Bollettino valanghe

Elkhorns

Wallowa Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

It will be possible to trigger an avalanche today as winds pick up and transport new storm snow onto the leeward side of ridgelines and cross-load mid-slope terrain features.  It also remains possible to trigger a deeper and more destructive avalanche in persistent 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).  

This forecast is sponsored by CB Construction, Inc. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    The snowpacks in the Northern Wallowas and Northern Elkhorns are currently weaker than the other forecast zones. Despite the warm weather and rain in late January, poor snowpack structure still exists. The possibility of triggering a persistent slab avalanche is still a very real one. The slab of snow sitting above the weak layers has continued to gain cohesion over the last couple of weeks.  This means that if you were to trigger a persistent slab avalanche, it would propagate further and be larger than you might think. Triggering one of these avalanches would have serious consequences. If you want to avoid avalanches you should stay off of slopes greater than 30 degrees. 

     

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    The 3-4" of new storm snow will be easily transported by SW winds today and deposited on NW-E facing terrain at and below ridgeline. An additional 3-4" of new storm snow today in the Northern Wallowas and 6" or more in the Elkhorns will only add stress to the weak old/new interface. This will create reactive wind slabs a foot thick or more with human-triggered avalanche possible.  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 leeside of ribs. Look for smooth pillows with a dabbled texture and if you get any kind of shooting crack or hollow-sounding snowpack underneath you, then make sure you stay off and out from underneath avalanche terrain. 

    (1/13/2024) Photo: Caleb Merrill

Avalanche Discussion

The persistent slab problem continues to plague or northern zone. There are weak layers toward the bottom of the snowpack that still remain reactive. Check out WAC forecaster, Caleb Merrill's recent observation from Mt. Howard a couple days ago.  Recreationsist should continue to be vigilant and seek out critical snowpack information to assess the reactivity of these deeply buried weak layers. The consequences of triggering an avalanche on these weak layers would be severe. 

The new storm snow is falling on a variable and weak old snow surface. This will create instabilities at the old/new interface. Where storm totals are around 6" or less 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). 

A big issue out there is that we had widespread surface hoar formation during the recent dry spell and cold clear nights. 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. Not a good situation.  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 propogate 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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