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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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Heightened avalanche danger today on north facing terrain steeper than 35 degrees above 7500' in elevation. These are shaded, isolated areas that remain cold throughout the day, this time of year. Before committing to any north facing slope steeper than 35 degrees(above 7500' ) today, take the time to evaluate the snow and terrain very carefully. Generally safe avalanche conditions continue to exist on terrain not mentioned above.

Problemi valanghivi

  • Persistent Slabs

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

    Snowpit data is pointing to a developing persistent slab problem in the Northern Elkhorns on north facing terrain that is typically sheltered from the wind. Snowpit data gathered near the base of Lakes Lookout reveal a potentially dangerous  crust/facet combination in the upper foot of the snowpack. This structurally weak area of the snowpack is sitting on an ideal sliding surface. I conducted two Extended Column Tests and both columns failed on weak sugar snow (facets) that has formed above our January 6 raincrust. The columns failed using a moderate amount of force. Both column failures exhibited full propagation. I would expect to find similar structural conditions in othe isolated areas in the Northern Elkhorns where we have a well defined raincrust from the January 6 rain event. It is recommended that recreationalists carefully assess or avoid narrow  north facing  terrain steeper than 35 degrees that is typically sheltered from sunlight and direct wind.

    Snowpit near base of Lakes Lookout. Column failed (full propagation) 8" down from the snow surface on facets that have developed above the January 6 raincrust.

Avalanche Discussion

Our weather for the past three weeks has set us up with a persistent grain type problem in the upper 12" of the snowpack. We are consistently seeing buried crusts and associated weak layers (persistent grain types ie. facets) in our snowpit data. Snow surface conditions throughout the region are generally firm, crusty, and slick. Many of these snow surfaces are holding surface hoar and near surface facets (persistent grain types) that will make it very difficult for the new snow that is forecasted to arrive to bond to these compromised snow surfaces. Structural weakness in the upper snowpack and at the snow surface, and new snow accompanied by wind in the forecast for tonight into tomorrow, is setting us up for an avalanche cycle moving forward into the new week. Starting tomorrow dangerous avalanche conditions could be on the table if we get the snow and wind that is forecasted. Cautious route finding and conservative decision making will be essential in order to avoid avalanche danger.

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