Avalanche forecast

Southern Wallowas

Wallowa Avalanche Center
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Avalanche danger

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

 Storm slabs 12-18" deep are a potential problem on all aspects. Sensitive wind slabs several feet thick may be present near and above treeline on NW-N-E aspects. Riders should avoid slopes > 30 degrees where storm totals exceed a foot or that are loaded by the wind.

This forecast is sponsored by Anthony Lakes Mountain Resort.

Avalanche problems

  • Wind Slabs

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

    The 12-18" or more of new storm snow has been easily transported by mostly SW winds and deposited on NW-E facing terrain at and below ridgeline. Today moderate S winds will continue this process.  This will create reactive wind slabs up to several feet thick.  Riders should avoid slopes > 30 degrees where recent signs of wind-loading are evident. This includes areas below cornices and ridgelines on NW - N - E facing aspects and cross-loaded terrain features mid-slope like on the lee side of sub-ridges. Look for smooth pillows with a dabbled texture and if you see shooting cracks or hear hollow-sounding snow underneath you, then exit off and out from underneath avalanche terrain.

    (2/16/2024) Minor cracking under skis and small windslabs on exposed NW facing terrain.

  • Storm Slabs

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

    The Southern Wallowas above 5500' received 1.5" of water and 12-18" of new snow on Thursday and Friday. This new storm snow fell onto existing variable snow surfaces. These old snow surfaces include slick melt-freeze crusts on southern exposures and potentially surface hoar on more protected slopes at and below treeline. Surface Hoar was widespread before this storm and there is uncertainty about whether it was buried intact. Please let us know what you are seeing out there.

    An additional consideration is the possibility of triggering loose dry avalanches on steep slopes ( >35 degrees) where the new snow lacks the cohesiveness to produce a slab avalanche. The large amount of snow involved and the fast movement of these sluffs downhill could be a potential threat to life and limb. Steer clear of steep slopes where the new snow is overlaying slick crusts, buried surface hoar, and/or the consequences of getting caught could take you into a terrain trap like a gully or tree fence. 

Avalanche Discussion

The new storm snow (12-18") has fallen on a variable and weak old snow surface. This has likely created instabilities at the old/new interface. Where storm totals are around 6" or less, and/or the new snow remains cohesiveless, 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. It can propagate fractures for long distances and while you may be on low-angle terrain, those fractures can propagate up onto a steep slope above you and release an avalanche. Likely locations for encountering buried surface hoar include more sheltered and protected slopes at and below treeline. If you are hearing the snowpack whoomph 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. 

Recent observations in the Elkhorns, Southern Wallowas, and Northern Wallowas paint a great picture of what this storm has left behind. 

 

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