Lawinenlagebericht

Northern Wallowas

Wallowa Avalanche Center
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Lawinengefahr

Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Kernpunkte

AN AVALANCHE WARNING HAS BEEN ISSUED FOR THE SOUTHERN WALLOWAS FOR THE NEXT 24 HOURS. DANGEROUS AVALANCHE CONDITIONS EXIST. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED.

Potent winter storms have been impacting our forecast area since New Year's Eve and have been bringing significant snowfall and strong SW winds to our local mountains. Since New Years the Southern Wallowas above 7,000' have picked up 3-4' on new snow. A warm front/cold front combo today will bring another 18-24" of new snow with 1.5-2.0" of water to elevations above 7,000'. The weight of all this new snow has stressd the snowpack to its breaking point. Natural avalanches have been reported and human-tirggerd avalanches are very likely. To make matters worse, the weight of a storm slab avalanche triggered by a rider could be enough stress to "step down" and propagate an even larger avalanche from deeper down in the snowpack at one of our persistent weak layers. The result would be a large and catastrophic avalanche. Travel in avalanche terrain is not recommended. Avalanches may run long distances and can run into mature forests, valley floors, or flat terrain.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1–3

    In the Southern Wallowas we can expect 18 - 24" of new snow (1.5-2.0" water) in the next 24 hours above 7,000' elev. and this is on top of the 3-4' the mountains have received since New Years.  The weight of all this new snow has stressed the snowpack to its breaking point. Natural avalanches have been reported by local sledders. One particular slide in the Cornucopia zone broke on a steep road cut. The 2' thick storm slab "stepped down" and triggered an even larger avalanche on a deeply buried weak layer. Natural avalanches are likely and human-triggered avalanches are very likely on slopes greater than 30 degrees.  As the Cornucopia slide demonstrates there is the troubling possibility a skier or rider could trigger a storm slab avalanche and the weight of the slab could "step down" and initiate a failure deeper in the snowpack in a persistent weak layer. The resulting avalanche could be catastrophic. The best way to stay safe in the backcountry the next few days is to avoid avalanche terrain all together. Stay off and out from under slopes greater than 30 degrees. 

  • Deep Persistent Slabs

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

    The fact is our exising snowpack was weak and chock full of persistent weak layers before this latest round of storms. In most locations the bottom two feet of the snowpack is composed of weak faceted grains (sugar snow) and then we have a scary crust/facet combo that is now buried deeper than 3' in many locations" that has been reactive with one snowmobile observer in the Cornucopia zone yesterday reporting an avalanche that had stepped down on this deeply buried weak layer. A storm slab avalanche triggered by a rider that "steps down" and propagates an even larger avalanche from deeper down in the snowpack would produce a large and catastrophic avalanche. Deep slab instabilities are a notorious "sleeping dragon". The persistent weak layer is usually buried more than 3' deep and it is hard for even forecasters to decipher how reactive it will be and when. The best thing to do is to avoid and stay out from underneath slopes greater than 30 degrees. Especially right now when our snowpack is stressed to the max with all this new snow. Don't poke the bear, folks. 

  • Wet Slabs

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

    A warm front impacting our area last night and through this morning has brought warm temperatures and rain to lower elevations. Most Snotel sites in NE Oregon are indicating a rain line hovering between 6,000 - 7,000 feet. Schneider Meadows (5400') at 5am has a temp of 33F. Any time you get rain on snow the snowpack can become unstable quickly. With all this new snow, the additional weight and loss of strength brought by the rain could produce wet slab avalanches 2-4' deep on a variety of aspects at elevations from 5,000 - 7,000'. Travel in avalanche terrain is not recommended. Avoid and stay out from underneath slopes greater than 30 degrees. 

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