Bollettino valanghe

Elkhorns

Wallowa Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The 18" of new snow that fell earlier in the week is not bonding well to the old snow surface. Loose dry avalanches can be triggered on steep solar aspects where slick melt-freeze crusts exist. On northerly aspects instability exists at the old/new interface down 12-18".  Sensitive wind slabs may be triggered on E-S aspects near ridgeline and leeward terrain features.  Carefully evaluate any slopes > 30 degrees for instability and avoid possible trigger points like convex rolls, unsupported slopes, and leeward terrain features near ridgeline.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    There is plenty of new snow, upwards of 18", available for transport by the wind onto leeward terrain features near ridgeline. The cold temps have kept this snow light and uncohesive. Light N to W winds have been able to move this snow onto E through S aspects near ridgeline and leeward terrain features in the alpine. Wind slabs will be especially reactive on solar aspects where the new snow has not bonded to slick melt-freeze crusts. Carefully evaluate any slope > 30 degrees for instability. Pay particular attention for areas where the new snow is sitting on slick crusts and avoid wind-drifted leeward terrain features denoted by smooth pillows below ridgeline and mid-slope.

  • Loose Dry

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

    The 12-18" of new snow is not bonding well to slick crusts on solar aspects where slope angles approach 35 degrees or more.  The problem with loose dry avalanches, or sluffs, is on steep icy slopes the debris can accelerate quickly and carry you into trees, rocks, or over cliffs.  Avoid steep slopes where 6" or more of new snow is sitting on melt-freeze crusts from last week's warm up.

  • Persistent Slabs

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

    The 12-18" of storm snow earlier this week fell on a weak and uncohesive old snow surface. This is a significant amount of weight on a fragile weak layer.  While human-triggered avalanches are unlikely there are certain places in the terrain where a slab avalanche could be triggered. Carefully evaluate slopes > 30 degrees for instability. If you find over a foot of new snow sitting on weak layer of uncohesive snow, then move to lower angle terrain.  Avoid convex rolls, unsupported slopes, and pockets of wind-drifted snow on E-S aspects near and below ridgeline. Be sure to ski or ride on slopes one at a time. 

Avalanche Discussion

The northern Elkhorn Mountains received significant amounts of snow early in the week. Most locations above 6,000' received 12" or more. This new snow is not bonding well to the old variable snow surfaces that range from stout melt-freeze crusts on solar aspects to weak uncohesive snow on more northerly slopes. It is time to be very dilegent in your snowpack assessment. There is alot of variability in snowpack structure and instablity across aspects. Do your homework before dropping in or on any slope greater than 30 degrees. If you are uncertain about the hazard - move to lower angle terrain. Remember...ski and ride one at a time. Avoid trigger points like convex rolls, rocky terrain, and wind-drifted areas below ridgeline. Choose slopes that are concave and don't funnel you into trees or into a terrain trap like a gully. Now is the time to dail it back and be cautious.

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