowpack.  If you step off your machine or boards and are sinking up to your boot tops in wet snow, it's time to head to terrain less than 30 degrees in steepness.  

    Wet Loose avalanches on an East aspect at 8,000' in the Western Wallowas.

    Photo: Wallowa Avalanche Center

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    As your search for soft snow leads you to shadier aspects, you need to have your wits about you. 

    Several persistent weak layers exist in our upper snowpack.  Forecasters and observers have been tracking two layers of Buried Surface Hoar that have shown a concerning level of reactivity in snowpack tests.   These persistent weak layers have been found between 1-2.5' from the surface and are mostly on Northwest-North-Northeast aspects near and above the treeline.  A slab of cohesive snow sits above these layers, and as this slab has stiffened, we have not been seeing obvious signs of stability without digging into the snowpack to look for the layer and test its reactivity with snowpack tests.  This means that the freebie red flag signs of instability such as cracking or collapsing (whumphing) will likely not be present as you travel in areas where these weak layers exist.   The zones where these layers have been noted the most are the Western and Southern Wallowas as well as the Elkhorn Mountains.   

    The Rain Crust that was buried on February 1st has weak snow around it and should also be on your radar.  This layer has been found about 3 feet from the surface of the snow and sits below a hefty cohesive slab.  

    In shallower snowpack areas on Northerly aspects that hold snowpack depths of around 3-4 feet, there remains an off chance to trigger a deep persistent slab avalanche that could fail on weak faceted snow near the ground.  An avalanche of this magnitude would be catastrophic.  

    To decrease your chances of getting mixed up in this sort of fight, a thorough snowpack analysis is suggested before committing to any slope greater than 30 degrees on Northeast through Northwest aspects near and above treeline.  When you have uncertainty around the presence of these persistent weak layers, choose simple terrain less than 30 degrees.  

Avalanche Discussion

The snowpack has undergone a big change in the last week in the way of very warm temperatures and freely moving water in the upper snowpack.  Colder temperatures and more snow are on the horizon, but we are not out of the woods!  Stay vigilant in your mountain travels and snowpack assessment.  Many of us have built a mental winter road map that suggests stabilizing deeper snowpack conditions by this point in the winter.  The weather and snowpack this season demand that we recalibrate that operational memory and accept the current conditions.  Make a conservative travel plan to avoid areas where you have a higher level of uncertainty of the presence of persistent weak layers.  Avoid wet sloppy snow conditions as this is where wet loose avalanches are more likely to occur. 

The recent warm spell has destabilized cornices to the point that they could break naturally or as you step or ride near them.  Check out Wallowa Alpine Huts guide Killian Sump's observation here that notes several natural cornice failures and a recent slab avalanche.  Give cornices a "wider than you think" buffer.  

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