Lawinenlagebericht

Northern Wallowas

Wallowa Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Winds out of the Northwest and Southwest have loaded new snow onto leeward aspects and cross-loaded mid-slope terrain features.  To reduce your chance of triggering an avalanche today, avoid wind-loaded start zones.  Persistent slab avalanches remain possible where buried surface hoar exists now 3 feet from the surface.  Determine whether this persistent weak layer is present in the terrain before committing to riding any slope greater than 30 degrees. 

This forecast is sponsored by Eagle Cap Mountain Guides, based out of La Grande. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    The Southern Wallowas around Norway Basin picked up 3-4" of new snow on Monday and Tuesday, while the Western Wallowas picked up higher amounts around 8-10".    Winds out of the Northwest and Southwest have loaded the new snow onto leeward aspects and cross-loaded mid-slope terrain features.   Observers in Norway Basin report thin wind slabs near and above treeline in leeward terrain.  Look for patterns of wind loading and clues to wind-loaded slopes as you travel through the mountains today.  Visual clues include rounded and smooth-looking deposits of snow.  Look for corniced ridgelines and windward areas that are stripped of new snow.  Avoid traveling in wind-loaded start zones to reduce your risk of triggering a wind slab.  

    (2/14/2023)

    Active wind loading during Monday's storm 

    Photo: cm

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3

    A layer of buried surface hoar that is now buried 2-3 feet was reactive to remote triggering last week.  While becoming less likely to trigger, careful slope scale evaluation will remain a prudent idea before committing to terrain greater than 30 degrees Near and Below Treeline on NW-N-E aspects.  As these layers of surface hoar become more deeply buried, they can be difficult to see in your snowpit wall, so it is recommended to conduct a shovel shear test and/or extended column test to see if there are any failures on this layer.  If you need to brush up on your snowpack test skills, here is a great resource.  While this persistent weak layer may be at the upper reaches of being able to be triggered by a skier or snowboarder, it remains more possible for snowmachine to trigger this layer- especially in an area where the new snow has been stripped by wind.  

    (2/9/2023)

    Photo of a remotely triggered persistent slab avalanche in the Southern Wallowas. This avalanche occurred on a northeast facing slope at 7600' . Avalanche occurred Wednesday or Thursday.

Avalanche Discussion

In addition to the above primary avalanche problems, expect to see some small Loose Dry avalanches on protected shady aspects in terrain steeper than 35 degrees.  On more solar aspects, we could also see small Loose Wet avalanches.  The warning signs of these will be pinwheels and rollerballs as the surface snow on solar aspects loses cohesion.  With both of these avalanche problems, avoid riding terrain that is above terrain traps such as gullies, cliffs, or dense trees.  

Here's the takehome as our snowpack continues to gain strength:  Avoid wind-loaded terrain.  Use small inconsequential test slopes to test the reactivity of wind slabs using your skis or machine.  Where shallow snowpacks exist (less than 4 feet), it is important to avoid areas that hold a cohesive slab above sugar snow.  Avoid trigger points such as rocky convex rollovers with terrain steeper than 35 degrees.  Be aware of avalanche paths that may be connected to areas with shallower snowpacks.  Even in times of decreased avalanche hazard, continue to only expose one rider at a time to avalanche terrain, keep eyes on them, and regroup in safe locations out of the runout of any avalanche path.  

Thank you for your recent observations...you are adding valuable information to our forecasts.  Keep 'em comin'! 

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