Bulletin d’avalanche

Southern Wallowas

Wallowa Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

It is likely that you could trigger a fresh windslab along leeward ridgelines and cross loaded mid slope terrain features today.  The 2-3 feet of new snow that has fallen in the last several days is sitting upon a variable thickness rain crust- which may serve as the perfect bed surface for storm slab avalanches.  Stick to slopes with slope angles less than 30 degrees and if witnessing any of the 5 red flags of instability, dial back your terrain choices even further.  

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    There is plenty of new snow available for transport, and with moderate NW winds yesterday and overnight, sensitive windslabs may be easy to trigger today.  Look for clues of windloading such as smooth looking pillows, wind stripped ridgelines, and cross loaded terrain features.  Sensitive fresh cornice development is another clue that there is windloading often just below these cornices.  Avoidance is the best strategy with windslabs.  

    (2/26/2021) W/NW winds have developed an interesting midslope corniced subridge.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    The Northern Wallowas have seen over three feet of snow since Monday 2/22.  This has all fallen on a variable thickness rain crust that formed on 2/22.  Observers on friday noted that by the end of the day, the snow was settling into a bit more of a cohesive slab at mid elevations.  Storm Slabs are most sensitive during and just after storms- so today will be the day to watch out for them!  Utilize quick "mitt pits" to see how well the snow has bonded to the 2/22 rain crust.  Use safe, unconsequential test slopes to see how the new snow will react to the weight of a person and machine.  

    (2/26/2021) 8k' SE

Avalanche Discussion

Yesterday, observers in the Northern Wallowas noticed numerous natural dry loose avalanches.  A mostly right side up upper snowpack was observed in the Northern Wallowas yesterday (see below).  Moderate results were noted in snowpack tests- mostly within density changes within the upper snowpack layers above the 2/22 crust.  It will be important to monitor this interface as we move through the week, as snow will likely continue with it's faceting process around this 2/22 crust.  As the snow settles with time, warmer temperatures, and the exposure to sun- it will develop into a more cohesive slab- Give the snowpack time to adjust to the new load.   When in doubt, recreate in avalanche resistent terrain less than 30 degrees and stay out from underneath avalanche paths.  

Régions couvertes